OpenTap: Software-defined data acquisition

We present OpenTap, a unified interface designed as an Infrastructure layer technology for a software-defined network measurement (SDNM) stack. OpenTap provides invocations for remotely capturing network data at various granularities, such as packet or NetFlow. OpenTap drivers can be developed that leverage open source network measurement tools such as tcpdump and nfdump. OpenTap software can be used to turn any computing device with network interfaces into a remotely controlled network data collection device. Although OpenTap was designed for SDNM, its interface generalizes to any data acquisition thereby providing software-defined data acquisition (SDDA). We illustrate this generality with OpenTap drivers that leverage Phidgets USB sensors to remotely capture environmental data such as temperature. We have completed an implementation of OpenTap that uses a REST API for the invocations. Using that implementation, we study a few use cases of OpenTap for automated network management and network traffic visualizations to characterize its utility for those applications. We find that OpenTap empowers rapid development of software for more complex network measurement functionality at the Control layer such as, joining network data with other sources, and creating network data aggregates such as traffic matrices. OpenTap significantly lowers the cost and development barrier to large-scale data acquisition thereby bringing data acquisition and analytics to an unprecedented number of users. Finally, at the Application layer, network measurement applications such as traffic matrix visualizations are easily implemented leveraging OpenTap at the Infrastructure layer in addition to the Control layer. All of these data processing software systems will be open source and available on GitHub by the time of the conference.