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Cisco 7921 Wireless DCHP Timeout after loosing connection

Unanswered Question
Jul 7th, 2008
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Running 7921

AP 1200 Software Version 12.3(4)JA


I'm having a problem that after I set the phone up. Everything comes up fine and works great but whenever I hit a deadzone or if it looses connection, the phone will try to configure the IP and then it gives me a DHCP timeout and never connects again. If I reset my TFTP settings it then works again. How can I prevent this?

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Georgios Nikitas Mon, 07/07/2008 - 22:30
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Are you using the latest firmware at your phone?


You can also choose to use a static ip for that specific phone.

lawsonlivingston Tue, 07/08/2008 - 05:30
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I'm using 1.1.1 on the phone. Also this is happening on all the 7921 phones I currently have, which is 5. I have noticed that if I turn the TFTP off then back on it will pick up but I don't want to have to do that for every phone.

Richard Atkin Tue, 07/08/2008 - 13:36
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What security are you using on the APs?


If it's something 'clever' like 802.1x, then it's not uncommon for devices to think one thing, and the infrastructure to think another (ie, phone thinks its on the network, but network disagrees, or vice-versa).


If you're running 802.1x, i'd suggest (if possible) that you need to have a WDS server / go lightweight.


Alternative, (if slightly cheekier) answers are;


A - Remove blackspots!


B - Use static addresses - this also decreases the initial connect time as no reliance upon DHCP

migilles Fri, 07/11/2008 - 17:59
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Don't think moving to static IP is a good idea as it requires more management overhead.

I am not sure if you are using a Cisco WLAN solution or 3rd party. We have seen this issue with some 3rd party solutions, which resulted in a 3rd party issue in regards to power save enabled clients.

For TFTP, not sure why this fixes the issue other than will restart the provisioning process. If TFTP is set for DHCP, then ensure the DHCP scope has option 150 defined for your CM's TFTP server.

rseiler Sat, 07/12/2008 - 15:59
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Why on earth are you running IOS version 12.3(4)JA on your AP1200's? That IOS version is from 2004 and has been deferred since 2005.


*Anyone* you would ask about that IOS version would have recommended 12.3(7)JA2 at a *minimum* since 2006!!!


Upgrade your AP1200 to 12.3(8)JEC1 (Mar 2008) and see if that resolves your issue.


I have a big red flag for this project if that is how old your IOS version is, what other fundamental problems are there in your deployment?

lawsonlivingston Mon, 07/14/2008 - 11:21
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I have upgraded all the AP to the latest version. I just started at this company a few months ago and I'm learning the Cisco system and what version we are running.


Also I had to do some modification in the IP through telnet, for some reason the company that set up the AP had added an extra WEP connection. Got rid of that and everything seems to be working fine.

migilles Mon, 07/14/2008 - 12:55
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Yes per my 7921G Deployment Guide @ http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7921g/6_0/english/deployment/guide/7921dply.pdf, you need 12.3(8)JEA or later to run the 7921G phone successfully.

12.3(8)JEC is ok for the 1230, but would suggest 12.4(3g)JA1 or later for the 1240.


For static WEP, need to ensure the keys on the AP and the client match. If you have 2 keys where one is tx on key 1 and the other is on key 2, then the other side needs to have the same key to be able to decrypt the packets.

I am also having the exact same issues. I have a Cisco TAC case running for 2 months and I am just going around in circles.From the TAC team (We recommend 12.3(8)JEC train for the older 1100 and 1200 series APs) which I have loaded onto the access points and this made no difference.


I have been running 7920 phones on the same network for 2 years with no issues.


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