Dynamic Network Interface Selection in Multihomed Mobile Hosts

Current mobile devices are often equipped with several network interfaces, which may be of different access technologies, both wireless and cellular. Different requirements of different applications can result in a different preference of the interface that should be used. Network connections should be placed in the best possible interface based on these requirements. During communication, changes in the availability or characteristics of an access network behind an interface may result in a situation where already established connections should to be moved from one interface to another. For this purpose, a variety of mobility management protocols supporting handoffs between interfaces have been proposed. Some of these protocols move all traffic from one interface to another at once, while some protocols allow simultaneous communication over different interfaces. However, the current solutions do not propose any means for the user or application to be able to dynamically influence the interface selection during the operation of a mobile device. In this paper, we will present an interface selection mechanism for multihomed mobile hosts. The mechanism allows for dynamic decision-making during the operation of a mobile device. In our solution, the local routing is controlled by user-defined rules defining which interface to be used for a certain traffic flow. The actual decision is based on the adaptation of these rules into availability and characteristics of the interfaces and access networks at any given time.