A Hyper-V test lab diagram is a visual portrayal of the configuration of virtual machines, virtual switches, and physical computers and switches for a specific test lab corresponding to a Test Lab Guide (TLG). Hyper-V test lab diagrams give the reader the layout of the resulting test lab so that the appropriate virtual components can be built in Windows Server 2012 Hyper-V and connected to physical components.

Here is an example Hyper-V test lab diagram (click on it to see a larger version):