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CS575 ATM: ATM Layer 1 1 4/11/2013 10:10  Rivier College CS575: Advanced LANs  ATM Technology: ATM Layer

ATM ATM Layer.ppt

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CS575 ATM: ATM Layer 1

14/11/2013 10:10  

Rivier College

CS575: Advanced LANs 

ATM Technology: ATM Layer

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CS575 ATM: ATM Layer 2

24/11/2013 10:10  

Overview

0 ATM Layer Functions

0 UNI ATM Cell Header Format

0 NNI ATM Cell Header Format

0 VP/VC/Transmission Path Concept

0 Virtual Channel and Virtual Path

0 ATM Switch Routing/Switching

0 ATM Virtual Path Switching

0 ATM Virtual Channel/Virtual Path Switching

0 Impact of Random Bit Errors on HEC Performance

0 Payload Type Indicator Encoding

0 Management Information Flows

Jain

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CS575 ATM: ATM Layer 3

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ATM Layer Functions

0 Support Virtual Paths and Virtual Channels0 Multiplexing/demultiplexing cell streams onto transmission path0 Cell header generation/extraction0 Provides cell routing functions (in ATM switch)0 Performs VPI/VCI translation at switching nodes0 Generic flow control0 Traffic control and congestion control

0 Support a set of ATM layer Quality of Service (QoS) classes

Higher Layers

ATM Adaptation Layer AAL) Convergence Sublayer CS)

  Segmentation and ReassemblySublayer SAR)

ATM Layer ATM) Virtual Channel VC)Virtual Path VP)

Physical Layer PL)Transmission Convergence Sublayer TC)

Physical Medium Sublayer PM)

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CS575 ATM: ATM Layer 4

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UNI ATM Cell Header Format

Generic Flow Control GFC) Virtual Path Identifier VPI)

Virtual Channel Identifier VCI)

Header Error Control HEC)

8 7 6 5 4 3 2 1

Payload Type PT)CellLossPriority  CLP)

Bit

Octet 1

2

3

4

5

Virtual Path Identifier VPI)

Virtual Channel Identifier VCI)

Virtual Channel Identifier VCI)

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CS575 ATM: ATM Layer 5

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NNI ATM Cell Header Format

Virtual Channel Identifier VCI)

Header Error Control

HEC)

8 7 6 5 4 3 2 1

Payload Type PT)CellLossPriority  CLP)

Virtual Path Identifier VPI)

Virtual Path Identifier VPI)

Virtual Channel Identifier VCI)

Virtual Channel Identifier VCI)

Bit

Octet

1

2

3

4

5

6

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CS575 ATM: ATM Layer 6

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VP/VC/Transmission Path Concept

Source: Stallings: Data and Computer Communications

74/11/2013 10 10

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CS575 ATM: ATM Layer 7

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Virtual Channel and Virtual Path

0 A virtual channel (VC) is a concept used to describe unidirectional transport

of ATM cells associated by a common unique identifier value

0 This identifier is called the virtual channel identifier (VCI) and is part of the

cell header

0 A virtual channel link is a means of unidirectional transport of ATM cells

between a point where a VCI value is assigned and the point where that

value is translated or removed

0 A concatenation of VC links is called a virtual channel connection (VCC)

0 VCCs are provided for the purpose of user-user (workstation-workstation),

user-network (workstation-switch), or network-network (switch-switch)

information transfer

0 ATM cells are transported across the ATM network on VCCs0 Cell sequence integrity is preserved for the cells belonging to the same VCC

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CS575 ATM: ATM Layer 8

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Virtual Channel and Virtual Path (Continued)

0 A virtual path (VP) is a concept used to describe unidirectional transport ofATM cells belonging to virtual channels that are associated by a common

identifier value

0 This identifier is called the virtual path identifier (VPI) and is also part of

the cell header

0 A virtual path link is terminated by the points where a VPI value is assigned

and translated or removed

0 A concatenation of VP links is called a virtual path connection (VPC)

0 VPCs are provided for the purpose of user-user (workstation-workstation),

user-network (workstation-switch), or network-network (switch-switch)

information transfer

0 A VPC is a labeled path which can be used to transport a bundle of VCCs

that have the same end points and to manage the resources used by these

connections

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CS575 ATM: ATM Layer 9

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Virtual Channel and Virtual Path (Concluded)

0 If the VPCs are permanent or semi-permanent and have reservedcapacity, establishing new VCCs requires simple connectionadmission decisions at the VPC terminators of existing VPCs

0 This would enable faster connection establishment since transitnodes are not involved in the connection set up

0

The virtual path concept also allows the possibility of segregatingtraffic types according to Quality of Service (QoS) requirements

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CS575 ATM: ATM Layer 10

ATM Switch Routing/Switching

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CS575 ATM: ATM Layer 11

ATM Virtual Path Switching

Source: Stallings: Data and Computer Communications

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CS575 ATM: ATM Layer 12

ATM Virtual Channel/Virtual Path Switching

Source: Stallings: Data and Computer Communications

134/11/2013 10:10  

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CS575 ATM: ATM Layer 13

Impact of Random Bit Errors on HECPerformance

Stallings: Data and Computer Communications

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CS575 ATM: ATM Layer 14

Payload Type Indicator Encoding

  PTI

Coding Interpretation

000

001

010

011

100

101

110

111

User data cell, congestion not experienced,SDU-type = 0

User data cell, congestion not experienced, SDU-type = 1

User data cell, congestion experienced,SDU-type = 0User data cell, congestion experienced,SDU-type = 1

Segment OAM F5 flow relatedcellEnd-to-end OAM F5 flow relatedcell

Reserved for future traffic control and resourcemanagementReserved for futurefunctions

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CS575 ATM: ATM Layer 15

Management Information Flows

0 The ATM Layer management information is carried via F4 - F5OAM cells

0 The OAM cell flow used for end-to-end management functionsmay be carried through the private ATM switch and madeavailable to the users

0 The F4 flow is used for segment (link between ATM nodes) or VPend-to-end management at the VP level using VCIs 3 and 4

0 The F5 flow is used for segment (link between ATM nodes) orVC end-to-end management at the VC level using PTI codepoints 4 and 5

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CS575 ATM: ATM Layer 16

W. Stalling, Local and Metropolitan Area Networks, 6th edition,

Prentice Hall, 2000, Chapter 11 

References

W. Stalling, Data and Computer Communications, 6th edition,Prentice Hall, 2002, Chapters 11-12

A. Wu, Advanced Local Area Networks, Lectures & Slides, RivierCollege, 2001.