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Stability Analysis of Tandem SIP Proxies. IEEE ICC 2012 - Communication QoS , Reliability and Modeling Symposium Arthur: Seyed Vahid Azhari, Hani Nemati Presenter: 侯宗佑. Outline. Introduction Fluid Flow Model Lyapunov stability Stabilizing Algorithm Conclusion. SIP protocol.
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Stability Analysis of Tandem SIP Proxies IEEE ICC 2012 - Communication QoS, Reliability and Modeling SymposiumArthur: Seyed Vahid Azhari, Hani Nemati Presenter:侯宗佑
Outline • Introduction • Fluid Flow Model • Lyapunovstability • Stabilizing Algorithm • Conclusion
SIP protocol Signaling Communications Protocol IETF,RFC 2543, latest RFC 3261 Setup, modify, tear down multimedia sessions Text-based protocol (like http, smtp) Media stream use RTP protocol
Lyapunov Stability Mostly used for non-linear dynamic system Stay near Equilibrium point
Fluid Flow Model(Cont’d) Assumption: • Infinite queues, • negligible packet loss and processing time, • only Invite and OK message State variable: weighted number of Invite message queues on proxy
Lyapunov Stability Equilibrium : (x1,x2) = (0,0)
Lyapunov Stability(Cont’d) Optimal rejection policy P2,rej = 0 has max value All rejection burden at upstream proxy
Stabilizing Algorithm Idetical: P1 >= 1:
Stabilizing Algorithm(Cont’d) Maximum Withstand-able Overload
Conslusion Modeled SIP topology Derive Lyapunov stability condition Proposed a simple overload control algorithm Optimal rejection policy