© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 1 ETH Zürich
Part III: Overview of Technologies, ATM, and IP
• Overview of Networking Technologies– Developments– High-speed Characteristics– Switching Techniques
• ATM (Asynchronous Transfer Mode) – Principles of Cell Switching – ATM Connection Management– ATM Layer and Adaptation Layer
• IP (Internet Protocol)– Key Elements– Protocol Stack
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 2 ETH Zürich
Networks
Networks provide an infrastructure for:• Interconnecting machines or services (connectivity),• Making available scarce resources (resource sharing),• Equalizing traffic volumes (load balancing), and• Providing alternative fallbacks (reliability).
Structuring networks according to dimensions:• Expansion (LAN, MAN, WAN),• Topology (star, ring, bus, meshed),• Performance (low-speed, high-speed, real-time),• Administration (public, private), and• Task (internet or physical net, intranet or virtual net).
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 3 ETH Zürich
Inventions in Telecommunications
Oscillating needle telegraph experimentsEarly telegraphy (Morse code dots and dashes)
Printing telegraph systemsBaudot multiplex telegraph (6 machines on one line)
First telephone channels constructed
First carrier telephonyCarrier telephony carries 12 voice channels on wire
60 voice channels over coaxial cable
600 voice channels over cable (T3) and microwave
3600 voice channels over cable and microwave
32000 voice channels over cable108000 voice channels over cable
Multimode optical fiber 45 Mbit/s
Multimode optical fiber 140 Mbit/s
Monomode optical fiber 565 Mbit/s
Monomode optical fiber 16 Gbit/s
18
50
18
60
18
70
18
80
18
90
19
00
19
10
19
20
19
30
19
40
19
50
19
60
19
70
19
80
19
90
20
00
Year
1800 voice channels over cable and microwave
1012
1011
1010
109
108
107
106
105
104
103
102
10
1Bandwidth
bit/s
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 4 ETH Zürich
Transmission Media
Fiber optical media:• Low error rates, long distances, low attenuation.
Attenuation[dB/km]
10 0 10 1 10 2 10 3
10 0
10 1
Frequency[MHz]
10 2
Copper(UTP)
Copper(Coaxial)
Fiber(Multimode)
Fiber(Monomode)
Fiber(Gradient)
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 5 ETH Zürich
Last MileProblem:• Connection
between thehome and thebackboneis serious.
• Requires ahuge capitalinvestment.
• Fiber ignoresthe lastmile problem.
Evolution of Bandwidth
Bandwidth[kbit/s]
1975
10 0
10 1
Time[year]
10 2
10 3
10 4
10 5
10 6
10 7
1980 1985 1990 1995 2000 2005
POTS
WAN
LAN
LANPOTSWAN
Local Area NetworkPlain Old Telephone ServiceWide Area Network
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 6 ETH Zürich
High Speed Networks – Overview (1)
High Speed Local Area Networks (LAN):• Fast Ethernet: 100 Mbit/s• Gigabit Ethernet: 1.0 Gbit/s• HIPPI: 800 Mbit/s• Fiber Channel: 100, 200, 400, or 800 Mbit/s• High Speed Token Ring: 100 Mbit/s (1 Gbit/s)
High Speed Metropolitan Area Networks (MAN):• FDDI: 100 Mbit/s• FDDI-II: 100 Mbit/s (incl. isochronous channels)• DQDB: 34 Mbit/s, 155 Mbit/s, or 622 Mbit/s
High Speed Wide Area Networks (WAN):• ATM-based B-ISDN: e.g., 2, 34, 155, 622, or 2,400 Mbit/s
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 7 ETH Zürich
High Speed Networks – Overview (2)
Carrier support (physical layer):• Plesiochronous Digital Hierarchy (PDH):
– e.g., DS-0: 0.064 Mbit/s (= 1 voice channel)
– T-1 (USA): 1.544 Mbit/s ( 24 voice channels) (also called DS-1)
– E-1 (Europe): 2.048 Mbit/s
– E-3 (Europe): 34.368 Mbit/s
– T-3 (USA): 44.736 Mbit/s (also called DS-3)
• Synchronous Digital Hierarchy (SDH) orSynchronous Optical Network (SONET):
– e.g., STS/OC-1: 51.84 MBit/s
– STS/OC-3: 155.52 MBit/s ( STM-1)
DS: Digital Signal
T: Telephone Line
OC: Optical Carrier
STS: Synchronous Transfer Signal Level
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 8 ETH Zürich
High Speed Networks – Overview (3)
Carrier support (physical layer) continued: • Wavelength Division Multiplexing (WDM)
Access technologies:• Cable TV• Frame Relay (FR)• xDSL (Digital Subscriber Line)• Satellite networks and wireless local loop
Service technologies:• Switched Multimegabit Data Service (SMDS)
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 9 ETH Zürich
HSTRFast EthernetxDSL
Token RingEthernet
FDDI,DQDB,CRMA
X.25 N-ISDN
STMATM LAN
Network Dimensions
System Bus 1980/90
1980 1990
10 -1
Transmissionrate
[Mbit/s]
10 -3 10 -2 10 0 10 1 10 2 10 3 10 4
10 -3
10 -2
10 -1
10 0
10 1
10 2
Distance[km]
10 3
Wide AreaNetwork 2000
2000
1985
Local Area Network 1995
MetropolitanArea
Network 1995
HIPPI 1990 ATM-based B-ISDN
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 10 ETH Zürich
Protocol Layer Architecture – Examples
SDH/SONETWDM
ADSL: Asymmetric Digital Subscriber LoopATM: Asynchronous Transfer ModeHDLC: High Data Link Control
IP: Internet Protocol PPP: Point-to-Point Protocol WDM: Wavelength Division Multiplexing
SDH/SONETADSL
TransmissionConvergence
Voice HDLCVideo
ATM PPP
IPVoice IP ... ...
Voice telnet...
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 11 ETH Zürich
Characteristics of High Speed Networks
Characteristics of high speed networks:• Low bit error rate (fiber optical media),• Higher packet error rate (buffer overflow),• Existing Jitter (different buffer lengths),• Small transmission units (cells), • Many connections (context data),• High bandwidth (fiber optical media), and• Extreme bandwidth-delay product.
Protocols have to deal with these issues to alleviate influences of delayed, corrupted, or lost data.
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 12 ETH Zürich
File Transfer Example
File size: 1 Mbyte
Link: San Diego – Boston
Signal delay: 25 ms
64 kbit/s channel:• 64 kbit/s * 25 ms = 1,600 bit• 0.02 % of file on link
2 Mbit/s channel:• 2 Mbit/s * 25 ms = 50,000 bit• 0.6 % of file on link
1 Gbit/s channel:• 1 Gbit/s * 25 ms = 25,000,000 bit• 8 ms for transmission, 17 ms idle
SAN BOS
SAN
BOS
1,600 bit
50,000 bit
25,000,000 bit
5000 km
Bits are smaller – not faster !
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 13 ETH Zürich
Effects on Data in Transit
Signal delay is dominating the transmission delay.• This grows worse for high transmission rates.
Buffer overflows dominate occurring errors.• The effect grows worse for fast and real-time traffic.
Error recovery has to be a trade-off between a waste of bandwidth or extending delays.• Bandwidth is much cheaper than tolerating high delays.• Multimedia applications normally don´t like delays.
A huge amount of data is in transit within high speed and long distance networks Path Capacity PC: PC = B * Dsignal
B: Bandwidth, Dsignal: Signal delay.
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 14 ETH Zürich
Switching Techniques – Overview
Switching Techniques:• Based on circuits, cells, frames, or packets.
Circuit switching suffers from fixed bandwidth constraints for bursty traffic.
Packet switching allows for variable bandwidth.
CircuitSwitching
(STM)
FastCircuit
SwitchingATM
FrameRelay
PacketSwitching
Fixed Behavior of Bandwidth Variable
MultirateCircuit
Switching
FastPacket
Switching
FrameSwitching
IntricacySimple Complex
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 15 ETH Zürich
Circuit information are stored during establishment times in a translation table.• Delay is determined by the
propagation delay and theprocessing in switches.
• Bounded to 450s by ITU-T. • Bit error rates are caused
by single bit errors (switch-ing malfunction) or bursts(loss of synchronization).
Inflexible, e.g., G.703 PCM.• Fixed bandwidth.
Circuit Switching
l1
l2
lm
IncomingLink
TimeSlot
OutgoingLink
TimeSlot
12…m12…m12…m
O1
O2
O3
…O1
O2
O3
…O1
O2
O3
…
32…142…m1m…1
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 16 ETH Zürich
Packet Switching
Based on user data that are encapsulated in packets. Concept is based on technology available in the 60s:
• Erroneous links:– Link-based error control in complex protocols.
• Low bandwidth links:– High delays (due to retransmissions) and low speed
(due to protocol processing) – Lacking support of real-time and multimedia traffic
• Software-based protocol implementations:– Variable sized packets require a complex buffering.
X.25 is the oldest example of packet switching nets.
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 17 ETH Zürich
Frame Relay (1)
Frame Relay supports connection-oriented services. Subscriber Network Interface (SNI) defined between
customer (router) and PTO equipment.• Support of pure data, not particularly voice etc.• Multiplexes flows of data being divided in data blocks.• Flows are carried in virtual channels which may exceed
their bandwidth as other channels are idle.• Frame Relay may carry X.25 packets/frames.
Performance:• Different implementation approaches exist, however,
2 Mbit/s access speeds are common.• Insufficient guarantees on bandwidth and delay variation.
PTO: Public Telecommunication Operator
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 18 ETH Zürich
Frame Relay (2)
Physical and data link layer specifications available. The data link layer is based on LAPD (ISDN):
• Data link services: addressing (DLCI, local significance).• Error control is left out as an end-to-end function.• Core LAPD frame:
DLCI: Data Link Connection IdentifierC/R: not usedEA: Extended Address
FECN: Forward Error Congestion NotificationBECN: Backward Error Congestion NotificationDE: Discard Eligibility
Flag Address Payload FCS Flag
1 2 variable 2 1Byte
DLCI C/R EA DLCI FECNBECN DE EA
6bit 1 1 4 1 1 1 1
01111110 01111110
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 19 ETH Zürich
Frame Relay (3)
Frame Relay DLCI assignments:
A simple sample Frame Relay network:
User B
User C
User A
Permanent Virtual Circuits16
1007
1451007
16, 145, 1007: DLCI
0 Reserved for Call Control Signaling1-15 Reserved16-1007 Assigned to Permanent Virtual Circuits (PVC)1008-1022 Reserved1023 Local Management Interface
Frame Relay Interface
Frame Relay Interface
Frame Relay Interface
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 20 ETH Zürich
Comparison
Summary of important functional differences:
Connection-orientedConnectionlessFrame BoundariesBit StuffingCRCError-Control ARQFlow-ControlMultiplexing of log. Channels
X.25–
FrameSwitching
or –
FrameRelay––––
Light weightHeavy weight
Technology
CRC: Cyclic Redundancy Check
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 21 ETH Zürich
Part II: Overview of Technologies, ATM, and IP
• Overview of Networking Technologies– Developments– High-speed Characteristics– Switching Techniques
• ATM (Asynchronous Transfer Mode) – Principles of Cell Switching – ATM Connection Management– ATM Layer and Adaptation Layer
• IP (Internet Protocol)– Key Elements– Protocol Stack
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 22 ETH Zürich
Cell-based Switching
Integration of a variety of services:• Bursts are smoothened.• Isochronous data are delivered according to their jitter.• Data may be multiplexed statistically, if the overall
bandwidth is sufficient. Efficiency: statistical multiplexing gain.
Delay problems occur in case of sending packets of different length. Extremely long blocking can be avoided, if cells of fixed-size are used. If the overall cell length is too big, a similar problem appears.
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 23 ETH Zürich
Handling Cells – Segmentation/Reassembly
To sent packets over cell-based networks, packets have to be segmented and reassembled again.
The segmentation and reassembly (SAR) functionality is placed right above the cell level.
Packet PacketCells
HLP
User Data
User Data
SAR HLP UD
User Data Cell UDSAR HLP Cell SAR User Data Cell SAR
User Data SAR User Data SAR
Cell Header
SAR Header. . .
. . . HLP Higher Layer Protocol Header
Total Cell LengthCell Payload Length
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 24 ETH Zürich
Structure of an ATM-based B-ISDN Network
Customer Premises Equipment
ATM-Switch
NNI
NNI
NNI
UNI
UNI
UNI
ATM-connectedMM-Workstation
ATM-connectedMM-Workstation
ATM: Asynchronous Transfer ModeMM: MultimediaNNI: Network Node InterfaceUNI: User Network Interface
ATM-Switch
ATM-Switch
ATM-Switch NNI
NNI
ATM-Switch
Core ATM-Switch
Edge ATM-Switch
ATM-Switch
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 25 ETH Zürich
B-ISDN Reference Model – I.321
Modeling communication systems is done in a logically hierarchical structure, e.g., ISO/OSI BRM.
Relation between OSI and B-ISDN/ATM undefined. The plane approach has been used within B-ISDN.
Physical Layer
ATM Layer
ATM Adaptation Layer
Higher Layer Protocols
Management Plane
Control P. User P.
Pla
ne M
anag
emen
t L
ayer
Man
agem
ent
P.: Plane
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 26 ETH Zürich
ATM Connections (1)
Connections, links, ATM equipment, and identifiers:
ATMEnd-system
ATMEnd-system
ATMCross-connect
ATMSwitch
ATMCross-connect
ATMSwitch
VCC 1
VPC 1 VPC 2 VPC 3
VCI 1 VCI 2 VCI 3
VPI 1 VPI 3 VPI 5VPI 2 VPI 4
VPL 1 VPL 3 VPL 5VPL 2 VPL 4
VC: Virtual Channel, VP: Virtual Path, L: Link, I: Identifier, C: Connection
Link
sE
quip
men
tId
entif
iers
“Con
nect
ions
”
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 27 ETH Zürich
ATM Connections (2)
Hierarchical connection concept includes:• Virtual Connections are identified by two identifiers, which
are significant only locally per link in the virtual connection.– Error-control is done end-to-end only, if required.
High quality links and a good call acceptance control.
– Flow-control is not provided. High bandwidth delay product.
• Virtual Channel (VC) is a uni-directional channel, identified by the Virtual Channel Identifier (VCI).
– Dynamically allocatable connections.• Virtual Path (VP) contains a group of VCs, identified by the
Virtual Path Identifier (VPI).– Statically allocatable connections.
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 28 ETH Zürich
ATM Connections (3)
Simultaneous support of many thousands of VCs requires the ATM cell to carry the VCI field.
Supporting many semi-permanent connections between endpoints, carrying many grouped VPs requires the ATM cell to carry the VPI field.
LinkVPI1
VPIk
VCIn
VCIm
VCI1
VCI2
VPI Virtual Path IdentifierVCI Virtual Channel Identifier
Pre-assigned VPI/VCI values:0/0 Unassigned, idle0/1 Meta-signaling0/3 Segment flow (between
VP end-points, F4)0/4 End-to-end F4 flow0/5 Signaling0/15 SMDS0/16 ILMI
ILMI: Integrated Layer Management InterfaceSMDS: Switched Multimegabit Data Service
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 29 ETH Zürich
ATM Switching (1)
Two types of switching may be performed. VP switching (ATM Cross-connect):
• Switching between VPs,• No evaluation and change of VCIs,• Change of VPIs, and• Variable number of VCs per VP possible.
VC/VP switching (ATM Switch):• Switching in close cooperation between VCs and VPs,• Evaluation of VCI and VPI in an intermediate system,• Change of VCI and VPI if necessary, and• Incoming VCs of one VP may be distributed between many
outgoing VPs.
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 30 ETH Zürich
ATM Switching (2)
Use of VPI in a B-ISDN network (cross-connect).
ATM
PHY
B-ISDN Network
ATM
PHY
ATM
PHY
VPIin VPIout
7 59 7
VPI = 7VCI = 1, 2, 3
VPI = 3VCI = 3, 4
VPI = 9VCI = 3, 4
VPI = 7VCI = 1, 2, 3
VPI = 5VCI = 1, 2, 3
VPI = 7VCI = 3, 4
VPIin VPIout
5 7
VPIin VPIout
7 3A
B
C
1
2
3
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 31 ETH Zürich
ATM Switching (3)
Use of VPI-VCI in a B-ISDN network (ATM switch).
ATM
PHY
B-ISDN Network
ATM
PHY
ATM
PHY
VPI-VCIin VPI-VCIout
7.1 5.17.2 7.37.3 5.29.3 7.49.4 5.3
VPI = 7VCI = 1, 2, 3
VPI = 3VCI = 3, 4
VPI = 9VCI = 3, 4
VPI = 7VCI = 1, 2, 3
VPI = 5VCI = 1, 2, 3
VPI = 7VCI = 3, 4
VPI-VCIin VPI-VCIout
5.1 7.25.2 7.15.3 7.3
VPI-VCIin VPI-VCIout
7.3 3.47.4 3.3A
B
C
1
2
3
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 32 ETH Zürich
ATM Layer – UNI Cell Format
GFC: Generic Flow-Controlused at the service interface.
PT: Payload Type definescontents of a cell:• User data congested,• User data non-congested,• Operation And Maintenance
(OAM) cells, and• Resource management cells.
CLP: Cell Loss Priority to identify low/high priority cells.
HEC: Header Error Control.
GFC
VPI
VCI
VCI
HEC
VPI
VCI
PT CLP
1
2
3
4
5
1 2 3 4 5 6 7 8bit
Byte
Header Payload
5 Byte 48 Byte
UNI: User-Network Interface
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 33 ETH Zürich
ATM Layer – NNI Cell Format
VPI: Virtual Path Identifiercomprises of 12 bit length.
PT: Payload Type definescontents of a cell:• User data congested,• User data non-congested,• Operation And Maintenance
(OAM) cells, and• Resource management cells.
CLP: Cell Loss Priority to identify low/high priority cells.
HEC: Header Error Control.
VPI
VCI
VPI
VCI
HEC
VCI
PT CLP
1
2
3
4
5
1 2 3 4 5 6 7 8bit
Byte
Header Payload
5 Byte 48 Byte
NNI: Network-Network Interface
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 34 ETH Zürich
Structure of the AAL
AAL includes sublayers:• Segmentation and
Reassembly (SAR) between packets/cells.
• Convergence sublayer(CS) for service-dependent adaptation:
– Common Part Con-vergence Sublayer(CPCS) and
– Service Specific Con-vergence Sublayer(SSCS).
• Layers may be empty.
CS-1
SAR-1
AAL 1
SSCS-2
CPCS-2
SAR-2
AAL 2
SSCS-3/4
CPCS-3/4
SAR-3/4
AAL 3/4
SSCS-5
CPCS-5
SAR-5
AAL 5
ATM Adaptation Layer
ATM Layer
Class A Class B Class C/D Class C/D
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 35 ETH Zürich
AAL Comparison
AAL 1
AAL Service ClassMessage Delimiter
Advanced Buffer AllocationMultiplexingCS Padding
CS Protocol OverheadCS ChecksumSAR Payload
SAR Protocol OverheadSAR Checksum
Criteria AAL 3/4 AAL 5AAL 2
Anonono00
no46/47 Byte
1/2 Byteno
Bnonoyes
0/46 Byte2 Byte
no1/47 Byte
3 Byteno
C/DBTAG
yesyes
4 Byte8 Byte
no44 Byte4 Byte10 bit
C/DBit in PTI
nono
0/47 Byte8 Byte32 bit
48 Byte0
no
PTI: Payload Type Information
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 36 ETH Zürich
ATM Functions per Layer – Summary
LayerAAL
ATM
PHY
Subl.CS
SAR
TC
PM
FunctionHandles transmission errorsHandles lost and misinserted cell conditionsHandles timing between source and destinationHandles cell delay variationSegments higher-layer information into 48 Byte fieldsReassembles cell payload in higher layer informationMultiplexes cells from different ATM channelsGenerates cell header (first four bytes)Performs payload type discriminationPerforms traffic shaping and flow controlRoutes and switches cells as neededIndicates cell loss priority and selects cells for discardingHEC header sequence generation and verificationCell delineationTransmission frame generation and recoveryBit timing
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 37 ETH Zürich
Part II: Overview of Technologies, ATM, and IP
• Overview of Networking Technologies– Developments– High-speed Characteristics– Switching Techniques
• ATM (Asynchronous Transfer Mode) – Principles of Cell Switching – ATM Connection Management– ATM Layer and Adaptation Layer
• IP (Internet Protocol)– Key Elements– Protocol Stack
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 38 ETH Zürich
IP Technology
Key elements of the technology used in the Internet:• Packet switching, using datagrams• No connection-dependent state information in the network• Distributed management• Many physical subnetwork technologies• One network protocol• Two transport protocols• Infrastructure for hundreds of different distributed
applications• Scalability: to accommodate exponential growth
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 39 ETH Zürich
IP Protocol Stack
Phys. Networklayer
Internetlayer
Applicationlayer
Ethernet DECnetATM
HTTP DNSFTP
IP
TCP UDPTransport
layer
Routing
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 40 ETH Zürich
Internet Protocol (IP)
IPv4 shows addressing problems:• Nearly exhausted Class B addresses. Classless Inter-
domain Routing (CIDR) provides short-term solution only.• Routing tables grow extremely fast .• IP unicast address space will run out due to radipdly, e.g.,
increasing Internet hosts and low-end Internet devices.
Next Generation Internet, IPv6, delivers solutions:• Extended addressing: 128 bit addresses.• Address hierarchy levels (hierarchy: subscriber, subnet, ...)• Anycast addresses to reach the “nearest” node of a group
(in terms of the routing metric).• Simplified IP header, including a flow label.
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 41 ETH Zürich
Internet Network Model
International ISP“Backbone”
RegionalISP B
LargeEnterprise
SmallEnterprise
ISP: Internet Service Provider SOHO: Small Office and Home
SOHO
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 42 ETH Zürich
Example – Backbone ISP: UUNET
http://www.caida.org/Tools/Mapnet/Backbones/
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 43 ETH Zürich
Example – Regional ISP: Switch
http://www.switch.ch
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 44 ETH Zürich
Switch – UUNET Interconnection
http://www.switch.ch
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 45 ETH Zürich
Co-location Model
Extensions broadens the model by other services: • More than a pure routing and traffic exchange role.• Content provider supported, e.g., with high volumes,
selection of non-local transit providers.• E.g., Multicast, Web, DNS, policy-based route services.
Router
Router Router
RouterRouter Router
RouterRouter
Router
RouterRouter
Router Multicast Router
Route Server
WebServer
DNSServer
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 46 ETH Zürich
Services Integrated Internet
QoS Guarantees
Configuration
Zone
State
Information
Required
Protocols
Status
Best-effort IntServ DiffServ
no
none
entire
network
none
none
operational
per data stream
per session
(dynamic)
end-to-end
data stream
per data stream,
in router
signaling
(RSVP)
matured
aggregated
log-term
(static)
domain-
oriented
(none, in
BB, in edge
router)
bit fields
(BB, COPS)
worked on
IntServ: Integrated Services, DiffServ: Differentiated Services, QoS: Quality-of-ServiceRSVP: Resource Reservation Protocol, BB: Bandwidth Broker, COPS: Common Open Policy Service
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 47 ETH Zürich
IntServ Implementation
Integrated Services Architecture (IntServ) supports best-effort and guaranteed services.
Traffic control functions:• Admission control,• Packet classifier, and• Packet scheduler.• Optional: Policy
control (COPS).
Protocol support:• Resource reservation,
E.g., RSVP (Resource Reservation Protocol).
Host and router require similar functionality.
PolicyControl
ResourceReservation
Application
AdmissionControl
PacketClassifier
PacketScheduler
Control
Data
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 48 ETH Zürich
The DiffServ Approach
Requirements for Differentiated Services proposals:• Aggregated bandwidth allocation without the need of
per-session signaling and complex router state,• Aggregated QoS guarantees with edge-complexity,• Long-term service contracts within a single domain,• Integrated and simplified accounting,• Better traffic isolation for performance predictability, and• Better services for users willing to pay more.
A set of new proposals for DiffServ:• Expedited Forwarding (EF) and• Assured Forwarding (AF).
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 49 ETH Zürich
DiffServ Implementation
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 50 ETH Zürich
References (1)
• F. Fluckiger: Understanding Networked Multimedia; Prentice Hall, London, England, 1995, ISBN 0–13–190992–4.
• R. Steinmetz: Multimedia Technologie; Springer Verlag, Bonn, Germany, 1999, ISBN 3-540-62060-5.
• M. de Prycker: Asynchronous Transfer Mode – Solution for Broadband ISDN; 3rd Edition, Prentice Hall, Englewood Cliffs, New Jersey, U.S.A., 1995, ISBN 0–13–342171–6.
• ITU-T – Maintenance Principles: Frame Relay Operation and Maintenance Principles and Functions; I.620, October 1996.
© 2000 B. Stiller, B. Plattner ETHZ-TIK, D. Bauer IBM Research CM III – 51 ETH Zürich
References (2)
• R. J. Vetter: ATM Concepts, Architectures, and Protocols; Communications of the ACM, Vol. 38, No. 2, February 1995, pp 30 – 38.
• B. G. Kim, P. Wang: ATM Network: Goals and Challenges; Com. of the ACM, Vol. 38, No. 2, February 1995, pp 39 – 44.
• M. de Prycker: Asynchronous Transfer Mode – Solution for Broadband ISDN; 3rd Edition, Prentice Hall, Engle-wood Cliffs, New Jersey, U.S.A., 1995, ISBN 0–13–342171–6.
• T. Braun: Die Internet-Protokollfamilie der nächsten Generation; Praxis der Informationsverarbeitung und Kommunikation, Vol. 19, No. 2, 1996, pp 94 – 102.
• X. Xiao, L. M. Ni: Internet QoS: A Big Picture; IEEE Network Magazine, Vol. 13, March/April 1999, pp 8 – 18.