Characterizing grandmaster, transparent, and boundary clocks with a precision packet probe and packet metrics

The IEEE 1588 packet probe has proved to be an effective tool for the measurement and analysis of network packet delay variation and latency. As more and more IEEE 1588 equipment is designed and deployed in the service of telecommunications networks and for other applications, in some cases with on-path support provided by boundary or transparent clocks, it has become important to be able to characterize this equipment. In many cases the packets themselves are the only timing signal available for study. Thus the packet probe is an essential tool for characterizing this equipment. Likewise, the same metrics developed for the analysis of network packet delay variation can be employed for equipment characterization. This paper, drawing on measurements of commercial equipment, describes how a packet probe along with traditional stability metrics and recently developed packet metrics can be used to characterize IEEE 1588 grandmaster clocks, boundary clocks, and transparent clocks.