Concurrent Multipath Transfer Using SCTP: Modelling and Congestion Window Management

Concurrent multipath transfer (CMT) using the stream control transmission protocol (SCTP) can exploit multihomed devices to enhance data communications. While SCTP is a new transport layer protocol supporting multihomed end-points, CMT provides a framework so that transport layer resources are used efficiently and effectively when sending to the same destination with multiple IP addresses. In this paper, we present two techniques for modelling the expected throughput of a CMT session; while one is based on renewal theory, the other uses a Markov chain. As far as we know, ours is the first paper to model CMT whilst considering practical transport layer resources like a shared receive buffer (RBUF). A comparison of the models showed the Markov chain to be more accurate, but suffered from scalability issues. Alternatively, the renewal model was more cost effective, but also less accurate. We also applied our models to a new problem called congestion window management, where the size of each congestion window is reconfigured for optimal performance. Again, we compared two approaches: a dynamic method that makes decisions based on instantaneous throughput, and a static method that uses an integer linear program (ILP) to generate a global solution. Results showed the static method outperforming the dynamic approach by as much as 12 percent.