A variety of different graphical user interfaces are generated that when displayed provide a visual and interactive representation of one or more performance metrics associated with the operation of a computer network. The graphical user interfaces may be used to monitor the underlay computer network for a virtualization infrastructure, as one example. Aspects include grouping the servers of a computer network into a plurality of aggregates, each aggregate comprising one or more servers. A set of probes are configured that are issued by an agent of a server in one aggregate and sent through the computer network to one or more agents in the server(s) of a different aggregate. Responses and other measurements taken based on the issuance of the probes is gathered and analyzed to generate metrics that are then used to generate, at least in part, the information provided in the graphical user interfaces.