Traffic Engineering to Minimize the Number of Rules in SDN Datacenters

Traffic engineering is one of the importantparts in a datacenter. Software defined networking (SDN) opens opportunities for easier traffic engineering. Functionalities of an SDN switch are determined by the forwarding rules installed on it. Because of the limited space on SDN switches, it is important to keep the number of rules as small as possible. If the number of rules in a switch is higher than a threshold, then the forwarding delay jumps up. A virtual tunnel based approach helps to reduce the number of rules in an SDN switch while preventing link flooding attack vulnerability. A virtual tunnel is basically a conceptual structure in the controller of an SDN network where a group of flows follow a common path. A wise formulation of tunnels can reduce the number of rules needed dramatically by forwarding multiple flows through the same tunnels with the tunnel's common rules. In this paper, we address this important issue and propose a mechanism to keep the number of rules minimum. We formulate two problems and propose clustering-based and greedy solutions with an approximation ratio. Our first problem is to build some tunnels using the minimum number of edges and rules. Our second problem considers some predetermined tunnels and finds an ID assignment to the flows so that the number of rules needed to forward them is minimum. We conduct extensive simulations and experiments on our datacenter to validate our proposed model.