Voice over Wireless with Cisco phones 7921 and 7925

[aleopoldie]

Hello experts,

I made an wireless audit for a company.

They have 2 WLCs 5508 in HA mode, with APs 2602 for indoor and 1552. Version of the WLC : 7.6.120.0

At the end of the day we noticed that the roaming between indoor and outdoor access points is sometimes failing and results to a complete disconnection of the wireless phone (7921 or 7925) from the network. When people go from the indoor to the outdoor area, there is no problem. The problem comes when people are coming from the outdoor to the indoor.

Also, on the WLC, the power lvl of the outdoor APs are set to 1 ... Is it good or not ?

My question is, is there any known issue about Voice over wireless with WLC 5508-7.6.120.0 with APs 2602 and 1552 ?

Maybe it should be better to upgrade to 7.6.130.0 ?

Thanks in advance,

Alexis

[Leo Laohoo]

Also, on the WLC, the power lvl of the outdoor APs are set to 1 ... Is it good or not ?

Any reason why the AP power level is set to full power?

Your phones should be running, a minimum of, 1.4(3) firmware.  

[aleopoldie]

There was a coverage issue and someone put the power lvl to 1. Is it ok or is it better to set to automatic ?

About the phones, the firmware is ok.

AL

[George Stefanick]

It is best to have a consistent link budget between your lowest common denominator and the access point radio. If you lowest devices is 50mW then your ap should be at 50mW.

[aleopoldie]

I don't really understand your answer...

They are using Wifi not only for voice but for data, guest and motorola scanners.

The problem is the radio 802.11a is also used for scanners and Data.

You think it's more a coverage issue ? Because from the indoor to the outdoor it's working. So for me, it's not a coverage issue right ?

[George Stefanick]

Typically you power the ap radio at 12.5 - 50 mw and measure the sell to -65 for voice. Then place he next ap with 20% cell overlap. Is your network designed to these specs to support voice?

[aleopoldie]

Normally yes.

Is there a way to troubleshoot what's going on with the phones ? Maybe a "show client detail MAC address* on the WLC ?

Here are some logs when the phones are losing the network :

*Dot1x_NW_MsgTask_4: Apr 09 12:44:21.320: #DOT1X-3-INVALID_WPA_KEY_MSG_STATE: 1x_eapkey.c:957 Received invalid EAPOL-key M2 msg in START  state - invalid secure bit; KeyLen 40, Key type 1, client 00:24:d7:83:56:dc

*apfMsConnTask_6: Apr 09 12:28:32.668: #APF-3-VALIDATE_CCKM_REASS_REQ_ELEMENT: apf_utils.c:2506 Could not validate the CCKM Reassociation request element.Received Timestamp deviation > 1sec in CCKM Info Element from mobile. Mobile:4c:00:82:85:6e:e1,  AP:1

*Dot1x_NW_MsgTask_1: Apr 09 12:26:53.964: #DOT1X-3-INVALID_REPLAY_CTR: 1x_eapkey.c:445 Invalid replay counter from client 74:26:ac:63:8c:a9 - got 00 00 00 00 00 00 00 03, expected 00 00 00 00 00 00 00 04

*Dot1x_NW_MsgTask_1: Apr 09 12:26:53.929: #DOT1X-3-INVALID_REPLAY_CTR: 1x_eapkey.c:445 Invalid replay counter from client 74:26:ac:63:8c:a9 - got 00 00 00 00 00 00 00 02, expected 00 00 00 00 00 00 00 04

*apfMsConnTask_4: Apr 09 12:24:34.959: #APF-3-VALIDATE_CCKM_REASS_REQ_ELEMENT: apf_utils.c:2506 Could not validate the CCKM Reassociation request element.Received Timestamp deviation > 1sec in CCKM Info Element from mobile. Mobile:78:da:6e:f6:5f:89,  AP:5

*Dot1x_NW_MsgTask_0: Apr 09 12:22:30.217: #DOT1X-3-INVALID_REPLAY_CTR: 1x_eapkey.c:445 Invalid replay counter from client 4c:00:82:85:1d:68 - got 00 00 00 00 00 00 00 03, expected 00 00 00 00 00 00 00 04

*Dot1x_NW_MsgTask_4: Apr 09 12:22:30.206: #DOT1X-3-INVALID_REPLAY_CTR: 1x_eapkey.c:445 Invalid replay counter from client 4c:00:82:85:b3:ac - got 00 00 00 00 00 00 00 03, expected 00 00 00 00 00 00 00 04

*Dot1x_NW_MsgTask_4: Apr 09 12:22:30.186: #DOT1X-3-INVALID_REPLAY_CTR: 1x_eapkey.c:445 Invalid replay counter from client 4c:00:82:85:b3:ac - got 00 00 00 00 00 00 00 02, expected 00 00 00 00 00 00 00 04

*Dot1x_NW_MsgTask_0: Apr 09 12:22:30.167: #DOT1X-3-INVALID_REPLAY_CTR: 1x_eapkey.c:445 Invalid replay counter from client 4c:00:82:85:1d:68 - got 00 00 00 00 00 00 00 02, expected 00 00 00 00 00 00 00 04

*Dot1x_NW_MsgTask_6: Apr 09 12:22:29.672: #DOT1X-3-INVALID_REPLAY_CTR: 1x_eapkey.c:445 Invalid replay counter from client 78:da:6e:f6:14:2e - got 00 00 00 00 00 00 00 03, expected 00 00 00 00 00 00 00 04

*Dot1x_NW_MsgTask_6: Apr 09 12:22:29.638: #DOT1X-3-INVALID_REPLAY_CTR: 1x_eapkey.c:445 Invalid replay counter from client 78:da:6e:f6:14:2e - got 00 00 00 00 00 00 00 02, expected 00 00 00 00 00 00 00 04

*apfMsConnTask_3: Apr 09 12:19:22.098: #APF-3-VALIDATE_CCKM_REASS_REQ_ELEMENT: apf_utils.c:2506 Could not validate the CCKM Reassociation request element.Received Timestamp deviation > 1sec in CCKM Info Element from mobile. Mobile:4c:00:82:85:6e:e1,  AP:5

*osapiBsnTimer: Apr 09 12:13:36.031: #LOG-3-Q_IND: spam_lrad.c:53542 The system is unable to find WLAN 2 to be deleted

[Rasika Nayanajith]

VALIDATE_CCKM_REASS_REQ_ELEMENT: apf_utils.c:2506 Could not validate the CCKM Reassociation request element.Received Timestamp deviation > 1sec in CCKM Info Element from mobile. Mobile:4c:00:82:85:6e:e1,  AP:5

Some of this messages describe in the following bug 

https://tools.cisco.com/bugsearch/bug/CSCti74211/

Resolution
This CSCti74211 problem is now believed no longer to occur with 792x firmware 1.4.2.

Check your firmware & make sure it has latest update.

Also, on the WLC, the power lvl of the outdoor APs are set to 1 ... Is it good or not ?

As others mentioned, this is NOT good. AP power to match with clients ( 7925G in this case), if that cause coverage gaps, then you have to install another AP to fix that, otherwise one way issues will be there. (ie 7925 hear AP, but AP cannot hear 7925)

HTH

Rasika

*** Pls rate all useful responses ****

[aleopoldie]

Thank you Manannalage. The code of the 7921/7925 is newer than 1.4.2 so i think this point is ok. But they still have 7.6.120.0 on their WLC5508.

Should i go to 7.6.130.0 ? I had many issues for other customers with 8.0...

About the AP power i will put it back to automatic. I was thinking that it's better to have automatic set for this but i wanted to be sure.

AL

[Leo Laohoo]

Is it ok or is it better to set to automatic ?

Set your TPC and DCA to automatic.  

[kdavison007]

If you have your AP power set too high then the phone might be able to "hear" the AP fine, but it will not be able to send traffic back.  This can cause one way audio issues with voice.  Read the Cisco 7925g deployment guide.  It will tell you to set TPC thresholds to avoid this.  I believe the settings are 11 min and 17 for a high.  In UNII 1 channels I believe most APs can still go to power 1, but in the higher channels you probably don't want to see power level 1 in most cases.  If all APs are up on power 1 with it set to automatic you might have a density problem and need to add access points.  You want smaller cells with voice.

[aleopoldie]

Ok i understand. About TPC thresholds, you mean configure the 802.11h global parameters with channel announcement and channel quiet mode to enabled ?

Or do you mean the TPC configuration in the 802.11a - RRM ?

In the deployement guide, they advise to do on this way:

Power lvl assignement method : Automatic

Maximum Power level Assignement : 17dBm (by default its 30 dBm)

MinimumPower level Assignement : 11dBm (by default its -10dBm)

Power threshold : -65dBm (by default its -70 dBm)

Should i configure these values ?

Also, the 5GHz in this network is not only used for voice, but for data/guest.

AL

[kdavison007]

I mean the TPC configuration under 802.11a RRM.  You're settings look correct.  Also enable 802.11h checkboxes so the AP announces when it will leave the channel.  5Ghz is fine to run clients and voice.  I would just put the WLAN for voice to platinum QoS and leave the client WLANs down at Gold or Silver.