Voice over wireless with three AP's and no WLC

UCcomp2007 · ‎10-11-2008

We plan on having three AP's for our desired coverage area with no WLC. Building A has inside AP, then outside has an AP for coverage between Building A and B, then Building B also has an inside AP).

If we set these up via Extended Service Set (i.e. all three AP's sharing the same SSID) will wireless VOIP calls drop when person using 7921 voip phone moves between buildings? Can you roam in this scenario without dropping a call? If you cannot roam, is their a "work around" we can use that will not required a WLC in the picture?

thanks in advance,

migilles · ‎10-12-2008

To have seamless roaming, the client needs to be able to use the same ssid, same 802.11 band and sufficient signal overlap of adjacent cells (i.e. -67 dBm). Also the AP must support a roaming protocol (i.e. IAPP or LWAPP), which will assist with switch address table updates to ensure packets are forwarded correctly after a client roam. Also the client must be able to roam without having to re-DHCP. Can do L3 roaming, but the infrastructire / AP must support that functionality allowing the client to use an IP from network A in network B.

See the 7921G Deployment Guide for more info.

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

UCcomp2007 · ‎10-15-2008

So the question still remains, can this be accomplished without a wireless lan controller?

How to roam without having to re-dhcp?

I assume l3 roaming can only be done when their is a WLC in the picture?

Regards,

Mario de Molina Gomez · ‎10-22-2008

If the SSID is attached to the same VLAN in the three APs, there's no need to re-dhcp. So The answer is yes, if you have enough signal all the time. What does it mean? You need about -67dBm of signal strengh everytime (and about 20 dBm of SNR), even when you are moving from one AP to another.