Routing in Wireless Networks with Intermittent Connectivity

Definition: Wireless networks with intermittent connectivity (also called Delay or Disruption Tolerant Networks), are characterized by sporadic availability of end-to-end paths between end hosts. Existing TCP/IP packet routing protocols cannot cope with the lack of reliable end-to-end connectivity. New routing mechanisms are necessary. The Internet has been exceedingly successful in establishing a global communication network built on the concept of a common set of TCP/IP protocols. Within the last ten years there have been tremendous research efforts spent adapting the TCP/IP protocol stack to various types of wireless and mobile networks. Routing has been recognized as the most challenging problem in networks with a dynamic topology. Protocols, such as AODV [15], DSR [10], OLSR [4] and many others have been thoroughly analyzed in multiple scenarios. Their main limitation comes from the fact that, by design, they work only if there is a contemporaneous end-to-end path between endpoints. These protocols are able to find a route only if the destination router can complete the route discovery protocol (for on-demand routing protocols) or successfully disseminate link state advertisements (for table-driven routing). Node mobility or sporadic channel availability increases route instability, causing an increase in routing overhead and a reduction in end-to-end connectivity. Under these circumstances, routing protocols cannot keep up with the topology changes, and the overall network performance is reduced. In this chapter we present an introduction to routing in networks with intermittent connectivity, and we cover several representative routing mechanisms. We begin by describing the main approach for message 1