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colmgrier
Beginner

UDLD:

1. Can UDLD aggressive mode work on copper links?

2. What UDLD mode should I use for layer 2/3 ether-channel ports.

3. Is the below best practice for fiber ports

UDLD - Single fiber ports links

UDLD aggressive - Port-channel fiber ports links

1 ACCEPTED SOLUTION

Accepted Solutions

Hi,

UDLD should not cause any issue to trunk and IP phone link. UDLD aggressive will prevent the any port goes into unidirection and when it detectes it, it will error disabled the port.

Just quoting how UDLD works from the doc cd and hope this will explain more:

In aggressive mode, UDLD detects a unidirectional link by using the previous detection methods. UDLD in aggressive mode can also detect a unidirectional link on a point-to-point link on which no failure between the two devices is allowed. It can also detect a unidirectional link when one of these problems exists:

•On fiber-optic or twisted-pair links, one of the ports cannot send or receive traffic.

•On fiber-optic or twisted-pair links, one of the ports is down while the other is up.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_50_se/configuration/guide/swudld.html#wp1020819

HTH,

jerry

View solution in original post

4 REPLIES 4
Jerry Ye
Cisco Employee

Hi,

Here are the answer to your questions:

1. UDLD aggressive mode can work with copper ports

2. Generally, UDLD aggressive should be use for all the ports

3. See answer to question #2.

HTH,

jerry

Thanks for the reply.

IS it a good idea to use UDLD with copper for trunk links and ip phone link?

Were should UDLD aggressive not be used?

Hi,

UDLD should not cause any issue to trunk and IP phone link. UDLD aggressive will prevent the any port goes into unidirection and when it detectes it, it will error disabled the port.

Just quoting how UDLD works from the doc cd and hope this will explain more:

In aggressive mode, UDLD detects a unidirectional link by using the previous detection methods. UDLD in aggressive mode can also detect a unidirectional link on a point-to-point link on which no failure between the two devices is allowed. It can also detect a unidirectional link when one of these problems exists:

•On fiber-optic or twisted-pair links, one of the ports cannot send or receive traffic.

•On fiber-optic or twisted-pair links, one of the ports is down while the other is up.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_50_se/configuration/guide/swudld.html#wp1020819

HTH,

jerry

shubhamkumarhcl
Beginner