Efficient Contact Graph Routing Algorithms for Unicast and Multicast Bundles

The challenging network topologies involving space communications motivated the introduction of new network architectures, to face the new constraints of delays and disruptions which make the core principles of the terrestrial Internet inapplicable. In a Delay/Disruption-Tolerant Network architecture (DTN), the nodes only have an accurate knowledge of their close neighborhood, which renders complicated to guaranty the reliability of a route leading to a remote destination. To address these issues, Contact Graph Routing (CGR) calculates the best route at each forwarding node but with a high processing cost. For the multicast case, the spanning tree would be vulnerable to capacity shortages or node breakdowns on remote branches. Besides unplanned disruptions, the delays only induced by the electromagnetic wave propagation bring questioning about the efficiency of a traditional spanning tree management. This paper describes a multicast implementation which intends to address these issues as well as the proposal of a new CGR algorithm showing significant lower algorithmic and software design complexities for both unicast and multicast load. The synergy between these two concepts motivates the presentation of them as a whole and this paper intends to highlight their benefits.