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Loss-free handoff in mobile networks is an extensive research area. Mobile IP (MIP) provided a solution to enable a mobile node to roam from one location to another while maintaining its network level connectivity. However, handoff latencies and longer triangular routing paths in MIP can severely degrade communication performance and in particular cripple connection oriented protocols like TCP. In this paper we propose an alternate approach for robust mobility. The scheme is based on the principle of 'interactive transparent networking' where all networking layers remain lightweight but are engineered for interactivity. This would allow principle intelligent actions to be performed at the application layer. With protocol interactivity we demonstrate a novel scheme that switches IP address in the TCP/IP stack on both end-points and perform loss-free rapid handoff. The scheme offers not only loss-free handoff, but also offers several fundamental system advantages; (i) it does not impose any changes on original network protocols or their dynamics, and (ii) it fully adheres to the end-to-end principle and do not require intermediary nodes as in MIP. We have achieved a real implementation of the scheme on FreeBSD and tested the real system over Internet with voice traffic. We show that this scheme can dramatically reduce handoff latency and improve TCP performance by offering shorter routes with loss-free handoffs and smooth, low-jitter voice stream.
Date of Conference: 3-7 April 2005