Table of Contents

1 DLDP Configuration Guide· 1-1

Configuring DLDP· 1-1

Network Diagram·· 1-1

Networking and Configuration Requirements· 1-1

Applicable Product Matrix· 1-1

Configuration Procedure· 1-2

Complete Configuration· 1-2

Precautions· 1-3

 

Configuring DLDP

Sometimes, unidirectional links may appear in networks. On a unidirectional link, one end can receive packets from the other end but the other end cannot.

Unidirectional links can be caused by fiber cross-connection or fiber cut (including single-fiber cut and lack of a fiber connection).

They can cause problems such as spanning tree topology loops.

You can use the Device Link Detection Protocol (DLDP) to monitor the link status of optical fiber cables and copper twisted pairs such as super category 5 twisted pairs. Once detecting a unidirectional link, DLDP shuts down the port or ask you to do so depending on your configuration.

Network Diagram

Figure 1-1 Network diagram for DLDP configuration

 

Networking and Configuration Requirements

l          Switch A and Switch B are connected through two pairs of fibers. The connecting ports are operating in mandatory full duplex mode at 1000 Mbps. Both of the switches support DLDP.

l          Configure DLDP to automatically disconnect the detected unidirectional link.

l          After the fibers are connected correctly, the port shut down by DLDP restores automatically.

Applicable Product Matrix

Product series	Software version	Hardware version
S5600 series Ethernet switches	Release 1510, Release 1602	All versions
S5100-SI/EI series Ethernet switches	Release 2200, Release 2201	All versions
S3600-SI/EI series Ethernet switches	Release 1510, Release 1602	All versions
S3100-EI series Ethernet switches	Release 2104, Release 2107	All versions
S3100-52P	Release 1500, Release 1602	S3100-52P

 

Configuration Procedure

l          Configure Switch A

# Configure the ports to work in mandatory full duplex mode at 1000 Mbps.

<SwitchA> system-view

[SwitchA] interface GigabitEthernet 1/1/3

[SwitchA-GigabitEthernet1/1/3] duplex full

[SwitchA-GigabitEthernet1/1/3] speed 1000

[SwitchA-GigabitEthernet1/1/3] quit

[SwitchA] interface GigabitEthernet 1/1/4

[SwitchA-GigabitEthernet1/1/4] duplex full

[SwitchA-GigabitEthernet1/1/4] speed 1000

[SwitchA-GigabitEthernet1/1/4] quit

# Enable DLDP globally.

[SwitchA] dldp enable

# Set the interval for sending DLDP packets to 15 seconds.

[SwitchA] dldp interval 15

# Configure DLDP to operate in enhanced mode.

[SwitchA] dldp work-mode enhance

# Configure DLDP to shut down a port automatically once a unidirectional link is detected on it.

[SwitchA] dldp unidirectional-shutdown auto

# Set the DelayDown timer to five seconds.

[SwitchA] dldp delaydown-timer 5

# Display the DLDP state.

[SwitchA] display dldp 1

# Restore the ports brought down by DLDP.

[SwitchA] dldp reset

l          Configure Switch B

The configuration on Switch B is the same as that on Switch A.

Complete Configuration

l          Configuration on Switch A

#

dldp interval 15

dldp work-mode enhance

dldp delaydown-timer 5

#

interface Gigabitethernet 1/1/3

 duplex full

 speed 1000

 dldp enable

#

interface Gigabitethernet 1/1/4

 duplex full

 speed 1000

 dldp enable

l          Configuration on Switch B

The configuration on Switch B is the same as that on Switch A.

Precautions

1)        When enabling DLDP on two connected devices, make sure that they are using the same software version. Otherwise, DLDP may malfunction.

2)        When optical fibers are cross-connected, two or three ports are in the disable state, and the remaining ports are in the inactive state.

3)        DLDP in the enhanced mode can identify unidirectional links caused by fiber cross-connection or fiber cut.

4)        DLDP in the normal mode can identify only unidirectional links caused by fiber cross-connection.