Changed DHCP scope on router, IP phones wont register

[sjhern]

We needed more IP addresses for our DHCP pool for the Voice VLAN and to accomodate for more phones. We disabled the old Pool, made the change to the new POOL, and rebooted the switches that the phones where on. Then the switches came back online and the phones obtained a new IP address from the NEW scope but was unable to register with the Call Managers. One of our Network Engineers thinks is something to do with the VLAN.dat file not properly being updated with those changes, and suggested deleting that file and allowing it to be regeneterated. Anyone have any insight to this issue?

[msolak]

do you have option 150 for TFTP assigned to you new scope?

greetings

mehmet

[mshavrov]

Most likely it's DHCP option 150. It defines TFTP server, from which a Cisco IP phone should get all initial configs. Just check the way how old scope was configured, and do the same way.

If you deleted old pool configuration, and lost your old config, then add following lines to your router DHCP configuration:

option 150 ip

Good luck,

Mike Shavrov

CCNP, CCDP, CCSP, Voice Specialisation, MCSE W2K, etc.

www.ciscoheadsetadapter.com

[Aaron Harrison]

VLAN.dat contains your switch VLAN db - if your phones are receiving IP addresses, then the VLAN must be operational and your ip-helpers are working fine...

Likelihood is that the option 150 is missing.

[sjhern]

Option 150 did point to our Publisher. Aka our TFTP server. The New Scope was Identical to the Old Scope except the Address range was larger.