As the Session Initiation Protocol(SIP) has gradually become the core protocol for the next generation networks and has been widely applied in telecom and other key sectors
increasingly higher availability of SIP servers is required.A complete high availability SIP stack solution has been presented on the basis of the re-analysis of the layered structure of the SIP stack
the protocol stack rolling upgrade strategy explained in detail and the problems to be encountered in its applications and the relevant resolutions studied.