Nortel 5520 ARP table issue

[dgjlee]

Stack of three 5520's, fully licensed for routing, Software version 6.2.1

I have a strange issue where devices are dropping out of the arp table on my stack. I have tried connecting voice equipment from three different manufactures, to three different vlans in this stack. Initially, when the equipment is first plugged in, I can ping the device from a different subnet and see its mac and ip entry in the arp table. After 5 to 7 minutes, I cannot ping the device and the arp entry has gone. If I then telnet directly onto the stack and ping the device, the arp entry comes back and the world is good again for 5 to 7 minutes.

The ARPLifeTime is set to 360 minutes and this is a very small network, maximum of 100 entries at any one time.

This is causing me an issue with a CS1000 upgrade to 7.5 as the DSP resources keep dropping of the network so registration is never complete.

I can get around this by adding static entries but really need to know why these devices are dropping out of the ARP table.

 

[VinceWhirlwind]

That sounds like fun.

I had an issue in an earlier version of software on those 5520s where the MAC address entry was migrating to the uplink port (for no apparent reason) and so the device became uncontactable that way.

Yours sounds like a similar issue. Mine was fixed via a firmware upgrade.

Is it only affecting phones and not PCs, though? That would make it a per-VLAN issue, which is interesting - what if you put some phones on untagged ports and see if they behave any differently?