3Com 4200G, 5500 Dldp Configuration Guide, Configuring Dldp, Both of the switches support Dldp

12

DLDP CONFIGURATION GUIDE

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 18 Network diagram for DLDP configuration

GE1/1/3	SwitchA	GE1/1/4
GE1/1/3	SwitchB	GE1/1/4

PC

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

■Configure DLDP to automatically disconnect the detected unidirectional link.

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

Applicable Products

Product series	Software version	Hardware version
Switch 5500	Release V03.02.04	All versions
Switch 5500G	Release V03.02.04	All versions
Switch 4500	Release V03.03.00	All versions

Configuration Procedure ■ Configure Switch A