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Wireless VoIP roaming - getting an 802.11g phone to roam with CCX / CCKM

Hello,

Our group is facing a pretty difficult issue at the moment, we are trying to deploy a wireless Avaya VoIP phone at one of our sites in Australia.

The site in question is located in Western Australia, which is on the other side of the continent to where our 5508 WLC is (in Sydney), so there is a latency of abouy 60-80ms between the sites. When testing the phone at the Sydney location, we're able to authenticate the phone via a number of methods (802.11x, 802.11x FT) and the phone can roam fine. When testing at the WA location, the 802.11x authentication method drops the call when roaming, and the 802.11x FT authentication method has about 2 seconds of dead air during roaming / reassociation.

The avaya phone supports a few different methods of "fast handoff" - CCKM and OKC - and we've only got the OKC (802.11 version of fast transition) method to work, not CCKM. The phone reports error messages when trying to connect to the network with CCKM enabled - specifically "No CCKM AP's" and "No CCX AP's".

So I have some questions...

1) Is a 60ms latency between sites a dealbreaker for wireless voice usually?

2) The voice engineer is convinced that CCX is disabled on the WLAN. My understanding of CCX (according to online Cisco docco) is that it can't be switched off. Is this the case? I know CCKM can be disabled (in the Layer 2 Authentication options) but can CCX or CCKM be enabled / disabled anywhere else?

3) The voice engineer has a point on one front - if we do a command "show ap ccx rm [APName] status", the command outputs "Beacon Request ..... Disabled." This seems to be related to CCX Location awareness - but even after switching this on in the WLC (both globally and for the WLAN), I cannot get this to enable.

3) We have had some minimal success getting the phone to connect with only CCKM Authentication enabled. The phone could not roam. When we did this, I looked at the Client information in the WLC of this device and the CCX Version read "Not Supported." Does this perhaps mean some kind of CCX compatibility problem?

4) Is there much of a difference between OKC (Fast Transition) and CCKM in terms of roaming time? I.e. are we better off trying to install a WLC at the location rather than getting this work remotely.

We're a bit lost on this. Anyone that's had experience in getting Wireless VoIP phones to roam on a wireless campus before, particularly where the WLC is remote, I'd love to hear from you.

Thanks,

Dave

8 REPLIES
Hall of Fame Super Gold

Wireless VoIP roaming - getting an 802.11g phone to roam with CC

One important information you haven't provided is the firmware of your WLC.

OKC support started from WLC firmware 7.4, if I remembered correctly.

Roaming times of 60ms is fine.

New Member

Wireless VoIP roaming - getting an 802.11g phone to roam with CC

Thanks Leo. During this testing, the software version was 7.4.100.60. Over the xmas holiday, one of the engineers upgraded the software to 7.5.102.0, though we have not done extensive testing on the new software yet.

The OKC method of fast roaming was our best success so far - we could get the phone to roam, but it had 2 - 3 seconds of dead air during the roam.

When you say a roaming time of 60ms is fine, are you referring to the roaming time or the inter-site latency? The 60ms RTT is the time it takes to ping the site in Western Australia to the WLC in Sydney.

Cheers

Re: Wireless VoIP roaming - getting an 802.11g phone to roam wit

In the WLAN you need to make sure that Aironet IE is enabled. And what encryption are you doing?

WPA/TIP or WPA2/AES? WPA2/AES is only supported on CCXv5 devices

Steve

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HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
New Member

Wireless VoIP roaming - getting an 802.11g phone to roam with CC

Hi, thanks Steve. Aironet IE is enabled.

The encryption is news to me. We intially tried WPA2/AES & WPA/TKIP together but had no success at all. We then moved to WPA/TKIP, and we were able to get the phone to connect to the WLAN using the CCKM settings, but it doesn't roam at all & the WLC reported the Clients CCX version was "Not Supported".

I think the phone has CCX version 4. Are you certain that the phone will only support WPA & WPA2 with CCX v5? Just that this sounds a little strange, the phone's documentation claims to support CCKM, but if you're right then there's no way we can secure our phone conversations? In previous testing, we did actually temporarily drop all authentication / encryption and the roaming worked perfectly.

Thanks for your help...

Re: Wireless VoIP roaming - getting an 802.11g phone to roam wit

You would only want to run one of them at a time, either WPA/TKIP or WPA2/AES. And yes I'm sure about WPA2 w/cckm is a v5 feature.

With a ccx v4 you would need to use WPA/TKIP

Steve

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HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
New Member

Re: Wireless VoIP roaming - getting an 802.11g phone to roam wit

Hi Stephen, I checked with the voice engineer and he's using WPA/TKIP like you say. In the Avaya phone menu, we have to select "Cisco-FSR" as the authentication method, and this restricts our encryption choices to WPA only. So we have tried this previously - the phone can connect to the network but still wont roam.

Any other ideas anyone? Specifically, does anyone know anything about whether CCX can be somehow enabled / disabled on the WLAN, or whether the 60ms latency between the sites would cause too many issues with voice and roaming?

Thanks

Hall of Fame Super Gold

Wireless VoIP roaming - getting an 802.11g phone to roam with CC

Hi David,

Can you try to disable 802.11n and see if you will observe any improvements?

Cisco Employee

Wireless VoIP roaming - getting an 802.11g phone to roam with CC

Make sure you're using the latest/good known code on the phone. Open TAC case.

http://downloads.avaya.com/css/P8/documents/100148232

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