On real-time delay monitoring in software-defined networks

The paper introduces a new loop-based method to measure end-to-end packet delay in software-defined network infrastructures. Although the method generates auxiliary service packets, it does not require any complementary support from the switching hardware. The prototype implementation shows the method is able to provide one-way delay values with microsecond precision on a steady load. Direct application of the method to each data flow in the network is straightforward, but can cause excessive hardware utilization. Thus, the paper proposes an algorithm to improve it by decomposing global end-to-end estimations into the set local ones whereas removing their redundancy. The algorithm makes it practically possible to monitor delay of each data flow in real-time.