An efficient flow monitoring scheme for SDN networks
Ze Yang, Kwan Lawrence Yeung · 2017
A flow monitoring scheme allows an SDN controller to periodically collect the statistics (e.g., data rates) of all flows in the network. The rate of a flow passing through multiple switches can be collected from any switch along the path. But if a flow only passes through a single switch, i.e., a lonely flow, its flow rate must be collected from that particular switch. While polling a switch for flow rates, two mechanisms can be used, poll-single and poll-all. With poll-single, the switch returns the rate of a specific flow (as specified in the polling request). With poll-all, the switch returns the rates of all flows traversing it. If the returned statistics contains redundant flow information, network bandwidth is wasted. In this paper, a new flow monitoring scheme called lonely flow first (LFF) is designed. In LFF, switches carrying lonely flows will be considered first, and the lonely flow switch with the minimum polling cost - a heuristic measure of polling efficiency - will be selected for polling first. Then the polling mechanism, poll-single or poll-all, will be determined based on the actual bandwidth consumption. When all lonely flow switches are polled, the remaining switches will be considered in the same manner. As compared to an existing greedy algorithm, we show that LFF consumes less network bandwidth and has a much lower time complexity.