11.5. Configuring UDLD

Overview

Function Introduction

The Unidirectional Link Detection protocol is a light-weight protocol that can be used to detect and disable one-way connections before they create dangerous situations such as Spanning Tree loops or other protocol malfunctions.

Principle Description

N/A

Configuration

image

Fig. 11.11 UDLD

The following configurations are same on Switch1 and Switch2.

step 1 Enter the configure mode

Switch# configure terminal

step 2 Enter the interface configure mode and enable udld

Switch(config)# interface eth-0-9
Switch(config-if)# no shutdown
Switch(config-if)# udld port
Switch(config-if)# exit

step 3 Enable udld globally

Switch(config)# udld enable

step 4 Set the message interval (optional)

If the message is not specified, use the default value: 15 seconds.

Switch(config)# udld message interval 10

step 5 Exit the configure mode

Switch(config)# end

step 6 Validation

Display the result on Switch1.

Switch# show udld eth-0-9
Interface eth-0-9
 ------------------------
UDLD mode : normal
Operation state : Bidirectional
Message interval : 10
Message timeout : 3
Neighbor 1
 ------------------------
Device ID : 4c7b.8510.ab00
Port ID : eth-0-9
Device Name : Switch
Message interval: 10
Message timeout : 3
Link Status : bidirectional
Expiration time : 29

Display the result on Switch2.

Switch# show udld eth-0-9
Interface eth-0-9
 -----------------------
UDLD mode : normal
Operation state : Bidirectional
Message interval: 10
Message timeout : 3
Neighbor 1
 -----------------------
Device ID : 28bc.83db.8400
Port ID : eth-0-9
Device Name : Switch
Message interval: 10
Message timeout : 3
Link Status : bidirectional
Expiration time : 23

Application cases

N/A