A Flow Distribution Algorithm with Segment Routing for Software-Defined Networking

Abstract

Previously, routers have been responsible for both data forwarding and network management. Software-Defined Networking (SDN) separates these functions into a data plane and a control plane in order to simplify network operations and enable the construction of programmable networks. However, flow updates transmitted using the OpenFlow protocol introduce a communication overhead. Since Ternary Content Addressable Memory (TCAM) is used to quickly search flow entries, the associated costs rise significantly as the scale of the network increases. To address these problems, a method has been proposed that reduces flow entry update work and minimizes traffic overhead by aggregating some flows on a specific path in an SDN-managed network using SR (Segment Routing)-MPLS (Multi-Protocol Label Switching). However, while overall work is reduced, the load on the specific path used for the flow aggregation increases.

This paper proposes a flow distribution algorithm with SR that efficiently utilizes network resources, while also addressing the two aforementioned limitations of Software-Defined Networking (SDN) to enable a more reliable SDN infrastructure. To evaluate the proposed algorithm, simulation experiments compared the proposed algorithm with the shortest-path algorithm on four network topologies with 13, 24, 48 or 58 nodes, and our results showed that the average standard deviation of the number of packets forwarded by each node under the proposed method was 861.04–1496.17 packets lower by comparison with the shortest-path method when the total number of transmitted packets was 50,000, and 1743.37–2950.34 packets lower when the total number of transmitted packets was 100,000. We also noted that the average path length for each packet under the proposed method was just 0.15–1.08 hops longer than that of the shortest-path method.