MSOCKS+: An architecture for transport layer mobility

Mobile nodes of the future will be equipped with multiple network interfaces to take advantage of overlay networks, yet no current mobility systems provide full support for the simultaneous use of multiple interfaces. The need for such support arises when multiple connectivity options are available with different cost, coverage, latency and bandwidth characteristics, and applications want their data to flow over the interface that best matches the characteristics of the data. In this paper we introduce and analyze an architecture called Transport Layer Mobility that allows mobile nodes to not only change their point of attachment to the Internet within a corporate domain, but also to control which network interfaces are used for the different kinds of data leaving from and arriving at the mobile node. We implement our transport layer mobility scheme using a split-connection proxy architecture and a new technique called TCP Splice that gives split-connection proxy systems the same end-to-end semantics as normal TCP connections. We introduce the architecture, present its system aspects, investigate its performance and present its reliability properties. The analytical aspects of the protocol, in particular its pseudo-code, its properties and its validation are given in a related Technical Report.