LLDP Configuration (Link Layer Discovery Protocol)

Owned by Tracy Yang
Jul 18, 2024
2 min read

LLDP is a standard link-layer discovery protocol which can broadcast its capability, IP address, ID, and interface name as TLVs (Type/Length/Value) in LLDP PDUs (Link Layer Discovery Protocol Data Units). 

An LLDP PDU includes 4 basic TLVs and several optional TLVs.

Basic TLVs include the Chassis ID, Port ID, TTL and End TLVs.

In L2/L3, you can select the following optional TLVs:

TLV Name

Description

mac-phy-cfg

MAC address of the system

management-address

Management IP address of the system

port-description

The port description of system

port-vlan

The VLAN ID of the port

system-capabilities

System capability (e.g. switching, routing)

system-description

System description

system-name

System name

Configuring the LLDP Mode

LLDP supports 4 modes: TxRx, Tx_only, Rx_only, and Disabled. By default, LLDP is disabled. 

In TxRx mode, the system transmits and receives LLDPDUs. In Tx_only, the system only transmits LLDPDUs. In Rx_only, the system only receives LLDPDUs. In Disabled, the system will not transmit or receive any LLDPDUs.

After enabling LLDP, each interface will be in tx_rx mode by default.

You can configure the system as shown below:

admin@XorPlus# set protocols lldp enable true
admin@XorPlus# set protocols lldp interface te-1/1/1 working-mode tx_rx 
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#

Selecting Optional TLVs

admin@XorPlus# set protocols lldp tlv-select mac-phy-cfg true
admin@XorPlus# set protocols lldp tlv-select management-address true
admin@XorPlus# set protocols lldp tlv-select port-description true 
admin@XorPlus# set protocols lldp tlv-select system-capabilities true
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#

Displaying LLDP Information

admin@XorPlus# show protocols lldp
Waiting for building configuration.
enable: true
tlv-select {
} 


admin@XorPlus# run show lldp neighbor all detail  
Local Port: te-1/1/1
LLDP info:
---------------------------------------------------------------------------------------
  Time To Live: 106
  Chassis Id: 68:21:5F:7F:10:C6
  Port ID: te-1/1/1
  Port Description: te-1/1/1
  System Name: PICOS
  System Description: Pica8, Inc.,AS5835_54T, PICOS 4.3.2/9b1219e332
  System Capability: B, RBridge, Router
  System Enabled Capability: Bridge, Router
  Management Address: 10.10.51.12
  Default VLAN ID: 1
  Auto Negotiation: Supported, Enabled
  Physical media capabilities: Others, 10base_T, 100base_TX, 100base_TXFD, 1000base_T, 1000base_TFD
  Media Attachment Unit type: 1000base_T_Full_Duplex
  802.3 Power via MDI :Not available


LLDP MED is not Enabled. 


Total entries displayed: 1

Configuring Other Parameters

You can configure other parameters, such as advertisement-interval, hold-time-multiplier, reinit-delay, and transmit-delay, in a similar manner.

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