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Ikoh Sylva
Ikoh Sylva

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Building a Multi-VPC Architecture on AWS

When people begin learning cloud networking, they often start with a single VPC.
And that’s fine… until you realize that real-world cloud environments rarely stop at just one VPC.

Image of the AWS management console

Organizations separate workloads for:

  • Security

  • Scalability

  • Team isolation

  • Environment segmentation (Dev, Staging, Production)

At that point, a new question arises:

How do these isolated networks communicate with each other securely?

That’s exactly what this hands-on project explores.

What We’ll Be Building

In this guide, we will:

  • Create two separate VPCs

  • Design public and private subnets in each VPC

  • Establish a VPC Peering connection

  • Configure route tables to enable communication

By the end, we’ll have a basic multi-VPC architecture, similar to what is used in real production environments.

Why This Matters

This project introduces core networking concepts every cloud engineer must understand:

  • Network isolation

  • CIDR block design

  • Routing between networks

  • Private communication without the internet

These are foundational skills for:

  • Cloud Engineers

  • DevOps Engineers

  • Solutions Architects

Architecture Overview

VPC-A (10.10.0.0/16)          VPC-B (10.20.0.0/16)
----------------------        ----------------------
Public Subnet                Public Subnet
Private Subnet               Private Subnet
        |                          |
        -------- VPC Peering -------
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No Internet Gateway or NAT Gateway required this is purely internal communication.

Step 1: Create VPC-A

  • Name: VPC-A

  • CIDR block: 10.10.0.0/16

Step 2: Create Subnets in VPC-A

  • Public Subnet: 10.10.1.0/24

  • Private Subnet: 10.10.2.0/24

Step 3: Create VPC-B

  • Name: VPC-B

  • CIDR block: 10.20.0.0/16

Step 4: Create Subnets in VPC-B

  • Public Subnet: 10.20.1.0/24

  • Private Subnet: 10.20.2.0/24

Step 5: Create VPC Peering Connection

  1. Go to VPC Dashboard → Peering Connections
  2. Click Create Peering Connection
  3. Select:
    Requester: VPC-A
    Accepter: VPC-B

  4. Create and accept the request
    Once accepted, the VPCs are logically connected but not yet able to communicate.

Image of the AWS VPC management console

Step 6: Update Route Tables (Critical Step)

This is where many beginners get stuck.

For VPC-A Route Table:

  • Destination: 10.20.0.0/16

  • Target: VPC Peering Connection

For VPC-B Route Table:

  • Destination: 10.10.0.0/16

  • Target: VPC Peering Connection

Without this step, traffic will not flow, even though peering exists.

How It Works

Now:

  • Traffic from VPC-A → VPC-B is routed through the peering connection

  • Traffic from VPC-B → VPC-A follows the reverse route

This enables private, secure communication between networks.

Testing the Setup

To validate:

  • Launch EC2 instances in each VPC

  • Use private IPs to ping between them

If configured correctly:

✔ Instances should communicate successfully

Important Limitations of VPC Peering

Understanding limitations is key:

  • No transitive routing (A → B → C won’t work automatically)

  • CIDR blocks must not overlap

  • Each route must be manually configured

What This Project Teaches You

It teaches you:

  • How real-world architectures are segmented

  • How cloud networking differs from traditional networking

  • How routing enables communication

  • How to design secure, isolated systems

Real-World Use Cases

This setup is commonly used for:

  • Connecting Dev and Production environments

  • Separating application tiers

  • Multi-team architectures

  • Microservices communication across VPCs

Image of the AWS cloud console

I’m also excited to share that I’ve been able to secure a special discount, in partnership with Sanjeev Kumar’s team, for the DevOps & Cloud Job Placement / Mentorship Program.

For those who may not be familiar, Sanjeev Kumar brings over 20 years of hands-on experience across multiple domains and every phase of product delivery. He is known for his strong architectural mindset, with a deep focus on Automation, DevOps, Cloud, and Security.

Sanjeev has extensive expertise in technology assessment, working closely with senior leadership, architects, and diverse software delivery teams to build scalable and secure systems. Beyond industry practice, he is also an active educator, running a YouTube channel dedicated to helping professionals successfully transition into DevOps and Cloud careers.

This is a great opportunity for anyone looking to level up their DevOps/Cloud skills with real-world mentorship and career guidance.

Do refer below for the link with a dedicated discount automatically applied at checkout;

DevOps & Cloud Job Placement / Mentorship Program.

If you also found this interesting and would love to take the next steps in the application process with AltSchool Africa do use my referral link below;

Apply here or use this Code: W2jBG8 during the registration process and by so doing, you will be supporting me and also getting a discount!

Special Offer: By signing up through the link and using the code shared, you’ll receive a 10% discount!

Don’t miss out on this opportunity to transform your future and also save while doing it! Let’s grow together in the tech space. Also feel free to reach out if you need assistance or clarity regarding the program.

I’m Ikoh Sylva, a passionate cloud computing enthusiast with hands-on experience in AWS. I’m documenting my cloud journey here from a beginner’s perspective, aiming to inspire others along the way.

If you find my contents helpful, please like and follow my posts, and consider sharing this article with anyone starting their own cloud journey.

Let’s connect on social media. I’d love to engage and exchange ideas with you!

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