There is supposed to be a failover configuration that works (we're not there yet), but it's not as obvious/trivial as one might suppose:
1. In order to provide the unified heatmap, there needs to be a master controller which any other controllers talk to. Failover is primarily in terms of other boxes being able to step into this role if the usual master goes down. 2. Controllers are licensed for a specific maximum number of APs. In a failover situation, there is nothing that takes into account that you may have license vacancies on controllers that are currently out of service, so your remaining live controllers need to have enough spare licenses to accommodate the orphaned APs. And I believe that they recommend that the master, because of its extra responsibilities, be only half loaded. 3. IIRC, which controller a given AP winds up on depends mainly on which one it first hears a DHCP response from. So I think the only way to default a specific AP to a specific controller may be to grossly manipulate your physical network topology to achieve this. We did it in the lab and got it working, but our live deployment hasn't yet grown to where we would do it on a production scale.... David Gillett > -----Original Message----- > From: John Rodkey [mailto:[EMAIL PROTECTED] > Sent: Tuesday, May 22, 2007 4:24 PM > To: [email protected] > Subject: [WIRELESS-LAN] 'Clustering' and 'failover' in the > context of Aruba > > We are currently considering expanding our existing wireless > environment to cover additional dorms. > By doing so, we will exceed the capacity of our current > controller, and can either add an additional controller card > or for a slight incremental cost, add another controller. We > planned to add the additional controller, with the idea that > the controller would allow redundancy/failover/clustering to > happen, so that if one controller were to go down, for > instance, the other would take over. > > We were subsequently told that this was a faulty > understanding of the failover function. > So we thought we might be able to try another approach: > every other WAP would be controlled by alternating controllers. > That way, if controller A, with waps 1,3,5,7,9... on it were > to go down, the coverage in any given building would be > halved, because controller B, with waps 2,4,6,8 ... would > continue to run. > Nope, that is a bad idea, says the contact: each controller > will maintain its own heat map and routing info, etc. and as > a result, there would be nowhere to look for a unified > picture of the wireless network. > > So I'm confused: what is the exact nature of controller > clustering or failover under Aruba? > Given somewhere in the neighborhood of 200 APs, how should > one configure the controllers > > John > > ********** > 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/.
