IP address of phone can't change to the new subnet

[qilin zhang]

Hello all,

Our phones can not obtain the new subnet ip address when they move to the new VLAN, it retains the old ip address, for 7900 series phones, we can use the DHCP release to release the old ip address and obtain the new ip address, but for 6900 series phones, some phones still can not obtain the new address after applying the DHCP release activity. We must do the factory reset to obtain the address.

The access switch is 2960 and core switch is 6509 with VSS, ccm version is 8.5. At first we use the DC as the DHCP server, we also tried to use 6509 as the DHCP server, but the problem still exists.

Why the phones can not renew the ip address?

Thanks,

Kirin

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[Mike Lydick]

Did you lower the lease time for the DHCP scope before transitioning to the new vlan. I see that a few phones will not move over even after a reboot. We have to physically release address of the phone or clear the config off the phone to get them to request a new address.

Mike

[qilin zhang]

If the phones move in the same VLAN, lower the lease time can force the phone to get a new ip address, but the situation is the phones are moved between VLANs, I think it will get the new ip address immediately.

Kirin,

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[Jonathan Schulenberg]

I sense a Wireshark in your immediate future. A customer of mine had this problem recently. After a lot of confusion a packet capture showed that the DHCP server was responding with an ACK (it should have sent a NACK) in response to the REQUEST from the phone. I have no idea what was wrong with their [Windows] DHCP server; however, they just revoked all of the leases which finally got the NACK response. After that the phone did a normal DISCOVER and we were golden.

[qilin zhang]

Does the problem exist in windows 2008?

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[aslamta123]

Hi,

We are also facing the same issue after we migrated to CCM 8.5. When a phone moved from one vlan to another vlan it retains the old vlan IP address. In our case disabling the old Vlan scope in DHCP server will only help to get the new IP address. We also tried with different DHCP serves like Adonis, Microsoft etc.

Wireshark capture at the client side shows the client sends DHCP discover but the relay agent offer the address from the old vlan.

Also tried to configure the same voice VLAN as a data on a switch port and connected a Laptop to that port, still the IP address of the old Vlan retains in laptop as well.

Rgds

Aslam

[qilin zhang]

Hi hAslam,

Do you have the same 69XX type phones as mine? I think that may be the 69XX phone problem. I will open a TAC case for this problem.

Kirin

[mmoulson1]

We had this problem on a recent migration from a CUCMBE to CUCM. We changed the option 150 on the DHCP scope but the phones did not like it, we also setup a new VLAN with a new DHCP range and still faced the issue. Our fix was to factory reset the phones! Sound a little drastic but we were moving onto newer phone loads any way and there were not many phones to reset as it was not a big implementation! We had various 79XX series phones.

Good luck I will keep an eye on this thread the see if any fix is posted!

Matty

[aslamta123]

Hi Kirin/Matty

Our issue got resolved by changing the parameters in DHCP server, the issue due to super scope in DHCP servers. As part of the migration we created new group in the DHCP and all the IPT vlans moved under this group. This acted as a super scope and DHCP server to offer an IP address from any one of networks configured under that group irrespective of the GIDDR. Coincidently the same happened on the ADONIS too. On Adonis DHCP this feature called shared-network.

After shifted the IPT vlans from this group the phones started getting the correct IP address..

Cheers

Aslam

[acampbell]

Guys,

I think we need to look at this.

69xx phones are troublesome on CUCM 8

http://www.cisco.com/en/US/partner/docs/voice_ip_comm/cuipph/6921_6941_6961/8_6/english/admin_guide/6921trb.html#wp1037000

Hope this helps

Alex