Having a hard time wrapping my head around the difference and particulars of Adapter FEX and VM-FEX.
I come from the networking side of the house and not the visualization so my misunderstanding may be on the vert side.
Lets use this diagram for reference.
It seems to me that for adapter-fex these things are true:
-VN-Link relationship is between the vEth on the upstream Nexus and the vNic running on the VIC.
-This VN-Link connection could be viewed as the uplink to the Nexus switch of the virtual switch running in the hypervisor
-VMs have their own vmware vNics that are associated to vEths on the virtual switch running in the hypervisor.
And for VM-Fex (non-directpath) this is true:
-the VN-Link relationship is between the vEth on the upstream Nexus and the vNic running on the VIC. (same as adapter-fex)
-No virtual switch sitting between the VMs vNICs and the vNIC on the VIC.
-the vmware vNICs used by the VMs are somehow directly connected to the vNics running on the VIC.
-The traffic from the VM to the VIC based vNIC would not have VNTags, then when the traffic goes from the VIC vNIC to the 5K that is where the VNTags come into play.
*** I feel like I am missing the concept of the connectivity that replaces the virtual switch here ***
I think the root of my misunderstanding is coming from using the term vNIC for both the NIC the VM sees and is using and the vNIC that is running on the VIC. I believe that the VM Host server sees the VIC based vNICs as hardware and uses them as it would any true hardware NIC. It is not that the VMs themselves are detecting and directly using the vNICs running on the VIC.
Hoping that I am just missing some key point that will make this very clear and make me feel dumb :)
Seems like it should not be this complicated.
Thanks for taking the time,
Eric
