IP phones getting addresses from wrong vlan

paul.p · ‎12-22-2002

My CM and 2620 gateway router are on one vlan and my data is on another. The 2620 is the dhcp server for the IP phones only and I have a dhcp server on the data vlan providing addresses for the computers. Most of my phones are working fine but some phones which were working and all new phones recently added are getting IPs from the data vlan. I can unplug a working phone and plug one of the non-working ones into the same port and it gets a data IP. If I release the IP and unplug my data dhcp server, the phone never gets an IP at all even though the phone is on the same vlan as the 2620. I checked the dhcp server on the 2620 and have plenty of unused addresses. I've tried moving the data dhcp server to a different port, thinking the port may be bridging the vlans but got no change.

allan.wells · ‎12-22-2002

Have you tried to set a static on a phone in the voice vlan and see if that works .

Then go back to dhcp.

Otherwise post your config so we can look at it.

paul.p · ‎12-23-2002

When I set a static IP, the phone works fine but then I go back to dhcp I once again get an address from the data vlan. This started suddenly and only affects a few of the 150 phones I have on the CM. Location dosen't matter as a working phone will continue to work when moved to a port where a non-working one was located.

paul.p · ‎12-23-2002

The problem appears to be in the 2620 router providing my IP addresses. When I removed all devices except the CM, 2620 router and phones which wern't working, I of course no longer get an IP from the data server but the phone still does not get an IP from the 2620. I cleared all the leased addresses and the phone started working. I reconnected the rest of the network, including the data dhcp server and restarted all phones. Now all my phones work and when I show the dhcp pool, I have the correct number registered, 149, whereas before I had 144 registered with the 2620 and 5 registered with the windows dhcp server. Looks like something was hosed up in the 2620.

s.fensom · ‎01-21-2003

Did you actually define this problem? i.e what is causing it? I use an AS5300 as the DHCP and have the same scenario.

paul.p · ‎01-22-2003

I was unable to actually identify what caused the problem and have had no relapses. Cisco tac, normally very good, wasn't much help on this and kept insisting the problem was a device on my network bridging the vlans. I know this wasn't the case because I disconnected everything from the data vlan and still could not get an ip address from the 2620 until I cleared the dhcp server.

Paul