[c-nsp] dhcp problems with ip phones

[Arne Larsen / Region Nordjylland]

Hi All.

I know this might be a bit of topic, but anyhow
I have dhcp problems with Siemens IP-phone endpoints under Cisco ws-c3750.
It's quite odd, the problem only happens between two Siemens phones.
Sometimes when an en endpoint tries to get an ip address via dhcp, an other answer on behalf.
The flow is like this.
Endpoint send an discover, the server sends an offer via the relay agent.
The endpoint sends an request and the server ack's.
After this the endpoint sends an gratuitous arp on the requested address, and then an other answers that it has the ip address.
I've pulled out the arp table before enabling a new endpoint to get the ip address list on the switch.
But after the decline I can't find the mac address in the arp table that I pull out before activating the new endpoint.
If I use a laptop or an other vendors ip phone I don't se the problem
Does anyone know off a similar problem, is there a known bug on Cisco ws-c3750 with software release 12.2(25r)SEE3.
I know that everyone will point towards the Siemens phones, and I'm doing that myself but I just what to be sure that I haven't missed something.

/Arne