Study of rule placement schemes for minimizing TCAM space and effective bandwidth utilization in SDN

Software Defined Networking (SDN) provides flexible route arrangement and specific packets processing through the resided flow table. The flow table is always implemented by using ternary content addressable memory (TCAM) for fast packet matching and forwarding. In addition to the route information, TCAM provides packet processing rules to deal with packet redirection, filtering, and dropping for network security consideration. The packet filtering rules are also placed in the flow table of a specific SDN switch that the packet will pass through. If the rule can be placed at the switch that most packets are aggregated, then it will save the overall TCAM utilization. However, it will consume more link bandwidth, if the packet shall be dropped before it reaches the switch that the associated rule is placed. This paper proposes the rule placement scheme by considering the tradeoff of TCAM space utilization and the bandwidth consumption in SDN networks. Practical network topologies were adopted for exhaustive simulations. The simulation results show that the proposed scheme achieves the desired objective.