Re-Rooting-Based Fault-Tolerant Broadcasting in Dense Gaussian Networks

Abstract: Dense Gaussian networks provide degree-4 interconnection topologies with small diameter and regular structure, making them suitable for efficient one-to-all broadcasting. However, node failures can disrupt the broadcast process when faulty nodes occupy internal forwarding positions. This paper proposes a lightweight fault-tolerant broadcasting method based on dynamic source relocation, or re-rooting. Instead of constructing redundant spanning trees or backup routing structures, the proposed method selects a new source node so that the faulty nodes are located at graph distance (k), the network diameter, from the new source. Consequently, faulty nodes become leaf-level nodes in the broadcast process and are not required to forward the message. For the single-fault case, the new source is selected directly from the graph-distance-(k) boundary of the faulty node. For the two-fault case, we prove that for any pair of faulty nodes in (G(k+(k+1)i)), there exists a node whose graph distance from both faulty nodes is exactly (k). The source-selection procedure requires (O(k)) time. Since the original one-to-all broadcast completes in (k) parallel steps and the relocation distance is at most (k), the proposed method completes in at most (2k) steps in the worst case. We also show that the two-fault guarantee does not generally extend to arbitrary three-fault configurations by giving a counterexample in (G(3+4i)). Simulation results confirm complete delivery to all non-faulty nodes under the tested one- and two-node failure scenarios, while the baseline broadcast may fail when faulty nodes occur at internal forwarding positions.