Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE 26.1.x

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Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE 26.1.x

Link layer discovery protocol use cases

Updated: April 10, 2026

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Describes Link Layer Discovery Protocol (LLDP) use cases in high-availability setups.

A Link Layer Discovery Protocol (LLDP) use case is a network topology scenario that demonstrates how LLDP operates independently in high-availability wireless unit configurations where active and standby units maintain separate protocol instances.

High-availability LLDP operation

In a high-availability (HA) setup, when two wireless units act as active and standby, the LLDP still runs independently in both.

When you execute the LLDP neighbors command, the system name as the neighbor entry in the uplink switch is displayed as hostname-stbdy .

Enable LLDP (CLI)

Enable Link Layer Discovery Protocol (LLDP) to allow network devices to advertise information about themselves to other devices on the network.

LLDP is used for network topology discovery and network management. Enable LLDP when you need devices to share information such as system name, port description, and VLAN configuration with neighboring devices.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Enable Link Layer Discovery Protocol (LLDP).

Example:

Device(config)# lldp run
3.

Return to privileged EXEC mode.

Example:

Device(config)# end

LLDP is now enabled and the device will begin advertising and receiving LLDP information from neighboring devices.

Enable LLDP timers (CLI)

Configure LLDP timer settings to control packet transmission rates and retention periods.
LLDP timers control how frequently LLDP packets are sent, how long receivers keep packets, and initialization delays. These settings optimize LLDP performance for your network environment.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Enable LLDP holdtime timer.

Example:

Device(config)# lldp holdtime time-in-seconds

Example:

Device(config)# lldp holdtime 100

The timer decides how long the receiver must keep the packet. Valid range is from 0 to 65535 seconds.
3.

Specify the delay for LLDP to initialize.

Example:

Device(config)# lldp reinit delay-in-seconds

Example:

Device(config)# lldp reinit 3

Valid range is from 2 to 5 seconds.
4.

Specify the rate at which LLDP packets are sent.

Example:

Device(config)# lldp timer time-in-seconds

Example:

Device(config)# lldp timer 7

Valid range is from 5 to 65534 seconds.
5.

Return to privileged EXEC mode.

Example:

Device(config)# end
LLDP timers are now configured with the specified holdtime, reinitialization delay, and transmission rate settings.

Enable LLDP TLV-Select (CLI)

Enable specific LLDP TLV types to control what information is advertised by the device.
LLDP TLV-Select allows you to control which Type-Length-Value elements are included in LLDP advertisements, providing granular control over the information shared with neighboring devices.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Enable type, length, and value (TLV) selection for LLDP.

Example:

Device(config)# lldp tlv-select tlv-type

Example:

Device(config)# lldp tlv-select port-vlan

Available TLV types:

  • mac-phy-cfg : IEEE 802.3 MAC, physical configuration, or status TLV.

  • management-address : Management address TLV.

  • port-description : Port description TLV.

  • port-vlan : Port VLAN ID TLV.

  • system-capabilities : System capabilities TLV.

  • system-description : System description TLV.
3.

Return to privileged EXEC mode.

Example:

Device(config)# end
The specified LLDP TLV type is now enabled and will be included in LLDP advertisements sent by the device.

LLDP verification

Use the following show commands to view the LLDP details independently in the active and standby controller.

Timer and status verification

To verify the timer and status in the active and standby controller, use the following command:

Device# 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

Neighbor details verification

To verify the neighbor details in the active controller, use the following command:

Device# 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
9500-SW             Tw0/0/0        120        B,R             Twe1/0/14

To verify the neighbor details in the standby controller, use the following command:

Device# 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
9500-SW             Tw0/0/0        120        B,R             Twe1/0/13
Total entries displayed: 1

LLDP neighbor TLV details verification

To verify the LLDP neighbor (TLV) detail, use the following command:

Device# show lldp neighbors detail
------------------------------------------------
Local Intf: Te0/0/0
Chassis id: 2cd0.2d62.be80
Port id: Te1/1
Port Description: TenGigabitEthernet1/1
System Name: HSRP-ROUTER-1-15.cisco.com
 
System Description:
Cisco IOS Software, IOS-XE Software, Catalyst 4500 L3 Switch  Software (cat4500e-UNIVERSAL-M), Version 03.09.00.E RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2016 by Cisco Systems, Inc.
Compiled Tue 19-Jul
 
Time remaining: 99 seconds
System Capabilities: B,R
Enabled Capabilities: B,R
Management Addresses:
    IP: 8.109.0.1
    IPV6: 2001:12:1::2
Auto Negotiation - not supported
Physical media capabilities:
    Other/unknown
Media Attachment Unit type - not advertised
Vlan ID: 109
Peer Source MAC: 2cd0.2d62.be80

Uplink switch LLDP details verification

To verify the LLDP details in the uplink switch, use the following command:

Device# show lldp neighbors detail
------------------------------------------------
Local Intf: Te1/1
Chassis id: d4e8.80b3.0420
Port id: Te0/0/0
Port Description: TenGigabitEthernet0/0/0
System Name: WLC-BGL15.cisco.com
 
System Description:
Cisco IOS Software [Bangalore], C9800 Software (C9800_IOSXE-K9), Experimental Version 17.9.20220630:200739
Copyright (c) 1986-2022 by Cisco Systems, Inc.
Compiled Thu 30-Jun-22 13:19
 
Time remaining: 107 seconds
System Capabilities: B,R
Enabled Capabilities: R
Management Addresses:
    IP: 8.109.0.47
    IPV6: FD09:8:109::45
Auto Negotiation - not supported
Physical media capabilities - not advertised
Media Attachment Unit type - not advertised
Vlan ID: 109

LLDP packet errors verification

To verify LLDP packet errors, use the following command:

Device# show lldp errors
LLDP errors/overflows:
Total memory allocation failures: 0
Total encapsulation failures: 0
Total input queue overflows: 0
Total table overflows: 0

LLDP traffic statistics verification

To verify LLDP traffic statistics, use the following command:

Device# show lldp traffic
LLDP traffic statistics:
Total frames out: 18470
Total entries aged: 0
Total frames in: 6156
Total frames received in error: 0
Total frames discarded: 0
Total TLVs discarded: 0
Total TLVs unrecognized: 0