UDLD and Loopguard

[cedar_lee]

Question for Spanning-tree experts.

Should udld and loopguard be used together on trunk ports? Or either one should be good enough? Why?

Thanks,

Cedar

[Reza Sharifi]

Hello Cedar,

For more protection, Cisco recommends both

use loop guard in conjunction with UDLD in order to provide the most protection. Loop guard prevents STP loops with the speed of the STP version that is in use. And UDLD takes care of the detection of unidirectional connections on individual EtherChannel links or in cases in which BPDUs do not flow along the broken direction.

Here is the best practice document for more info

http://www.cisco.com/en/US/products/hw/switches/ps700/products_white_paper09186a00801b49a4.shtml

HTH

Reza

[cedar_lee]

Thanks so much Reza for the answer.

Cedar