Layer-5 temporally-spliced path for efficient Disruption Tolerant Networking

DTN (Delay/Disruption Tolerant Networking) inserts a new layer between the application layer (L7) and the transport layer (L4) for reliable communication on long-delay, intermittent, or lossy inks. Such a new layer, however, should provide not only a single rich service but also various rich services. We are proposing Layer-5 (L5) inserted between L7 and L4 to provide multiple rich services. One of the rich services of L5 is the L5 temporally-spliced path (L5-TSP). It is an application-to-application path composed of multiple L4 paths, which may not exist at the same time, spliced in L5 in the nodes called splicers. This paper proposes L5-TSP Protocol (L5-TSPP) for reliable communication on lossy links. L5-TSPP places splicers at both ends of a lossy link. It uses TCP on reliable links while UDP on lossy links. It uses partial acknowledgement to enable end nodes to know progress of communication. L5-TSPP is implemented on Linux. It takes 61 msec for connection establishment in L5-TSPP while 530 msec in TCP at packet loss rate of 10 % on a lossy link. It takes 18 sec to send a 1GB file in L5-TSPP while 73 sec in TCP at packet loss rate of 1 %.