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
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:
â¢On fiber-optic or twisted-pair links, one of the ports cannot send or receive traffic.
â¢On fiber-optic or twisted-pair links, one of the ports is down while the other is up.