End-to-End Adaptive Error Control for a Resilient and Disruption Tolerant Transport Protocol

Abstract

While there has been an increase in the growth of networking technologies to suit the current demand of applications and users, networks are still susceptible to disruption. Communication networks operating in any domain come with inherent challenges that make end-to-end connections harder to maintain. This argument calls for protocols that are disruption tolerant and can offer resilience. Res-TP is a new transport protocol that directly addresses the challenges posed by challenged networks. It offers QoS (quality of service) and varying degrees of reliability depending on the class of data being communicated. Apart from a reliable-connection mode which offers full end-to-end reliability using ARQ (automatic repeat request), the protocol also includes quasi-reliable mode that offers statistical reliability by using end-to-end FEC (forward error correction) codes, unreliable-connection mode that does not implement either ARQ or FEC but relies on link-layer FEC, and unreliable datagram that transparently passes UDP traffic. While the fully-reliable connection mode offers closed-loop error control, the quasi-reliable mode offers open-loop error control. This leaves a gap within the spectrum to analyze the benefits of employing both closed-loop and open-loop error control. Hyrbid error control, with both FEC and ARQ, is a simple way to offer high end-to-end reliability and performance during moderate error conditions. In this thesis, the reliable-connection mode (ResTP-ARQ) along with hybrid error control mechanisms (ResTP-NACK and ResTP-NACK+MACK) are implemented. The protocols are simulated using ns-3 (network simulator-3) and are compared against the quasi-reliable mode to examine their tradeoffs. They are also compared against the traditional TCP and UDP protocols in an identical network scenario.