Packet Loss Recovery of Signaling Traffic in SCTP

The Stream Control Transmission Protocol (SCTP) was de-veloped to be a viable solution for transportation of signal-ing traffic within IP-based networks. Signaling traffic is dif-ferent from ordinary bulk traffic in many ways. One exam-ple of this is that the requirements of timely delivery usually are much stricter. However, the loss recovery mechanisms in SCTP are not fully optimized to these requirements. For in-stance, if packet loss occurs when the amount of outstand-ing data is small, a SCTP sender might be forced to rely on lengthy timeouts for loss recovery. This paper presents a number of proposals that try to solve this particular problem, with focus on the Early Retransmit mechanism. We propose a modification to Early Retransmit, to adapt it to signaling scenarios, and evaluate its performance experimentally. The results show that the modified Early Retransmit mechanism is able to provide significant reductions in loss recovery time. In some cases, the time needed to recover from packet loss was reduced with as much as 67%. 1