The controller keeps a running average of response times for each authentication server. Two main parameters are used to compute the expected authentication time (response time) for an authentication server.
1) Number of outstanding requests for that authentication server
2) Moving average of the authentication time per client for that authentication server.
The expected authentication time value is calculated after each client authentication/reauthentication. If the times are similar then the load will be more or less evenly distributed. If a server has a quicker average response time, it will get more requests. A server is "sticky" when it comes to a specific client; meaning whenever possible the same server is used for reauths.
Alterations or prioritizing one over another is not supported at this time.
There is a specifc mathematical algorithm that determines the exptected time taken to authenticate. If you need those specifics, please contact your local Aruba team.