A packet resequencing protocol for fault-tolerant multipath transmission with non-uniform traffic splitting

Abstract

A multipath switching system serves as a useful abstraction for achieving bandwidth aggregation by means of switched connection inverse multiplexing. The characteristic features of such a system include non-uniform nominal traffic splitting weights, variable path bandwidths, large variable delays, and possibility of packet loss. Maintaining traffic integrity under these conditions presents a major design issue and a criterion for implementation success. This paper examines the inadequacies and limitations manifested by the existing sequence control techniques in the asynchronous multipath switching environment, introduces a notion of rank, which is associated with independent enumeration of the alternating series of packets for each pair of the available switching paths, and defines a novel rank-based packet resequencing protocol that relies on conveying information on the relative ordering of the available paths, rather than the absolute packet order. The properties of the new protocol are discussed and the operations of the ingress and egress controllers are described.