ATM Networks - Computer Science & Engineering at WashUjain/talks/ftp/netsem2.pdf · ATM Networks...
Transcript of ATM Networks - Computer Science & Engineering at WashUjain/talks/ftp/netsem2.pdf · ATM Networks...
Raj JainThe Ohio State University
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ATM Networks
Raj JainProfessor of Computer and Information Science
The Ohio State UniversityColumbus, OH 43210
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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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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)