Abstract: Delay-tolerant Networking (DTN) makes successful communication in sparse mobile ad-hoc networks and other challenged environments where there is no end to end path established unlike traditional networking. The performance and efficiency of routing protocols in DTN depends on various mobility models in which node travels and node characteristics. Through the evolution of various routing protocol in different scenario using simulation tool comparative study can be done. This paper focus on the existing routing protocols techniques and Comparative study of existing routing protocols of Delay-Tolerant Networks based upon the metrics like Delivery Ration and Overhead Ratio.

Keywords: Intermediant connectivity; Delay Tolerent Network; routing; DTN