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Devices no longer showing up in "mac-address-table"

We've recently had a problem that at first we thought might have been related to VxWorks 12.0.3T on the AP350's, but yesterday it started appearing with a different piece of equipment.

The problem is this. We have lost connectivity with these devices on the network. Their IP addresses stopped pinging, their MAC addresses have disappeared from the "mac-address-table" on the switches they're on. The ports show "up/up" that they're connected to, but it appears that nothing is on the link.

The first time we had the problem it was with AP350's and we had just upgraded the switch OS and the VxWorks on the AP's. At that time 6 or 7 devices spread out across the plant "disappeared" and we had to play around quite a bit for them to come back. They would disappear a few times and finally a cisco tech suggested we move to 12.04 VxWorks and the problems seemed to go away.

This time they aren't Vxworks, or even 802.11b access points, they are 900Mhz ARLAN access-points running fairly old OS's and have been stable for quite awhile. The OS's on the network haven't been upgraded for quite awhile (at least a month) but yesterday we were changing what VLAN we had our user VLAN on from 1 to a higher #. Right after the change, no devices could connect to the ARLANS, but we could get in and monitor them, but then all of a sudden they "went-away". Now we only see the "up/up" interface but nothing else... The switches are 2950 series switches running the latest release IOS (12.1(19)EA1a)

Is there anything I can do to figure out why these devices no longer register mac addresses or that we can't see them. Any hints on what to debug would be appreciated!!


Re: Devices no longer showing up in "mac-address-table"

If you do a show vlan on the 2950 does it show up/active . My guess is the vlan is not active . Because it was in the default vlan (1) it worked before . Just because you create the virtual interface for the vlan does not make it active. Do the following command . Also make sure the vlan is not in the shutdown state .

conf t

vlan XXX state active

Re: Devices no longer showing up in "mac-address-table"

Yes, the vlan is/was up and active. Most of the other ports in the switch went to the same VLAN and those users were working just fine. Also, after the equipment was power-cycled (yesterday) it came back in a fully functional state with nothing else needed.

However, I am still wondering if there are any other diagnositic tools/commands I might be able to use to see if there is something on a port. We were pretty mystified when the mac-address of the item disappeared from the switches table. Had no idea as to where to go from there, but have had it happen with two different device types. The only similarity in device types is that they are both wireless access-points, but although most we've had problems with were 802.11b AP's, these ones were non-standard 900Mhz AP's that are very old...