RADIUS

Authorization Sequences

There are several different methods in which the end user, the AAA server, and the network equipment communicate during a transaction. Specifically, there are three different sequences in which each machine is contacted.

The agent sequence

In this sequence, the AAA server acts as a middleman of sorts between the service equipment and the end user. The end user initially contacts the AAA server, which authorizes the user’s request and sends a message to the service equipment notifying it to set that service up. The service equipment does so, notifies the AAA machine, and the notification is passed on to the end user, who then begins using the network. This sequence is typically used in broadband applications in which quality of service (QoS) is part of an existing contract.

The pull sequence

Dial-in users frequently encounter this sequence. The end user in this situation connects directly to the service equipment (terminal gear or other NAS machinery), which then checks with an AAA server to determine whether to grant the request. The AAA server notifies the service equipment of its decision, and the service equipment then either connects or disconnects the user to the network.

The push sequence

The push sequence alters the trust relationship between all of the machines in a transaction. The user connects to the AAA server first, and when the request to the server is authorized, the AAA server distributes some sort of authentication “receipt” (a digital certificate ...