Posted on April 22, 2019 4:55 pm
 |  Asked by Neal
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Is there a UDLD (Unidirectional Link Detection) available on Arista? I see on the sh interface there is a uni-link but cannot find any info on it.

Thank you in advance for your help.

Ethernet1 is up, line protocol is up (connected)
Hardware is Ethernet, address is 2899.3af2.0735 (bia 2899.3af2.0735)
Ethernet MTU 9214 bytes , BW 10000000 kbit
Full-duplex, 10Gb/s, auto negotiation: off, uni-link: n/a

Posted by Kishore Sukumaran
Answered on May 10, 2019 11:56 am

Hello Neal,

Thanks for your question.

Arista devices currently do not support UDLD (Unidirectional Link Detection). This is because the UDLD protocol uses an external vendor specific heartbeats.

However, we do have a RFE (Request For Enhancement) in place created for this RFE1636. Besides this, we do have a bridge assurance feature which could be used for detecting unidirectional link failures and is also supported by other vendors. Bridge assurance is globally enabled by default, but also must be enabled on per port basis by designating the port as a network port and configuring spanning-tree portfast networok command.

Please refer to section from the EOS manua for more details on this:

Also, on Arista the 10G(and greater) links have fault detection mechanism which detects a uni-directional link failure.If a link detects a fault in signal then it signals a local fault and propagates a remote fault to the other end which brings the interface down.

Hope this information helped.


OK Thanks for the info. I’ll go through the manual and try it out on our test switches.

(Neal at May 13, 2019 2:01 pm)

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