Wide-Area Networks - CCIE Routing and Switching Exam Certification Guide - page 236

In Figure 5-25, A, B, and C are in the same peer group and D is in a different peer group at the
same level. Also, addresses A and B identify different interfaces on the same switch.

A peer group with a level of 48 uses the first 6 bytes of the ATM address for routing and is at a
higher level than a peer group at level 56.

Interim Local Management Interface (ILMI)
ILMI is an ATM Forum standard that specifies the use of mechanisms and formats previously
defined by the Simple Network Management Protocol (SNMP). Although it is based on SNMP,
ILMI communication uses a transport other than IP that traverses only the physical ATM link.
ILMI messages are carried over a well-known PVC. The ATM Forum PVC for ILMI uses the
VCI 16.

ILMI provides the following:
•

Configuration, status, and control information about physical and ATM-layer parameters
of the ATM interface

•

Interface attributes organized in a standard Management Information Base (MIB)
structure

•

Access to the adjacent ATM Interface Management Entity (IME) through the ILMI
communication protocol

•

Address registration across a UNI

•

Auto-configuration of a LAN Emulation Client (LEC)

The ILMI protocol supports bidirectional exchanges of ATM interface parameters between
IMEs. Using SNMP queries, a network management system can report on the status of the
physical layer, ATM layer, VCs or VPs, ES address registration, and service registration such as
LAN emulation (LANE) service.

When ILMI is enabled on both ends of a link, a management system can retrieve information
on the interface number, interface address, media type, number of VPIs and VCI supported,
number of VCs or VPs active, type of interface (NNI or UNI), QoS parameters, adjacent node
identification, plus much more.

For PNNI, SVC signaling operation, adjacent node discovery, and LANE registration, ILMI
must be enabled and configured.

When configuring ILMI, the following parameters must be configured to the same values at
both ends of the link:
•

ILMI VPI/VCI —The VPI and VCI reserved for ILMI messages; typically 0/16.

•

ILMI Polling —Enabled or disabled.

•

Trap Enabled —Enables or disables the sending of unsolicited event and alarm reports.