This disclosure describes techniques that include collecting flow data associated with communications between network devices, and determining, based on the flow data, one or more virtual networks over which the communications are taking place. In one example, this disclosure describes a system configured to perform operations comprising: storing virtual network configuration information associated with a first virtual network and a second virtual network established within a network; collecting underlay flow data associated with communications between a first server and a second server, wherein each of the first server and the second server are implemented as bare metal servers; determining, based on the underlay flow data and the stored virtual network configuration information, that the first server and the second server have communicated over the first virtual network; and generating a user interface.