FTRS: A mechanism for reducing flow table entries in software defined networks

A flow table in an OpenFlow based switch is used to not only operate the switch, but also carry out the control function of the Software Defined Network (SDN) controller. However, as a core participant of network management, its limited storage has been a significant roadblock for the industrialization of SDN. It is a significant problem to reduce the number of flow entries needed in the almost full-filled flow tables, and at the same time, to retain the original QoS as much as possible — or known as the “Flow Table Congestion Problem” (FTCP). We propose a mechanism called “Flow Table Reduction Scheme” (FTRS) to efficiently solve FTCP and evaluate the performance of FTRS both via simulation and experiment. The results show that FTRS is able to reduce the number of flow entries by 98% at most of the size of flow table with no influence on network's normal functions.