Always-on is enabled for each subscriber individually through a local subscriber profile or a RADIUS profile. Always-on is disabled for all subscribers by default.
If Always-on is enabled for a subscriber, when the idle time-out limit is reached the subscribers IP/PPP session remains connected as long as the subscriber is reachable. This is true even if the airlink between the mobile device and the RN (Radio Node) is moved from active to dormant (inactive) status. When the idle timeout limit is reached, the PDSN determines Mobile Node availability using LCP keepalive messages. A response to these messages indicates that the "always-on" status should be maintained. Failure to respond to a predetermined number of LCP keepalive messages causes the PDSN to tear-down (disconnect) the subscriber session.
When always-on is enabled, the subscriber must have an idle time-out period configured (default is 0, no time-out). Failure to configure an idle time-out results in the LCP keepalive messages never being sent and the subscriber session stays up indefinitely.
The RADIUS attribute 3GPP2-Always-On defined in a subscriber profile stored remotely on a RADIUS server can be used to enable Always-on for the subscriber. The attribute has two possible values, inactive and active. To enable Always-on, set the attribute to active.
For more information on the attributes, if you are using StarOS 12.3 or an earlier release, refer to the AAA and GTPP Interface Administration and Reference. If you are using StarOS 14.0 or a later release, refer to the AAA Interface Administration and Reference.