Thank you for replying to this post. Can you elaborate more "we do not support double plan tagging, you'll have to strip on the switch". Here is the design we have currently with another router from another vendor. Our S tag vlan is 1, and we have two C tags as 2 and 3.
We would like to replace the router with barracuda handling QinQ. If you can give more explanation on this then that would be great. I will open a case with Barracuda on this as well if that is the correct way to go.
core switch (running BGP) -------(trunk port vlan 2 and 3)----->router<----(vlan 1)---express route vender device. The router does QinQ to pass the S tag and C tags to azure.