Abstract Delay tolerant networks (DTNs) are a class of networks that experience frequent and long-duration partitions due to sparse distribution of nodes. The topological impairments experienced within a DTN pose unique challenges for designing effective DTN routing protocols, both for unicast and multicast applications. Certain types of DTNs depend on mobility to deliver messages and opportunistically exploit unplanned contacts among nodes to share information. Such network conditions present unique challenges to message routing. This talk presents challenges in DTN routing, new methods for both unicast and multicast routing, performance analysis of DTN routing schemes, and analysis of commonly-used mobility models and their extensions to model more realistic mobility scenarios. Specifically, core-assisted routing schemes for unicasting and controlled epidemic routing schemes for multicasting are discussed. This talk also presents the performance analysis of fundamental DTN routing schemes for important performance metrics such message delivery ratio, message delay, and buffer occupancy. Further, new results on the characteristics of commonly-used mobility models and their extensions will be discussed. Speaker Bio Muhammad Abdulla is a Ph.D. candidate in the department of Computer Science at George Mason University. His research focuses on delay tolerant networks and mobility models.