Migration support for indirect transport protocols

TCP as a reliable transport protocol performs well in traditional networks, but suffers significant performance reduction in hybrid networks. The higher bit and burst error probabilities of wireless links and disruptions caused by handoffs trigger TCP's congestion avoidance mechanisms even if the transmission path is not congested. The model of indirect transport protocols subdivides the end-to-end transport connection into several subconnections, operating over wired subpaths and over wireless subpaths. This way, the problem stated above can be avoided. Transport gateways are used to interconnect two subconnections. Due to the potential mobility of wireless attached stations, the migration of transport gateways to network nodes located nearby the current location of the mobile stations is needed. With a straight forward migration approach transport communication is interrupted up to 1.4 seconds. Modifications of the Mobile IP network layer to reduce disruption times are suggested. The key idea is to enable transport layer communication while transport protocol status information is forwarded to the new transport gateway and to delay the migration.