You never know what people are going to do so all you can do is take the protocol to the limit in high density areas. They might try to fire up video conferencing via wireless or tell everyone on the class to down load a file to their laptops. There could be a major event and everyone whips out their phones or tablets and tries to connect to CNN to see what is going on. With everyone having at least 2 wireless devices it gets crazy in high density areas.
In our high density areas, like an auditorium, I never have more than 3 2.4 radios going. I may put in 4-5 APs but will disable the 2.4 radios on all but 3 APs. I run load balancing and it works well. We are an Enterasys shop. It is tough to do controlled testing because who has the resources to fire up 100 + laptops to test various configurations? From my understanding of the protocol adding more than 3 2.4 radios in a single room will have diminishing returns due to co-channel interference. Obviously not all APs are equal, so some will handle more clients than others within the same channel, but at some point physics is against you, i.e. the air is saturated. The other thing against you is Wi-Fi hotspots. Those things typically choose a non-standard channel like 7 or 4. Does that make anyone else crazy? That is just interference to the campus wireless. We had a high density area that was working fine for years. Students were just using it to check email on their phones etc. We are in the process of moving to Google and now folks are getting excited about Google+. Without testing they just schedule a meeting in one of the rooms and fire up Google+ over wireless and expect everything to just be fine to have a virtual meeting. "It worked fine from my desk". Folks just think wireless is the same thing as wired. To them a network connection is a network connection. I'm not sure how to manage community expectations when it comes to wireless. We had another event where we had 100 people or so in a room all with their own laptops going to the same website all at the same time. It went off pretty well, I was amazed actually. I got a complaint from someone in IT that he got dropped a couple of times throughout the day. I'm thinking, really? that's all you've got? but to him wireless is the same a wired......Expectations. It's a crazy world out there. John On Wed, Nov 28, 2012 at 9:23 AM, Gogan, James P <[email protected]> wrote: > We currently have a mix of Cisco (legacy) and Aruba (last two years) APs > (although we're good at keeping any given building single brand, as much as > possible). We've generally gone with an engineering rule of thumb of > 20-30 clients per access point.**** > > ** ** > > We've noticed issues with channel flapping and inadequate load balancing > on our Aruba APs in large classrooms where we have, based on our client per > AP engineering, large numbers of APs. After an on-site visit from an > Aruba engineer, his comment was that we have TOO MANY APs in our classrooms > and high density areas. His recommendation (using the Aruba AP135s) was > that we design based on 80 clients per AP (minimum 50, average 80, max > 100), and to design based on 50 clients per AP for the older AP125s.**** > > ** ** > > I'd be curious to know what others think about that recommendation -- > seems pretty significantly different from everything we've been told and > designed for in the past. (BTW, the engineer also noted that he's not a > sales guy and the sales guys would suggest differently -- figures).**** > > ** ** > > Thoughts?**** > > ** ** > > -- Jim Gogan**** > > ITS-Networking**** > > Univ of North Carolina at Chapel Hill**** > > ** ** > > ** ** > ********** Participation and subscription information for this EDUCAUSE > Constituent Group discussion list can be found at > http://www.educause.edu/groups/. > > -- John Kaftan IT Infrastructure Manager Utica College ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
