The Impact of SCTP on SIP Server Scalability and Performance

Abstract — The Stream Control Transmission Protocol (SCTP) is a relatively recent transport protocol, offering features beyond TCP. Although SCTP is an alternative transport protocol for the Session Initiation Protocol (SIP), we do not know how SCTP features influence SIP server scalability and performance. To estimate this, we measured the scalability and performance of two servers, an echo server and a simplified SIP server on Linux, for both SCTP and TCP. Our measurements found that using SCTP does not significantly affect data transfer latency. However, the number of sustainable associations drops to 17-21 % or to 50 % of the TCP value if we adjust the acceptable gap size of packet reordering. I