About Configuring RADIUS for Dynamic Interfaces

Dynamic interfaces can be configured automatically through authentication and authorization by the RADIUS server. Initially, you create the static portion of the interface column by creating an ATM interface, ATM 1483 subinterface, and underlying ATM permanent virtual circuit (PVC).

subscriber Command

For dynamic interfaces that do not have a PPP layer, such as IPoA, the subscriber command allows you to configure an ATM 1483 subinterface to automatically be authenticated by the RADIUS server. The subscriber command uses a RADIUS username and optional password for identification and is available only for bridged Ethernet and IPoA configurations. This command is used for dynamic encapsulations that do not provide the authentication information remotely, as PPP does.

When PPP is a layer of the dynamic interface, once the PPP interface is dynamically created, the RADIUS username and password are obtained from the remote client, and authentication is performed with the RADIUS server. The attributes obtained from RADIUS can then be used to configure any higher-layer dynamic interfaces, such as IP, that are built over PPP.

Placing Dynamic IP Routes in the Routing Table

If you want to insert a dynamic IP route into the routing table of the relevant virtual router to point to the subscriber's subinterface, you can use the Framed-Route [22] RADIUS attribute to do so. Defined by RFC 2865—Remote Authentication Dial In User Service (RADIUS) (June 2000), the Framed-Route attribute can be returned in Access-Accept messages to specify the route as follows:

Framed-Route = ipAddress/mask nextHop

For dynamic IP interfaces, the next hop might not be known when you create the user record. In this case, use the value 0.0.0.0 for the next hop; the E-series router then assigns the subinterface associated with the user as the next hop in the routing table.