There does seem to be some conflicting info out there in the Cisco documentation. In reality, you only need to enable 7920 AP CAC if you need to support a mixed deployment of 7920 and 7921/7925 phones. The 7.0.116.0 config guide link below might help shed light on the issue.
http://www.cisco.com/en/US/docs/wireless/controller/7.0MR1/configuration/guide/cg_wlan.html#wp1179895 Here is the important snippet. Guidelines for Configuring QBSS Follow these guidelines when configuring QBSS on a WLAN: •7920 phones are non-WMM phones with limited CAC functionality. The phones look at the channel utilization of the access point to which they are associated and compare that to a threshold that is beaconed by the access point. If the channel utilization is less than the threshold, the 7920 places a call. In contrast, 7921 phones are full-fledged WMM phones that use traffic specifications (TSPECs) to gain access to the voice queue before placing a phone call. The 7921 phones work well with load-based CAC, which uses the percentage of the channel set aside for voice and tries to limit the calls accordingly. Because 7921 phones support WMM and 7920 phones do not, capacity and voice quality problems can arise if you do not properly configure both phones when they are used in a mixed environment. To enable both 7921 and 7920 phones to co-exist on the same network, make sure that load-based CAC and 7920 AP CAC are both enabled on the controller and the WMM Policy is set to Allowed. These settings become particularly important if you have many more 7920 users than 7921 users. In regards to what to do on the lab, it is in the 7925 deployment guide as you had pointed out. So if the task asked you to simply configure a WLAN for 7925 best practices, I'd first ask the proctor and say there is conflicting Cisco documentation in regards to enabling this setting. If they don't give you any direction, I'd enable the 7920 AP CAC option since the authoritative guide on how to configure wireless for a 7925 says to do it. Jeff Rensink On Thu, Jan 24, 2013 at 5:40 AM, Jeen Sern Chew <[email protected]> wrote: > Is "7920 AP CAC" check-box in the WLC required as best practice for the > the 7925G phones/voice WLAN? > > I find this confusing because different documents says differently. I > personally don't think it is because WMM is 802.11e standard and that is > enough. In the 7925G deployment guide pg. 52, it says to enable "7920 AP > CAC". I wonder if this was brought over from the 7921 phones? Both FastLane > and IPExpert workbooks doesn't state to enable it. Another document from > Cisco, "Voice Over Wireless LAN (VoWLAN) Troubleshooting Guide" has a > checklist of best practice for voice. There is a task in there that states > to make sure "7920 Client CAC" is disabled, but not about enabling "7920 AP > CAC". > > I guess in the real world it would be safe to have both WMM and "7920 AP > CAC" enabled but in the lab there's a possibility to be marked down for > over-configuration. > > What is your point of view on this? Or is there something that understood > wrongly? > > Thanks. > > Regards, > Jeen chew > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > >
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com
