420-24T losing VLAN assignments

[pg1942]

We've been experiencing a problem with two of our stacks of 420 switches, running HW:#02 FW:3.1.0.5 W:v3.1.0.04 and we wondered if anyone has experienced a similar problem?

On several occasions they have lost the VLAN assignments for one of the VLANs on the bottom switches in the stack. There are four VLANs defined on these switches and it only occurs to one VLAN and only on the bottom 3 switches in the stack of 7.

This has happened three times now in the last few weeks. Twice this week on one stack, once on another a few weeks ago. This morning it appeared to have happened overnight since we've lost several classrooms that were working yesterday.

The problem only seems to happen to one of the VLANs (PVID 16) What we would see is that on the VLAN Configuration screen all the ports that should be showing a '+' as members of VLAN 16 on the bottom three switches would have turned to '-' and they wouldn't be members of any of the other VLANs when we check the VLAN configuration screen for other VLAN Ids

However, on the VLAN Port Configuration screen the PVID will still show as members of VLAN 16.

We're not seeing any errors in the switch logs and when we manually reconfigure all is well - until the next time.

We have ten stacks of 420s on this site and we've only seen it happen on two. The kits been in here for about three years and we've not had any problems previously.

 

[dane775]

I think the 420 had some unusual problems. It was replaced by the 425.

Since you're only having this problem on 2 stacks it begs a few questions. What's different about those stacks? Do they have more traffic, more VLANs, a more complex config? Is there anything you can think of that would make those stacks more susceptible to problems?

I would factory reset the stack and reconfigure it. Check all cascade cables (very carefully...the modules and cables can be a bit unstable).

You're on the latest code, so an upgrade wouldn't apply (since other stacks are okay, it doesn't point to code issues anyway, but it can't be ruled out).

If possible...move the switches around in the stack to see if the problem follows switches or stays on the bottom 3 units.

Good luck...

 

[networkmuti]

I've had the same problem on Baystack 450 switches. Ports automatically assign themselves (membership and PVID) to VLAN 1. This would be especially prevelant duraing/after a software upgrade, where almost an entire switch might 'jump' to VLAN 1.

The problem in our case however, is probably related to the fact that we are running EAP on our switch ports. The workaround so far has been to disable EAP on the affected port, change the VLAN config and then re-enable EAP.