This image shows a hub-and-spoke architecture topology which is a more flexible solution including transit routing capabilities with a firewall in a hub VCN.

An on-premises data center connects to an OCI Region using FastConnect through the dynamic routing gateway (DRG).

The OCI Region hosts three tenancies/VCNs and the DRG directs traffic to each of the three tenancies.

• DRG attachment A directs to Tenant A - VCN which hosts a server.
• The next DRG attachment directs to the Central VCN which hosts a virtual appliance.
• DRG attachment B directs to Tenant B - VCN which hosts a server.