User's Manual

idle-timeout <time> [seconds]
logon-lifetime <0-255>
stats-timeout <time> [seconds]
Authentication Server Load Balancing
Load balancing of authentication servers ensures that the authentication load is split across multiple
authentication servers, thus avoiding any one particular authentication server from being overloaded.
Authentication Server Load Balancing functionality enables the Dell Mobility Controller to perform load
balancing of authentication requests destined to external authentication servers (Radius/LDAP etc). This
prevents any one authentication server from having to handle the full load during heavy authentication
periods, such as at the start of the business day.
Earlier, the controller used the first authentication server in the server group list. The remaining servers in that
server group will be used in sequential order only when an authentication server is down. Thus, the controllers
performed fail-over and not load balancing of authentication servers.
The load balancing algorithm computes the expected time taken to authenticate a new client for each
authentication server and chooses that authentication server for which the expected authentication time is
least. The load balancing algorithm maintains re-authentication stickiness i.e. at the time of re-authentication
the request will be forwarded to the same server where it was authenticated earlier.
Enabling Authentication Server Load Balancing Functionality
A new load–balancing enable parameter has been introduced in aaa server-group test command to
enable authentication server load balancing functionality.
aaa server-group <sg_name>
load-balance
auth-server s1
auth-server s2
You can use the following command to disable load balancing:
aaa server-group<sg_name>
no load-balance
If you configure internal server in the server group, load balancing is not applicable to the internal server. Internal
server will be used as fall back when all the other servers in the server group are down.
Dell Networking W-Series ArubaOS 6.4.x | User Guide Authentication Servers | 249