Highly Efficient Transport Protocol for Large Capacity Data Files and its details

Abstract

We describe a protocol named Non-ordered Block Transfer on Explicit Multi-Unicast (NBT on XCAST). The purpose of this protocol is to save network bandwidth and to reduce server load in delivering large-capacity stored files. In general, files are transfered on a unicast basis. However, the unicast wastes bandwidth by sending the same large-capacity files when responding to each client's requests. In addition, server load increases. To solve this problem, Non-ordered Block Transfer (NBT) has been proposed as an efficient transfer system for large-capacity stored files using asynchronous transfer mode (ATM) multicast. However, NBT with ATM has not been implemented and has a limited area of use. In this paper, to solve this problem we propose an NBT protocol using XCAST (NBT on XCAST), which is proposed as a multicast scheme. XCAST can be implemented in a pure IP network without limitation of the data link layer protocol. Our proposed system is especially effective when the server frequently transfers large-capacity stored files. We discuss bandwidth consumption efficiency, a retransmission scheme, and experimental results of a partial performance using NBT on XCAST.