What ports can I configure UDLD on?

[danielseijas3010]

Hi Everyone,

The cisco book to prepare for 300-115 CCNP-Switch test is kind of contradictory when it comes to where the UDLD security feature can be configured. There is one section of the book that says that only fiber-optic switchports can be configured with the UDLD feature, however, immediately after there is a section that shows the command to enable the feature on fiber and copper switchports. 

So can I configure UDLD on fiber ports or only or also on copper ports?

Best Regards

Daniel

[AllertGen]

Hello.

You can use UDLD. But in most cases in copper wired connections you no need it because connection is checking by link negotiations.

Best Regards.

[Rolf Fischer]

Hi Daniel,

perhaps the books refers to the two configuration modes of UDLD.

When you enable UDLD in the global configuration mode, it is automatically enabled on all fiber ports (exclusively). But you can overwrite the global configuration on a per-port basis (interface configuration mode) and in this way enable it on copper ports as well. As Allen already said it is debatable wheather it makes sense or not to enable UDLD on copper ports.

HTH
Rolf

[Ganesh Hariharan]

Hi Everyone,The cisco book to prepare for 300-115 CCNP-Switch test is kind of contradictory when it comes to where the UDLD security feature can be configured. There is one section of the book that says that only fiber-optic switchports can be configured with the UDLD feature, however, immediately after there is a section that shows the command to enable the feature on fiber and copper switchports. So can I configure UDLD on fiber ports or only or also on copper ports?Best Regards Daniel

Hello Daniel,

UDLD allows devices connected through fiber-optic or copper Ethernet cables (for example, Category 5 cabling) to monitor the physical configuration of the cables and detect when a unidirectional link exists.

And there are certain cases where a copper LAN port gets stuck - remaining up/up state while the neighbor is down/down. UDLD will detect this failure on the stuck port and errdisable it.

Have a look on the below link for UDLD configuration on both the ports.

UDLD with Fiber & Copper

Hope it Helps..

-GI