Wireless and 7921G Issues.

[Waldo Roca Martin]

Hi everone.

I have made a new installation with CUCMBE, a WLC CT5508, AP1262N x 70 and 7921 x 100.

The firmware of the phone is 1.4SE1

We use a SSID only for voice and the APs are maninly used for voice. The currently configuration in de WLC have every frecuency selecte "All", "auto" in 7921, QOS in "premium", WLL "Allowed". Everything else is per default. 

I didn't configure QOS in the switches ports connected to APs because I though It wasn't necesary. The porsts are Giga and are coneccted to the core throught 10Gb fiber. May be that was a error.

Now everything is done but we have some issues.

1. We experimente frecuently voice cuts (arround 5 secondos)

2. The phones unregister/register of CM frecuenly.

That happend even when the user are speaking in the same place (a office site per example).

But the main problem was the costumer didn't want give the 7921 phones to the users before the number plan migration so now the system is working in production and the costumer is angry of corse (I alerted him)

Anyway.

I going to change some configuration and I need your advise please. These are the steps.

1. Change the frecuency just work in "b/g" in the WLC and the phone. (is it better "a" to 5Ghz?)

2. Update the 7921G firmware to the 1.4(2)

3. Change the WLL to Requiered.

4. About the QOS in switches. Is that necesary in a WLAN enviromet?

And do you think another option to see/change?

Another thing.

I have seen this post about optimice tha WLAN for voice. He say this.

4.     Use 8 channels, configure the Cisco 7921G to only scan those 8 channels. (This is very important)

a.     36,40,44,48,149,153,157,161

http://www.goatnetworking.com/forum/viewtopic.php?f=8&t=15

Someone know where can I configure that at the pohone? do I have to do something to the WLC?

Thank you.

Best Regards

[Stephen Rodriguez]

Waldo Geraldo Faldo?

1. Change the frecuency just work in "b/g" in the WLC and the phone. (is it better "a" to 5Ghz?)

     IMHO, I would keep the phones on the 5Ghz if you designed the wireless to support 5GHz voice, as there are less interferrers in that spectrum

2. Update the 7921G firmware to the 1.4(2)

     Yes, I would go to 1.4(2)

3. Change the WLL to Requiered.

         WMM allowed should be fine

4. About the QOS in switches. Is that necesary in a WLAN enviromet?

     Yes, you still want to have QoS on the LAN to support the phones.  While it's not a needed thing for the LAN per-se, it is needed for the AP.  AP's are essentially half duplex hubs.  If the packet from the LAN hits the AP with no QoS mark, it will be put in the best effort queue instead of the priority queue.  If you don't have QoS enabled on the LAN, and the appropriate trust configured, the switch will strip the QoS mark.

Steve(Stephan Ur-kel)

[Waldo Roca Martin]

Hehehe. Hi Ur-kel.

Ok I hope with that changes the wifi works better.

If you have other option to check, please tell me.

What about specific the channels at the phone?

Thank you.

[migilles]

Yes you should use 1.4(2) as there is enhanced scanning to allow for even more seamless roaming in that release.

If you are having issues on certain channels (UNII-1; 36-48); then you could possibly be hitting CSCtx43105, which will be resolved in the 1.4(3) release.  This issue is rare and occurs only with Cisco 11n APs.

We do have an ES load with a fix for CSCtx43105.

If it turns out that you still have issues wtih 1.4(2) and the issues are specific to channels 36-48, then open a TAC case and request 1.4.2ES.3 for the 7921.

Yes generally 5 GHz is recommended over 2.4 GHz for many reasons.

5 GHz has more channels and less interferers to contend with.

Also Bluetooth works better with 5 GHz.

But if you did not survey for voice on 5 GHz, then be careful as there may be some coverage issues.

Also please review the 7921G Deployment Guide and ensure you have your deployment per those guidelines.

http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7921g/6_0/english/deployment/guide/7921dply.pdf

[Waldo Roca Martin]

Thank you for the help.

Today I have done some changes.

1 I have update the 7921G firmware to 1.4.2.

2 I have configured QoS in the switches port connected to APs.

3 I have tried configure the radio in the ssid to "a". But I couldn't do it because just 30 APs of the 70 works in that frecuency. All of them work in "b/g" but only 30 in "a"

Anyone know why? How can I change that?

Now the WLAN works much better for voice, but they still are sufferring some voice cuts. We have to check when that cuts happend to try whats going on.

Last thing

refered to this

If you are having issues on certain channels (UNII-1; 36-48);

Are there any way to set a specifi group of channels to scan?

Thank you

Regards.

[Stephen Rodriguez]

what kind of AP do you have?  if you have the 1230/1231/1232, they may not have the 5GHz radio module.

Are you also trusting COS to the portchannel the WLC is connected to?

Steve

[Waldo Roca Martin]

Hi steve

The most of my APs are 1262N.

No I I forgot that.

That port are in trunk mode. I will check that.

Thank you.

Regards

[goatnetworking]

Here is how to set the channels on a 7921G.

1. Enable the web access in CUCM.. (Versions may differ)

You have to set "Web Access*" to Full, then check the box to the right.

Then enter a password in the "Admin Password" field

2. Go to the phones web page  https://

      - Admin is the username

     - Enter the password you entered into CUCM

3. Go to the Profile page, click Advanced in the upper right.

     - You then select the channels that you want to use.

Don't forget to save the profile.

You need to set the channels on the wireless network to match the channels that you are scanning on the phone. If the phone is not scanning the channel that you have on an AP, the phone will not see it.

I always trust DSCP instead of COS. COS can be lost going over an access port, but the DSCP will stay with the packet on any switch link.

[Waldo Roca Martin]

Hi Again.

Thank you for the answers.

I already have setting the QoS but we keep suffer cuts on calls.

I have configured the next commands.

In WLC port, every trunk port, and port which there is a AP.....

auto qos voip trust

In Port-channels ports the IOS doesn't permit me configure auto qos so I have configured these commands.

queue-set 2

priority-queue out

mls qos trust cos

In ports which there is a Cisco-Phone.

auto qos voip cisco-phone

But that doesn't improve the calls. .

The most of the switches are 3750 connected with the core by fiber, so I thing it is not a broadband problem.

The WLC use a 1 Gb port. May be I would have to create a portchannel there with 2 ports.

I gona try specific the channels Thanks Scape.

May be add the mls qos voip dscp at the trunks and APs.

I dont't know what more I could do.

I have attached the network diagram. May be that could help.

Thanks.

[Waldo Roca Martin]

Hi again

We are detecting the people who have calls cuts are using a older AP which the costumer already have.

This model is.

AIR-LAP1252G-E-K9

Primary software version 7.0.230

Boot Version 12.4.18.1

IOS Version 12.4.23cJA4

Mini IOS Version 3.0.51.0

The model we installed and is working well is.

IR-LAP1262N-E-K9

Primary software version 7.0.230

Boot Version 12.4.23.0

IOS Version 12.4.23cJA4

Mini IOS Version 7.0.112.74

Do you thing I have to update the mini IOS?

Can be it the problem?

Thanks.

[goatnetworking]

Waldo, I have both of those models deployed. I have found that the 1262 is an all around better AP. Plus the 1262 takes standard POE.

[zhenningx]

From this link:

http://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob41dg/ch5_QoS.html#wp1073579

You should configure "trust dscp" for the ap switch ports and "trust cos" for the wlc switch ports.

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[migilles]

Would suggest to upgrade to 7.0.235.0.

Open a TAC case if you need further support.

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