This image is an architecture diagram of the deployment of an Oracle E-Business Suite application in a single availability domain while ensuring high availability.

The architecture consists of a virtual cloud network (VCN) with the bastion, an internal load balancer, an internal application tier, an external load balancer, an external application tier, and database hosts placed in separate subnets of VCN in a single availability domain. In the following architecture diagram, the external load balancer is deployed in a public subnet, and all the other instances are deployed in private subnets.

The bastion host and the internal load balancer receive requests through the dynamic routing gateway (DRG) and the external load balancer receives requests from the internet gateway. The DRG is the gateway that connects your on-premises network to your cloud network. To enable communication between the DRG and the customer-premises equipment, use IPSec VPN or Oracle Cloud Infrastructure FastConnect.

The load balancer instances receive requests over port 8080 or 8888, and then send it to the application servers. The application servers process these requests and forward it to the database instances over port 1521. You can access the instances in private subnets over port 22 through the bastion host or the DRG if you have set up an IPSec VPN tunnel between your data center and Oracle Cloud Infrastructure DRG.