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Switch management features 75
Figure 22
How LLDP works
1. The Ethernet Routing Switch and router advertise chassis or port IDs
and system descriptions to each other.
2. The devices store the information about each other in local MIB
databases, accessible using SNMP.
3. A network management system retrieves the data stored by each device
and builds a network topology map.
LLDP operational modes
LLDP is a one-way protocol. An LLDP agent can transmit information
about the capabilities and current status of the system associated with its
MAC service access point (MSAP) identifier. The LLDP agent can also
receive information about the capabilities and current status of the system
associated with a remote MSAP identifier. However, LLDP agents cannot
solicit information from each other.
You can set the local LLDP agent to transmit only, receive only, or to both
transmit and receive LLDP information. You can configure the state for
LLDP reception and transmission using SNMP or CLI commands.
Connectivity and management information
The information fields in each LLDP frame are contained in a Link Layer
Discovery Protocol Data Unit (LLDPDU) as a sequence of short, variable
length, information elements known as type, length, value (TLV). Each
LLDPDU includes the following four mandatory TLVs:
• chassis ID TLV
Nortel Ethernet Routing Switch 2500 Series
Overview — System Configuration
NN47215-500 (323162-B) 02.02 Standard
4.1 19 November 2007
Copyright © 2007, Nortel Networks
.