M Network Layer Mobility : An Architecture and Survey

change their point of attachment to the network. In such an environment, in order for mobile devices to run without disruption , an internetworking infrastructure is needed. In addition, a common networking protocol is required which can support network-wide mobility. Mobile devices also need to communicate with the existing pool of information servers and file servers, which means that internetworking solutions for connecting stationary and mobile systems are also required. Unfortunately, the Internet Protocol (IP), which forms the fabric of the current worldwide data communication network, falls short of meeting this demand. The current Internet suite of protocols — Transmission Control Protocol/Internet Protocol (TCP/IP) — were designed under the assumption that end systems are stationary. If, during an active network session, one end of the connection moves, the network session is broken. Naturally, all networking services layered on top of TCP/IP are also disrupted when end systems become mobile. There are two approaches for solving this problem. One is to completely redesign internetworking protocols with the specific goal of supporting mobile end systems. The other approach is to provide additional services, which make mobile internetworking possible, at the network layer in a backward-compatible manner. The first approach, though an interesting possibility from a research viewpoint, is infeasible because it would require radical changes to the currently deployed networking infrastructure. The latter approach is the focus of our investigation. To ensure interoperability with the existing infrastructure, the handling of mobility should be completely transparent to the protocols and applications running on stationary hosts. In other words, from a stationary end system's perspective, a mobile host should appear like any other stationary host connected to the Internet. This means that the same naming and addressing conventions, those originally developed for stationary hosts, must apply to mobile hosts. In addition, any changes in a mobile's network attachment point should be completely hidden from the protocols and applications running on stationary hosts. In this article we explore various network-layer concepts that play a crucial role in the design of mobile networking systems. We show that mobility is essentially an address translation problem and is best resolved at the network layer. We have identified the fundamental services that must be supported at the network layer to carry out the task of address translation. Using these service primitives as building blocks, we describe a network-layer architecture which enables smooth integration of mobile end systems within the …