Email Messaging over Heterogeneous Networks and Interfaces

Communication from a device with multiple interfaces is not a new concept, e.g., we have mobile phones with multiple radios, or laptops with Ethernet, WLAN and 3G connectivity. Mobile IP (MIP) is the primary mechanism to enable seamless communication and switching over multiple interfaces. This is possible since all the interfaces support the Internet Protocol, and have a common addressing scheme, a unified network and transport layers. MIP is a well understood and mature solution. However, when communication should happen over multiple interfaces, where the only common denominator is the ability to transfer bits, most of the OSI-layers below the application layer differ.Thus, MIP or any similar IP-based technology can not be used. This stems, among other things, from the fact that in this scenario addressing schemes vary and some of them are non-IP. This paper presents the architecture and implementation of a new messaging system. We make use of disruption-tolerant network concepts to enable messaging over heterogeneous links. We provide reliable and unreliable transport, message priorities, and load balancing over multiple interfaces. The application programming interface, the way messaging applications are built, is the familiar email system.