TCP Westwood Performance Over Multiple Paths

Since its first introduction, TCP has been the major facility to transport best-effort traffic in the Internet. It has been enhanced repeatedly over 3 decades, and is now an integral part of every single computing facility. Today, Internet is again on the move toward more reliable and robust network services. In fact, fault tolerance and network security have become significant issues. To improve fault tolerance, many diverse approaches have been proposed. A promising approach consists in deploying multiple paths between origin and destination. Unfortunately, distributing packets of the same TCP connection over multiple paths can create out-of-sequence delivery with negative impact on conventional TCP which infers network congestion from duplicate ACKs. In this paper, we expose the side effects of the multiple path deployment on TCP Reno and SACK performance, and contrast its behavior to that of TCP Westwood. TCP Westwood is robust to out of sequencing and achieves better throughput.