Underlay-overlay correlation

This invention describes a system that gathers two types of network traffic information: data about the physical network infrastructure (underlay) and data about the virtual networks running on top of it (overlay). When someone wants to know about a specific data flow between two virtual networks, the system looks at all the collected data. It then identifies exactly which physical network devices handled that particular virtual network traffic, especially within a specified time. The claims narrow this to a specific method of correlating and adding overlay data to underlay records.