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LS21
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AP roaming with Cisco 7925G

Mon Feb 18, 2013 3:51 pm

Hi Guys,

Having a hard time getting Cisco 7925G phones to roam 'cleanly' in a Cisco unified wireless environment; Cisco 2504 controller with Cisco LAP1142n (lightweight) APs. The phone SSID is not broadcast and is using WEP encryption.

The problem is that when the user is walking around the property, traversing from AP to AP in-call (external and internal calls), they notice the point at which the phone roams from AP to AP - it's literally two or three seconds of no sound and then the call resumes back again. Please note that the call does not disconnect, you only lose Audio. Obviously, to any normal person this may be acceptable but to my client it is not (billionaire, or there abouts).

Fast SSID change has been enabled, we've tried locking the SSID to 802.11a only, b only and g only but with only slightly better results when locked to B. We've lowered the client roaming threshold RSSI to -75dB from -80dB, this also yielded better results but still a couple of seconds gap exists. Cisco TAC came in on a Webex session earlier, changed a few QoS settings and advanced wireless settings on the controller, but to no avail. Wireless signal has been proven to not be an issue; several AIRMagnet PRO surveys have been carried out showing the signal throughout the property to meet the -67dB requirement.

Just wondering if anyone else has ever had the same problem? If so, what did you do to remedy the issue? Our next plan of attack is to try the new 2600 and 3600 lightweight APs/different phone handsets.

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Re: AP roaming with Cisco 7925G

Mon Feb 18, 2013 4:02 pm

Have you tried using WPA2 instead?
som om sinnet hade svartnat för evigt.

LS21
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Re: AP roaming with Cisco 7925G

Tue Feb 19, 2013 4:18 am

Yes, also tried WPA & WPA2 with CCKM.

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Re: AP roaming with Cisco 7925G

Tue Feb 19, 2013 11:12 am

Hell try no security just to see if you can get it to roam. Make it as simple as possible and then complicate it. Also try showing the SSID though that may not make much of a difference.
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LS21
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Re: AP roaming with Cisco 7925G

Tue Feb 19, 2013 3:41 pm

javin wrote:Hell try no security just to see if you can get it to roam. Make it as simple as possible and then complicate it. Also try showing the SSID though that may not make much of a difference.


It's a good idea thank you Javin, unfortunately we just aren't able to do that. The location is in among other apartments and offices filled with people, this in a production environment where the phones are currently being used. We are very cautious with our security!

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Re: AP roaming with Cisco 7925G

Wed Feb 20, 2013 11:37 am

We use 7925s with aruba APs and I do not believe we have issues with roaming. Our SSID is visible but I think we are using WPA2. I was just tossing out things that I can think of. You do have the phone vlan firewalled/ACLed off from the rest of the network incase someone IS able to get on that SSID, right?
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Re: AP roaming with Cisco 7925G

Wed Feb 20, 2013 4:18 pm

LS21 wrote:
javin wrote:Hell try no security just to see if you can get it to roam. Make it as simple as possible and then complicate it. Also try showing the SSID though that may not make much of a difference.


It's a good idea thank you Javin, unfortunately we just aren't able to do that. The location is in among other apartments and offices filled with people, this in a production environment where the phones are currently being used. We are very cautious with our security!


If security was such a concern, you wouldnt be running WEP. Even WPA1 is easily compromised now with a kiddie scripter running backtrack or something similar. Even WPA2 can be compromised from a "better hacker".

However, try creating a new broadcasted SSID on the WLAN controller and dont use security, apply one phone and try roaming with it to check if that makes a difference. Have you done any wireless site analysis? Are the channels correctly setup where they dont overlap with one another? Do you have any tool to test traffic as you roam with a laptop to see if packets are lost as roaming occurs?

LS21
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Re: AP roaming with Cisco 7925G

Thu Feb 21, 2013 3:40 am

We're only using WEP at the moment because this is the configuration where we're seeing the best results. I know all about the security risks involved with WEP, however having a password is better than having no password...

We would ideally like to run WPA2-CCKM but the roaming is even worse. I believe the issue to be with the way Cisco gear hands over the authentication keys, this is a hunch based on what the TAC wireless guy said.

As previously stated, we have conducted several AirMagnet PRO surveys detailing SNR, packet loss, iPerf results and signal mapping throughout the premises. Cisco have also reviewed the survey pro results and agree that the wireless deployment is sound.

I'm pushing to get equipment in NFR from Cisco to lab it up with/without security, away from the production environment.

@Javin, do you lose any voice when roaming from AP to AP on Aruba i.e. imagine you were mid-conversation, would you lose a word or two?

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Re: AP roaming with Cisco 7925G

Thu Feb 21, 2013 1:38 pm

I am asking the guy on site that uses it. He stated that he usually sits in one spot when on the phone. We will do a test later today hopefully when I have him do some work across the plant.
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Re: AP roaming with Cisco 7925G

Thu Jun 06, 2013 4:57 am

Hello, I'm having the same experience with the 7925g and 2504 WLC and interestingly enough I did exactly the same changing thresholds, key types, even manually locking in Power levels on AP's tto try to at least ensure I have a known coverage environment. The roaming is rubbish and you get the 2-3sec audio cut when roaming AP's. Escalating through Tac has resulted in a similar response. Did anyone make any inroads into this?

I can't believe I'm the only one experiencing this issue (at 2 separate sites).

Dave

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Re: AP roaming with Cisco 7925G

Tue Aug 27, 2013 9:57 am

I've seen this as well but it wasn't with a Cisco WLC. I think it was Ruckus wireless gear and without any tweaking it's about a 4-5 second drop. I've had 7925Gs in prod with Cisco wireless gear and had clean roams before.

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Re: AP roaming with Cisco 7925G

Mon Mar 09, 2015 8:10 am

Hello,

I have the same issue with Cisco 7925g and WS-SVC-WISM-1-K9. Please, somebody has the solution?

I have detected audio cut when roaming in some APs, not in all.

Thanks.

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Re: AP roaming with Cisco 7925G

Thu Apr 07, 2016 4:32 pm

Check the power settings on the AP's. They shouldn't realistically be running more than 17dbm. If the AP's are running to much power that could give you one way audio. Dynamic Transmit Power Control (DTPC) can help with this issue. Set the max power to 17 under TPC. That will keep the AP's and phones talking at the same strength.


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