Tip

This is the documentation for the 19.12 version. Looking for the documentation of the latest version? Have a look here.

Link Layer Discovery Protocol

The Link Layer Discovery Protocol (LLDP) service provides a method for discovering which routers are connected to a LAN segment, and offers a way to discover the topology of a network.

Configuring the LLDP Service

LLDP is configured in two places: Global router parameters and per-interface parameters.

LLDP Router Configuration

Three LLDP commands are available in configuration mode (Configuration Mode) to configure global LLDP parameters for this router:

lldp system-name:

The router hostname advertised by LLDP.

lldp tx-interval:

Transmit interval, which controls the time between LLDP messages in seconds.

lldp tx-hold:

Transmit hold time, which is a multiple of the transmit interval used for the Time-To-Live (TTL) of the LLDP message.

Tip

If the transmit interval is 5 and the transmit hold time is 4, then the advertised TTL of the LLDP message is 20 (4*5=20).

Example:

tnsr(config)# lldp system-name MyRouter
tnsr(config)# lldp tx-hold 3
tnsr(config)# lldp tx-interval

These parameters can be changed at any time.

LLDP Interface Configuration

Additional LLDP commands are available in config-interface mode (Interface Command) to configure per-interface LLDP identification:

lldp port-name:

The name of the interface as advertised by LLDP.

lldp management (ipv4|ipv6) <ip-address>:

The IPv4 and/or IPv6 address advertised by LLDP as a means to manage this router on this interface.

lldp management oid <oid>:

An object identifier associated with the management IP address on this interface.

Example:

tnsr(config)# interface TenGigabitEthernet3/0/0
tnsr(config-interface)# lldp port-name MyPort
tnsr(config-interface)# lldp management ipv4 192.0.2.123
tnsr(config-interface)# lldp management ipv6 2001:db8::1:2:3:4
tnsr(config-interface)# exit
tnsr(config)#

Warning

Due to a limitation of the underlying API, all LLDP interface parameters must be configured at the same time and cannot be changed. This will be fixed in a later release.