Two Wireless controllers load balance and failover question

Difan Zhao · ‎04-13-2009

I have two 4404 controllers and each can take 100 APs. I have 140 APs in total. With the default settings (no master controller, no configuration of Prime, secondary controller on APs), each controller will take 70 APs, right?

Then I will need to configure each AP with an IP address, name ...etc. My question is, when one Controller failed, these 70 APs will try to associate with another controller, right? However only 30 APs can because another controller can maximum manage 100 APs. Then in this case, will these 30 APs lose their static IP addresses and names? When the failed controller came back online, will the 70 APs automatically go back to this controller and have their IP, name configuration back?

Thanks!

Scott Fella · ‎04-13-2009

With default setting you have no control how many ap's go to what wlc. It doesn't matter, because you will need to specify the primary and secondary. You might as well stage all the ap's you want on one wlc first and set that wlc to master, then when you have finished that, set the other wlc to master and have the ap's join that wlc which will be the primary fro those ap's.

You only can support 100 ap's so depending what code you use, 30 ap's that are not able to join will just keep trying. If you run 5.2 (I think is buggy) you can set the priority on the ap's so that ap's that you set up with a higher priority will be able to join and the others will again sit there until the othe wlc comes back up. Static IP address will not dissapear because the wlc doesnt' accept any more connections. Once both wlc are up, the ap's will go back to their primary wlc as long as ap fallback is enabled and mobility is configured right.

-Scott
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Difan Zhao · ‎04-14-2009

Thank you Fella5! So you mean that after APs first get associated with controllers, they will decide and remember which one is primary and which one is secondary, right? So I don't have to manually configure each AP to tell them which one is primary, correct? So in this case I don't have to configure anything special on the controller at all but just keep default and I don't have to worry about AP gets associated with different controller and doesn't come back to the previous controller?

Thanks!

Scott Fella · ‎04-14-2009

When an AP successfully joins, it will know of that AP and any others configured in th emobility group. It is still best practice to set these due to the join process. The AP will try to join that wlc first, but if that wlc is busy, it will deny the AP and then that AP might join the othe WLC if not busy. Setting these parameters, allows you to controll what ap's you want on which WLC. If you don't care what AP goes on what WLC, then yes you can leave it default and allow the WLC to make the decision.

-Scott
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