SRC Software in the IMS Environment
Figure 7 shows the Juniper Networks layered IMS architecture.
The northbound Rq interface of the policy and control layer allows integration with SRC applications, such as the portals, the Application Services Gateway, and the Admission Control Plug-In (ACP).
When the SRC IMS Gateway fails over or is restarted, it needs to use the session ID that is acquired during service activation to deactivate the service. This information can be passed to the SAE if the IMS Gateway synchronizes states with the SAE. If state synchronization is enabled, the current session information can be transferred so that the IMS Gateway does not have to keep a local and persistent copy of the data. The IMS Gateway registers its interoperable object reference (IOR) with the SAE so that the SAE can communicate with the IMS Gateway.
If two SRC IMS Gateways synchronize states with the SAE, one IMS Gateway can provide redundancy for the other IMS Gateway. The first IMS Gateway connected to the SPDF is the primary IMS Gateway, and the other IMS Gateway is the redundant (standby) IMS Gateway. After the IMS Gateway asks the SAE to activate services for the session, the session information is passed to the SAE as activation attributes that are stored in the SAE's session store. The SAE synchronizes states with the standby IMS Gateway, so that the standby IMS Gateway can become the primary IMS Gateway if the primary IMS Gateway becomes unavailable.