C-1
Cisco BPX 8600 Series Installation and Configuration
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
A P P E N D I X
C
ATM: An Overview
This chapter is an overview of Asynchronous Transfer Mechanism (ATM) on the BPX 8600 Series.
ATM transmits broadband information using fixed length, relatively small, 53-byte cells suitable for
carrying both constant rate data (such as, voice and video) as well as bursty data.
ATM evolved from the Broadband Integrated Services Digital Network (B-ISDN) standard, which in
turn is an extension of ISDN. ISDN defines service and interfaces for public telecommunications
networks.
B-ISDN utilizes a 7-layer reference model similar to the Open Systems Interconnection (OSI) 7-layer
architecture. ATM redefines the lower three levels as shown in Figure C-1. These are the Physical
Layer, the ATM layer, and the ATM Adaptation Layer (AAL).
Figure C-1
B-ISDN Model
Physical Layer
The physical layer is divided into two parts:
Higher layer functions
Convergence sublayer
(CS)
Physical
layer
SAR
ATM layer
TC
PM
AALs
(ATM
adaptation
layers)
Management plane
Control plane
User plane
Service specific, e.g., FR-SSCS
Common part convergence
sublayer CPCS
Segmentation and reassembly
Cell header insert/extract
Cell multiplexing/demultiplexing
VPI/VCI addressing and translation
Generic flow control
Transmission convergence
Physical medium
H8021
Содержание BPX 8600 Series
Страница 43: ...P A R T 1 The BPX Switch ...
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Страница 151: ...P A R T 2 Installation ...
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Страница 261: ...P A R T 3 Initial Configuration and Network Management ...
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Страница 291: ...P A R T 4 Configuring Connections ...
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Страница 481: ...P A R T 5 Troubleshooting and Maintenance ...
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Страница 531: ...P A R T 6 BPX Specifications ...
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Страница 563: ...P A R T 7 Appendices ...
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Страница 624: ...Glossary 24 Cisco BPX 8600 Series Installation and Configuration Release 9 3 0 Part Number 78 10674 01 Rev D0 July 2001 ...
Страница 630: ...Index 6 Cisco BPX 8600 Series Installation and Configuration Release 9 3 0 Part Number 78 10674 01 Rev D0 July 2001 ...