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Chapter 1 Overview
22 Avaya M770 M-ACCF/SF ATM Access Modules User’s Guide
Figure 1.14 UNI Management Entities
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.
Avaya M770 Multifunction Switch
(M-ACCF O
C-12 Module)
ATM Switch
(M770 ATM Switch)
UME
UME in
ATM Access
Module