Assessing the quality of flow measurements from OpenFlow devices

Since its initial proposal in 2008, OpenFlow has evolved to become today’s main enabler of Software-Defined Networking. OpenFlow specifies operations for network forwarding devices and a communication protocol between data and control planes. Although not primarily designed as a traffic measurement tool, many works have proposed to use measured data from OpenFlow to support, e.g., traffic engineering or security in OpenFlow-enabled networks. These works, however, generally do not question or address the quality of actual measured data obtained from OpenFlow devices. Therefore, in this paper we assess the quality of measurements in real OpenFlow devices from multiple vendors. We demonstrate that inconsistencies and measurement artifacts can be found due to particularities of different OpenFlow implementations, making it impractical to deploy an OpenFlow measurement-based approach in a network consisting of devices from multiple vendors. In addition, we show that the accuracy of measured packet and byte counts and duration for flows vary among the tested devices, and in some cases counters are not even implemented for the sake of forwarding performance.