TCAM space-efficient routing in a software defined network

Abstract

Software Defined Networking (SDN) enables centralized control over distributed network resources. In SDN, a central controller can achieve fine-grained control over individual flows by installing appropriate forwarding rules in the network. This allows the network to realize a wide variety of functionalities and objectives. However, despite its flexibility and versatility, this architecture comes at the expense of (1) laying a huge burden on the limited Ternary Content Addressable Memory (TCAM) space, and (2) limited scalability due to the large number of forwarding rules that the controller must install in the network. To address these limitations, we introduce a switch memory space-efficient routing scheme that reduces the number of entries in the switches, and at the same time guarantees the load balancing on link resources utilization. We consider the static and dynamic versions of the problem, analyzing their complexities and propose respective solution algorithms. Moreover, we also consider the case of fine-grained control for the flows, and develop a 2-approximation algorithm to achieve load balancing on the TCAM space usage. Experiments show our algorithms can reduce TCAM usage and network control traffic by 20%−80% in comparison with the benchmark algorithms on different network topologies.