Switchless SR-IOV config with ConnectX-5 MCX556A-EDAT on Windows Server 2016

Hi All,

I am trying to configure a quick setup without switch so I can have my VMs using SR-IOV and talk to each other:

  • Windows Server 2016

  • MCX556A-EDAT x1

  • 100Gbe cable x1


  1. Connect Port1 to Port2 using the 100Gbe cable directly to form a loop

  2. On Port 1, create a VM Switch with SR-IOV enabled in Hyper-V

  3. Install VM1 and configure to use the VM Switch

  4. Install VM2 and configure to use the VM Switch


  1. VM1 can connect to host

  2. VM2 can connect to host

  3. Host can connect back to either VM1 or VM2

  4. Confirmed SR-IOV is activated successfully on both VM1 and VM2


  1. VM1 cannot connect to VM2

Is there any isolation for VMs if they are on SR-IOV? If I turn SR-IOV off so they fallback to VMQ, they can start connecting to each other without any problem, so it is quite obvious SR-IOV has caused them not communicating.

Or do I have to use a switch to make this setup work?