blueprint01 wrote:
Okay, that is clear. But what if I connect the two swtiches with each other? Then there are two ways for Switch A to reach Switch B, direct and via core switch. Isn't there a loop? I though it is necessary to connect the two swtiches with each other (perhaps twice with LACP) because of performance reason, isn't it?
If you connect the three physical switches to each other than that would indeed create a loop.
It does depend on your total physical network infrastructure how the physical switches should be best connected. There is not really a definitive need for two "close to ESXi"-switches to be directly connected, as long as there is connectity between them through the core switch.
With some advanced Spanning Tree configuration (called MSTP) you could create several spanning trees at the same time, keeping different links up and down depedning on the VLANs. However, that involves some planning and configuration before getting into that.