Learn About Designing a Secure Multitier Topology in the Cloud

In a multitier application topology, your resources have distinct access-control requirements and traffic-flow constraints. Organize your resources in compartments, and define Oracle Cloud Infrastructure Identity and Access Management (IAM) policies to control users' access to the resources in each compartment. Isolate the resources in each tier in separate subnets.


The following architecture shows the cloud resources grouped in compartments, based on the nature of the resources. The bastion hosts, compute instances, load balancers, and databases are in a single virtual cloud network (VCN), but are attached to different subnets.

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  • Compartments provide logical boundaries to isolate your resources in the cloud, based on the user groups that are responsible for managing the resources. Compartments also enable you to track and manage the usage of cloud resources by each department in your organization. Note that a compartment is global to the tenancy; that is, it spans all the regions.
  • The resources in this architecture are distributed across three availability domains (AD). In a region that has a single AD, you can distribute the compute instances across the fault domains within the AD for high availability.
  • The Networks compartment contains the VCN and the associated gateways.
  • The compute instances in this architecture are attached to AD-specific subnets. To protect the subnets against AD failure, Oracle recommends that you use regional subnets, which span the entire region.
  • The Shared Services compartment contains compute instances that are shared across the tenancy.
  • The Admin compartment contains the bastion hosts that are exposed to traffic from the internet.
  • The Business Logic compartment contains the compute instances that host the web servers and application servers. It also contains the load balancers.
  • The Database compartment contains the database instances.