Load-balancing algorithm for distributing Session Initiation Protocol (SIP) requests to a cluster of SIP servers

This paper introduces the several load balancing algorithms for distributing Session Initiation Protocol (SIP) request to a cluster of SIP servers. Our load balancer algorithm Transaction Least Work Left is used to allocate work to least values of the servers. It is combine knowledge of the SIP. Two types of state exist in SIP. The first, session state, is created by the INVITE transaction and is destroyed by the BYE transaction. The session-oriented nature of SIP has important implications for load balancing. The SIP is a protocol of growing importance, with uses for VOIP, IPTV, audio conferencing, instant messaging. We Session-aware request assignment (SARA) is the process where a system assigns requests to servers such that sessions are properly recognized by that server, and subsequent requests corresponding to that same session are assigned to the same server. We compare our algorithms to several well-known approaches and present scalability results. Our algorithm, Transaction Least-Work-Left (TLWL), achieves its performance by integrating several features: dynamic estimates of back-end server load, knowledge of the SIP protocol, recognizing variability in call length, distinguishing transactions from calls and exploiting differences in processing costs for different SIP transaction.