Anycast Routing Algorithm with Special Composite Distance

Anycast members are all equivalent servers. The quality of service data is more important than that of the request data which is anycast datagram. It is also widely recognized that the communications are asymmetric and the downloading flows from the servers may require more network resource than the upload request transmission in terms of clients in many cases. Routing for an anycast datagram also is a process to locate a server for the client, whose result will affect the quality of service requested. A novel anycast routing algorithm called anycast routing algorithm with special composite distance (ASCD) is proposed. The route for an anycast destination is selected by a shortest composite distance which is computed by metrics including hop number, reverse data transmission delay, reverse residual bandwidth, and server load. Differing from other approaches, ASCD uses values of bandwidth and delay on the reverse direction from the destination node (servers) of an anycast datagram to its source node (client), rather than the normal direction from the source to the destination. The best server/path selected by ASCD can increase the probability of giving more network resources for the service data. ASCD can balance the server load to some extent, too.