Reliability Mechanism for the Core Control Network-Element S-CSCF in IMS

The reliability of core control network-element S-CSCF is the key premise for the continual IMS services and the deployment of commercial IMS networks. According to the analysis of S-CSCF's functions and features, this paper proposes one design and implementation method to ensure the reliability of S-CSCF, including the contents consistency, fault detection, the successive switch from the main to standby server and recovery. The reliability mechanism is implemented and tested in the open source OpenIMS Core project. The experiment result shows that it is a feasible, effective, low-cost method. The standby S-CSCF2 rapidly restores the service without user's experience lost when some wrong is with the faulty working S-CSCF1.