Algorithm for controlling transaction consistency in SIP session control systems

Fault-tolerance of session control systems based on the session initiation protocol (SIP) is achieved by multiplying sessionstateful servers and by replicating their session states. Replication can cause service inconsistency. An update commit algorithm (UCA) for adaptive consistency control is proposed. Analytic and simulation results show that the UCA provides the user- and operator-tolerable consistency/performance trade-offs.