Regionalized Routing

Operators/service providers may have OCS deployments which are segmented based on ranges of subscriber identities (for example, MSISDNs) such that a given group of OCSs can only serve the subscriber range it has been assigned to serve. To support this architecture, the DSR RBAR application can be provisioned with higher priority ART rules to be invoked prior to the invocation of PCA to perform regionalized routing based on subscriber's identity. If RBAR invocation fails, the DAL configuration should be provisioned such that RBAR is invoked on the mate DSR or an Answer response with a non-successful Result-Code/Experimental-Result AVP is generated and sent to the originator of the Diameter transaction.

In regionalized OCS deployments, it is likely that RBAR is invoked at one DSR NE (DSR that has direct peer connectivity with the online charging client) while PCA OC-DRA is invoked at another NE (DSR that has direct peer connectivity with OCSs in the serving region). ART rules corresponding to PCA for OC-DRA invocation should be configured such that PCA is invoked only if the Destination-Host and/or Destination-Realm is served by the same DSR (where RBAR was invoked). In cases where the Destination-Host and/or Destination-Realm are not served by the same DSR, the Request is routed to the DSR serving the Destination-Host and/or Destination-Realm (called the target DSR) and PCA is invoked for OC-DRA on the target DSR. OC-DRA invoked on the target DSR can be configured to operate in any of the OCS Pool Selection modes for routing within the target region.

Figure 5-3 Regionalized OCS Server Pool Selection

Note:

In cases where a session initiation request (CCR-I) is routed to OC-DRA on a target DSR, RBAR may have to be invoked for subsequent in-session request (CCR-U/T) messages for that session as well (for example, for non-proxy-compatible online charging clients). If MSISDN is not present in CCR-U/T messages, regionalized routing cannot be supported