Effect of SCTP Multistream Function Applied to Parallel Downloading

Parallel Downloading, which divides a file into many pieces and assigns each piece to one of the servers which store the file, has been proposed and reported to achieve high speed file retrieval from many servers in parallel. The conventional method which adopts TCP as a transport protocol has a problem that its performance deteriorates in the network where packet losses frequently occur at the data-link layer. To address this issue, we have researched a parallel downloading method which uses SCTP instead of TCP as a transport protocol and focuses on its multistream feature. It is believed that the multistream function is a promising technique to alleviate the effect of packet loss problems in ubiquitous networks including wireless networks. We discuss how to realize the effective parallel downloading method using SCTP multistream and evaluate it. Here, we use only one server to simplify the problem. In this paper, on the network with various condition described by delay and loss rate, we conducted simulation experiments using various combination of parameters such as the number of concurrent requests, that of streams, and the division number. As a result, characteristics on parallel downloads using SCTP multistream have been clarified.