3.4.2. Network Connectivity (VPC Peering, Transit Gateway, VPN, Direct Connect)

💡 First Principle: Efficient network connectivity options (e.g., VPC Peering, Transit Gateway, VPN, Direct Connect) enable SysOps Administrators to securely connect VPCs and hybrid cloud environments.

Scenario: You need to connect 5 development VPCs to a central shared services VPC in AWS. Additionally, your on-premises data center needs a secure, high-bandwidth connection to your AWS VPCs for large data transfers.

SysOps Administrators need to manage connections between different VPCs within AWS and between AWS and on-premises networks to support distributed applications and hybrid cloud architectures.

Key Network Connectivity Options:

• VPC Peering: (A networking connection between two VPCs that enables you to route traffic between them privately.) Connects two VPCs directly, allowing instances to communicate as if in the same network. Not transitive (A peered to B, B to C, A cannot talk to C). Best for a small number of direct connections.
• AWS Transit Gateway (TGW): (A network transit hub that connects your VPCs and on-premises networks to a single gateway.) Scales to connect many VPCs and on-premises networks in a hub-and-spoke model. Supports transitive routing and simplifies complex network topologies.
• AWS VPN (Virtual Private Network): (Provides secure, encrypted connections over the public internet.)
  • Site-to-Site VPN: Encrypted IPsec tunnel between on-premises and VPC. Good for secure, flexible connectivity.
  • Client VPN: Remote access for individual users to VPCs.
• AWS Direct Connect: (A cloud service solution that links your internal network to AWS over a dedicated, private connection.) Provides a dedicated, private network connection from premises to AWS, bypassing the public internet. Offers consistent high bandwidth and low latency. Ideal for large data transfers or real-time applications.

⚠️ Common Pitfall: Using VPC Peering for a large number of VPCs, leading to a complex and unmanageable mesh network.

Key Trade-Offs: Simplicity (VPC Peering for few VPCs) vs. scalability and complexity (Transit Gateway for many VPCs). Cost/performance (Direct Connect) vs. flexibility/speed of setup (VPN).

Reflection Question: How would you use VPC Peering or AWS Transit Gateway for inter-VPC connectivity, and AWS Direct Connect or AWS VPN for hybrid cloud connectivity, to enable secure and efficient network communication?