IAS supports RADIUS Accounting, which an administrator can use to track network usage for auditing and billing purposes. RADIUS Accounting provides the following benefits:
Real-time data collection.
Accounting data can be collected at the centralized place.
Third-party products can be used to analyze RADIUS accounting data to provide charge-back, performance, and exception reports.
When a client is configured to use RADIUS Accounting, at the start of service delivery it generates an Accounting Start packet describing the type of service being delivered and the user it is being delivered to. The packet is then sent to the RADIUS Accounting server, which sends back an acknowledgment that the packet has been received. At the end of service delivery, the client generates an Accounting Stop packet describing the type of service that was delivered and statistics (optional), such as elapsed time, input and output octets, or input and output packets. It then sends that data to the RADIUS Accounting server, which sends back an acknowledgment that the packet has been received.
The Accounting-Request packet (whether for the Start or Stop packet) is submitted to the RADIUS accounting server through the network. If no response is returned within a length of time, the request is re-sent a number of times. The client can also forward requests to an alternate server or servers in the event that the primary server is down or unreachable. An alternate server can be used either after a number of tries to the primary server fail, or in a round-robin fashion. If the RADIUS accounting server is unable to successfully record the accounting packet, it does not send an Accounting-Response acknowledgment to the client. For example, when the log file gets filled up, IAS starts discarding accounting packets. This prompts the NAS to switch to the backup IAS server.