•A new neighbor is discovered. A new LLDP frame is received carrying device information new to the local device.

•The LLDP operating mode of the port changes from Disable or Rx to TxRx or Tx.

This is the fast sending mechanism of LLDP. With this mechanism, the specified number of LLDP frames is sent successively at the 1-second interval. The mechanism helps LLDP neighbors discover the local device as soon as possible. Then, the normal LLDP frame transmission interval resumes.

Receiving LLDP frames

An LLDP-enabled port operating in TxRx mode or Rx mode confirms the validity of TLVs carried in every received LLDP frame. If the TLVs are valid, the information is saved and an aging timer is set. When the TTL value in the Time to Live TLV carried in the LLDP frame becomes zero, the information ages out immediately.

Protocols and standards

•IEEE 802.1AB-2005,Station and Media Access Control Connectivity Discovery

•ANSI/TIA-1057,Link Layer Discovery Protocol for Media Endpoint Devices

Recommended LLDP configuration procedure

StepRemarks

Optional.

1.Enabling LLDP on ports. By default, LLDP is enabled on ports.

Make sure LLDP is also enabled globally, because LLDP can work on a port only when it is enabled both globally and on the port.

 

 

Optional.

 

 

LLDP settings include LLDP operating mode, packet encapsulation, CDP

 

 

compatibility, device information polling, trapping, and advertisable TLVs.

2.

Setting LLDP parameters

By default:

• The LLDP operating mode is TxRx.

 

on ports.

 

• The encapsulation format is Ethernet II.

 

 

 

 

• CDP compatibility is disabled.

 

 

• Device information polling and trapping are disabled.

 

 

• All TLVs except the Location Identification TLV are advertised.

 

 

 

3.

Configuring LLDP

Required.

By default, global LLDP is disabled.

 

globally.

 

To enable LLDP to work on a port, enable LLDP both globally and on the port.

 

 

 

 

 

 

 

Optional.

4.

Displaying LLDP

You can display the local LLDP information, neighbor information, statistics,

and status information of a port, where:

 

information for a port.

• The local LLDP information refers to the TLVs to be advertised by the local

device to neighbors.

• The neighbor information refers to the TLVs received from neighbors.

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