Flow-table Distribution in Software-Defined Networks

The switch's flow-table is usually implemented by using ternary content addressable memory (TCAMs). In SDN, TCAM supports just a few thousand or tens of thousands of entries (which is according to the different hardware). However, SDN needs to provide a variety of services, such like the security services, virtual private network (VPN), quality of service (QoS), load balancing, traffic monitoring and accounting, network address translation (NAT), etc. These services will need a lot of policies to complete, which is mapping to a large number of rules. So, how to store all the rules in the SDN switch becomes a serious problem. Our method decomposes a large SDN flow-tables into small ones and then distributing them across the network. Our goal is to reduce the total number of table entries and also balance the number of table entries in each switch. When the SDN tables update, our method also reduces the controller communication cost.