pNIC, vNIC, and vmNIC Confusion

I have been using both remote desktop and vSphere Client quite often lately. Yesterday, I had a remote desktop session with a Windows Server 2003 physical server and also had vSphere Client (connected to an ESXi server) open with a console window of a Windows Server 2003 virtual machine (VM). Sometimes it’s easy to get confused, but, it’s important to remember that the vSphere Client and the remote connection to Windows Server 2003 are both using the physical NIC card adapter (pNIC).

However, if I log into Windows Server 2003 on the physical machine and disable the network adapter and then log onto the Windows Server 2003 VM through vSphere Client and disable the network adapter, I will get two different results. Not thinking clearly, I actually did this and immediately got kicked out of the Windows Server 2003 remote desktop connection; I got the intended result on the Windows Server 2003 VM, which was access to the server but no internet connectivity within Windows Server 2003. What happened?

I’m sure you already know, but what occurred was that my remote desktop connection was using a pNIC adapter, so, by disabling it, I immediately cut myself off from connectivity to the server. vSphere Client is also using the pNIC adapter to connect to the server (in-fact, in this case, the same pNIC the vSwitch with the respective VM is installed on is being used). However, when I disabled the network adapter on the Windows Server 2003 VM, I actually disabled the virtual NIC (vNIC) adapter not the physical adapter. So, since I was connected to Windows Server 2003 through the vSphere Client (which is using the pNIC adapter used by the ESXi host), I didn’t get kicked off the Windows Server 2003 OS. The VM just lost internet connectivity, which is what I was trying to accomplish.

Long story short, just keep your pNICs, vNICs, and vmNICs straight and your good to go. Remember that the pNIC is the physical NIC on the server that the hypervisor is installed on. The virtual object that is linked to the pNIC and used to provide connectivity between the vSwitch and the physical switch via the pNIC is the vmNIC. Finally, the vNIC provides connectivity between the virtual guest operating system and the vSwitch. Got it…good! Now don’t disconnect yourself like I did!