📖 What is Amazon VPC Peering?
Amazon VPC Peering is a networking connection between two Virtual Private Clouds (VPCs) that enables routing traffic between them using private IP addresses. This allows instances in different VPCs to communicate as if they were within the same network.
"Remember that VPC peering is non-transitive. If VPC A is peered with B, and B with C, A is NOT automatically peered with C."
📚 Certification: AWS Certified Cloud Practitioner (CLF-C02)
🔑 What are the Key Concepts of Amazon VPC Peering?
- ▸ Enables communication using private IP addresses, ensuring that traffic remains within the AWS network and does not traverse the public internet.
- ▸ Follows a non-transitive routing model, meaning if VPC A is peered with B, and B with C, A cannot reach C.
- ▸ Requires that the peering VPCs have non-overlapping CIDR blocks to prevent routing conflicts and ensure packets reach the correct destination.
- ▸ Supports connectivity across different AWS accounts and different AWS regions, allowing for flexible and scalable multi-account cloud architectures.
- ▸ Requires manual updates to the route tables of both VPCs to explicitly direct traffic to the peering connection ID.
🎯 How does Amazon VPC Peering appear on the CLF-C02 Exam?
You may be asked to identify the best way to connect two VPCs so that instances can communicate using private IP addresses without using a public gateway.
A scenario might describe a company with three VPCs (A, B, and C) where A is peered with B and B with C; you must determine if A can talk to C.
❓ Frequently Asked Questions
When should I use a Transit Gateway instead of VPC Peering?
Use VPC Peering for simple one-to-one connections. Use Transit Gateway for complex 'hub-and-spoke' architectures involving many VPCs to simplify management and avoid a complex mesh of peering connections.
Can I peer VPCs that belong to different AWS accounts?
Yes, VPC peering supports cross-account connections. One account sends a peering request, and the owner of the second account must accept that request to establish the link.