I'm having a trouble to migrate phones from existing CM5 to CUCM8.6 because all the phones still refer the old CM5 as their DHCP server.
I've changed the "ip helper-address 192.168.2.11" <--old CM5 ip to "ip helper-address 192.168.2.21".
I've reload the phones, factory reset, shut unshut the port but all to no avail.I even deleted one the DHCP subnet in the old CM5 but they still managed to getting ip address from it.
This is really strange.
Is there any possibility that you have anoither DHCP server on your netowrk? Did you check the phone Network Configuration Setting and verify if the dhcp server is being showed as " 192.168.2.11"?
Also try connecting a PC to the same switch port where phone is connected and verify which ip address you are getting?
Phones are still showing 192.168.2.11 as the DHCP server. It should display 192.168.2.21 (new CUCM) because we've pointing the ip helper address to here.
The only DHCP server in the network is our Core switch (10.10.x.x) and CM5 (192.168.2.11/12).
If i connecting my PC/laptop to the same port it will get data ip address, so it's pointless.
Now, i'm doing workaround solution. Creating new DHCP pool is the Core switch with similar configuration i created in the CUCM. Phones are able to registering at the new CUCM.
Does this mean our new CUCM aren't releasing ip address? Is there anyway to verify CUCM DHCP leasing status?
There should be no problem with CUCM releasing ip address. Did you try restarting the dhcp monitor service of the CUCM after setting new dhcp?
Can you post your dhcp scope configuartion(screen shot from cucm)?
I didnt realise you had a data vlan in there :-)
Is your Call Manager showing "Cisco DHCP Monitor Service " "Activated" on the Cisco Call Manager 'Cisco Unified Serviceability' page?.
Try stopping and starting DHCP service again from Tools--> Service Activation page.
Inorder to check the DHCP lease you may use below link. Not sure if the link is applicable for version 8.6 as well.