Proactive-LRU: An Efficient Flow Table Management Scheme in SDNs

A Software Defined Network (SDN) separates an existing network structure into a control plane and a data plane and centrally manages the network at the control plane. SDN is able to control the network in detail and operate efficiently by managing the traffic by flow unit. However, if the performance of the switches comprising the SDN varies greatly from one to another, it has a problem of delayed handling of traffic due to the bottleneck caused by an overhead concentration at the controller when the message exchanges between the low performance switch and the controller for flow table replacement increase in number. This research paper suggests a flow table management scheme, called Proactive-LRU, to alleviate this problem and compares its performance to that of the existing replacement algorithms such as LRU, LFU, and FIFO. Proactive-LRU scheme is a flow table management scheme that deletes the flow from all switches available within the forwarding path when a flow is deleted and reduces the number of message exchanges and the controller overhead. In order to compare the performance of the suggested scheme against that of the existing algorithms (FIFO, LRU, LFU), video traffic and web browsing traffic have been mixed in certain ratios in an SDN environment for the experiment. The analysis of the results showed that the number of message exchanges as well as the overhead and table overflow of switches in the suggested scheme were significantly reduced.