What is VPC peering in AWS? Step by Step Guide to set it up

VPC (Virtual Private Cloud) peering is very important in cloud computing. What’s it exactly? It works how? Whether you’re new to IT or a pro, here you will learn VPC peering and its importance.

VPC peering connects two VPCs in the same or separate regions of a cloud provider’s network. It lets these VPCs communicate like a single network. Facilitates data transfer and cross-application communication.

Why are VPC connections of importance? Join VPCs to exploit the best of each network, increase cloud performance and stability, and optimize cloud architecture. It also connects VPCs without complicated hacks / any expensive solutions.

VPC sharing benefits, application cases, and considerations are covered in this article.

Table of Contents

What is VPC in AWS?

AWS VPC stands for Virtual Private Cloud in AWS. It’s like your very own private corner in the vast AWS cloud world.

Imagine you can create these isolated sections within AWS, where you’re the boss. You get to launch all sorts of AWS resources, but here’s the catch – it’s all in your own virtual network that you design.

Users can launch AWS resources in their defined virtual network. You decide the IP addresses, set up the route tables, and even create subnets. It’s like tailoring your networking environment to fit your exact needs.

This means that businesses can make their computer room work for them. AWS VPC is like that ultimate toolkit for flexibility and customization in the cloud.

How does VPC peering work?

VPC peering works by establishing a direct network connection between two VPCs. This connection requires tables & network setups routing.

When VPCs are peered, they can communicate with each other using private IP addresses, even if they are located in different regions or accounts.

You need to specify the VPCs you want to connect and establish a peering connection between them to set up VPC peering. Once the peering connection is established, you can update the route tables in each VPC to include the CIDR blocks of the peered VPCs. This allows traffic to flow between the VPCs seamlessly.

Each VPC can connect to multiple VPCs, but each peering is between two specific VPCs. VPC peering isn’t transitive; indirect peering doesn’t create direct connections.

Setting up VPC peering in AWS

To set up VPC peering in AWS, follow these steps:

Go to the Amazon VPC console.

Here’s what you will see when you go to VPC console.

Select “Peering Connections” from the navigation pane.

Select “Create Peering Connection” to create the connection.

Give a name for your peering connection.

In the VPC (Requester) field, select the VPC that you created in the previous steps.

In the VPC (Accepter) field, select the VPC that you want to peer with.

OPTIONAL: (Optional) In the Peering options section, you can configure the following options:

Allow automatic acceptance – If you select this option, the peering connection will be automatically accepted by the accepter VPC.
Allow traffic between VPCs – If you select this option, traffic will be allowed to flow between the two VPCs.

Look at the local VPC panel, you will see “pending acceptance”, in the status field of your peering connection.

Accept the request for VPC peering from your local VPC.

As you can see, the status is active. Now the VPC peering connection is all set.

To send and receive traffic across this VPC peering connection, you must add a route in one or more of your VPC route table.

Now in the route tables, you will see two types of route tables:-

A default route table for default VPC
A custom route table for custom VPC

Select the route table that you want to add the route to.

Choose Actions, Edit routes.

In the Add route dialog box, enter the following information:

Destination – The CIDR block of the other VPC.

Target – The VPC peering connection that you created.

After saving the connection should look like this.

Watch our Step-by-Step tutorial:-

Troubleshooting common issues with VPC peering

While setting up VPC peering, you might encounter some common issues. Here are a few troubleshooting tips:-

Route table misconfiguration

Ensure that the route tables in each VPC are correctly configured to include the CIDR blocks of the peered VPCs. Incorrect route table configurations can result in connectivity issues.

Security group rules

Check the security group rules in each VPC to ensure that they allow the necessary inbound and outbound traffic for the peered VPCs. Misconfigured security group rules can prevent communication between peered VPCs.

Internet Gateway or NAT Gateway

If you’re experiencing connectivity issues to resources outside the peered VPCs, check if an Internet Gateway or NAT Gateway is required in either VPC to enable internet access.

Advantages of VPC peering

VPC peering offers several advantages that make it a valuable tool in cloud networking:-

Enhanced resource sharing:- With VPC peering, you can share resources like EC2 instances, RDS databases, and S3 buckets between peered VPCs.
Simplified network architecture: VPC peering simplifies network architecture by eliminating the need for complex workarounds or costly solutions to achieve connectivity between VPCs.
Improved application integration: VPC peering enables seamless communication between applications running in different VPCs. This is particularly useful in scenarios where you have microservices architecture or multiple tiers of an application spread across different VPCs. With VPC peering, these applications can communicate with each other directly, without the need for public endpoints or complex networking configurations.

Best practices for using VPC peering

To make the most of VPC peering, consider the following best practices:-

Carefully plan your network architecture:- Before setting up VPC peering, thoroughly plan your network architecture and determine which VPCs need to be connected.
Use non-overlapping CIDR blocks: To establish VPC peering connections, ensure that the CIDR blocks of the peered VPCs do not overlap.
Monitor network traffic: Regularly monitor network traffic between the peered VPCs to ensure optimal performance and detect any potential issues.
Implement security measures: Apply appropriate security measures, such as network ACLs and security groups, to control access and secure communication between the peered VPCs.

Limitations of VPC peering

While VPC peering offers numerous benefits, it’s important to be aware of its limitations:-

Cross-region limitations:- VPC peering is limited to the same cloud provider’s network and cannot be established between VPCs in different cloud providers. Additionally, VPC peering is not available across regions in certain cloud providers, so you need to ensure that the regions you require for peering are supported.
CIDR block overlapping: VPC peering requires non-overlapping CIDR blocks between the peered VPCs. If the CIDR blocks overlap, we cannot establish VPC peering. This can be a limitation when you have pre-existing VPCs with overlapping IP ranges that you want to peer.
Bandwidth limitations: VPC peering has certain limitations on the bandwidth and throughput between the peered VPCs. These limitations vary based on the cloud provider and the instance types used in the VPCs. If you require high-speed or high-bandwidth communication between VPCs, alternative solutions might be more suitable.

Alternatives to VPC peering

Consider the following alternatives:-

VPN connections

If you require secure communication between VPCs that are not in the same cloud provider’s network, consider using VPN connections.

Transit Gateway

Cloud providers like AWS offer Transit Gateway, which allows you to connect multiple VPCs and remote networks using a central hub.

Direct Connect

If you need dedicated and high-performance connectivity between your on-premises network and VPCs, consider using Direct Connect. Direct Connect provides a private, dedicated network connection that bypasses the public internet.

Conclusion

Powerful Cloud Networking: VPC peering enables seamless VPC communication.
Benefits: Enhances resource sharing, simplifies network architecture, improves application integration.
Awareness of Limitations: Understand limitations and consider alternatives.
Comprehensive Understanding: Know how VPC peering works, its advantages, limitations, and setup in AWS and Azure.
Optimize Cloud Infrastructure: Leverage VPC peering for enhanced cloud performance and reliability.