Avaya M-ACCF/SF ATM Address Registration, Networkhostidentifier, ATM Layer and Cell Structure

Chapter 1 Overview

Figure 1.14 UNI Management Entities

Avaya M770 Multifunction Switch

(M-ACCF OC-12 Module)

UME in

ATM Access

Module

ATM Switch

UME

(M770 ATM Switch)

ATM Address Registration

In order to establish an ATM connection, both the user and the network must know the ATM addresses used at that User-to-Network Interface (UNI). An example of an ATM address is shown below.

47.00.79.00.00.00.00.00.00.00.00.00.00.00.A0.3E.00.00.01.00

An ATM address consists of three sections of information and is 20 bytes in length:

network:host:identifier

Where network is a network prefix assigned to the device by the ATM Switch, and is 13 bytes long.

Where host is the edge-device identifier, and is 6 bytes long.

Where identifier identifies the client within the edge-device, and is 1 byte long.

ILMI provides a mechanism for the edge-device (in this case the ATM access module) to inform the ATM Switch of the addresses it represents.

When the ATM access module initializes, the ATM Switch sends a network prefix to the module. The module then tries to register itself with the ATM Switch by attaching the prefix to the front of its MAC address, and an identifier to the end of the address. It then sends this back to the ATM switch. If acceptable, the ATM Switch registers the address as the ATM Module’s ATM address.

The ATM Layer and Cell Structure

This section describes the cell structure, and how the ATM Layer uses the information stored in the cell header to perform each of its tasks.

The ATM Layer’s primary responsibility is to manage the sending and receiving of cells between the user and the network.

The ATM Layer accepts the user data and control information from the ATM Adaptation Layer, adds the cell header, and passes the resulting 53 byte cell to the physical layer.

In addition, it also receives cells from the physical layer, strips off the cell header and passes the remaining 48 bytes to the higher layer protocols.

22 Avaya M770 M-ACCF/SF ATM Access Modules User’s Guide