From the Cisco slides I’ve seen on the feature, when in dual 5 Ghz mode, one radio acts as the high-performance micro cell for the 802.11ac clients and the other radio acts as a macro cell with the legacy clients joining it.
As for the use of 40 GHz channels, at least in my buildings, the propagation of 5 GHz is so poor that I have absolutely no problem running every radio at 40-wide with no overlapping channels - all 5 Ghz radios running at full power. This is even the case with our recent dense deployments where there are WAPs in every-other room. Jeff On 4/7/16, 6:26 PM, "The EDUCAUSE Wireless Issues Constituent Group Listserv on behalf of James Andrewartha" <WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU on behalf of jandrewar...@ccgs.wa.edu.au> wrote: >On 07/04/16 19:44, Kees Pronk wrote: >> “you could in theory double the airtime available” >> >> I would be interested in your actual experience with this. Now that a >> few vendors have taken this approach and others stay away from this. >> >> Arguments in favor of 5/5 you will find these abundant on the vendors >> marketing pages, but how about : >> >> Extra COGS (band pass filters etc), extra complexity with your channels >> plans (need a lot of separation between the 5/5 radios), you must enable >> DFS channels on every AP but what about false positive radar detects? >> What about the 2 radio’s ‘deafening’ each other while trying so >> send/receive at the same time. >> >> Please keep us posted and maybe others testing with this >> 1. Innovation >> 2. Marketing gimmick > >My vote is for 2. Marketing gimmick. Why? Because "airtime available" >isn't the limiting factor for 802.11ac performance, it's "distance from >AP" (well, the high SNR required to get the best rates). So I'd much >rather a full-featured AP with a single 5GHz radio than one with two >5GHz or band-selectable radios. That way I can have a nice dense >deployment with low powered APs and waste money on radios I'm not going >to use. Lowering the AP power also increases the possibility of using >40GHz channels without interference from other APs, which again is what >you need to get the most out of 11ac. > >Yes, there's an increased cost in cabling and switch ports, but OTOH >they should run off 802.3af power, not 802.3at which would delay having >to upgrade some of our older switches. > >In terms of our deployment, we have 1 AP per classroom, and sparser >coverage in other areas. I used to see 75-80% on 5GHz, now it's a bit >lower after I reduced the radio power per vendor recommendation. This is >with primarily Apple devices, which are pretty good at picking 5GHz >without band steering. > >Outside of classrooms 2.4GHz is still needed for coverage, it goes >through walls in ways 5GHz can only dream of. I tried using DFS channels >and 40MHz at the start of the year but I was getting a lot of radar >alerts so went back to 20MHz and non-DFS in 5GHz. > >-- >James Andrewartha >Network & Projects Engineer >Christ Church Grammar School >Claremont, Western Australia >Ph. (08) 9442 1757 >Mob. 0424 160 877 > >********** >Participation and subscription information for this EDUCAUSE Constituent Group >discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
