Spine Device Interface Summary As previously stated, the validated design includes up to 4 spine devices and up to 96 leaf devices that are interconnected by one or two high-speed Ethernet interfaces. A spine device must support 192 high-speed Ethernet interfaces to connect to 96 leaf devices using 2-member aggregated ethernet interfaces.
QFX10008 and QFX10016 switches were used as they can achieve the 192 ports necessary for this reference design. See QFX10008 Hardware Overview or QFX10016 Hardware Overview for information on supported line cards and the number of high-speed Ethernet interfaces supported on these switches.
I'm wondering if you need, at some point, physical switches to connect the cables to servers (even though you have virtual switches), or if there is something else in between cable and server.