3Com 4500 VLAN 1 interface problems.

[grdrager]

I have 3 edge stacks of 4500s connected back to a 4900 core that I'm having a periodic problem with. The VLAN 1 interface is becoming non-communicative and I'm not sure what to try next.

By non-communicative, I mean the I can't ping the interface, nor can I ping other devices if I'm connected to the switch. The interface itself shows both physical and protocol as up. In addition, downstream devices that are on the management vlan (primarily distributed wireless APs)are dead. Traffic to/from other vlans is fine (the 4900s do all the inter-vlan routing), so user workstations are not effected.

This morning I came into all three stacks in this state. In the past I had rebooted the stacks to clear the issue. I tried to do a bit more debug this morning, and found that if I simply reassigned the IP address to the interface (literally using the same IP/subnet that it was already showing as up and running), the whole fabric would reset and then the switch was working again.

Any ideas on where I might look next or how to monitor a situation like this?

 

[SYQUEST]

Although I am not using the same hardware you have, I had a similar situation when I set up a VLAN between a CISCO C2950G-24EI and a 3COM 2226+ Baseline (3C16475BS).

First I built the config in the C2950 then built the config in the BS 2226+. I tested the VLAN functions and everything appeared to work OK. Saved configs on both switches. Then I powered down the BS 2226+ to install it in its permanent home. Got everything installed and powered up. Checked the configs everything looked OK. Ran the same tests to verify VLAN path continuity and everything worked OK. Three days later, the vendor that was going to use the VLAN showed up and installed their hardware. I put up patch cords to connect their hardware. The links came, but no ping or continuity!. I tried all kinds of things - no results! So I deleted the VLAN config in the BS 2226+ and then built it right back and it came alive! So far it has not failed again. That was back in September 2006 and both switches are on UPS.

Don't know if that is something strange about 3COM switches or what?

....JIM....