Routing in opportunistic mobile ad hoc networks (MANETs) is characterized by intermittent and sporadic communication opportunities between portable devices. As a result, a path between the source and the destination(s) may only exist for a brief and unpredictable period of time, thereby leading to network partition. Most existing routing approaches store data packets locally and forward them when in reach of a mobile peer that carries the data packets closer to the destination. Through a survey of recent literature, this chapter will provide an overview of the routing protocols that exploit intermittent communication opportunities for increased data transmission success in MANETs, and characterize them using the following three aspects: (1) how does the protocol discover and exploit the intermittent communication opportunities in a mobile environment? (2) How does the protocol address multicast, which is a common data dissemination pattern in an opportunistic communication environment? and (3) What kind of real-world applications are enabled by the use of opportunistic routing protocols?.
