Building a Scalable and Secure Multi-VPC AWS Network Infrastructure - Building a Scalable and Secure Multi-VPC AWS Network Infrastructure

Building a Scalable and Secure Multi-VPC AWS Network Infrastructure

Publication date: July 7, 2023 (Document history)

Amazon Web Services (AWS) customers often rely on hundreds of accounts and virtual private clouds (VPCs) to segment their workloads and expand their footprint.This level of scale often creates challenges around resource sharing, inter-VPC connectivity, and on-premises facilities to VPC connectivity.

This whitepaper describes best practices for creating scalable and secure network architectures in a large network using AWS services such as Amazon Virtual Private Cloud (Amazon VPC), AWS Transit Gateway, AWS PrivateLink, AWS Direct Connect, Gateway Load Balancer, AWS Network Firewall, and Amazon Route 53. It demonstrates solutions for managing growing infrastructure—ensuring scalability, high availability, and security while keeping overhead costs low.


AWS customers begin by building resources in a single AWS account that represents a management boundary which segments permissions, costs, and services. However, as the customer’s organization grows, greater segmentation of services becomes necessary to monitor costs, control access, and provide easier environmental management. A multi-account solution solves these issues by providing specific accounts for IT services and users within an organization. AWS provides several tools to manage and configure this infrastructure, including AWS Control Tower

        A diagram depicting AWS Control Tower initial deployment

AWS Control Tower initial deployment

When you set up your multi-account environment using AWS Control Tower, it creates two Organizational Units (OUs):

  • Security OU – Within this OU, AWS Control Tower creates two accounts:

  • Log Archive

  • Audit (This account corresponds to the security Tooling account discussed previously in the guidance.)

  • Sandbox OU – This OU is the default destination for accounts created within AWS Control Tower. It contains accounts in which your builders can explore and experiment with AWS services, and other tools and services, subject to your team’s acceptable use policies.

AWS Control Tower allows you to create, register, and manage additional OUs to expand the initial environment to implement the guidance.

The following diagram shows the OUs initially deployed by AWS Control Tower. You can expand your AWS environment to implement any of the recommended OUs included in the diagram, to meet your requirements.

        A diagram depicting AWS organizational OUs.

AWS organizational OUs

For further details on multi-account environment using AWS Control Tower, refer to Appendix E in the Organizing Your AWS Environment Using Multiple Accounts whitepaper.


In this whitepaper, “Control Tower” is a broad term for the scalable, secure, and performantmulti-account/multi-VPC setup where you deploy your workloads. This setup can be built using any tool. You can find more information about best practices, design principles and benefits of multi-account cloud foundation in the Organizing Your AWS Environment Using Multiple Accounts whitepaper.

Most customers begin with a few VPCs to deploy their infrastructure. The number of VPCs a customer owns is usually related to their number of accounts, users, and staged environments (production, development, test, and so on). As cloud usage grows, the number of users, business units, applications, and Regions that a customer interacts with also grow, leading to the creation of new VPCs.

As the number of VPCs grows, cross-VPC management becomes essential for the operation of the customer’s cloud network. This whitepaper covers best practices for three specific areas in cross-VPC and hybrid connectivity:

Are you Well-Architected?

The AWS Well-Architected Framework helps you understand the pros and cons of the decisions you make when building systems in the cloud. The six pillars of the Framework allow you to learn architectural best practices for designing and operating reliable, secure, efficient, cost-effective, and sustainable systems. Using the AWS Well-Architected Tool, available at no charge in the AWS Management Console, you can review your workloads against these best practices by answering a set of questions for each pillar.

For more expert guidance and best practices for your cloud architecture—reference architecture deployments, diagrams, and whitepapers—refer to the AWS Architecture Center.