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UDLD 6500-3750

I have a network with Cat 6500 as distribution and 3750 stacks as access. The access stacks is connected to distribution with 10Gig links in a layer 2 solution with STP.

I use 10GigSR X2 modules and 6708+6716 linecards.

My problem: UDLD aggressive is enabled och both distribution switches. But UDLD seems to work only on a few access switches. When I enable UDLD on some of the 3750 stacks, the link goes to err-disable (even though the link seems to be ok).

The configuration on the 3750 stacks are identical.

I run 12.2.33SXH and 12.2.46

Anybody have any idea?


Hall of Fame Super Silver

Re: UDLD 6500-3750

Hello Jorgen,

A possible alternate way to protect from undirectiona links is to use

STP loop guard enable it on all links on both sides of each link.

Note also that if using Rapid STP UDLD is too slow for it.

We use Rapid STP with Rapid STP + spanning-tree loopguard + storm control 1%.

We have had problems with 6708 in 12.2(18)SXF that have been resolved moving to 12.2(33)SXH2.

Our access switches are C4506.

Hope to help


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