External Subscriber Monitor Overview
You use the External Subscriber Monitor application with the event notification method of logging in subscribers and creating subscriber sessions. You can use event notification when you integrate devices into the SRC network that do not notify the SAE about subscriber events, such as when a subscriber logs in or when the address assignment is terminated.
External Subscriber Monitor must view all RADIUS accounting messages associated with subscriber sessions. External Subscriber Monitor is stateless and cannot synchronize the current set of subscribers when there is a failure. If events are missed because of a software or network failure, the overall state recovers when RADIUS interim updates are sent. For example, missed ipUp events become effective when the next interim update is sent, and missed ipDown events time out after the configured RADIUS time to live.
External Subscriber Monitor is configured as a pseudo–RADIUS server and acts as a RADIUS accounting server. Configure the router or RADIUS server to duplicate accounting packets to External Subscriber Monitor. When External Subscriber Monitor is the pseudo-RADIUS server, it handles software failures more robustly. The pseudo-RADIUS server does not acknowledge failed accounting requests and gives the RADIUS client the option to retransmit the accounting packet to a backup External Subscriber Monitor.