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.

To enable LLDP, TNSR requires global settings for LLDP and at least one interface must participate in LLDP.

LLDP Router Configuration

Three LLDP commands are available in configuration mode (Configuration Mode) to configure global LLDP parameters for this router. All of these commands are required to activate LLDP.

lldp system-name <name>

The router hostname advertised by LLDP.

lldp tx-interval <seconds>

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

lldp tx-hold <value>

Transmit hold multiplier, which is multiplied by the transmit interval to calculate the total time used for the Time-To-Live (TTL) of the LLDP message.

Tip

If the transmit interval is 30 and the transmit hold multiplier is 4, then the advertised TTL of the LLDP message is 120 (4*30=120).

Warning

The LLDP timer options do not have default values and must be manually set.

Example:

tnsr(config)# lldp system-name MyRouter
tnsr(config)# lldp tx-interval 30
tnsr(config)# lldp tx-hold 4

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 <name>

The name of the interface as advertised by LLDP. This must be present on an interface for it to participate in 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.

Warning

LLDP requires lldp port-name to be present on at least one interface to function.

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. When LLDP parameters change, TNSR requires a dataplane restart for the new settings to take effect. See Known Issues.

LLDP Status

LLDP status cannot be viewed natively in TNSR at this time, but the status may be obtained directly from the dataplane at the CLI using the command dataplane shell sudo vppctl show lldp:

tnsr# dataplane shell sudo vppctl show lldp
Local interface          Peer chassis ID    Remote port ID  Last heard  Last sent  Status
TenGigabitEthernet3/0/0  54:78:1a:c0:ab:80  Fa0/1           17.1s ago   25.3s ago  active

Alternately, run the command directly from a host shell prompt and not through the TNSR CLI using sudo dp-exec vppctl show lldp.

Warning

In either of these examples, the user account must have access to sudo to run the command.