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New Member

Have to "clear arp" table to get traffic to pass

I have a very unusual problem that I can't figure out. We have a 2800 series router we are using as our voice gateway. It has been running fine for about 6 months but then a few days ago, it started dropping off the network every 10 minutes or so. We initially found that unplugging the patch cable and pluggint it back in would correct the problem temporarily for another 10 minutes or so. However, now we have discovered that the simply running "clear arp" on the router gets it back up and running.

Here is what happens. The router drops off the network, not pingable by CallManager or Unity. If we do a clear arp, it is immediately back up and going again.

We have updated the IOS, even changed from spservices to ip voice ios, moved it to a different switch, and even set the arp entries manually, but we still have to clear arp every few minutes to keep it up. When it stops responding on the network, we can console into it and look at the arp table, and its right. But until we issue a clear arp, it can't connect to certain network devices like CM and Unity.

Any ideas?

New Member

Re: Have to "clear arp" table to get traffic to pass

The problem is almost surely due to duplicate addresses somewhere. Someone has probably accidentally configured the gateway address as the static IP address on a different device on the same LAN segment. Or, the gateway address was accidentally given out via DHCP.

Regardless, I'd bet money that something like this happened.

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