I have a strange problem here (or at least I think it’s strange)..
I’m using one WS-C2960-24TC-L and a WS-C2960-48TC-L running 12.2(44)SE1 software version.
I configured an etherchannel between those two devices using multimode fiber and GLC-FE-100FX connectors. I have two interfaces being part of this etherchannel .
At the beginning, I didn’t configured UDLD and I had the following behavior:
- I can disconnect one connector at the time (the RX or the TX), on one of the switches and I still have connectivity between the devices. I found some information that this is because this software version and this particular SFP connector has Far End Fault Indication capability.
I moved on and load the 12.2(50)SE software version on one of the devices. Then I got the following behavior:
- When I disconnect the RX or the TX from the first fiber link (on the 12.2(50)SE device) => no connectivity between the devices;
- When I disconnect the RX or the TX from the second fiber link I do have connectivity between the devices.
So what I imagined is that, Far End Fault Indication is not supported on this software version (even if there was a known issue related to this and it is supposed to be solved starting from the 12.2 (37)SE release) and I tried to configure “udld aggressive” as workaround. I globally enabled UDLD but there was no change in the behavior : the link was DOWN at one end ant it was still UP at the other end like UDLD didn’t even exist. Here below is the output of the “show udld Gi0/1” on one side :
Port enable administrative configuration setting: Enabled / in aggressive mode
Port enable operational state: Enabled / in aggressive mode
Current bidirectional state: Unknown
Current operational state: Advertisement
Message interval: 7
Time out interval: 5
No neighbor cache information stored
On the other side, the link was down but the interface was not put in errdisable => there was no connectivity between the devices.
I reinstalled the 12.2(44)SE1 on both switches and let the udld activated. This time, the faulty link was DOWN on both ends (so I had connectivity between the devices via the other link) but the faulty interface was not put in errdisable.
Did anyone already encounter this kind of behavior or I’m missing something somewhere.
It looks like the 12.2(44)SE1 works fine even if UDLD is not enabled. So there must be the Far End Fault capability doing the job….. ? But again, why the interface is not put in errdisable state ?
As for the 12.2(50)SE software version , this is not working even if UDLD is enabled ?