2.9.7 Routing and Load-balancing
Base RADIUS routing utilizes the same mechanisms as Diameter by means of encapsulating the RADIUS messages in a Diameter wrapper. Specific Diameter AVPs in the Diameter wrapper are created based on information from the corresponding RADIUS message and configuration information. The Diameter wrapper contains the following AVPs and Diameter header information which is then used to route the Diameter wrapper using existing Diameter routing mechanisms.
Table 2-10 RADIUS Message Mapping
| Diameter AVP | RADIUS Message Type | Value |
|---|---|---|
| Application-ID | Any | Derived based on configured mapping from RADIUS command code. |
| Command-Code | Any | Derived based on configured mapping from RADIUS command code. |
| Origin-Realm | CoA or Disconnect | Derived via configured mapping from ingress peer. |
| Not CoA or Disconnect | Derived via configured mapping from NAS-Identifier, NAS-IP(v6)-Address, or ingress peer. | |
| Origin-Host | COA or Disconnect | Derived via configured mapping from ingress peer. |
| Not CoA or Disconnect | Derived via configured mapping from NAS-Identifier, NAS-IP(v6)-Address, or ingress peer. | |
| Destination-Realm | CoA or Disconnect | Derived via configured mapping from NAS-Identifier, NAS-IP(v6)-Address, or ingress peer. |
| Not CoA or Disconnect | Domain part of User-Name, if possible, else same value as Origin-Realm (see above). | |
| Destination-Host | CoA or Disconnect | Derived via configured mapping from NAS-Identifier or NAS-IP(v6)-Address. |
| Not CoA or Disconnect | Destination-Host omitted. |
Load-balancing in RADIUS is the same as for Diameter with respect to route groups, weighted loadsharing, so on. Only Peer Route Groups are supported for RADIUS peers – Connection Route Groups are not applicable.
As RSR uses the Diameter routing mechanisms, all Diameter routing capabilities can be used to route RADIUS messages. For instance, if a response is not received in a timely manner after a RADIUS request is forwarded to a RADIUS server, RSR can resend the request a configurable number of times, and if a response is still not received, the request can be routed to an alternate server. RSR does not support the Diameter "alternate routing on answer" capability. RSR supports receipt of Status-Server message from RADIUS clients. RSR can be configured to respond to Status-Server with either Access-Accept or Accounting-Response.