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Rivier College
CS575: Advanced LANs
ATM Layers & Protocols
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ATM Layers
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ATM Layers and Sublayers
Higher Layers
Convergence Sublayer (CS)
ATM Adaptation Layer (AAL)
Segmentation and Reassembly Sublayer
(SAR)
ATM Layer (ATM)
Virtual Channel (VC)
Virtual Path (VP)
Transmission Convergence Sublayer (TC)
Physical Layer (PL)
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Physical Medium Sublayer
(PM)
ATM Layers
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ATM Information Transport Concept
ATM Network
User
Higher
Layer
AAL
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User
Error Recovery
&
Flow Control
End - to - End
Higher
Layer
Edge - to - Edge
AAL
ATM
Layer
ATM
Layer
ATM
Layer
ATM
Layer
Physical
Layer
Physical
Layer
Physical
Layer
Physical
Layer
ATM Layers
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Functions of ATM Layers
Higher layers
ATM
Adaptation
Layer
Convergence
Sublayer
Segmentation
and
reassembly
Sublayer
ATM Layer
Physical
Layer
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High layer functions
Convergence
Segmentation and reassembly
Generic flow control
Cell Header generation/extraction
Cell VPI/VCI translation
Cell multiplexing
Cell rate decoupling
HEC sequence generation/verification
Transmission
Cell
convergence
delineation
Transmission frame
Sublayer
adaptation
Transmission frame
generation/recovery
Physical medium Bit timing
Sublayer
Physical medium
ATM Layers
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Physical Layer:
Physical Medium (PM) Sublayer
0 Specify physical medium and transmission characteristics (e.g.,
multimode or single mode fiber)
0 Insertion and extraction of timing information
0 Specify bit timing, line coding
Higher Layers
ATM Adaptation Layer (AAL)
Convergence Sublayer (CS)
Segmentation and Reassembly Sublayer (SAR)
ATM Layer (ATM)
Virtual Channel (VC)
Virtual Path (VP)
Transmission Convergence Sublayer (TC)
Physical Layer (PL)
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Physical Medium Sublayer (PM)
ATM Layers
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Physical Layer Interfaces
0 Three major categories of physical layer interfaces for ATM networks:
- The existing Plesiochronous Digital Hierarchy (PDH):
(Designed for used over copper media)
= DS-1 (1.544 Mbps)
= DS-3 (44.736 Mbps)
= E1 (2.048 Mbps)
= E3 (34.368 Mbps)
= E4 (139.264 Mbps)
- The new Synchronous Digital Hierarchy (SDH):
(Designed for used over fiber optic links)
= STS-3 (155.52 Mbps)
= STS-12 (622.080 Mbps)
- Physical media used on the local premises for ATM LANs
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ATM Layers
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Physical Layer Interfaces (continued)
0 Interfaces specified by the ATM Forum UNI Specification V3.1:
- SONET STS-3c (OC-3c) Interface
= Based on SDH/SONET standards
= For public and private UNI
= 155.52 Mbps
= Single mode and multimode fiber
- DS-3 Interface
= Based on ANSI T1E1.2/94-002R1 standard
= For public and private UNI
= 44.736 Mbps
= Physical Layer Convergence Protocol (PLCP) defined to carry DS-3
ATM cells (excluding PLCP overhead, 40.704 Mbps available for
ATM cells)
= Coaxial cable media
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ATM Layers
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Physical Layer Interfaces (concluded)
0 Other interfaces:
-
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155 Mbps STS-3 over UTP-5
34.368 Mbps (E-3)
139.264 Mbps (E-4)
1.544 Mbps (T-1)
2.048 Mbps (E-1)
ATM Layers
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Transmission Convergence (TC) Sublayer
0 For transmission, receive cells from ATM layer
0 Pack/map cells into appropriate transport format
- Cell-based
- PLCP-based
= DS-1
= DS-3
- SDH/SONET-based
0 Deliver cells to PM sublayer for transmission
0 Insert idle cells in order to provide a continuous flow of cells (cell rate
decoupling)
0 HEC generation/verification
0 For receiving, extract cells from bit or byte stream received from PM
sublayer
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ATM Layers
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Transmission Convergence (TC) Sublayer
(concluded)
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0
0
0
Cell delineation (detect cell boundaries)
Remove idle cells on receiving
Verify cell headers
Deliver valid cells to the ATM layer
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ATM Layers
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HEC Operation at Receiver
Source: Stallings: Local and Metropolitan Networks p327
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ATM Layers
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Cell Delineation
Source: Kyas: ATM Networks p155
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ATM Layers
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B-ISDN/ATM Protocol Reference Model
Source: Stallings: Data and Computer Communications
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ATM Layers
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References
W. Stalling, Local and Metropolitan Area Networks, 6th edition,
Prentice Hall, 2000, Chapter 11
W. Stalling, Data and Computer Communications, 6th edition,
Prentice Hall, 2002, Chapters 11-12
A. Wu, Advanced Local Area Networks, Lectures & Slides, Rivier
College, 2001.
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ATM Layers
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