Cisco Catalyst 3750 Series Switches

Catalyst 3750/3750-E/3750-X Series Switches Using LLDP Configuration Example

Document ID: 113397

Updated: Jan 23, 2012



This document provides a sample configuration and verification for the Link Layer Discovery Protocol (LLDP) features on the Catalyst 3750/3750-E/3750-X Series Switches. Specifically, this document shows you how to configure the port-based traffic control features on a Catalyst 3750 switch.



Make sure that you meet these requirements before you attempt this configuration:

  • Have basic knowledge of configuration on Cisco Catalyst 3750/3750-E/3750-X Series Switches

  • Have basic understanding of LLDP features

Components Used

The information in this document is based on Cisco Catalyst 3750 Series Switches.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


Refer to the Cisco Technical Tips Conventions for more information on document conventions.

LLDP Overview

LLDP is a neighbor discovery protocol that allows non-Cisco devices to advertise information about themselves to other devices on the network. Cisco switches supports the IEEE 802.1AB LLDP which allow non-Cisco devices for interoperability between other devices. LLDP runs over the data-link layer which allows two devices running different network layer protocols to learn about each other.

LLDP discovers neighbor devices by using a set of attributes that contain type, length, and value descriptions. These attributes are referred to as TLVs. LLDP supported devices can use TLVs to receive and send information to their neighbors. This protocol can advertise details such as configuration information, device capabilities, and device identity.

The switch supports these basic management TLVs, which are mandatory LLDP TLVs:

  • Port description TLV

  • System name TLV

  • System description TLV

  • System capabilities TLV

  • Management address TLV

These organizationally-specific LLDP TLVs are also advertised to support LLDP-MED:

  • Port VLAN ID TLV (IEEE 802.1 organizationally specific TLVs)

  • MAC/PHY configuration/status TLV (IEEE 802.3 organizationally-specific TLVs)


In this section, you are presented with the information needed to configure the LLDP features described in this document.

Note: Use the Command Lookup Tool (registered customers only) in order to obtain more information on the commands used in this section.

Network Diagram

This document uses this network setup:



This document uses these configurations:

Catalyst 3750 Switch
Switch#configure terminal

!--- Enable LLDP globally on the switch.

Switch(config)#lldp run

!--- Specify time for the device to hold LLDP information.

Switch(config)#lldp holdtime 180

!--- Set the time for sending frequency of LLDP updates.

Switch(config)#lldp timer 50

!--- Enable LLDP specific to an interface.

Switch(config)#interface gigabitethernet 1/0/1

!--- Enable the interface to send LLDP.

Switch(config-if)#lldp transmit

!--- Enable the interface to receive LLDP.

Switch(config-if)#lldp receive

!--- Return to privileged EXEC mode.


!--- Save the configurations in the device.

switch(config)#copy running-config startup-config

!--- Disable LLDP feature on the switch.

Switch(config)#no lldp run


Use this section to confirm that your configuration works properly.

The Output Interpreter Tool (registered customers only) (OIT) supports certain show commands. Use the OIT in order to view an analysis of show command output.

Use the show lldp interface [interface-id] command in order to display information about interfaces with LLDP enabled.

For example:

Switch#show lldp interface gigabitethernet1/0/1
    Tx: enabled
    Rx: enabled
    Tx state: IDLE
    Rx state: WAIT FOR FRAME

Use the show lldp neighbors command in order to display information about neighbors.

For example:

Switch#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
Nortel IP Phone     Gi1/0/1        180        T               0019.e1e7.018d
Polycom SoundPoint IGi1/0/19       180        T               0004.f22f.88b7
Baseline Switch 2426Gi1/0/18       180        P,B             Ethernet0/26
Baseline Switch 2426Gi1/0/22       180        P,B             Ethernet0/26

Total entries displayed: 4

Use the show lldp neighbors detail command in order to display information about neighbors in detail.

For example:

Switch#show lldp neig detail

Chassis id:
Port id: 0019.e1e7.018d
Port Description: Nortel IP Phone
System Name - not advertised

System Description:
Nortel IP Telephone 1230E, Firmware:062AC53

Time remaining: 166 seconds
System Capabilities: B,T
Enabled Capabilities: T
Management Addresses - not advertised
Auto Negotiation - supported, enabled
Physical media capabilities:
    Symm Pause(FD)
    Symm, Asym Pause(FD)
Media Attachment Unit type: 16

MED Information:

    MED Codes:
          (NP) Network Policy, (LI) Location Identification
          (PS) Power Source Entity, (PD) Power Device
          (IN) Inventory

    F/W revision: 062AC53
    Manufacturer: Nortel-05
    Model: IP Phone 1230E
    Capabilities: NP, LI, PD, IN
    Device type: Endpoint Class III
    Network Policy(Voice): Unknown
    PD device, Power source: Unknown, Power Priority: High, Wattage: 6.0

Use the show lldp traffic command in order to display LLDP counters.

For example:

Switch#show lldp traffic 

LLDP traffic statistics:

   Total frames out: 560

   Total entries aged: 0

   Total frames in: 211

   Total frames received in error: 0

   Total frames discarded: 0

   Total TLVs discarded: 208

   Total TLVs unrecognized: 208

Use the show lldp errors command in order to display LLDP error counters.

For example:

Switch#show lldp errors

LLDP errors/overflows:
    Total memory allocation failures: 0
    Total encapsulation failures: 0
    Total input queue overflows: 0
    Total table overflows: 0

Related Information

Updated: Jan 23, 2012
Document ID: 113397