TCP-R: TCP mobility support for continuous operation

The T C P R ( T C P Redirection) is an extension of TCP, which maintains active T C P connections when the disconnection occurs due to the change of the I P address or the ch,ange of the network device. In mobile computing environments, the IP address may be changed frequently as the host moves across subnets or changes a network device. However, it is difficult for most nwtwork applications to work continuously in such a situation. There is much research to support such dynamics in th,e network layer, but these attempts in the IP layer tend to incur some complexi t y . This paper is intended as an investigation of the end-to-end mobility support in transport layer. W e developed the simple and secure redirection mechanism in TCP, which enables us t o keep our working activities without any intermediate agents. W e also show that TCP-R can serve as a solution to th,e retransmission timeout problem which frequently occurs in mobile environments. W e implemented and evaluated a prototype of T C P R b y modifying FreeBSD. The measured performance indicates that T C P R can maintain operation continuously with minimal overhead and complexity.