Contact networking: A localized mobility system

MobileIP, the standard for Internet mobility, enables transparent mobility for a mobile node, but requires communication to take a multihop path through the node's Home Agent. Although a user with a multipleinterface mobile node may desire the ability to communicate locally, perhaps while disconnected from the Internet, MobileIP offers no such support. Contact Networking provides lightweight, localized network communication to a node with diverse network interfaces. The goal is to provide support for local connectivity equivalent to that provided by MobileIP for remote connectivity. The concept of link-layer awareness enables Contact Networking to tailor its operation to different links, using link-layer native services to implement abstract services when possible. Interface management and autoconfiguration insulate the user from concerns about the number and type of interfaces available. In this paper, we motivate the need for localized mobility, and present the design and architecture of Contact Networking. Details of our prototype implementation illustrate the complexities of providing a localized mobility facility.