Set Up a Hub-and-Spoke Network Topology by Using Local Peering Gateways

A hub-and-spoke network, also called star network, has a central component that's connected to multiple networks around it. The overall topology resembles a wheel, with a central hub connected to points along the edge of the wheel through multiple spokes. Setting up this topology in the traditional on-premises data center can be expensive. But in the cloud, there’s no extra cost.

Use the hub-and-spoke architecture to build creative and powerful networking solutions in the cloud for the following common use cases:

  • Setting up separate development and production environments.

  • Isolating the workloads of different customers, such as the subscribers of an independent software vendor (ISV) or customers of a managed service provider.

  • Segregating environments to meet compliance requirements, such as payment card industry (PCI) and Health Insurance Portability and Accountability Act (HIPAA) requirements .

  • Providing shared information technology services such as log server, domain name system (DNS), and file sharing from a central network.

Architecture

This reference architecture shows an Oracle Cloud Infrastructure region with a hub virtual cloud network (VCN) connected to two spoke VCNs. Each spoke VCN is peered with the hub VCN by using a pair of local peering gateways (LPGs).

The architecture shows a few sample subnets and virtual machine (VMs). Security lists are used to control network traffic to and from each subnet. Every subnet has a route table that contains rules to direct traffic bound for targets outside the VCN.

The hub VCN has an internet gateway for network traffic to and from the public internet. It also has a dynamic routing gateway (DRG) to enable private connectivity with your on-premises network, which you can implement by using Oracle Cloud Infrastructure FastConnect, Site-to-Site VPN, or both.

You can use either Oracle Cloud Infrastructure Bastion or a Bastion host to provide secure access to your resources. This architecture uses OCI Bastion.

The following diagram illustrates the reference architecture.


Description of hub-spoke-oci.png follows
Description of the illustration hub-spoke-oci.png

hub-and-spoke-oci.zip

The architecture has the following components:
  • On-premises network

    This network is the local network used by your organization. It is one of the spokes of the topology.

  • OCI region

    An OCI region is a localized geographic area that contains one or more data centers, hosting availability domains. Regions are independent of other regions, and vast distances can separate them (across countries or even continents).

  • OCI virtual cloud network and subnet

    A virtual cloud network (VCN) is a customizable, software-defined network that you set up in an OCI region. Like traditional data center networks, VCNs give you control over your network environment. A VCN can have multiple non-overlapping classless inter-domain routing (CIDR) blocks that you can change after you create the VCN. You can segment a VCN into subnets, which can be scoped to a region or to an availability domain. Each subnet consists of a contiguous range of addresses that don't overlap with the other subnets in the VCN. You can change the size of a subnet after creation. A subnet can be public or private.

  • Security list

    For each subnet, you can create security rules that specify the source, destination, and type of traffic that is allowed in and out of the subnet.

  • Route table

    Virtual route tables contain rules to route traffic from subnets to destinations outside a VCN, typically through gateways.

  • Dynamic routing gateway (DRG)

    The DRG is a virtual router that provides a path for private network traffic between VCNs in the same region, between a VCN and a network outside the region, such as a VCN in another OCI region, an on-premises network, or a network in another cloud provider.

  • OCI Bastion

    Oracle Cloud Infrastructure Bastion provides restricted and time-limited secure access to resources that don't have public endpoints and that require strict resource access controls, such as bare metal and virtual machines, Oracle MySQL Database Service, Autonomous Transaction Processing (ATP), Oracle Cloud Infrastructure Kubernetes Engine (OKE), and any other resource that allows Secure Shell Protocol (SSH) access. With OCI Bastion service, you can enable access to private hosts without deploying and maintaining a jump host. In addition, you gain improved security posture with identity-based permissions and a centralized, audited, and time-bound SSH session. OCI Bastion removes the need for a public IP for bastion access, eliminating the hassle and potential attack surface when providing remote access.

  • Bastion host

    The bastion host is a compute instance that serves as a secure, controlled entry point to the topology from outside the cloud. The bastion host is provisioned typically in a demilitarized zone (DMZ). It enables you to protect sensitive resources by placing them in private networks that can't be accessed directly from outside the cloud. The topology has a single, known entry point that you can monitor and audit regularly. So, you can avoid exposing the more sensitive components of the topology without compromising access to them.

  • Local Peering Group (LPG)

    An LPG provides peering between VCNs in the same region. Peering means the VCNs communicate using private IP addresses, without the traffic traversing the internet or routing through your on-premises network.

  • OCI Site-to-Site VPN

    OCI Site-to-Site VPN provides IPSec VPN connectivity between your on-premises network and VCNs on OCI. The IPSec protocol suite encrypts IP traffic before the packets are transferred from the source to the destination and decrypts the traffic when it arrives.

  • OCI FastConnect

    Oracle Cloud Infrastructure FastConnect creates a dedicated, private connection between your data center and OCI. FastConnect provides higher-bandwidth options and a more reliable networking experience when compared with internet-based connections.

Recommendations

Your requirements might differ from the architecture described here. Use the following recommendations as a starting point.

  • VCNs

    When you create a VCN, determine the number of CIDR blocks required and the size of each block based on the number of resources that you plan to attach to subnets in the VCN. Use CIDR blocks that are within the standard private IP address space.

    Select CIDR blocks that don't overlap with any other network (in Oracle Cloud Infrastructure, your on-premises data center, or another cloud provider) to which you intend to set up private connections.

    After you create a VCN, you can change, add, and remove its CIDR blocks.

    When you design the subnets, consider your traffic flow and security requirements. Attach all the resources within a specific tier or role to the same subnet, which can serve as a security boundary.

    Use regional subnets.

  • Security lists

    Use security lists to define ingress and egress rules that apply to the entire subnet.

Considerations

When you design a hub-and-spoke network topology in the cloud, consider the following factors:

  • Cost

    The only components of this architecture that have a cost are the compute instances and FastConnect (port hours and provider charges). The other components have no associated cost.

  • Security

    Use appropriate security mechanisms to protect the topology.

    The topology that you deploy by using the provided Terraform code incorporates the following security characteristics:
    • The default security list of the hub VCN allows SSH traffic from 0.0.0.0/0. Adjust the security list to allow only the hosts and networks that should have SSH access (or whatever other services ports are required) to your infrastructure.
    • This deployment places all components in the same compartment.
    • Spoke VCNs are not accessible from the internet.
  • Scalability

    Consider the service limits for VCNs and subnets for your tenancy. If more networks are required, request an increase in the limits.

  • Performance

    Within a region, performance isn’t affected by the number of VCNs. When you peer VCNs in different regions, consider latency. When you use spokes connected through OCI Site-to-Site VPN or OCI FastConnect, the throughput of the connection is an additional factor.

  • Availability and redundancy

    Except for the instances, the remaining components have no redundancy requirements.

    The OCI Site-to-Site VPN and OCI FastConnect components are redundant. For further redundancy, use multiple connections, preferably from different providers.

Deploy

The Terraform code for this reference architecture is available in GitHub. You can pull the code into Oracle Cloud Infrastructure Resource Manager with a single click, create the stack, and deploy it. Alternatively, you can download the code from GitHub to your computer, customize the code, and deploy the architecture by using the Terraform CLI.

Note:

The Terraform code includes most of the components shown in the architecture diagram including a VM for bastion host. The service VM, workload VM, OCI Site-to-Site VPN, OCI FastConnect, and OCI Bastion are not included in the code, although they are shown in the diagram.
  • Deploy by using Oracle Cloud Infrastructure Resource Manager:
    1. Click Deploy to Oracle Cloud

      If you aren't already signed in, enter the tenancy and user credentials.

    2. Review and accept the terms and conditions.
    3. Select the region where you want to deploy the stack.
    4. Follow the on-screen prompts and instructions to create the stack.
    5. After creating the stack, click Terraform Actions, and select Plan.
    6. Wait for the job to be completed, and review the plan.

      To make any changes, return to the Stack Details page, click Edit Stack, and make the required changes. Then, run the Plan action again.

    7. If no further changes are necessary, return to the Stack Details page, click Terraform Actions, and select Apply.
  • Deploy by using the Terraform CLI:
    1. Go to GitHub.
    2. Clone or download the repository to your local computer.
    3. Follow the instructions in the README document.

Explore More

Learn about this architecture and about related architectures:

Change Log

This log lists only the significant changes: