Mastering AWS Side-to-Side VPN: A hands-on guide


In an era where remote work and hybrid architecture have become the norm, maintaining seamless connectivity between on-premise infrastructure and cloud-based servers has never been more critical. Enter AWS Side-to-Side VPN, a powerful tool that bridges the gap between your office servers and your AWS cloud environment. In this comprehensive guide, we will delve into the world of Side-to-Side VPN, covering everything from the basics to advanced configurations, and even providing a hands-on demonstration.

What is a Side-to-Side VPN?

Before we dive into the technical details, let’s clarify what a Side-to-Side VPN connection is. At its core, a Side-to-Side VPN (Virtual Private Network) allows secure communication between your AWS Virtual Private Cloud (VPC) and your on-premise network. The term VPN, short for Virtual Private Network, emphasizes the key feature here: secure, private, and encrypted communication.

It’s important to note that VPN connections use the public internet, which, while encrypted, can sometimes exhibit unpredictable performance and pose security concerns. Nevertheless, Side-to-Side VPNs offer a robust solution for connecting your AWS cloud to your on-premise infrastructure.

Key Concepts

To fully grasp AWS Side-to-Side VPN, it’s essential to understand some key concepts:

  1. VPN Connection: This is the core of the Side-to-Side VPN, defining the secure communication channel between your VPC and on-premise network.
  2. VPN Tunnels: Think of tunnels as the pathways through which data travels between networks. They encapsulate data and ensure its secure transfer.
  3. Customer Gateway: The device or software on your on-premise network that initiates the VPN connection.
  4. Virtual Private Gateway: On the AWS side, the Virtual Private Gateway acts as the VPN concentrator, managing and terminating VPN connections.
  5. Transit Gateways: These act as transit hubs, simplifying connectivity between multiple VPCs and on-premise networks, reducing the need for individual VPN connections.

Important Considerations

Before you embark on setting up your Side-to-Side VPN, there are some crucial considerations to keep in mind:

  1. IPv6 Traffic: VPN connections on a Virtual Private Gateway do not support IPv6 traffic.
  2. Cider Block Overlaps: Ensure there are no overlapping cider blocks when connecting your VPC to on-premise networks.
  3. Path MTU Discovery: AWS does not support Path MTU Discovery, a technique for avoiding IP fragmentation. Be aware of this limitation.

Understanding Tunnels

To better understand how Side-to-Side VPNs work, let’s use the analogy of a tunnel. In networking, tunnels enable data movement between networks, allowing private communication over the public internet. Imagine two networks as distant cities with an obstruction (the public internet) between them. Tunnels, like VPNs, are the means to dig through this obstruction and ensure secure data transfer.

When data is sent via a VPN, it gets encapsulated and routed through routers (VPN concentrators). The data knows it will be securely transported to its destination without worrying about the specifics of the journey. This encapsulation and secure routing make VPNs an essential tool for secure communication.

How VPNs Work

Now, let’s demystify how VPNs operate. Whether you’re working from home or connecting to your office network, you might have used a VPN client such as Node VPN, Secure VPN, OpenVPN, or Cisco VPN. VPNs function by creating a secure tunnel between your device (the client) and a VPN server.

Consider a developer working from home and trying to connect to the office network. Public internet access isn’t secure, and most companies don’t allow direct public access to their networks. Here’s how a VPN comes to the rescue:

  1. The developer’s request is sent to the VPN client.
  2. The VPN client encrypts the data traffic and sends it to the VPN server securely.
  3. The VPN server decrypts the data, processes it, and sends it to its destination.
  4. When data is sent back, it follows the same encrypted path in reverse.

In essence, a VPN creates a secure communication channel, making your data transfer far more secure than browsing without one. While it doesn’t make you completely invisible, it significantly enhances your security.

Creating a Side-to-Side VPN

Now, let’s explore how to set up a Side-to-Side VPN using the AWS console. While this is a simplified demonstration, it will give you an idea of the steps involved.

  1. Customer Gateway: Begin by creating a Customer Gateway in the AWS console. This represents the device or software on your on-premise network. Specify its name, IP address, and other relevant details.
  2. Virtual Private Gateway: Next, create a Virtual Private Gateway on the AWS side. This serves as the VPN concentrator. Set the Autonomous System Number (ASN) and other configuration options.
  3. VPN Connection: Create the VPN connection. Link it to your Virtual Private Gateway and specify routing options, tunnel settings, and pre-shared keys.
  4. Transit Gateway (Optional): If needed, you can use Transit Gateways to simplify connectivity between multiple VPCs and on-premise networks.

Remember to customize your configurations based on your specific requirements, and ensure that all network details are accurately entered.

Accelerating Side-to-Side VPN Connections

For enhanced performance, AWS offers Accelerated Side-to-Side VPN Connections. These leverage AWS Global Accelerator to optimize data routing from your on-premise network to the closest AWS edge location. This results in improved application performance and reduced congestion on your VPN connection.

To enable acceleration, select the option when creating a new Side-to-Side VPN attachment on a Transit Gateway.


AWS Side-to-Side VPN is a powerful tool for maintaining secure and efficient connectivity between your AWS cloud resources and on-premise infrastructure. Understanding the key concepts and considerations is crucial for successful implementation. While this guide provides an overview and a glimpse into the AWS console, deploying a Side-to-Side VPN requires careful planning and configuration tailored to your organization’s needs. With the right setup, you can ensure seamless communication and data security across your hybrid architecture.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top