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What is LLDP?

Link Layer Discovery Protocol (LLDP) is a standard network discovery protocol similarly to Cisco Discovery Protocol (CDP) or Nortel Discovery Protocol. It helps network administrator to identify network devices. It allows devices to advertise and discover connected devices and their capabilities. Basically Cisco Discovery Protocol runs on Layer 2 (data link layer) on all Cisco manufactured devices. To support non-Cisco devices and to allow for interoperability between other devices, the switch supports the IEEE 802.1AB Link Layer Discovery Protocol (LLDP). LLDP also runs over the data link layer which allows two systems running different network layer protocols to learn about each other.

 

Configuring LLDP is pretty much exactly the same as CDP. We just need to change the “cdp” part to “lldp” of the commands. While CDP is enabled by default whereas LLDP is not enabled by default.

 

Some LLDP Commands:

 

Verifying LLDP when Disabled

uccollabing#show lldp

% LLDP is not enabled

 

Verifying LLDP when Enabled

 

uccollabing#show lldp

Global LLDP Information:

Status: ACTIVE

LLDP advertisements are sent every 30 seconds

LLDP hold time advertised is 120 seconds

LLDP interface reinitialisation delay is 2 seconds

 

Enabling LLDP : You need to enter the command to enable LLDP.

uccollabing(config)#lldp run

 

Diasable LLDP : You need to enter the below command to disable LLDP.

uccollabing(config)#no lldp run

 

To see neighbor devices using LLDP, enter the below commands: It will give you details like Device ID, Local Interface, Hold-time, Capability, Port ID etc.

uccollabing#show lldp neighbors

Capability codes:

(R) Router, (B) Bridge, (T) Telephone, (C) DOCSIS Cable Device

(W) WLAN Access Point, (P) Repeater, (S) Station, (O) Other

Device ID Local Intf Hold-time Capability Port ID

Router Fa0/1 120 R Fa0/0

Router Fa0/1 120 R Fa0/0

Total entries displayed: 2

 

To see a detailed information on lldp, enter the below commands.

uccollabing#show lldp neighbors detail

————————————————

Chassis id: 0001.C916.6501

Port id: Fa0/0

Port Description: FastEthernet0/0

System Name: Router

System Description:

Cisco IOS Software, 1841 Software (C1841-ADVIPSERVICESK9-M), Version 12.4(15)T1, RELEASE SOFTWARE (fc2)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2007 by Cisco Systems, Inc.

Compiled Wed 18-Jul-07 04:52 by pt_team

Time remaining: 90 seconds

System Capabilities: R

Enabled Capabilities: R

Management Addresses – not advertised

Auto Negotiation – supported, enabled

Physical media capabilities:

100baseT(HD)

Media Attachment Unit type: 10

Vlan ID: 1

————————————————

Chassis id: 00E0.B0D6.A101

Port id: Fa0/0

Port Description: FastEthernet0/0

System Name: Router

System Description:

Cisco IOS Software, 1841 Software (C1841-ADVIPSERVICESK9-M), Version 12.4(15)T1, RELEASE SOFTWARE (fc2)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2007 by Cisco Systems, Inc.

Compiled Wed 18-Jul-07 04:52 by pt_team

Time remaining: 90 seconds

System Capabilities: R

Enabled Capabilities: R

Management Addresses – not advertised

Auto Negotiation – supported, enabled

Physical media capabilities:

100baseT(HD)

Media Attachment Unit type: 10

Vlan ID: 1

Total entries displayed: 2

uccollabing#

 

Hope this helps!

What is LLDP? Some LLDP basic and useful commands was last modified: March 19th, 2017 by Administrator
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