Users Guide

278 | Authentication Servers Dell Networking W-Series ArubaOS 6.4.x| User Guide
Using the CLI
The commands below configure timers you can apply to clients. If the optional seconds keyword is not
specified for the idle-timeout and stats-timeout parameters, the value defaults to minutes.
(host)(config) #aaa timers
dead-time <minutes>
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 Controller to perform load balancing of
authentication requests destined for 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.
Previously, the controller used the first authentication server in the server group list. The remaining servers in
that group would be used in sequential order only when an authentication server was down. Thus, the
controllers performed fail-over instead of 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 with the shorted expected authentication time.
The load balancing algorithm maintains re-authentication stickiness, meaning that at the time of re-
authentication, the request is forwarded to the same server where it was originally authenticated.
Enabling Authentication Server Load Balancing Functionality
A new load–balancing enable parameter has been introduced in the 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 an internal server in the server group, load balancing is not applicable to the internal server. The
Internal server will be used as a fall-back when all other servers in the group are down.