Voice VLAN devices getting data vlan IP

Unanswered Question
Apr 14th, 2010

Ok this is a weird problem. My Cisco phones at random times (days or weeks) and random phones (different buildings) are getting a data vlan IP address. The phones are still up and when a user can receive (phone rings) and call other extensions but when they connect the phone goes busy. If you power cycle the phone it will receive a new IP address on the voice vlan.

I am assuming this is a routing program since it is coming across vlans to get the data vlan IP. We have 2 separate vlans on 2 different DHCP server. The data vlan DHCP server is windows server 2003 and the Voice vlan is currently on our cisco 4507r. We did have a server 2000 box with the DHCP server for the voice vlan but changed it to see it there was a difference. I had ip helper-address pointing to the DHCP server and still had phones getting a data vlan IP.

The 4507r is the core of the network. The Cisco Voice servers are connected to the gi eth ports on the 4507. The data vlan DHCP server is also connect to the gi eth ports on the 4507r. The vlans are configured for the ports.

It is only happening with Cisco IP Phones 7970 series phones.

I am lost and do not know where else to look to try and trouble shot this.

I have this problem too.
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Giuseppe Larosa Wed, 04/14/2010 - 11:17

Hello Jmaurer,

>> It is only happening with Cisco IP Phones 7970 series phones.

This is a starting point.

Have you recently updated the CCM or CUCM cluster? this can have pushed a firmware upgrade on the phones and the new phone load can be affected by the issue.

To be honest you may find better help in IP Telephony forum under Unified Communications.

Hope to help


jmaurer1205 Wed, 04/14/2010 - 12:39

Ok I will place this post over there.

We have had this problem since before I started here about 2 years ago. We have updated the phones several times without out a resolution. Also we recently upgraded to CUCM to the latest and still have this problem. The phone vendor is looking into this still but I thought maybe there was traffic issue or a route confusion somewhere that might be a vlan or routing problem.


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