2920 dropping fibre connection to core intermittently

[ccsadmin]

Hi All,

I'm relatively new to the HP switching world and was hoping someone could provide me with some advice. Over the past few months, two seperate cabinets have developed an issue of losing connection back to the core switch. The lights on the switch look normal, but at the core switch side the SFP module has no lights/traffic. The only way to resolve the issue is to manually power cycle the switches. Usually this was happening once every few weeks, but it has happened twice this morning. Restarting the core switch has no effect. At first I thought maybe it was a firmware issue, but both of the cabinets are on completely different revisions. We have around 10 cabinets dotted around the site in total and only these 2 are experiencing the issue. Could it be that we have introduced a loop into these cabinets and loop-detection is killing SFP? If that is the case, how would we go about resolving/identifying the issue?

Would be really grateful for any input, am in a bit of pickle now!

[parnassus]

Greetings!

Well, the first thing to do is to gather the status of your involved switches (so a lot of show ... commands, just to start with), things to check are, as example:

• software versions involved
• topology (who is who and who is connected to) for uplink/downlink involved interfaces
• status of involved interfaces (detail) to catch errors, if an
• STP topology
• Loop-Protection
• SFP Transceivers status (show tech transceivers)
• running configuration for involved ports/uplinks

With the information above one can start to diagnose the issue or, at least, exclude non-relevant items...