what’s the internet: “nuts and bolts” view

Transport Layer 3-1

Whatrsquos the Internet ldquonuts and boltsrdquo view

millions of connected computing devices hosts = end systems examples of hosts

running network apps examples of

applications

local ISP

companynetwork

regional ISP

router workstation

servermobile

Transport Layer 3-2


communication links fiber copper radio

satellite transmission rate = bandwidth

bull typical bandwidth for modem wireless

routers forward packets (chunks of data) whatrsquos in a packet

local ISP

companynetwork

regional ISP

router workstation

servermobile

Transport Layer 3-3

Whatrsquos the Internet ldquonuts and boltsrdquo view protocols control sending

receiving of msgs eg TCP IP HTTP FTP PPP

Internet ldquonetwork of networksrdquo loosely hierarchical public Internet versus private

intranet Internet standards

RFC Request for comments IETF Internet Engineering

Task Force

local ISP

companynetwork

regional ISP

router workstation

servermobile

Transport Layer 3-4

Whatrsquos the Internet a service view communication

infrastructure enables distributed applications Web email other

examples communication services

provided to apps connection-oriented reliable

bull example apps Connectionless unreliable

bull example apps

Transport Layer 3-5

Whatrsquos a protocolhuman protocols ldquowhatrsquos the timerdquo ldquoI have a questionrdquo introductions

network protocols machines rather than

humans all communication

activity in Internet governed by protocols

protocols define format order of msgs sent and received among network entities and actions taken on msg

transmission receipt

Transport Layer 3-6

Whatrsquos a protocola human protocol and a computer network protocol

Q Why are protocols so important

Hi

Hi

Got thetime

200

TCP connection req

TCP connectionresponseGet httpwwwawlcomkurose-ross

ltfilegttime

Transport Layer 3-7

A closer look at network structure network edge

applications and hosts network core

routers network of networks

access networks physical media communication links

Transport Layer 3-8

Protocol ldquoLayersrdquoNetworks are complex many ldquopiecesrdquo

hosts routers links of various

media applications protocols hardware software

Question Is there any hope of organizing structure of

network

Or at least our discussion of networks

Transport Layer 3-9

Organization of air travel

a series of steps

ticket (purchase)

baggage (check)

gates (load)

runway takeoff

airplane routing

ticket (complain)

baggage (claim)

gates (unload)

runway landing

airplane routing

airplane routing

Transport Layer 3-10

ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

departureairport

arrivalairport

intermediate air-trafficcontrol centers

airplane routing airplane routing

ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeofflanding

airplane routing

Layering of airline functionality

Layers each layer implements a service via its own internal-layer actions relying on services provided by layer below


Why layeringDealing with complex systems explicit structure allows identification relationship of

complex systemrsquos pieces layered reference model for discussion

modularization eases maintenance updating of system change of implementation of layerrsquos service

transparent to rest of system eg change in gate procedure doesnrsquot affect rest of

system layering considered harmful


Internet protocol stack application supporting network applications

FTP SMTP STTP transport host-host data transfer

TCP UDP network routing of datagrams from source

to destination IP routing protocols

link data transfer between neighboring network elements

PPP Ethernet physical bits ldquoon the wirerdquo

application

transport

network

link

physical


messagesegment

datagram

frame

sourceapplicationtransportnetwork

linkphysical

HtHnHl M

HtHn M

Ht M

M

destination

applicationtransportnetwork

linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation


Internet transport protocols services

TCP service connection-oriented setup

required between client and server processes

reliable transport between sending and receiving process

flow control sender wonrsquot overwhelm receiver

congestion control throttle sender when network overloaded

does not provide timing minimum bandwidth guarantees

UDP service unreliable data transfer

between sending and receiving process

does not provide connection setup reliability flow control congestion control timing or bandwidth guarantee

Q why bother Why is there a UDP


Transport vs network layer

network layer logical communication between hosts

transport layer logical communication between processes relies on enhances

network layer services

Household analogy12 kids sending letters to 12

kids processes = kids app messages = letters in

envelopes hosts = houses transport protocol = Ann

and Bill network-layer protocol =

postal service


Reliable data transfer getting startedWersquoll incrementally develop sender receiver

sides of reliable data transfer protocol (rdt) consider only unidirectional data transfer

but control info will flow on both directions

use finite state machines (FSM) to specify sender receiver

state1

state2

event causing state transitionactions taken on state transition

state when in this ldquostaterdquo next state

uniquely determined by next event

eventactions


Rdt10 reliable transfer over a reliable channel

underlying channel perfectly reliable no bit errors no loss of packets

separate FSMs for sender receiver sender sends data into underlying channel receiver read data from underlying channel

Wait for call from above packet = make_pkt(data)

udt_send(packet)

rdt_send(data)

extract (packetdata)deliver_data(data)

Wait for call from

below

rdt_rcv(packet)

sender receiver


Rdt20 channel with bit errors

underlying channel may flip bits in packet checksum to detect bit errors

the question how to recover from errors acknowledgements (ACKs) receiver explicitly tells

sender that pkt received OK negative acknowledgements (NAKs) receiver

explicitly tells sender that pkt had errors sender retransmits pkt on receipt of NAK

new mechanisms in rdt20 (beyond rdt10) error detection receiver feedback control msgs (ACKNAK) rcvr-

gtsender


rdt20 FSM specification

Wait for call from above

snkpkt = make_pkt(data checksum)udt_send(sndpkt)

extract(rcvpktdata)deliver_data(data)udt_send(ACK)

rdt_rcv(rcvpkt) ampamp notcorrupt(rcvpkt)

rdt_rcv(rcvpkt) ampamp isACK(rcvpkt)

udt_send(sndpkt)

rdt_rcv(rcvpkt) ampamp isNAK(rcvpkt)

udt_send(NAK)

rdt_rcv(rcvpkt) ampamp corrupt(rcvpkt)

Wait for ACK or

NAK

Wait for call from

belowsender

receiverrdt_send(data)


rdt20 operation with no errors






udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)


rdt20 error scenario






udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)


rdt20 has a fatal flaw

Stop and Wait Sender sends one packet then waits for receiver response

What happens if ACKNAK corrupted sender doesnrsquot know what happened at receiver canrsquot just retransmit possible duplicate

Handling duplicates sender adds sequence number to each pkt sender retransmits current pkt if ACKNAK garbled receiver discards (doesnrsquot deliver up) duplicate pkt


rdt21 sender handles garbled ACKNAKs

Wait for call 0 from

above

sndpkt = make_pkt(0 data checksum)udt_send(sndpkt)

rdt_send(data)

Wait for ACK or NAK 0 udt_send(sndpkt)

rdt_rcv(rcvpkt) ampamp ( corrupt(rcvpkt) ||isNAK(rcvpkt) )


rdt_send(data)

rdt_rcv(rcvpkt) ampamp notcorrupt(rcvpkt) ampamp isACK(rcvpkt)

udt_send(sndpkt)




above

Wait for ACK or NAK 1


rdt21 receiver handles garbled ACKNAKs

Wait for 0 from below

sndpkt = make_pkt(NAK chksum)udt_send(sndpkt)

rdt_rcv(rcvpkt) ampamp not corrupt(rcvpkt) ampamp has_seq0(rcvpkt)

rdt_rcv(rcvpkt) ampamp notcorrupt(rcvpkt) ampamp has_seq1(rcvpkt)

extract(rcvpktdata)deliver_data(data)sndpkt = make_pkt(ACK chksum)udt_send(sndpkt)




rdt_rcv(rcvpkt) ampamp (corrupt(rcvpkt)

sndpkt = make_pkt(ACK chksum)udt_send(sndpkt)






rdt21 discussion

Sender seq added to pkt two seq rsquos (01)

will suffice Why must check if

received ACKNAK corrupted

twice as many states state must

ldquorememberrdquo whether ldquocurrentrdquo pkt has 0 or 1 seq

Receiver must check if

received packet is duplicate state indicates

whether 0 or 1 is expected pkt seq

note receiver can not know if its last ACKNAK received OK at sender


rdt22 a NAK-free protocol

same functionality as rdt21 using ACKs only instead of NAK receiver sends ACK for last pkt

received OK receiver must explicitly include seq of pkt being

ACKed

duplicate ACK at sender results in same action as NAK retransmit current pkt


rdt22 sender receiver fragments


above


rdt_send(data)

udt_send(sndpkt)

rdt_rcv(rcvpkt) ampamp ( corrupt(rcvpkt) || isACK(rcvpkt1) )

rdt_rcv(rcvpkt) ampamp notcorrupt(rcvpkt) ampamp isACK(rcvpkt0)

Wait for ACK

0

sender FSMfragment



extract(rcvpktdata)deliver_data(data)sndpkt = make_pkt(ACK1 chksum)udt_send(sndpkt)

rdt_rcv(rcvpkt) ampamp (corrupt(rcvpkt) || has_seq1(rcvpkt))

udt_send(sndpkt)

receiver FSMfragment


rdt30 channels with errors and loss

New assumption underlying channel can also lose packets (data or ACKs) checksum seq

ACKs retransmissions will be of help but not enough

Approach sender waits ldquoreasonablerdquo amount of time for ACK

retransmits if no ACK received in this time

if pkt (or ACK) just delayed (not lost) retransmission will be

duplicate but use of seq rsquos already handles this

receiver must specify seq of pkt being ACKed

requires countdown timer


rdt30 sender

sndpkt = make_pkt(0 data checksum)udt_send(sndpkt)start_timer

rdt_send(data)

Wait for

ACK0

rdt_rcv(rcvpkt) ampamp ( corrupt(rcvpkt) ||isACK(rcvpkt1) )


above


rdt_send(data)




stop_timerstop_timer

udt_send(sndpkt)start_timer

timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action


Performance of rdt30

rdt30 works but performance stinks Why


rdt30 stop-and-wait operation

first packet bit transmitted t = 0

sender receiver

RTT

last packet bit transmitted t = L R

first packet bit arriveslast packet bit arrives send ACK

ACK arrives send next packet t = RTT + L R


Pipelined protocolsPipelining sender allows multiple ldquoin-flightrdquo yet-to-be-

acknowledged pkts range of sequence numbers must be increased buffering at sender andor receiver

Two generic forms of pipelined protocols go-Back-N selective repeat


Pipelining increased utilization


sender receiver

RTT

last bit transmitted t = L R



last bit of 2nd packet arrives send ACKlast bit of 3rd packet arrives send ACK


Go-Back-NSender k-bit seq in pkt header ldquowindowrdquo of up to N consecutive unackrsquoed pkts allowed

ACK(n) ACKs all pkts up to including seq n - ldquocumulative ACKrdquo may deceive duplicate ACKs (see receiver)

timer for each in-flight pkt timeout(n) retransmit pkt n and all higher seq pkts in window


GBN receiver

ACK-only always send ACK for correctly-received pkt with highest in-order seq may generate duplicate ACKs need only remember expectedseqnum

out-of-order pkt discard (donrsquot buffer) -gt isnt this bad Re-ACK pkt with highest in-order seq


GBN inaction


Selective Repeat

receiver individually acknowledges all correctly received pkts buffers pkts as needed for eventual in-order

delivery to upper layer

sender only resends pkts for which ACK not received sender timer for each unACKed pkt

sender window N consecutive seq rsquos again limits seq s of sent unACKed pkts


Selective repeat sender receiver windows


Selective repeat

data from above if next available seq in

window send pkt

timeout(n) resend pkt n restart

timerACK(n) in

[sendbasesendbase+N] mark pkt n as received if n smallest unACKed

pkt advance window base to next unACKed seq

senderpkt n in [rcvbase rcvbase+N-1]

send ACK(n) out-of-order buffer in-order deliver (also

deliver buffered in-order pkts) advance window to next not-yet-received pkt

pkt n in [rcvbase-Nrcvbase-1]

ACK(n)

otherwise ignore

receiver


Selective repeat in action


Selective repeat dilemmaExample seq rsquos 0 1 2 3 window size=3

receiver sees no difference in two scenarios

incorrectly passes duplicate data as new in (a)

Q what relationship between seq size and window size


TCP Overview RFCs 793 1122 1323 2018 2581

full duplex data bi-directional data flow in

same connection MSS maximum segment

size connection-oriented

handshaking (exchange of control msgs) initrsquos sender receiver state before data exchange

flow controlled sender will not

overwhelm receiver

point-to-point one sender one receiver

reliable in-order byte steam no ldquomessage boundariesrdquo

pipelined TCP congestion and flow

control set window size send amp receive buffers

socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment

applicationwrites data

applicationreads data


TCP segment structure

source port dest port

32 bits

applicationdata

(variable length)

sequence number

acknowledgement numberReceive window

Urg data pnterchecksum

FSRPAUheadlen

notused

Options (variable length)

URG urgent data (generally not used)

ACK ACK valid

PSH push data now(generally not used)

RST SYN FINconnection estab(setup teardown

commands)

bytes rcvr willingto accept

countingby bytes of data(not segments)

Internetchecksum

(as in UDP)


TCP seq rsquos and ACKsSeq rsquos

byte stream ldquonumberrdquo of first byte in segmentrsquos data

ACKs seq of next byte

expected from other side

cumulative ACK piggybacking

Q how receiver handles out-of-order segments

A TCP spec doesnrsquot say - up to implementor

Host A Host B

Seq=42 ACK=79 data = lsquoCrsquo


Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt

of echoedlsquoCrsquo

host ACKsreceipt of

lsquoCrsquo echoesback lsquoCrsquo

timesimple telnet scenario


TCP Round Trip Time and TimeoutQ how to set TCP

timeout value longer than RTT

but RTT varies too short premature

timeout unnecessary

retransmissions too long slow

reaction to segment loss

Q how to estimate RTT SampleRTT measured time

from segment transmission until ACK receipt ignore retransmissions

SampleRTT will vary want estimated RTT ldquosmootherrdquo average several recent

measurements not just current SampleRTT


Example RTT estimationRTT gaiacsumassedu to fantasiaeurecomfr

100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)

SampleRTT Estimated RTT


TCP reliable data transfer

TCP creates rdt service on top of IPrsquos unreliable service

Pipelined segments Cumulative acks TCP uses single

retransmission timer

Retransmissions are triggered by timeout events duplicate acks

Initially consider simplified TCP sender ignore duplicate acks ignore flow control

congestion control


TCP sender eventsdata rcvd from app Create segment with

seq seq is byte-stream

number of first data byte in segment

start timer if not already running (think of timer as for oldest unacked segment)

expiration interval TimeOutInterval

timeout retransmit segment

that caused timeout restart timer Ack rcvd If acknowledges

previously unacked segments update what is known

to be acked start timer if there are

outstanding segments


TCP sender(simplified)

NextSeqNum = InitialSeqNum SendBase = InitialSeqNum

loop (forever) switch(event)

event data received from application above create TCP segment with sequence number NextSeqNum if (timer currently not running) start timer pass segment to IP NextSeqNum = NextSeqNum + length(data)

event timer timeout retransmit not-yet-acknowledged segment with smallest sequence number start timer

event ACK received with ACK field value of y if (y gt SendBase) SendBase = y if (there are currently not-yet-acknowledged segments) start timer

end of loop forever

Commentbull SendBase-1 last cumulatively ackrsquoed byteExamplebull SendBase-1 = 71y= 73 so the rcvrwants 73+ y gt SendBase sothat new data is acked


TCP retransmission scenarios

Host A

Seq=100 20 bytes data

ACK=100

timepremature timeout

Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100


TCP retransmission scenarios (more)

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

Cumulative ACK scenario

Host B

X


ACK=120

time

SendBase= 120


TCP ACK generation [RFC 1122 RFC 2581]

Event at Receiver

Arrival of in-order segment withexpected seq All data up toexpected seq already ACKed

Arrival of in-order segment withexpected seq One other segment has ACK pending

Arrival of out-of-order segmenthigher-than-expect seq Gap detected

Arrival of segment that partially or completely fills gap

TCP Receiver action

Delayed ACK Wait up to 500msfor next segment If no next segmentsend ACK

Immediately send single cumulative ACK ACKing both in-order segments

Immediately send duplicate ACK indicating seq of next expected byte

Immediate send ACK provided thatsegment startsat lower end of gap


Fast Retransmit

Time-out period often relatively long long delay before

resending lost packet Detect lost segments

via duplicate ACKs Sender often sends

many segments back-to-back

If segment is lost there will likely be many duplicate ACKs

If sender receives 3 ACKs for the same data it supposes that segment after ACKed data was lost fast retransmit resend

segment before timer expires


TCP Flow Control

receive side of TCP connection has a receive buffer

speed-matching service matching the send rate to the receiving apprsquos drain rate app process may be

slow at reading from buffer

sender wonrsquot overflowreceiverrsquos buffer by

transmitting too much too fast

flow control


TCP Flow control how it works

(Suppose TCP receiver discards out-of-order segments)

spare room in buffer= RcvWindow

= RcvBuffer-[LastByteRcvd - LastByteRead]

Rcvr advertises spare room by including value of RcvWindow in segments

Sender limits unACKed data to RcvWindow guarantees receive

buffer doesnrsquot overflow


TCP Connection Management

Recall TCP sender receiver establish ldquoconnectionrdquo before exchanging data segments

initialize TCP variables seq s buffers flow control info (eg RcvWindow)

client connection initiator Socket clientSocket = new Socket(hostnameport

number) server contacted by client Socket connectionSocket = welcomeSocketaccept()



Three way handshake

Step 1 client host sends TCP SYN segment to server specifies initial seq no data

Step 2 server host receives SYN replies with SYNACK segment server allocates buffers specifies server initial seq

Step 3 client receives SYNACK replies with ACK segment which may contain data


TCP Connection Management (cont)

Closing a connection

client closes socket clientSocketclose()

Step 1 client end system sends TCP FIN control segment to server

Step 2 server receives FIN replies with ACK Closes connection sends FIN

client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait



Step 3 client receives FIN replies with ACK

Enters ldquotimed waitrdquo - will respond with ACK to received FINs

Step 4 server receives ACK Connection closed

Note with small modification can handle simultaneous FINs

client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed


TCP Congestion Control

end-end control (no network assistance)

sender limits transmission LastByteSent-LastByteAcked CongWin Roughly

CongWin is dynamic function of perceived network congestion

How does sender perceive congestion

loss event = timeout or 3 duplicate acks

TCP sender reduces rate (CongWin) after loss event

three mechanisms AIMD slow start conservative after

timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow

multiplicative decrease cut CongWin in half after loss event

additive increase increase CongWin by 1 MSS every RTT in the absence of loss events probing

Long-lived TCP connection


TCP Slow Start

When connection begins CongWin = 1 MSS Example MSS = 500

bytes amp RTT = 200 msec

initial rate = 20 kbps

available bandwidth may be gtgt MSSRTT desirable to quickly

ramp up to respectable rate

When connection begins increase rate exponentially fast until first loss event


TCP Slow Start (more)

When connection begins increase rate exponentially until first loss event double CongWin every

RTT done by incrementing CongWin for every ACK received

Summary initial rate is slow but ramps up exponentially fast

Host A

one segment

RTT

Host B

time

two segments

four segments


Refinement After 3 dup ACKs

CongWin is cut in half window then grows linearly

But after timeout event CongWin instead set to 1 MSS window then grows

exponentially to a threshold then grows

linearly

bull 3 dup ACKs indicates network capable of delivering some segmentsbull timeout before 3 dup ACKs is ldquomore alarmingrdquo

Philosophy


Refinement (more)Q When should the

exponential increase switch to linear

A When CongWin gets to 12 of its value before timeout

Implementation Variable Threshold At loss event Threshold is

set to 12 of CongWin just before loss event


Summary TCP Congestion Control

When CongWin is below Threshold sender in slow-start phase window grows exponentially

When CongWin is above Threshold sender is in congestion-avoidance phase window grows linearly

When a triple duplicate ACK occurs Threshold set to CongWin2 and CongWin set to Threshold

When timeout occurs Threshold set to CongWin2 and CongWin is set to 1 MSS


TCP sender congestion control

Event State TCP Sender Action Commentary

ACK receipt for previously unacked data

Slow Start (SS)

CongWin = CongWin + MSS If (CongWin gt Threshold) set state to ldquoCongestion Avoidancerdquo

Resulting in a doubling of CongWin every RTT


CongestionAvoidance (CA)

CongWin = CongWin+MSS (MSSCongWin)

Additive increase resulting in increase of CongWin by 1 MSS every RTT

Loss event detected by triple duplicate ACK

SS or CA Threshold = CongWin2 CongWin = ThresholdSet state to ldquoCongestion Avoidancerdquo

Fast recovery implementing multiplicative decrease CongWin will not drop below 1 MSS

Timeout SS or CA Threshold = CongWin2 CongWin = 1 MSSSet state to ldquoSlow Startrdquo

Enter slow start

Duplicate ACK

SS or CA Increment duplicate ACK count for segment being acked

CongWin and Threshold not changed


1

23

0111

value in arrivingpacketrsquos header

routing algorithm

local forwarding tableheader value output link

0100010101111001

3221

Interplay between routing and forwarding


u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)

N = set of routers = u v w x y z

E = set of links = (uv) (ux) (vx) (vw) (xw) (xy) (wy) (wz) (yz)

Graph abstraction

Remark Graph abstraction is useful in other network contexts

Example P2P where N is set of peers and E is set of TCP connections


Graph abstraction costs

u

yx

wv

z2

2

13

1

1

2

53

5 bull c(xxrsquo) = cost of link (xxrsquo)

- eg c(wz) = 5

bull cost could always be 1 or inversely related to bandwidthor inversely related to congestion

Cost of path (x1 x2 x3hellip xp) = c(x1x2) + c(x2x3) + hellip + c(xp-1xp)

Question Whatrsquos the least-cost path between u and z

Routing algorithm algorithm that finds least-cost path


Routing Algorithm classificationGlobal or decentralized

informationGlobal all routers have complete

topology link cost info ldquolink staterdquo algorithmsDecentralized router knows physically-

connected neighbors link costs to neighbors

iterative process of computation exchange of info with neighbors

ldquodistance vectorrdquo algorithms

Static or dynamicStatic routes change slowly

over timeDynamic routes change more

quickly periodic update in response to link

cost changes


A Link-State Routing Algorithm

Dijkstrarsquos algorithm net topology link costs

known to all nodes accomplished via ldquolink

state broadcastrdquo all nodes have same info

computes least cost paths from one node (lsquosourcerdquo) to all other nodes gives forwarding table

for that node iterative after k iterations

know least cost path to k destrsquos

Notation c(xy) link cost from node x

to y = infin if not direct neighbors

D(v) current value of cost of path from source to dest v

p(v) predecessor node along path from source to v

N set of nodes whose least cost path definitively known


Dijsktrarsquos Algorithm

1 Initialization 2 N = u 3 for all nodes v 4 if v adjacent to u 5 then D(v) = c(uv) 6 else D(v) = infin 7 8 Loop 9 find w not in N such that D(w) is a minimum 10 add w to N 11 update D(v) for all v adjacent to w and not in N 12 D(v) = min( D(v) D(w) + c(wv) ) 13 new cost to v is either old cost to v or known 14 shortest path cost to w plus cost from w to v 15 until all nodes in N


Dijkstrarsquos algorithm example

Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5


Dijkstrarsquos algorithm discussion

Algorithm complexity n nodes each iteration need to check all nodes w not in N n(n+1)2 comparisons O(n2) more efficient implementations possible O(nlogn)

Oscillations possible eg link cost = amount of carried traffic

A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1

initiallyhellip recompute

routinghellip recompute hellip recompute


Distance Vector Algorithm (1)

Bellman-Ford Equation (dynamic programming)

Definedx(y) = cost of least-cost path from x to y

Thendx(y) = min c(xv) + dv(y)

where min is taken over all neighbors of x


Bellman-Ford example (2)

u

yx

wv

z2

2

13

1

1

2

53

5Clearly dv(z) = 5 dx(z) = 3 dw(z) = 3

du(z) = min c(uv) + dv(z) c(ux) + dx(z) c(uw) + dw(z) = min 2 + 5 1 + 3 5 + 3 = 4

Node that achieves minimum is nexthop in shortest path forwarding table

B-F equation says



Dx(y) = estimate of least cost from x to y

Distance vector Dx = [Dx(y) y є N ] Node x knows cost to each neighbor v c(xv) Node x maintains Dx = [Dx(y) y є N ] Node x also maintains its neighborsrsquo distance

vectors For each neighbor v x maintains

Dv = [Dv(y) y є N ]


Distance vector algorithm (4)

Basic idea Each node periodically sends its own distance

vector estimate to neighbors When node a node x receives new DV estimate

from neighbor it updates its own DV using B-F equation

Dx(y) larr minvc(xv) + Dv(y) for each node y ∊ N

Under minor natural conditions the estimate Dx(y) converge the actual least cost dx(y)



Iterative asynchronous each local iteration caused by

local link cost change DV update message from

neighbor

Distributed each node notifies

neighbors only when its DV changes

neighbors then notify their neighbors if necessary

wait for (change in local link cost of msg from neighbor)

recompute estimates

if DV to any dest has

changed notify neighbors

Each node


x y z

xyz

0 2 7

infin infin infininfin infin infin

from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

infininfin infin7 1 0

cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table

Dx(y) = minc(xy) + Dy(y) c(xz) + Dz(y) = min2+0 7+1 = 2

Dx(z) = minc(xy) + Dy(z) c(xz) + Dz(z) = min2+1 7+0 = 3


Distance Vector link cost changes

Link cost changes node detects local link cost

change updates routing info recalculates

distance vector if DV changes notify neighbors

ldquogoodnews travelsfastrdquo

x z14

50

y1

At time t0 y detects the link-cost change updates its DV and informs its neighbors

At time t1 z receives the update from y and updates its table It computes a new least cost to x and sends its neighbors its DV

At time t2 y receives zrsquos update and updates its distance table yrsquos least costs do not change and hence y does not send any message to z


Distance Vector link cost changesLink cost changes good news travels fast bad news travels slow - ldquocount to infinityrdquo problem 44 iterations before algorithm stabilizes see text

Poissoned reverse If Z routes through Y to get to X

Z tells Y its (Zrsquos) distance to X is infinite (so Y wonrsquot route to X via Z)

will this completely solve count to infinity problem

x z14

50

y60


Comparison of LS and DV algorithms

Message complexity LS with n nodes E links

O(nE) msgs sent DV exchange between

neighbors only convergence time varies

Speed of Convergence LS O(n2) algorithm requires

O(nE) msgs may have oscillations

DV convergence time varies may be routing loops count-to-infinity problem

Robustness what happens if router malfunctions

LS node can advertise incorrect

link cost each node computes only its

own table

DV DV node can advertise

incorrect path cost each nodersquos table used by

others bull error propagate thru network


Multiple Access Links and Protocols

Two types of ldquolinksrdquo point-to-point

PPP for dial-up access point-to-point link between Ethernet switch and host

broadcast (shared wire or medium) traditional Ethernet upstream HFC 80211 wireless LAN


Multiple Access protocols single shared broadcast channel two or more simultaneous transmissions by nodes

interference collision if node receives two or more signals at the same time

multiple access protocol distributed algorithm that determines how nodes share

channel ie determine when node can transmit communication about channel sharing must use channel

itself no out-of-band channel for coordination


Ideal Mulitple Access Protocol

Broadcast channel of rate R bps1 When one node wants to transmit it can send

at rate R2 When M nodes want to transmit each can

send at average rate RM3 Fully decentralized

no special node to coordinate transmissions no synchronization of clocks slots

4 Simple


MAC Protocols a taxonomy

Three broad classes Channel Partitioning

divide channel into smaller ldquopiecesrdquo (time slots frequency code)

allocate piece to node for exclusive use

Random Access channel not divided allow collisions ldquorecoverrdquo from collisions

ldquoTaking turnsrdquo Nodes take turns but nodes with more to send can

take longer turns


Channel Partitioning MAC protocols TDMA

TDMA time division multiple access access to channel in rounds each station gets fixed length slot (length = pkt trans time) in each round unused slots go idle example 6-station LAN 134 have pkt slots 256 idle

TDM (Time Division Multiplexing) channel divided into N time slots one per user inefficient with low duty cycle users and at light load

FDM (Frequency Division Multiplexing) frequency subdivided


Channel Partitioning MAC protocols FDMA

FDMA frequency division multiple access channel spectrum divided into frequency bands each station assigned fixed frequency band unused transmission time in frequency bands go idle example 6-station LAN 134 have pkt frequency bands 256 idle



frequ

ency

bands time


Random Access Protocols

When node has packet to send transmit at full channel data rate R no a priori coordination among nodes

two or more transmitting nodes ldquocollisionrdquo random access MAC protocol specifies

how to detect collisions how to recover from collisions (eg via delayed

retransmissions) Examples of random access MAC protocols

slotted ALOHA ALOHA CSMA CSMACD CSMACA


Slotted ALOHA

Assumptions all frames same size time is divided into equal

size slots time to transmit 1 frame

nodes start to transmit frames only at beginning of slots

nodes are synchronized if 2 or more nodes

transmit in slot all nodes detect collision

Operation when node obtains fresh

frame it transmits in next slot

no collision node can send new frame in next slot

if collision node retransmits frame in each subsequent slot with prob p until success


Slotted ALOHA

Pros single active node can

continuously transmit at full rate of channel

highly decentralized only slots in nodes need to be in sync

simple

Cons collisions wasting slots idle slots nodes may be able to

detect collision in less than time to transmit packet

clock synchronization


Slotted Aloha efficiency

Suppose N nodes with many frames to send each transmits in slot with probability p

prob that node 1 has success in a slot = p(1-p)N-1

prob that any node has a success = Np(1-p)N-1

For max efficiency with N nodes find p that maximizes Np(1-p)N-1

For many nodes take limit of Np(1-p)N-1 as N goes to infinity gives 1e = 37

Efficiency is the long-run fraction of successful slots when there are many nodes each with many frames to send

At best channelused for useful transmissions 37of time


Pure (unslotted) ALOHA unslotted Aloha simpler no synchronization when frame first arrives

transmit immediately

collision probability increases frame sent at t0 collides with other frames sent in [t0-

1t0+1]


CSMA (Carrier Sense Multiple Access)

CSMA listen before transmitIf channel sensed idle transmit entire frame If channel sensed busy defer transmission

Human analogy donrsquot interrupt others


CSMA collisions

collisions can still occurpropagation delay means two nodes may not heareach otherrsquos transmissioncollisionentire packet transmission time wasted

spatial layout of nodes

noterole of distance amp propagation delay in determining collision probability


CSMACD (Collision Detection)CSMACD carrier sensing deferral as in CSMA

collisions detected within short time colliding transmissions aborted reducing channel

wastage collision detection

easy in wired LANs measure signal strengths compare transmitted received signals

difficult in wireless LANs receiver shut off while transmitting

human analogy the polite conversationalist


CSMACD collision detection


ldquoTaking Turnsrdquo MAC protocolschannel partitioning MAC protocols

share channel efficiently and fairly at high load inefficient at low load delay in channel access 1N

bandwidth allocated even if only 1 active node Random access MAC protocols

efficient at low load single node can fully utilize channel

high load collision overheadldquotaking turnsrdquo protocols

look for best of both worlds


ldquoTaking Turnsrdquo MAC protocolsPolling master node

ldquoinvitesrdquo slave nodes to transmit in turn

concerns polling overhead latency single point of

failure (master)

Token passing control token passed from one

node to next sequentially token message concerns

token overhead latency single point of failure (token)


Ethernet uses CSMACD

No slots adapter doesnrsquot

transmit if it senses that some other adapter is transmitting that is carrier sense

transmitting adapter aborts when it senses that another adapter is transmitting that is collision detection

Before attempting a retransmission adapter waits a random time that is random access


Ethernet CSMACD algorithm

1 Adaptor receives datagram from net layer amp creates frame

2 If adapter senses channel idle it starts to transmit frame If it senses channel busy waits until channel idle and then transmits

3 If adapter transmits entire frame without detecting another transmission the adapter is done with frame

4 If adapter detects another transmission while transmitting aborts and sends jam signal

5 After aborting adapter enters exponential backoff after the mth collision adapter chooses a K at random from 012hellip2m-1 Adapter waits K512 bit times and returns to Step 2


Ethernetrsquos CSMACD (more)Jam Signal make sure all other

transmitters are aware of collision 48 bits

Bit time 1 microsec for 10 Mbps Ethernet for K=1023 wait time is about 50 msec

Exponential Backoff Goal adapt retransmission

attempts to estimated current load

heavy load random wait will be longer

first collision choose K from 01 delay is K 512 bit transmission times

after second collision choose K from 0123hellip

after ten collisions choose K from 01234hellip1023

Seeinteract with Javaapplet on AWL Web sitehighly recommended


Slide 2

Slide 3

Whatrsquos the Internet a service view

Whatrsquos a protocol

Slide 6

A closer look at network structure

Protocol ldquoLayersrdquo



Why layering

Internet protocol stack

Encapsulation



Reliable data transfer getting started









rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat


Selective repeat dilemma



TCP seq rsquos and ACKs

TCP Round Trip Time and Timeout

Example RTT estimation


TCP sender events

TCP sender (simplified)




Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction


Routing Algorithm classification










PowerPoint Presentation


Slide 85



Multiple Access protocols






Slotted ALOHA

Slide 95


Pure (unslotted) ALOHA


CSMA collisions

CSMACD (Collision Detection)


ldquoTaking Turnsrdquo MAC protocols

Slide 103



Ethernetrsquos CSMACD (more)

Transport Layer 3-2


communication links fiber copper radio

satellite transmission rate = bandwidth

bull typical bandwidth for modem wireless

routers forward packets (chunks of data) whatrsquos in a packet

local ISP

companynetwork

regional ISP

router workstation

servermobile

Transport Layer 3-3






Task Force

local ISP

companynetwork

regional ISP

router workstation

servermobile

Transport Layer 3-4






bull example apps

Transport Layer 3-5







Transport Layer 3-6



Hi

Hi

Got thetime

200

TCP connection req


ltfilegttime

Transport Layer 3-7





Transport Layer 3-8





network


Transport Layer 3-9


a series of steps

ticket (purchase)

baggage (check)

gates (load)

runway takeoff

airplane routing

ticket (complain)

baggage (claim)

gates (unload)

runway landing

airplane routing

airplane routing


ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

departureairport

arrivalairport



ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeofflanding

airplane routing
















application

transport

network

link

physical


messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103




Transport Layer 3-3






Task Force

local ISP

companynetwork

regional ISP

router workstation

servermobile

Transport Layer 3-4






bull example apps

Transport Layer 3-5







Transport Layer 3-6



Hi

Hi

Got thetime

200

TCP connection req


ltfilegttime

Transport Layer 3-7





Transport Layer 3-8





network


Transport Layer 3-9


a series of steps

ticket (purchase)

baggage (check)

gates (load)

runway takeoff

airplane routing

ticket (complain)

baggage (claim)

gates (unload)

runway landing

airplane routing

airplane routing


ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

departureairport

arrivalairport



ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeofflanding

airplane routing
















application

transport

network

link

physical


messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103




Transport Layer 3-4






bull example apps

Transport Layer 3-5







Transport Layer 3-6



Hi

Hi

Got thetime

200

TCP connection req


ltfilegttime

Transport Layer 3-7





Transport Layer 3-8





network


Transport Layer 3-9


a series of steps

ticket (purchase)

baggage (check)

gates (load)

runway takeoff

airplane routing

ticket (complain)

baggage (claim)

gates (unload)

runway landing

airplane routing

airplane routing


ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

departureairport

arrivalairport



ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeofflanding

airplane routing
















application

transport

network

link

physical


messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103




Transport Layer 3-5







Transport Layer 3-6



Hi

Hi

Got thetime

200

TCP connection req


ltfilegttime

Transport Layer 3-7





Transport Layer 3-8





network


Transport Layer 3-9


a series of steps

ticket (purchase)

baggage (check)

gates (load)

runway takeoff

airplane routing

ticket (complain)

baggage (claim)

gates (unload)

runway landing

airplane routing

airplane routing


ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

departureairport

arrivalairport



ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeofflanding

airplane routing
















application

transport

network

link

physical


messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103




Transport Layer 3-6



Hi

Hi

Got thetime

200

TCP connection req


ltfilegttime

Transport Layer 3-7





Transport Layer 3-8





network


Transport Layer 3-9


a series of steps

ticket (purchase)

baggage (check)

gates (load)

runway takeoff

airplane routing

ticket (complain)

baggage (claim)

gates (unload)

runway landing

airplane routing

airplane routing


ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

departureairport

arrivalairport



ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeofflanding

airplane routing
















application

transport

network

link

physical


messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103




Transport Layer 3-7





Transport Layer 3-8





network


Transport Layer 3-9


a series of steps

ticket (purchase)

baggage (check)

gates (load)

runway takeoff

airplane routing

ticket (complain)

baggage (claim)

gates (unload)

runway landing

airplane routing

airplane routing


ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

departureairport

arrivalairport



ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeofflanding

airplane routing
















application

transport

network

link

physical


messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103




Transport Layer 3-8





network


Transport Layer 3-9


a series of steps

ticket (purchase)

baggage (check)

gates (load)

runway takeoff

airplane routing

ticket (complain)

baggage (claim)

gates (unload)

runway landing

airplane routing

airplane routing


ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

departureairport

arrivalairport



ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeofflanding

airplane routing
















application

transport

network

link

physical


messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103




Transport Layer 3-9


a series of steps

ticket (purchase)

baggage (check)

gates (load)

runway takeoff

airplane routing

ticket (complain)

baggage (claim)

gates (unload)

runway landing

airplane routing

airplane routing


ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

departureairport

arrivalairport



ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeofflanding

airplane routing
















application

transport

network

link

physical


messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

departureairport

arrivalairport



ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeofflanding

airplane routing
















application

transport

network

link

physical


messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103

















application

transport

network

link

physical


messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





messagesegment

datagram

frame


linkphysical

HtHnHl M

HtHn M

Ht M

M

destination


linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHnHl M

HtHn M

HtHnHl M HtHnHl M

router

switch

Encapsulation






















postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103

























postal service






state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103









state1

state2




eventactions






udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103









udt_send(packet)

rdt_send(data)


Wait for call from

below

rdt_rcv(packet)

sender receiver








gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103











gtsender








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103











udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

belowsender









udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103











udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)








udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103











udt_send(sndpkt)


udt_send(NAK)


Wait for ACK or

NAK

Wait for call from

below

rdt_send(data)









above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103












above


rdt_send(data)




rdt_send(data)


udt_send(sndpkt)




above



















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





















rdt21 discussion














ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103








ACKed





above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103







above


rdt_send(data)

udt_send(sndpkt)



Wait for ACK

0

sender FSMfragment





udt_send(sndpkt)













rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103















rdt30 sender


rdt_send(data)

Wait for

ACK0



above


rdt_send(data)






timeout


timeout

rdt_rcv(rcvpkt)

Wait for call 0from

above

Wait for

ACK1

rdt_rcv(rcvpkt)


rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





rdt30 in action


rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





rdt30 in action







sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103










sender receiver

RTT











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103











sender receiver

RTT










GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103









GBN receiver




GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





GBN inaction


Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





Selective Repeat








Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103







Selective repeat


window send pkt


timerACK(n) in







ACK(n)

otherwise ignore

receiver















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103


















overwhelm receiver





socketdoor

TCPsend buffer

TCPreceive buffer

socketdoor

segment






32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103







32 bits

applicationdata

(variable length)

sequence number



FSRPAUheadlen

notused



ACK ACK valid



commands)



Internetchecksum

(as in UDP)









Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103












Host A Host B



Seq=43 ACK=80

Usertypes

lsquoCrsquo

host ACKsreceipt


host ACKsreceipt of







timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103








timeout unnecessary









100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103






100

150

200

250

300

350

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

RTT (milliseconds)









congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103











congestion control



















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103






















end of loop forever




Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103






Host A


ACK=100


Host B

Seq=92 8 bytes data

ACK=120

Seq=92 8 bytes data

Seq=

92

tim

eout

ACK=120

Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout

lost ACK scenario

Host B

X

Seq=92 8 bytes data

ACK=100

time

Seq=

92

tim

eout

SendBase= 100

SendBase= 120

SendBase= 120

Sendbase= 100



Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103






Host A

Seq=92 8 bytes data

ACK=100

loss

tim

eout


Host B

X


ACK=120

time

SendBase= 120



Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103






Event at Receiver





TCP Receiver action






Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





Fast Retransmit









TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





TCP Flow Control






flow control

















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103




















Three way handshake










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103










client

FIN

server

ACK

ACK

FIN

close

close

closed

tim

ed w

ait







client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103










client

FIN

server

ACK

ACK

FIN

closing

closing

closed

tim

ed w

ait

closed










timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103













timeout events

rate = CongWin

RTT Bytessec


TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





TCP AIMD

8 Kbytes

16 Kbytes

24 Kbytes

time

congestionwindow





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





TCP Slow Start












Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103









Host A

one segment

RTT

Host B

time

two segments

four segments






linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103









linearly


Philosophy

















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103




















Slow Start (SS)











Enter slow start

Duplicate ACK




1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





1

23

0111


routing algorithm


0100010101111001

3221



u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





u

yx

wv

z2

2

13

1

1

2

53

5

Graph G = (NE)



Graph abstraction





u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103






u

yx

wv

z2

2

13

1

1

2

53


- eg c(wz) = 5















cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103














cost changes



















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103






















Step012345

Nu

uxuxy

uxyvuxyvw

uxyvwz

D(v)p(v)2u2u2u

D(w)p(w)5u4x3y3y

D(x)p(x)1u

D(y)p(y)infin

2x

D(z)p(z)infin infin

4y4y4y

u

yx

wv

z2

2

13

1

1

2

53

5





A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103








A

D

C

B1 1+e

e0

e

1 1

0 0

A

D

C

B2+e 0

001+e1

A

D

C

B0 2+e

1+e10 0

A

D

C

B2+e 0

e01+e1











u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103












u

yx

wv

z2

2

13

1

1

2

53




B-F equation says


















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





















neighbor





recompute estimates



Each node


x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





x y z

xyz

0 2 7


from

cost to

from

from

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 3

from

cost to

x y z

xyz

infin infin

infin infin infin

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz

0 2 3

from

cost to

x y z

xyz

0 2 3

from

cost tox y z

xyz

0 2 7

from

cost to

x y z

xyz


cost to

infin2 0 1

infin infin infin

2 0 17 1 0

2 0 17 1 0

2 0 13 1 0

2 0 13 1 0

2 0 1

3 1 0

2 0 1

3 1 0

time

x z12

7

y

node x table

node y table

node z table









x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103










x z14

50

y1









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103









x z14

50

y60












own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103















own table





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





















4 Simple








take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103











take longer turns











frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103














frequ

ency

bands time









Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103












Slotted ALOHA











Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





Slotted ALOHA




simple

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103

















1t0+1]






CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103









CSMA collisions
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103
























failure (master)





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103





























Slide 2

Slide 3



Slide 6





Why layering


Encapsulation












rdt21 discussion




rdt30 sender

rdt30 in action

Slide 31



Pipelined protocols


Go-Back-N

GBN receiver

GBN in action

Selective Repeat


Selective repeat









TCP sender events





Fast Retransmit

TCP Flow Control



Slide 59


Slide 61


TCP AIMD

TCP Slow Start


Refinement

Refinement (more)




Graph abstraction














Slide 85









Slotted ALOHA

Slide 95




CSMA collisions




Slide 103




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