The image shows an example of a single network architecture with an hosts Customer Premises Equipment and connects to an OCI region using either FastConnect or Site-to-Site VPN through a DRG which uses a DRG attachment to connect to the VCN.

The OCI Region hosts a VCN which includes one public and two private subnets. The public subnet includes the Web Tier or Bastion service.

One private subnet includes the App Tier and the other private subnet includes the database.