I have one Vnet (VNet1) in region 1 which is connected to on-premises using s2s VPN. I have got this peered with a second Vnet (Vnet2) in the same region following hub-spoke network pattern. VNet2 is configured to use Vnet1 Gateway transit for on-premises connectivity.
Now I have a third Vnet (Vnet3) in region3 which is also a spoke for Vnet1. Since this is in a different region I used VNet-VNet VPN (since Global Vnet peering doesn't support transitive gateway.) I reused the existing VPN that was used for S2S on Vnet1 for the Vnet1-Vnet3 connectivity.
The question is how do I support transit Gateway feature from VNet3->Vnet1 to achieve on-premises connectivity? To test it out I have setup UDR to route all traffic from Vnet3 to VPN Gateway. So this should bring the traffic to Vnet1. But this doesn't allow me to reach on-premises. Shouldn't Vnet1 routes know that the traffic is for on-premises and route it accordingly? Do I need some kind of NVA in Vnet1?
Any help would be appreciated.
