Configuring for Network Management Applications

LLDP (Link-Layer Discovery Protocol)

LLDP Packet Forwarding: An 802.1D-compliant switch does not forward LLDP packets, regardless of whether LLDP is globally enabled or disabled on the switch.

One IP Address Advertisement Per-Port: LLDP advertises only one IP address per-port, even if multiple IP addresses are configured by lldp config < port-list> ipAddrEnable on a given port.

802.1Q VLAN Information. LLDP packets do not include 802.1Q header information, and are always handled as untagged packets.

Effect of 802.1X Operation. If 802.1X port security is enabled on a port and a connected device is not authorized, LLDP packets are not transmitted or received on that port. Any neighbor data stored in the neighbor MIB for that port prior to the unauthorized device connection remains in the MIB until it ages out. If an unauthorized device later becomes authorized, LLDP transmit and receive operation resumes.

Neighbor Data Can Remain in the Neighbor Database After the

Neighbor Is Disconnected. After disconnecting a neighbor LLDP device from the switch, the neighbor can continue to appear in the switch’s neighbor database for an extended period if the neighbor’s holdtime-multiplieris high; especially if the refresh-intervalis large. Refer to “Changing the Time-to-Live for Transmitted Advertisements” on page 13-46.

Mandatory TLVs. All mandatory TLVs required for LLDP operation are also mandatory for LLDP-MED operation.

Determining the Switch Port Number Included in Topology Change

Notification Traps. Enabling topology change notification on a switch port and then connecting or disconnecting an LLDP-MED endpoint on that port causes the switch to send an SNMP trap to notify the designated management station(s). The port number included in the trap corresponds to the internal number the switch maintains for the designated port, and not the port’s external (slot/number) identity. To match the port’s external slot/number to the internal port number appearing in an SNMP trap, use the walkmib ifDescr command, as shown in the following figure:

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