Since VDX doesn't support Q-in-Q; you can possibly make this work by not tagging native VLAN on the port(s) connecting to the switch that does QinQ.
The VDX will first look up the source and destination macs, it then moves towards VLAN and fails to read the outer VLAN with eth type 9100. As a result it handles the traffic as native untagged traffic and sends it across.
no switchport trunk tag native-vlan
Principal Technical Support Engineer