A Prediction-Based Overload Control Algorithm for SIP Servers

Overload is a challenging problem for a SIP server because the built-in overload control mechanism based on generating rejection messages could not prevent the server from collapsing due to congestion. In this scenario, the paper presents an overload mechanism combining a local and a remote solution. The local part of the overload control mechanism is based on the appropriate queueing structure and buffer management of the SIP proxy. The remote overload control mechanism is based on feedback reports provided by the SIP proxy to the upstream neighbors. These reports permit the traffic regulation necessary to avoid the critical condition of overload. The main paper contributions are the design of key components of a remote control mechanism, the proposal of a new approach for dynamic load estimation, and the use of a prediction technique in the remote control loop.