Gate Switch Selection for In-Band Controlling in Software Defined Networking

Abstract

In software defined networking (SDN), control connections between switches and the aqfd 4controller are established by either an in-band or an out-of-band control mechanism. In this paper, we focus on in-band controlling. In an in-band controlling, a switch constructs a control connection (usually TCP connection) to the controller through a data path. To ensure path availability, better load balancing, and robustness, multi-path TCP (MPTCP) has been introduced for control channels instead of TCP. Since MPTCP has multiple subflows, each subflow may acquire different paths to fully utilize MPTCP for control connection of SDN. Essentially, the controller should be connected to multiple gate switches first and then, each non-gate switch fabricates an MPTCP connection with multiple subflows to the controller through the gate switches. In such MPTCP-based in-band controlling environment, the selection of gate switches is crucial in achieving availability and reliability of the control channel. For example, multiple subflows through the chosen gate switches should be disjoint as much as possible. In this paper, we first illustrate an objective of in-band controlling and then, we propose a heuristic algorithm to compute a gate switch set that achieves the objective. To be specific, we want to make the subflows disjoint and short lengthed for high availability. We investigate the performance of the proposed algorithm with the two baseline algorithms, i.e., exhaustive search and random search . Through extensive simulation, we demonstrate that the proposed algorithm performs much better than the random search and is comparable to the exhaustive search.