8841 dhcp timeout

[Cevollrath]

Has anyone encountered 8841’s dhcp timeout after attempting to reconnect from loss of wireless signal? My 8841’s are continuously moving between buildings and wireless controllers. Occasionally they lose wireless connection, when attempting to reconnect, I get a dhcp timeout and the connection attempts stop. It has become an issue with multiple wireless phones. 

[Leo Laohoo]

Depends on the firmware of the phone.
There were several bugs in relation to "out of range" behaviours.
Consider getting a firmware update first and see if the situation improves.

[Cevollrath]

I apologize, I made a typo on the phone model. The wireless phones are 8821’s I’m sure you gathered that from the description. The phones are all running the latest firmware. 

[Leo Laohoo]

Ok so when the phones are in this condition, what happens if the phone is powered off & then on?

[Cevollrath]

The results vary. Occasionally they will reconnect. More often then not, I have to remove the batteries and walk them into another building to hit another wireless controller.

[pieterh]

was there any change in the environment or was this behaviour always present, but increased?

find hints in the lVoice Over Wireless LAN (VoWLAN) Troubleshooting Guide

you mention multiple wireless controllers

1) do these have a common DHCP scope/subnet for the phones? or does each has its own scope?
    check this document section roaming between subnets

2) are all WLCs in the same mobility group ?

the phone may "hang on" to the old ip-address too long before requesting a new one

[Cevollrath]

No environmental changes. We have gradually added more 8821’s to the network over the last year. Each WLC has a common scope/subnet. The phones do disassociate and release IP addresses but looking through logs it seems that the subsequent DHCP requests just time out. I can usually walk far enough to hit a new WLC and obtain an address that way, but in my opinion that is not a valid fix since we are constantly adding new wireless phones