On analytical model for optimal SIP server hop-by-hop overload control

In this paper, we present analytical results of the analysis of the queueing system that models signalling hop-by-hop load control mechanism for SIP server. The so-called hop-by-hop overload control, known from recent IETF drafts and RFCs, is based on hysteretic load control with two thresholds for reducing potential oscillations between the control-on and control-off states under certain loading conditions. Adjustment of thresholds values makes possible the load control of signalling traffic and therefore meeting blocking requirements. New approach that allows fast computation of joint stationary probability distribution of finite M₂|M|1|R queue with bi-level hysteretic input load control is proposed. Illustrative numerical example is given to demonstrate some optimization issues.