The dashboards uses CDP information from the ESXi hosts to create a dashboard where the switch(s) for a given ESXi host can be found, including switch information and which ports are connected to the ESXi host.
It is a requirement that CDP is enabled in the switch interfaces which the ESXi hosts are connected to.
A full description of the dashboard and how to implement it can be found here:
https://michaelryom.dk/vrops-dashboard-host-network-connectivity-insight