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Distributed SDN architecture for NoC-based many-core SoCs

In the Software-Defined Networking (SDN) paradigm, routers are generic and programmable forwarding units that transmit packets according to a given policy defined by a software controller. Recent research has shown the potential of such a communication concept for NoC management, resulting in hardware complexity reduction, management flexibility, real-time guarantees, and self-adaptation. However, a centralized SDN controller is a bottleneck for large-scale systems. Assuming an NoC with multiple physical subnets, this work proposes a distributed SDN architecture (D-SDN), with each controller managing one cluster of routers. Controllers work in parallel for local (intra-cluster) paths. For global (inter-cluster) paths, the controllers execute a synchronization protocol inspired by VLSI routing, with global and detailed routing phases. This work also proposes a short path establishment heuristic for global paths that explores the controllers" parallelism. D-SDN outperforms a centralized approach (C-SDN) for larger networks without loss of success rate. Evaluations up to 2,304 cores and 6 subnets shows that: (i) D-SDN outperforms C-SDN in path establishment latency up to 69.7% for 1 subnet above 32 cores, and 51% for 6 subnets above 1,024 cores; (ii) D-SDN achieves a smaller latency then C-SDN (on average 54%) for scenarios with more than 70% of local paths; (iii) the path success rate, for all scenarios, is similar in both approaches, with an average difference of 1.7%; (iv) the data storage for the C-SDN controller increases with the system size, while it remains constant for D-SDN.