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AWS Hybrid Connectivity Patterns

March 11, 2025
AWS Hybrid Connectivity Patterns

Hybrid connectivity is about connecting AWS networks to data centers, branch offices, and other clouds with the right tradeoff between speed, cost, reliability, and security.

The main building blocks are Site-to-Site VPN, Direct Connect, Direct Connect Gateway, and Transit Gateway.

Site-to-Site VPN

Site-to-Site VPN creates encrypted tunnels over the public internet. On the AWS side, a Virtual Private Gateway or Transit Gateway terminates the connection. On the customer side, a customer gateway represents the on-prem device or software endpoint.

VPN is fast to deploy and cost-effective. It is suitable for smaller environments, backup paths, and early-stage hybrid connectivity.

The tradeoff is internet dependency. Bandwidth and latency are less predictable than a private circuit.

That tradeoff is often acceptable. A surprising number of hybrid projects do not need a premium network on day one. They need something reliable enough to validate routing, identity, and operational ownership first.

Direct Connect

Direct Connect provides a dedicated private physical connection into AWS. It is better for high throughput, stable latency, and large data movement.

Direct Connect is not encrypted by default. If encryption is required, run VPN over Direct Connect or encrypt at the application layer.

Lead time is also a real factor. Direct Connect often takes weeks or more than a month because physical connectivity and partner coordination are involved.

Direct Connect Gateway

A Direct Connect Gateway lets one Direct Connect connection reach VPCs across regions. It is useful when a company has multiple regional VPCs and wants to avoid one physical connection per region.

This is a routing construct, not a security boundary. Route control and account design still matter.

It is also the basis for a common enterprise pattern: one expensive private link, shared across multiple VPCs or accounts through a hub design.

Transit Gateway

Transit Gateway is the hub for large AWS networks. It supports thousands of VPC and on-prem attachments, route tables, cross-account sharing through RAM, and cross-region peering.

The key design power is segmentation. You can create route tables that allow shared services to talk to application VPCs while preventing east-west traffic between application domains.

That is the point many teams miss. TGW is not just a scaling primitive. It is a routing policy primitive.

VPN vs Direct Connect

Use VPN when:

  1. You need quick setup.
  2. Traffic volume is moderate.
  3. Cost matters more than deterministic latency.
  4. The connection is backup or temporary.

Use Direct Connect when:

  1. Traffic volume is high.
  2. Latency and stability matter.
  3. Data transfer economics justify the circuit.
  4. The connection is strategic and long-lived.

Then ask a second question: do you need high resiliency or maximum resiliency? One circuit is a connection. Two well-placed circuits are a network design.

The Common Enterprise Pattern

For serious hybrid environments, combine them:

  1. Direct Connect for primary private connectivity.
  2. VPN for encrypted backup or overlay encryption.
  3. Transit Gateway for multi-VPC routing and segmentation.

The architecture should make failure paths explicit. A hybrid network is only resilient if routing, encryption, and operational ownership are designed together.

The biggest design mistake is optimizing the primary path and hand-waving the failure path.

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