[Reference: Palo Alto Networks provides best practices for using transit gateways and Security VPCs to enhance HA and security in AWS environments., Palo Alto Networks AWS Design Guide, Transit VPC and Security VPC:, Another recommended approach is to use a Transit VPC along with a Security VPC. The Transit VPC provides a centralized routing hub, while the Security VPC hosts the VM-Series firewalls to inspect and secure outbound traffic., Reference: The design guide for AWS deployments recommends this architecture to achieve scalable and resilient HA configurations., Palo Alto Networks AWS Transit VPC Guide, , ]