How it works...

In very simple words, under the hood, vSwitches or dvSwitches are parts of the ESXi host code that logically connect a virtual network adapter to a physical network adapter by ensuring the configuration conditions are applied. By adding the network adapter to a virtual machine, we have created a network identity that conforms and complies with IETF standards. 

Furthermore, the network adapter to port group mapping can be modified at any time in the virtual machine life cycle providing great levels of agility. In addition, the inherent nature of virtualization is that, virtual machines are mobile across the environment and the hosts need to explicitly advertise when there is a movement of the virtual machine. 

While all the complexity is dealt with and abstracted by the ESXi hosts, there is very little configuration modification required on the underlying network fabric.