IBM ATM OC-3c manual Interim Local Management Interface Ilmi, ATM Address Registration

Interim Local Management Interface (ILMI)

The ATM Forum produced the Interim Local Management Interface (ILMI) to increase monitoring and diagnostic facilities, and to provide ATM address registration at the User-to-Network Interface (UNI).

ILMI uses a Management Information Base (MIB) and the SNMP protocol.

Each device that provides ILMI support contains a UNI Management Entity (UME), which uses SNMP to access management information stored in the ILMI MIB of the adjacent switch, see Figure 2-9.

Figure 2-9UNI Management Entities

Asynchronous Transfer Mode (ATM) Layer 2-13

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.

47007900000000000000000000:00A03E000001:00

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 Module) to inform the ATM Switch of the addresses it represents.

When the ATM Module initializes, the ATM Switch sends a network prefix to the ATM Module. The ATM 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.