Loss Recovery in Short TCP/SCTP Flows

The Transmission Control Protocol (TCP) has been the dominant transport protocol within IP-based networks for many years, mainly due to the reliability it provide to its users and the congestion control it employs. However, as the amount of signaling traffic within IP-based networks have increased significantly in recent years, it has become clear that TCP is not suited for this kind of traffic. In order to meet the requirements of signaling traffic the Stream Control Transmission Protocol (SCTP) was developed by the Internet Engineering Task Force (IETF). SCTP is heavily influenced by TCP and is therefore similar to TCP in many ways. One example is the SCTP loss recovery and congestion control mechanisms which are almost identical to those of TCP. The primary purpose of this work is to study the performance and behavior of the TCP/SCTP loss recovery mechanisms for short flows. Using a simple client/server model, we evaluate the performance of these mechanism over a wide range of bandwidths, link delays and packet loss patterns. The experiments evaluate one TCP implementation and two SCTP implementations, and were conducted using network emulation. The experimental results show that there exist strong dependencies between the position of packet loss and the actual transmission time of the corresponding flow. In addition to these dependencies, we also found a number of implementation mistakes in the examined protocol implementations