atm networks - computer science & engineering at washujain/talks/ftp/netsem2.pdf · atm...

Raj JainThe Ohio State University

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ATM Networks

Raj JainProfessor of Computer and Information Science

The Ohio State UniversityColumbus, OH 43210

[email protected]

Raj Jain

jain@cse horizontal


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ATM: OverviewATM Protocol LayersAdaptation LayersLAN EmulationNetwork Interfaces

Overview


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ATM Networks: OverviewSTM = Synchronous Transfer Mode,ATM = Asynchronous Transfer Mode

Allows any-speed and even variable rate connectionATM = Short fixed size 53-byte cells

Connection oriented ⇒ Virtual Channels (VC)


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Labels vs addresses⇒ Better scalability in number of nodes

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49

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Slotted system ⇒ Better scalability in distance-bandwidthSwitches vs routers⇒ Cheaper due to fixed size, short address, simplicitySeamless ⇒ Same technology for LAN, MAN, WANData, voice, video integrationEveryone else is doing it


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History of ATM1980: Narrowband ISDN adoptedEarly 80's: Research on Fast PacketsMid 80's: B-ISDN Study Group formed1988: ATM chosen for B-ISDNJune 1989: 48+5 chosen (64+5 vs 32+4)October 1991: ATM Forum foundedJuly 1992: UNI V2 released by ATM Forum1993: UNI V3 and DXI V11994: B-ICI V1


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PrivateNNI

Private

UNI

Public

UNI

ATM Network Interfaces

Computer PrivateSwitch

PublicSwitch

RouterDigitalService

Unit

DXI

B-ICI

Public

UNI

Public

NNI

Private

UNI

PrivateSwitch

PublicSwitch

B-ICI

PublicSwitch

Regional Carriers

PublicSwitch

LongDistanceCarrier

Computer

Computer


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ATM Network InterfacesUser to Network Interface (UNI):Public UNI, Private UNINetwork to Node Interface (NNI):

Private NNI (P-NNI)Public NNI = Inter-Switching System Interface (ISSI)Intra-LATA ISSI (Regional Bell Operating Co)Inter-LATA ISSI (Inter-exchange Carriers)⇒Broadband Inter-Carrier Interface (B-ICI)

Data Exchange Interface (DXI)Between packet routers and ATM Digital Service Units (DSU)


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Protocol Layers

ATM Layer

ATM Adaptation

Layer

PhysicalLayer

ATM Layer

PhysicalLayer

ATM Layer

ATM Adaptation

Layer

PhysicalLayer


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Protocol LayersThe ATM Adaptation Layer

How to break application messages to cellsThe ATM Layer

Transmission/Swiching/ReceptionCongestion Control/Buffer managementCell header generation/removal at source/destinationReset connection identifiers for the next hop (at switch)Cell address translationSequential delivery


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Original Classes of Traffic

Class A Class B Class C Class DTimeSynch

Required Not Required

Bit Rate Constant Variable

ConnectionMode

Connection oriented Connectionless

AAL AAL 1 AAL 2 AAL 3/4/5 AAL 3/4/5Examples Circuit

emulationCompressed

VideoFrameRelay

SMDS


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AAL 5Designed for data trafficLess overhead bits than AAL 3/4⇒ Simple and Efficient AAL (SEAL)No per cell length field, No per cell CRC

PADUserPayload Length CRC-32Control

4220-64kB

10PTI bit indicates last cell

0-40


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ATM Cell Header FormatGFC=Generic Flow Control

(Was used in UNI but not in NNI)VPI/VCI=0/0 ⇒ Idle cell; 0/n ⇒ SignallingHEC: 1 + x + x2 + x8

VCI PTIHeader Error Check (HEC)

VCIVPI VCI

GFC/VPI VPI

CLP

Payload


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Connection IdentifiersEach cell contains a 24/28-bit connection identifierFirst 8/12 bits: Virtual Path, Last 16 bits: Virtual CircuitVP service allows new VC's w/o orders to carriers

VC1VC2VC3

VC1VC2VC3

VC1VC2VC3

VP1

VP2

VP3

Link


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VP/VC Assignment/Use

Switch

23 56Video Data

37 34VoiceData

2

1

233

564655

766

1122

Port

0/370/340/230/56

VPI/VCI

In

0/230/560/650/76

VPI/VCI

3456

Port

Out


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LAN Emulation

Problem: Need new networking s/w for ATMSolution: Let ATM network appear as avirtual LANLAN emulation implemented as a devicedriver below the network layer

Bridge Bridge

ATM


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ExistingApplications

PhysicalLayer

LANEmulation

IP IPX

NDIS ODI

AAL5

ATMPhysical

Layer

ATM

LANEmulation

PhysicalLayer

AAL5

ATMPhysical

Layer

MediaAccessControl

Bridging

PhysicalLayer

ExistingApplications

PhysicalLayer

IP IPX

NDIS ODI

ATM Host

ATM Switch

ATM-LAN Bridge

LAN HostProtocol Layers

MediaAccessControl

NDIS = Network Driver Interface SpecificationODI = Open Datalink Interface


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FeaturesOne ATM LAN can be multiple virtual LANsLogical subnets interconnected via routersNeed drivers in hosts to support each LANOnly IEEE 802.3 and IEEE 802.5 frameformats supportedDoesn't allow passive monitoringNo token management (SMT), collisions,beacon frames

Standard IEEE 802.3 or 802.5 FrameLE Header (2 Bytes)


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LAN EmulationLAN Emulation Server (LES)

ATM Switches ATM client B

Bridge

2. Clients sendmessages onthe VC

1. Clients getreceipient’saddress fromLES and setup aVC.

Broadcast/Unknown Server (BUS) Non-ATM client

4. Messages for non-ATM clients areforwarded through abridge

3. Messages forATM clients aredelivered directly.


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OperationInitialization: Client gets Server's address from awell known ATM addressRegistration: Client sends a list of its MACaddresses to ServerAddress Resolution: Client sends ARP request toServer

Server, Clients, Bridges answer ARPClient setups a direct connection

Broadcast/Unknown Server (BUS):Forwards multicast traffic to all members


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Physical Media DependentLayers (PMDs)

Multimode Fiber: 100 Mbps using 4b/5b (TAXI),155 Mbps SONET STS-3c, 155 Mbps 8b/10bSingle-mode Fiber: 155 Mbps SONET STS-3cShielded Twisted Pair (STP): 155 Mbps 8b/10bCoax: 45 Mbps, DS3Unshielded Twisted Pair (UTP)

UTP-3 (phone wire) at 51.84 Mbps, CAP-16 codingUTP-5 (Data grade UTP) at 155 Mbps, NRZI coding


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Summary

ATM Overview: History, Why and What

Interfaces: PNNI, NNI, B-ICI, DXI

Protocol Layers: AAL, ATM, Physical layers, Cell format

LAN Emulation

IP over ATM


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ReferencesR, Handel, M. Huber, and S. Schroder, ATM Networks,Addison-Wesley, 1994.D.E. McDysan and D.L. Spohn, ATM: Theory and Applications,McGraw-Hill, 1994L.G. Cuthbert and J-C Sapanel, ATM: The broadbandTelecommunication Solution IEE 1993, London, 161 pp.David Benham, ATM in Local Area Networks, 11 April 1994,Hughes LAN Systems, (800)395-LANs, (415)966-7300.Communications of ACM, Special issue on ATM, February1995Presentation ATM Basics, ATM Forum, Fax on demand (415)-688-4318, Document #5007, 8 pp.Computer based training (CBT) diskettes, ATM Forum


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ReferencesRFC 1577, “Classical IP and ARP over ATM’’ by M. Laubach,January 1994.RFC 1483, “Multiprotocol Encapsulation over ATM AdaptationLayer 5’’ by J. Heinanen, July 1993.User-Network Interface Specifications, V3.0, Prentice-Hall,September 10, 1993., (515)-284-6751From ATM Forum, (415)-578-6860

B-ICI V1.1DXI V1DS1 Phy V1.052 Mb/s Category 3 UTP155 Mb/s Category 5 UTP


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Information SourcesATM Forum (415)578-6860 [email protected]

http://www.atmforum.comInternet Engineering Task Force

IP over ATM: [email protected] over Large Clouds: [email protected]@thumper.bellcore.comRFCs: [email protected] (Send Help in message)Draft RFC's: [email protected]

Internet News: [email protected]@indiana.edu

International Telecommunications Union (ITU)

atm networks - computer science & engineering at washujain/talks/ftp/netsem2.pdf · atm...

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