Session Initiation Protocol (SIP) is an application layer protocol designed to create, manage, and terminate multimedia sessions in the IP multimedia subsystem (IMS). The widespread use of this protocol results in high traffic volume over SIP proxies, requiring delicate
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Session Initiation Protocol (SIP) is an application layer protocol designed to create, manage, and terminate multimedia sessions in the IP multimedia subsystem (IMS). The widespread use of this protocol results in high traffic volume over SIP proxies, requiring delicate CPU allocation to flows. In this paper, we analyze the optimization problem of resource allocation in SIP proxies with two objective functions: maximizing total throughput and minimizing the least squares. Maximizing total throughput, prioritizes intra-domain flows over inter-domain ones, as the latter pass through two intermediate proxies. On the other hand, minimizing the least squares corresponds to a max-min fairness policy. Hence, we use round robin scheduling in proxies. In addition, we propose a SIP overload control algorithm that limits re-transmissions and prevents instability of proxies by controlling the length of SIP message backlog for each flow. This algorithm leads to better use of processing resources, in comparison with existing overload control algorithms.
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