UDLD Unidirectional Link Detection on port XXX

[giovannip]

Hello everyone,

I’m reaching out for some advice regarding an issue we’ve encountered with our network switches. We’ve had a switch go offline twice, and on both occasions, we saw the following error on the switches in the stack: "UDLD unidirectional link detection on port 1/52."

Has anyone experienced something similar, or could provide insights into what might be causing this issue? Any suggestions on how to resolve it and prevent it from recurring would be greatly appreciated.

Thanks in advance!

Gio

[PhilipDAth]

The two most common causes (IMHO):

• Cabling fault.  This issue is meant to trigger when a fibre cable can only send but not receive.
• Firmware bug.

[giovannip]

Hi PhilipDAth,

The strange thing is that it worked for months, and the same error occurs on both fiber ports in aggregation. After a forced reboot (by unplugging the power cable), it starts working correctly again. This happended twice in the last month

We have three other switches of the same model configured the same way, and we have never encountered this problem.

Thank you,
Giovanni

[PhilipDAth]

Any firmware updates in that time?

Are you using genuine Meraki optics?

[giovannip]

Dear PhilipDAth,

No updates and yes we are using Meraki optics: UDLD is in "Alert-only" mode but traffic is stopped.

Giovanni