For dynamic transit AA subscribers, AA can automatically detect new IP addresses and create a local subscriber context with no interaction with RADIUS or Diameter policy control. When transit-auto-create is enabled within a transit policy, the ISA detects IP flows on an AA parent subscriber that do not map to an existing transit AA subscriber. When auto-create is enabled, AA subscriber contexts are auto-created under the parent diverted SAPs and spokes using the transit-IP-policy name and subscriber IP address as the AA-sub name. The default app-profile configured against the transit-ip-policy is applied to these subscribers.
By default, auto-created subscribers are persistent and never removed (without removal of the AA group). ISAs may periodically be shut down and then no shutdown to clear the aa-subs to avoid running out of sub context, or, inactive subscribers may be automatically removed after a timeout period by using the transit-auto-create context command for inactivity-monitoring. With this, periodically AA removes any inactive auto-created subscriber where an inactive sub is defined as having no active flows in the last period.