A highly efficient transport protocol for large capacity data files non-ordered block transfer on XCAST

This paper describes on a protocol named NBT (NBT: non-ordered block transfer) which efficiently transfers large-capacity stored files, and is applicable in a pure IP network. Ordinary file transfer is performed on unicast basis. However, the unicast wastes bandwidth by sending the same large-capacity file to each request, when plural download-requests are simultaneously made. NBT has been proposed to alleviate this problem. Since the original NBT adopts ATM as a multicast scheme, the network domain in which the NBT can be used is restricted. As the solution, adoption of explicit multicast (XCAST) is proposed as a multicast scheme, resulting in a flexible NBT. The proposed system is especially effective when the server frequently transfers large capacity files.