Experimental Evaluation of Convergence Layers in Delay Tolerant Networks

Abstract

Traditional Internet protocols like TCP/IP and UDP/IP are not designed to perform efficiently in Delay Tolerant Networks (DTN) environments that operate in environments with high delays, significant losses, and intermittent connectivity. DTN uses the Bundle Protocol (BP) in the Bundle layer for storing and forwarding data units to deal with the absence of an end to end connection. Since BP is an overlay protocol that can be used above different transport layer protocols, the corresponding convergence layer protocol needs to be used to allow data flow from BP to the transport protocol and vice versa. The convergence layer enhances the underlying transport protocol by adding services like reliable delivery and message boundaries and some additional functionality to the transport layer protocol that makes it suitable to function in extreme environments. This Thesis work focuses on the performance evaluation of the Licklider Transmission Protocol (LTP) convergence layer running over Datagram Congestion Control Protocol (DCCP) under various realistic DTN conditions. The performance comparison of LTPCL/DCCP with other convergence Layers such as LTPCL/UDP and TCPCL/TCP is also performed. Tests are conducted enabling communication between Nodes using LTP over UDP and LTP over DCCP and TCPCL over TCP protocol. The discussion of different metrics, such as Throughput and File Delivery Time (FDT) of these convergence layer protocols under various Bit Error Rates (BER), propagation delays and link disruption are also examined.