Interfaces and Hardware Component Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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Interfaces and Hardware Component Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

Enable LLDP snoop

Updated: July 31, 2026

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This topic describes how to enable Link Layer Discovery Protocol (LLDP) snoop on an L2 interface to troubleshoot problems at the client ports.

If you have LLDP enabled on all Ethernet interfaces, the system enables Link Layer Discovery Protocol (LLDP) snoop on all L2 interfaces by default. You can use LLDP snooping to troubleshoot problems at the client ports.

Note

LLDP snoop is enabled only when LLDP RX is enabled and LLDP TX (transmit) is disabled either on interface or global LLDP configuration.

To enable LLDP snoop on an L2 interface, perform the following steps:

Procedure

	1.	Enter global configuration mode. Example: `Router#configure`
	2.	Enter interface configuration mode for the target L2 interface. Example: `Router(config)# interface FourHundredGigE 0/0/0/5`
	3.	Enter LLDP configuration mode for the interface. Example: `Router(config-if)#lldp`
	4.	Enable LLDP on the interface. Example: `Router(config-if)#enable`
	5.	Disable LLDP transmit operation on the interface. Example: `Router(config-if)#transmit disable`
	6.	Commit the configuration. Example: `Router(config-if)#commit`
	7.	Verify the configuration. Example: RP/0/RP0/CPU0:router#show run Fri Jan 21 17:45:17.529 UTC Building configuration... !! IOS XR Configuration 7.7.1.06I !! Last configuration change at Fri Jan 21 17:20:27 2022 by cisco ! hostname router1 logging console disable username xxxx group root-lr group cisco-support secret 10 $6$JELNK0oJaZZN7K0.$8YmyRWkq3D92i.lJc5QSdDkq4kUjU.g9U7sYIIAV1QVnSBemng5q.5EyYv6xSL9niDxRmKaFEATs9BkitDqpr. ! line console exec-timeout 0 0 absolute-timeout 0 session-timeout 0 ! line default exec-timeout 0 0 absolute-timeout 0 session-timeout 0 ! vty-pool default 0 99 line-template default call-home service active contact smart-licensing profile CiscoTAC-1 active destination transport-method email disable destination transport-method http ! ! interface MgmtEth0/RP0/CPU0/0 shutdown ! interface FourHundredGigE0/0/0/0 lldp enable transmit disable ! l2transport ! ! interface FourHundredGigE0/0/0/1 shutdown ! interface FourHundredGigE0/0/0/2 shutdown ! interface FourHundredGigE0/0/0/3 shutdown ! interface FourHundredGigE0/0/0/4 shutdown ! interface FourHundredGigE0/0/0/5 lldp enable transmit disable ! l2transport ! ! interface FourHundredGigE0/0/0/6 shutdown ! interface FourHundredGigE0/0/0/7 shutdown ! interface FourHundredGigE0/0/0/8 shutdown ! interface FourHundredGigE0/0/0/9 shutdown ! interface FourHundredGigE0/0/0/10 shutdown ! interface FourHundredGigE0/0/0/11 shutdown ! interface FourHundredGigE0/0/0/12 shutdown ! interface FourHundredGigE0/0/0/13 shutdown ! interface FourHundredGigE0/0/0/14 shutdown ! interface FourHundredGigE0/0/0/15 shutdown ! interface FourHundredGigE0/0/0/16 shutdown ! interface FourHundredGigE0/0/0/17 shutdown ! interface FourHundredGigE0/0/0/18 shutdown ! interface FourHundredGigE0/0/0/19 shutdown ! interface FourHundredGigE0/0/0/20 shutdown ! interface FourHundredGigE0/0/0/21 shutdown ! interface FourHundredGigE0/0/0/22 shutdown ! interface FourHundredGigE0/0/0/23 shutdown ! interface HundredGigE0/0/0/24 shutdown ! interface HundredGigE0/0/0/25 shutdown ! interface HundredGigE0/0/0/26 shutdown ! interface HundredGigE0/0/0/27 shutdown ! interface HundredGigE0/0/0/28 shutdown ! interface HundredGigE0/0/0/29 shutdown ! interface HundredGigE0/0/0/30 shutdown ! interface HundredGigE0/0/0/31 shutdown ! interface HundredGigE0/0/0/32 shutdown ! interface HundredGigE0/0/0/33 shutdown ! interface HundredGigE0/0/0/34 shutdown ! interface HundredGigE0/0/0/35 shutdown ! l2vpn bridge group bg1 bridge-domain bd1 interface FourHundredGigE0/0/0/0 ! interface FourHundredGigE0/0/0/5 ! ! ! ! end RP/0/RP0/CPU0:router# router0 <———> router1 <———-> router2 0/0/0/0 0/0/0/0/5 RP/0/RP0/CPU0:router0#config Fri Jan 21 17:16:41.713 UTC RP/0/RP0/CPU0:router0(config)#lldp RP/0/RP0/CPU0:router0(config-lldp)#exit RP/0/RP0/CPU0:router0(config)#int hu 0/0/0/0 RP/0/RP0/CPU0:router0(config-if)#no shut RP/0/RP0/CPU0:router0(config-if)#end Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]:yes RP/0/RP0/CPU0:router1#config Fri Jan 21 17:17:41.459 UTC RP/0/RP0/CPU0:router1(config)#int FourHundredGigE 0/0/0/0 RP/0/RP0/CPU0:router1(config-if)#no shut RP/0/RP0/CPU0:router1(config-if)#l2transport RP/0/RP0/CPU0:router1(config-if-l2)#exit RP/0/RP0/CPU0:router1(config-if)#lldp RP/0/RP0/CPU0:router1(config-lldp)#enable RP/0/RP0/CPU0:router1(config-lldp)#transmit disable RP/0/RP0/CPU0:router1(config-lldp)#exit RP/0/RP0/CPU0:router1(config-if)#exit RP/0/RP0/CPU0:router1(config)#int FourHundredGigE 0/0/0/5 RP/0/RP0/CPU0:router1(config-if)#no shut RP/0/RP0/CPU0:router1(config-if)#l2transport RP/0/RP0/CPU0:router1(config-if-l2)#exit RP/0/RP0/CPU0:router1(config-if)#lldp RP/0/RP0/CPU0:router1(config-lldp)#enable RP/0/RP0/CPU0:router1(config-lldp)#transmit disable RP/0/RP0/CPU0:router1(config-lldp)#exit RP/0/RP0/CPU0:router1(config-if)#exit RP/0/RP0/CPU0:router1(config)#l2vpn bridge group bg1 RP/0/RP0/CPU0:router1(config-l2vpn-bg)#bridge-domain bd1 RP/0/RP0/CPU0:router1(config-l2vpn-bg-bd)#interface FourHundredGigE 0/0/0/0 RP/0/RP0/CPU0:router1(config-l2vpn-bg-bd-ac)#exit RP/0/RP0/CPU0:router1(config-l2vpn-bg-bd)#interface FourHundredGigE 0/0/0/5 RP/0/RP0/CPU0:router1(config-l2vpn-bg-bd-ac)#end Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]:yes RP/0/RP0/CPU0:router0#config Fri Jan 21 17:16:41.713 UTC RP/0/RP0/CPU0:router0(config)#lldp RP/0/RP0/CPU0:router0(config-lldp)#exit RP/0/RP0/CPU0:router0(config)#int hu 0/0/0/0 RP/0/RP0/CPU0:router0(config-if)#no shut RP/0/RP0/CPU0:router0(config-if)#end Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]:yes RP/0/RP0/CPU0:router0#sh lldp neighbors Fri Jan 21 17:21:15.857 UTC 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 router2 HundredGigE0/0/0/0 120 R FourHundredGigE0/0/0/5 Total entries displayed: 1 RP/0/RP0/CPU0:router0# RP/0/RP0/CPU0:router0#sh lldp neighbors Fri Jan 21 17:21:15.857 UTC 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 router2 HundredGigE0/0/0/0 120 R FourHundredGigE0/0/0/5 Total entries displayed: 1 RP/0/RP0/CPU0:router0# RP/0/RP0/CPU0:router2#sh lldp neighbors Fri Jan 21 17:21:20.998 UTC 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 router0 FourHundredGigE0/0/0/5 120 R HundredGigE0/0/0/0 Total entries displayed: 1 RP/0/RP0/CPU0:router2# RP/0/RP0/CPU0:router1#show controllers npu stats traps-all instance all location all \| inc LLDP Fri Jan 21 17:24:07.964 UTC LLDP 0 22 RPLC_CPU 206 1538 6 4000 3975 IFG 1520 0 0 LLDP_SNOOP 0 28 RPLC_CPU 206 1538 6 4000 3862 NPU N/A 16 0 RP/0/RP0/CPU0:router1#

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Enable LLDP snoop

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