VoIP over WLAN - Client Roaming Settings

[Frank Wagner]

Hello,

what would you suggest, are the best settings in the "Client Roaming Section" of the WLC Configuration for the following requirements:

VoIP over WLAN deployment, 802.11a, WLC 4402, 25 - 30 access points (mainly 1252, a few 1130), 7925G phones.

In the moment the settings are set to default, that means: Min. Rssi = -85; Hysteresis = 3; Scan Tresh. = -72; Trans. Time = 5

Unfortunately we are not completely satisfied with the roaming behavior of our phones, so there is the question,

if the roaming behavior of the phones can be improved. Sometimes it looks like the phone takes too much time to make a roaming decision.

Thanks,

Greeting Frank

[Aaron]

Frank, those settings only apply to Intel clients and are not used by 7925Gs.  For the phones, I would recommend:

• run the current firmware (1.3.4 SR1)
• go through the 7925G Deployment Guide recommendations, chapter and verse (http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7925g/7_0/english/deployment/guide/7925dply.pdf)

Aaron

[Frank Wagner]

Hello Aaron,

thanks for your answer.

The phones are already running on firmware 1.3.4 SR1.

And meanwhile, I think I know the 7925G Deployment Guide by heart.

But sometimes the phone simply makes the wrong roaming decision.

Unfortunately it's not 1 out of hundred, it's one out of 10 decisions that's wrong.

Maybe it would be a suggestive feature in the future if one can set "default roaming routes" for the phone.

Greetings Frank

[Elliott Shawd]

So your wireless network was properly surveyed for and channel/power settings for aps are configured properly? Do you have your WLAN set up for CCKM and WMM? Do you have qos set up for voice?

[Frank Wagner]

Our wireless wireless network has been surveyed twice.

The first time to figure out the positions of the Access Points and because there have been changes in amount of APs

and position of some APs, a second time to figure out the ideal power level and channel settings for the changed environment.

The amount of APs and some positions changed, because sometimes there have been two APs in the same office

with an RSSI, let's say 60-65 and the phone was permanently changing the AP, what impacted the quality of the phone call.

The WMM and QOS settings are set for the WLAN, as described in the 7925G Deployment Guide.

CCKM is not set, because we are using WPA2-PSK.

Isn't CCKM of note only, when using 802.1x authentication?

Greetings Frank

[Aaron]

Frank, what version of code are you running on the WLCs/APs?  If 6.0.182.0 thru 6.0.196.0,then do please note that the APs are susceptible to:

CSCta29484: Radio stops beaconing for 10-second period (fixed in 6.0.196.0)

CSCte89891 Radio may stop transmitting beacons periodically (affects 6.0.196.0 too)

If the phone doesn't receive beacons for one second, it'll roam to another AP.

Aaron

[Frank Wagner]

Hello,

we are running the 7.0.98 code.

Greetings, Frank

[Aaron]

7.0.98.0 is not susceptible to those known beaconing problems.

I would recommend opening a TAC case, and being prepared to collect multichannel, NTP-sychronized wireless packet traces, coordinated with phone traces, WLC/AP debugs, and wired packet traces.

Aaron

[Frank Wagner]

Thanks Aaron.

We will definitely consider this possibility.

[Dominic Stalder (old profile)]

Hi Frank

have you been able to solve your problems. We have the same issues with 7921 (1.3.4SR1) and 7.0.98.0, but we are not able to solve the problems.

Regards

Dominic

[Frank Wagner]

Hello Dominic,

at the moment we are redesigning the problematic spots in our network

and this will hopefully help to resolve our problems.

Greetings Frank

[Dominic Stalder (old profile)]

Hi Frank

thanks for the feedback. Actually we are working with the TAC and hopefully we gonna have a solution today or tomorrow.

As soon as I now more I will post it here.

Regards

Dominic

[Frank Wagner]

Hello Dominic,

Did you get your problems solved in the meantime?

Greetings Frank

[Dominic Stalder (old profile)]

Hi Frank

no not at all, we are working with the TAC since 2 weeks and with the business unit (developers) voice and wireless since 2 days, but actually we do not have a solution.

Regards

Dominic

[Dominic Stalder (old profile)]

Hi Frank

how are you doing with your VoIP design? We also redesigned some spots, but we still have voice gaps and it is annoying.

Regards

Dominic