Questions tagged [udld]

For questions about the Unidirectional Link Detection protocol.

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Why would a unidirectional link failure cause a switching loop?

Based on what I've read so far about UDLD and LoopGuard, it seems that in the case of a unidirectional link failure, a switching loop would form because the blocking port would transition into a ...
Ian Vaughn's user avatar
2 votes
2 answers
6k views

What is the difference between UDLD and BFD?

I understand is UDLD is almost BFD for layer2. Meaning in a control plane and forwarding plane separated router architecture BFD if running on the control plane can detect control plane failures but ...
bhatru's user avatar
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3 votes
2 answers
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UDLD on Nexus 5548 and Nexus 2232

Do you know if I turn on UDLD the 5K and 2K will speak UDLD to each other and do you feel this is a benefit to detect any link issues between the 5K and the FEX? Thanks
Smithy2k3's user avatar
  • 311
5 votes
1 answer
9k views

UDLD state: tx/rx loop detected

Relevant Log messages Feb 1 03:39:08.338 EST: %IPV6-4-DUPLICATE: Duplicate address FE80::212:44FF:FE4D:4400 on GigabitEthernet8/20 Feb 1 03:39:08.904 EST: %UDLD-SP-4-UDLD_PORT_DISABLED: UDLD ...
A L's user avatar
  • 3,310
15 votes
5 answers
5k views

Should i run UDLD with spanning tree?

Can spanning tree and UDLD be run together, and if so, is this a good idea?
Aaron's user avatar
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12 votes
1 answer
875 views

UDLD in VSS configurations

Since a VSS is a single system image, does it make sense to enable UDLD for links between the switch pair? We've seen some recovery problems that we feel might be due to UDLD mistakenly identifying an ...
JPFlathead's user avatar