Understanding disruptive monitoring capabilities of programmable networks

The design shift proposed by OpenFlow, with its simple stateless dataplane, initially contributed to the success of Software-Defined Networks. Its lack of state, however, prevents the implementation of many dataplane algorithms. Network applications must therefore offload stateful operations to the control plane, thereby increasing latency and limiting network scalability. Thus, recent research efforts centered on the addition of stateful properties to switches. In this paper, we discuss the impact of emerging programmable dataplane abstractions on network monitoring. In particular, we investigate the need for dataplane states in the design of scalable monitoring applications. We argue that these abstractions are ill-suited for software switches as they retain hardware-specific limitations. Furthermore, we analyse the impact of stateful dataplane designs on the control plane visibility of the network. Finally, we identify opportunities for improvement in the design of stateful software switches.