Cai Zhi-ping

The distributed network monitoring model with bounded delay constraints

We address the problem of optimizing a distributed monitoring system and the goal of the optimization is to reduce the cost of deployment of the monitoring infrastructure by identifying a minimum aggregating set subject to delay constraint on the aggregating path. We show that this problem is NP-hard and propose approximation algorithm proving the approximation ratio with lnm+1, where is the number of monitoring nodes. At last we extend our modal with more constraint of bounded delay variation.

An overview of software-defined network measurement technologies

In recent years, with the continuous expansion of the size of networks, the complexity of network structure and functionality and the volume of network traffic have immensely increased. This has resulted in severe challenges in configuring, operating and managing traditional networks. As a prominent way of monitoring and handling network status in order to optimize network structure, enhance the quality of service and achieve network error detection and recovery, software-defined networks, as a new emerging network structure, has considered all of these problems and suits these network applications well. This paper is a survey of the state-of-the-art research on measurement technologies in software-defined networks, of which we detail the design concept, performance approach, measurement objects, technical advantages and disadvantages from three standpoints: network performance, topology, and traffic measurement. We mainly cover latency, packet loss and bandwidth measurements when considering network performance measurement. Finally, the technological approaches are summarized and future research issues are discussed.