Voice gaps when roaming with 7921

[p-vincent]

Hi all,

I have a setup with 3 ap1242 and UC520, no WLC. When moving around with a CP7921 there is a voice gap (about 2-3 seconds) when the 7921 switches from AP. The call does not get disconnected.

IOS running on AP:

c1240-k9w7-mx.124-10b.JA

Phone version:

CP7921G-1.2.1

Can anyone help me figure out what causes this problem?

[dromer]

I made all these recommended changes and there is no difference for me. About 150 packets always get lost when roaming. The only solution at the moment is to use load 1.1.1.

If you are opening a SR you can refer to mine: 610980291

[migilles · Accepted solution]

There is an issue with the autonomous AP (CSCsx07150), where CCKM is failing. This appears to be handing the TSPEC that we send for SCCP traffic (UP4).

The workaround here is to enable "admit-traffic" under the ssid config. In the AP webpage, it is listed as "Call Admission Control", which will add the admit-traffic command.

Below is an example:

dot11 ssid voice

vlan 21

authentication open eap eap_methods

authentication network-eap eap_methods

authentication key-management wpa cckm

admit-traffic

This will go into the next 7921/7925 Deployment Guide to ensure that admit-traffic is always enabled.

[Leo Laohoo]

Thanks for this Michael. +5

[JON O'NAN]

Does this bug apply to Autonomous AP's in general or just when using CCKM. I have a customer experiencing the same loss of speech during a roam although initially we were using PSK with TKIP and then tried WEP. The issue was less apparent with WEP but still unacceptable.

[migilles]

It is only with autonomous APs. If admit-traffic is not enabled, the CCKM IE is missing from the reassociation response, which will then cause about a 1.5 second voice gap will occur.

For WPA-PSK, there is an issue with the WLAN controller and 7921/7925, where in some cases the keys during the WPA handshake can come a little early and must wait for the retry which is 1 second later (1 second is the lowest allowed value currently). This doesn't apply to autonomous APs as it has a default WPA timeout of 200ms and can be adjusted as necesary.

[p-vincent]

Hi Migilles,

I've implemented the commands remotely in their AP's, have to go there on monday so will have feedback by then. Will keep you posted!

Thanks for your help.

[p-vincent]

Hi Migilles,

Sorry for my late post. Problem solved with your solution!

Thanks for the professional help.

[guilhem.perez]

Hi,

I'm meeting the same issue with autonomous APs (voice gap when roaming).

I've tried using WPA-PSK TKIP, using Wep key.

Could you tell me what is your last config (Wep, wpa-psk, or WPA2 with a WDS AP?). Could you post your AP config?

Best regards

Thanks.

Guilhem

[migilles]

Try adding admit traffic to the ssid like below.

But below is a config for using WPA+CCKM not WPA-PSK.

dot11 ssid voice

vlan 21

authentication open eap eap_methods

authentication network-eap eap_methods

authentication key-management wpa cckm

admit-traffic

[guilhem.perez]

Hi,

Thanks for your response, I've add admit-traffic using remote access.

I'm waiting wy customer feedback Wednesday.

I'll let you know, at the moment it's looking better.

Thank you for your help.

[i.va]

Hi p-vincent!

What commands endet up doing the trick?

I also have this issue with 7921 phones, 17 Aironet 1230b AP's, and WPA-PSK. The "roaming-gap" seems to be larger with the 7921 phones than with 7920 phones.

Ingo

[p-vincent]

Hi,

Actually the admit-traffic solved my problem completely.

Added this command under the ssid config for my Voice SSID, rebooted all AP's and after that no more voice gaps.

[i.va]

Ok thanks! I will give it a try!

[alessandro.dona]

Hi to all,

i can confirm command admit-traffic under dot11 ssid "voice" works also foe WPA-PSK

I have Ap1242 with 12.4-10b-JDA3 and 7921 21 with load 1.3.4

Regards,

Alessandro.

[gbonivento]

Hi Michael,

thanks a lot for your help: your suggestion solved the roaming problem I was encountering by one of my customers.

Rated +5 :-)

My setup is a little bit different from cases already mentioned on this discussion. I'll therefore post my setup here below, it could be helpful for other guys experiencing same problems.

IOS version : 12.3(8)JEC2

7921 Firmware : 1.3.2

Roaming : WDS/CCKM

Authentication : LEAP

When the IP-Phone roams between two AP the customer encounters a voice gap of about 1 second. On the AP log following errors appear:

Apr 10 10:36:03: %DOT11-6-ASSOC: Interface Dot11Radio0, Station aaaa.bbbb.cccc Reassociated KEY_MGMT[CCKM FastRoaming]

Apr 10 10:36:03: %DOT11-4-MAXRETRIES: Packet to client aaaa.bbbb.cccc reached max retries, removing the client

Apr 10 10:36:03: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station aaaa.bbbb.cccc Reason: Previous authentication no longer valid

Apr 10 10:36:09: %DOT11-6-ASSOC: Interface Dot11Radio0, Station aaaa.bbbb.cccc Associated KEY_MGMT[CCKM]

Regards, Gio.