chapter 3 slides (distributed systems)

Slides for Chapter 3: Networking and Internetworking

From Coulouris, Dollimore and Kindberg

Distributed Systems: Concepts and Design

Edition 3, © Addison-Wesley 2001

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3

© Addison-Wesley Publishers 2000

Figure 3.1Network types

Range Bandwidth (Mbps) Latency (ms)

LAN 1-2 kms 10-1000 1-10WAN worldwide 0.010-600 100-500MAN 2-50 kms 1-150 10Wireless LAN 0.15-1.5 km 2-11 5-20Wireless WAN worldwide 0.010-2 100-500Internet worldwide 0.010-2 100-500



Figure 3.2Conceptual layering of protocol software

Layer n

Layer 2

Layer 1

Message sent Message received

Communicationmedium

Sender Recipient



Figure 3.3Encapsulation as it is applied in layered protocols

Presentation header

Application-layer message

Session header

Transport header

Network header



Figure 3.4Protocol layers in the ISO Open Systems Interconnection (OSI) model

Application

Presentation

Session

Transport

Network

Data link

Physical

Message sent Message received

Sender Recipient

Layers

Communicationmedium



Figure 3.5OSI protocol summary

Layer Description ExamplesApplication Protocols that are designed to meet the communication requirements of

specific applications, often defining the interface to a service. HTTP, FTP, SMTP,CORBA IIOP

Presentation Protocols at this level transmit data in a network representation that isindependent of the representations used in individual computers, which maydiffer. Encryption is also performed in this layer, if required.

Secure Sockets(SSL),CORBA DataRep.

Session At this level reliability and adaptation are performed, such as detection offailures and automatic recovery.

Transport This is the lowest level at which messages (rather than packets) are handled.Messages are addressed to communication ports attached to processes,Protocols in this layer may be connection-oriented or connectionless.

TCP, UDP

Network Transfers data packets between computers in a specific network. In a WANor an internetwork this involves the generation of a route passing throughrouters. In a single LAN no routing is required.

IP, ATM virtualcircuits

Data link Responsible for transmission of packets between nodes that are directlyconnected by a physical link. In a WAN transmission is between pairs ofrouters or between routers and hosts. In a LAN it is between any pair of hosts.

Ethernet MAC,ATM cell transfer,PPP

Physical The circuits and hardware that drive the network. It transmits sequences ofbinary data by analogue signalling, using amplitude or frequency modulationof electrical signals (on cable circuits), light signals (on fibre optic circuits)or other electromagnetic signals (on radio and microwave circuits).

Ethernet base- bandsignalling, ISDN



Figure 3.6Internetwork layers

Underlying network

Application

Network interface

Transport

Internetwork

Internetwork packets

Network-specific packets

MessageLayers

Internetworkprotocols

Underlyingnetworkprotocols



Figure 3.7Routing in a wide area network

Hosts Linksor local networks

A

D E

B

C

1

2

5

43

6

Routers



Figure 3.8Routing tables for the network in Figure 3.7

Routings from D Routings from E

To Link Cost To Link CostABCDE

336

local6

12201

ABCDE

4456

local

21110

Routings from A Routings from B Routings from C

To Link Cost To Link Cost To Link CostABCDE

local1131

01212

ABCDE

1local

214

10121

ABCDE

22

local55

21021



Figure 3.9Pseudo-code for RIP routing algorithm

Send: Each t seconds or when Tl changes, send Tl on each non-faulty outgoing link.Receive: Whenever a routing table Tr is received on link n:

for all rows Rr in Tr {if (Rr.link | n) {

Rr.cost = Rr.cost + 1;Rr.link = n;if (Rr.destination is not in Tl) add Rr to Tl; // add new destination to Tlelse for all rows Rl in Tl {

if (Rr.destination = Rl.destination and (Rr.cost < Rl.cost or Rl.link = n))

Rl = Rr;// Rr.cost < Rl.cost : remote node has better route// Rl.link = n : remote node is more authoritative

}}

}



Figure 3.10Simplified view of the QMW Computer Science network

file

compute

dialup

hammer

henry

hotpoint

138.37.88.230

138.37.88.162

bruno138.37.88.249

router/sickle

138.37.95.241138.37.95.240/29

138.37.95.249

copper138.37.88.248

firewall

web

138.37.95.248/29

server

desktop computers 138.37.88.xx

subnet

subnet

Eswitch

138.37.88

server

server

server

138.37.88.251

custard138.37.94.246

desktop computers

Eswitch

138.37.94

hubhub

Student subnetStaff subnet

otherservers

router/firewall

138.37.94.251

1000 Mbps EthernetEswitch: Ethernet switch

100 Mbps Ethernet

file server/gateway

printers

Campusrouter

Campusrouter

138.37.94.xx



Figure 3.11Tunnelling for IPv6 migration

A BIPv6 IPv6

IPv6 encapsulated in IPv4 packets

Encapsulators

IPv4 network



Figure 3.12TCP/IP layers

Messages (UDP) or Streams (TCP)

Application

Transport

Internet

UDP or TCP packets

IP datagrams

Network-specific frames

MessageLayers

Underlying network

Network interface



Figure 3.13Encapsulation in a message transmitted via TCP over an Ethernet

Application message

TCP header

IP header

Ethernet header

Ethernet frame

port

TCP

IP



Figure 3.14The programmer's conceptual view of a TCP/IP Internet

IP

Application Application

TCP UDP



Figure 3.15Internet address structure, showing field sizes in bits

7 24

Class A: 0 Network ID Host ID

14 16

Class B: 1 0 Network ID Host ID

21 8

Class C: 1 1 0 Network ID Host ID

28

Class D (multicast): 1 1 1 0 Multicast address

27

Class E (reserved): 1 1 1 1 unused0



Figure 3.16Decimal representation of Internet addresses

octet 1 octet 2 octet 3

Class A: 1 to 127

0 to 255 0 to 255 1 to 254

Class B: 128 to 191

Class C: 192 to 223

224 to 239 Class D (multicast):

Network ID

Network ID

Network ID

Host ID

Host ID

Host ID

Multicast address

0 to 255 0 to 255 1 to 254

0 to 255 0 to 255 0 to 255

0 to 255 0 to 255 0 to 255

Multicast address

0 to 255 0 to 255 1 to 254240 to 255 Class E (reserved):

1.0.0.0 to 127.255.255.255

128.0.0.0 to 191.255.255.255

192.0.0.0 to 223.255.255.255

224.0.0.0 to 239.255.255.255

240.0.0.0 to 255.255.255.255

Range of addresses



Figure 3.17IP packet layout

dataIP address of destinationIP address of source

header

up to 64 kilobytes



Figure 3.18IPv6 header layout

Source address(128 bits)

Destination address(128 bits)

Version (4 bits) Priority (4 bits) Flow label (24 bits)

Payload length (16 bits) Hop limit (8 bits)Next header (8 bits)



Figure 3.19The MobileIP routing mechanism

Sender

Home

Mobile host MH

Foreign agent FAInternet

agent

First IP packet addressed to MH

Address of FAreturned to sender

First IP packettunnelled to FA

Subsequent IP packetstunnelled to FA



Figure 3.20Firewall configurations

Internet

Router/Protected intraneta) Filtering router

Internet

b) Filtering router and bastion

filter

Internet

R/filterc) Screened subnet for bastion R/filter Bastion

R/filter Bastion

web/ftpserver

web/ftpserver

web/ftpserver



Figure 3.21IEEE 802 network standards

IEEE No. Title Reference

802.3 CSMA/CD Networks (Ethernet) [IEEE 1985a]

802.4 Token Bus Networks [IEEE 1985b]

802.5 Token Ring Networks [IEEE 1985c]

802.6 Metropolitan Area Networks [IEEE 1994]

802.11 Wireless Local Area Networks [IEEE 1999]



Figure 3.22Wireless LAN configuration

LAN

Server

WirelessLAN

Laptops

Base station/access point

Palmtop

radio obstruction

A B C

DE



Figure 3.23ATM protocol layers

Physical

Application

ATM layer

Higher-layer protocols

ATM cells

ATM virtual channels

MessageLayers

ATM adaption layer



Figure 3.24ATM cell layout

Flags DataVirtual channel idVirtual path id

53 bytes

Header: 5 bytes



Figure 3.25Switching virtual paths in an ATM network

VPI in VPI out

23

45

VPI = 3

VPI = 5

VPI = 4

Virtual path Virtual channels

VPI = 2

VPI : virtual path identifier

VP switch VP/VCswitch

VP switch

Host

Host

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