UDLD on routed ports

[dm2020]

Hi All,

I have been reading up on UDLD and one of the primary use cases of using this protocol is to prevent L2 loops if a link becomes unidirectional. Does UDLD have any advantages on a routed ports or should this used on L2 ports only?

Thanks

[balaji.bandi]

UDLD on L2 port,  More information can be found here :

https://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/10591-77.html

[dm2020]

Hi

Thanks for the reply.

I have checked our switches and UDLD is enabled on our L3 ports with full bidirectional neighbor states so it does seems that IOS-XE allows UDLD on routed ports. Are you saying that there is no benefit to this and the benefit is on L2 ports only?

Thank you

[Reza Sharifi]

Hi,

UDLD is a layer 2 protocol to detect physical faults (layer-1). So, I don't see why it can't be used for both l2 and l3 links..

HTH

[Leo Laohoo]

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@dm2020 wrote:

Does UDLD have any advantages on a routed ports or should this used on L2 ports only?

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Is UDLD auto-recovery going to be enabled?  
IF it is, don't enable UDLD:  Auto-recovery simply defeats the purpose of UDLD plus, on a routed port(s), may cause high CPU (if the port goes up/down very, very often) which will ultimately lead to a crash.