In-order delivery approach for 3D NoCs

Routing algorithms can be classified into deterministic and adaptive methods. In deterministic methods, a single path is selected for each pair of source and destination nodes, and thus they are unable to distribute the traffic load over the network. Using deterministic routing, packets reach a destination in the same order they are delivered from a source node. Adaptive routing algorithms can greatly improve the performance by distributing packets over different routes. However, it requires a mechanism to reorder packets at destinations. Thereby, a large reordering buffer and a complex control mechanism are required at each node. This motivated us to propose a method guaranteeing in-order delivery while sending packets through alternative paths. The proposed method combines the advantages of both deterministic and adaptive routing algorithms. We introduce several routing algorithms working together in the network without creating cycles. By using these algorithms, packets of different flows use different routes while packets belonging to the same flow follow a single path. In this way, traffic is distributed over the network while addressing in-order delivery. We employ this approach on three-dimensional Networks-on-Chip.