Multiple OCS Pools Mode

When OC-DRA is operating in Multiple OCS Pools mode, session initiation requests are loaded balanced across a pool of available OCS servers connected to the PCA DSR that can serve the request. OC-DRA relies on the RBAR application to be invoked prior to the invocation of PCA to populate the Destination-Host AVP and/or Destination-Realm AVP in session initiation requests. The hostname that RBAR uses to populate session initiation request's Destination-Host AVP can be a real hostname or a virtual hostname that is used to represent a pool of OCS servers that can serve the request. OC-DRA forwards the session initiation request without any modification to DSR where PRT/RL is used to route the session initiation request to one of the available OCSs within the selected pool of OCS servers.

Note:

OC-DRA removing the Destination-Host AVP from the Online Charging Diameter Request when operating in the Single OCS Pool mode ensures that the request will not be accidentally rejected by the PRT or by the OCS Server if the Destination-Host AVP contained the PCA DSR's hostname

Note:

OC-DRA does not specify the PRT/RL that is used by DRL to route Diameter request messages to an available OCS. The PRT selected for routing is based on DRL's PRT precedence rules.

Note:

When operating in Multiple OCS Pools mode, OC-DRA assumes (for example, does not verify) that RBAR was previously invoked to populate Destination-Host and/or Destination-Realm AVP of CCR-I/E messages received. It is entirely up to the operator to ensure that RBAR is invoked prior to PCA invocation as PCA will forward CCR-I/E messages received without any modification to DRL for routing using the PRT. A failure of RBAR invocation prior to PCA when OC-DRA is operating in Multiple OCS Pools mode may lead to unexpected routing results (for example, unable to route), each depending on PRT/RL configuration.

Figure 5-2 Local OCS Server Pool Selection