Generation and delivery times of bundles routed by Schedule-Aware Bundle Routing (SABR) with and without the load-balancing enhancement

Delay- and disruption-tolerant networking (DTN) enables communication in networks afflicted by long propagation delays and sporadic connectivity. DTN routing protocols such as Schedule-Aware Bundle Routing (SABR) exist to route data bundles in deterministic networks, such as those found in deep-space environments, where node contacts are predictable. This article begins with an overview of DTN architecture and the SABR algorithm. SABR’s method of final route selection (forwarding rules) is closely examined. The article then addresses a limitation of SABR whereby the algorithm may overlook parallel channels, leading to network congestion. To mitigate this, an enhancement is proposed. This enhancement aims to optimise data bundle distribution across candidate routes in networks with parallel channels, thus alleviating congestion and enhancing overall network performance. This is achieved with simple modifications to SABR’s forwarding rules to avoid the concentration of data bundles on a minority of node contacts. The enhancement is demonstrated through simulations in a reference scenario implemented in DtnSim.