I'm looking for some directions. Has anyone implemented the use case described in this lab [Palo Alto Networks: VM-Series Advanced Deployment with site-to-site vpn to onprem?
Question. Which vpc did you attach the vpn traffic for both the inbound and outbound traffic to pass through the firewall?
It seems like if you attach the VPN in a VPC other than the Untrusted VPC, your inbound and outbound traffic will bypass firewall. If you use IPSec as this documentation You will not be able to achieve full HA on the PA.
Another approach worth investigating:
If you make an internal load balancer in the untrusted vpc & attach the site-to-site VPN there you can force both traffics to be inspected. However, there's a setback on this, you will need an ILB since the VPN traffic is considered private you can't use the existing NLB, so adding a second LB requires adding another route for the GCP health check which will not be possible since route has to be unique.
Has anyone implemented something similar, can you share some thoughts and ideas?