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: September 8, 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

Enter global configuration mode.
Example:
```
Router#configure
```
Enter interface configuration mode for the target L2 interface.
Example:
```
Router(config)# interface FourHundredGigE 0/0/0/5
```
Enter LLDP configuration mode for the interface.
Example:
```
Router(config-if)#lldp
```
Enable LLDP on the interface.
Example:
```
Router(config-if)#enable
```
Disable LLDP transmit operation on the interface.
Example:
```
Router(config-if)#transmit disable
```
Commit the configuration.
Example:
```
Router(config-if)#commit
```

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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