5.1.2.3. Design for Azure VPN Gateway and ExpressRoute

💡 First Principle: Securely and reliably extending an on-premises network to the cloud is fundamental for creating seamless hybrid environments that bridge existing infrastructure with cloud resources, supporting diverse requirements for performance, security, and cost.

Scenario: You are designing the network connectivity for a hybrid application. Critical business data needs to be synchronized daily between on-premises and Azure, requiring a dedicated, high-bandwidth, and highly secure connection. Non-critical dev/test traffic can traverse the internet securely.

Azure VPN Gateway and Azure ExpressRoute are Azure services that establish secure connections between on-premises networks and Azure VNets.

Key Design Considerations:

• Azure VPN Gateway:
  • Purpose: Establishes secure, encrypted tunnels (IPsec/IKE VPN) over the public internet.
  • Use Cases: Hybrid connectivity for non-critical workloads, dev/test environments, or when cost is a primary concern.
  • Performance: Bandwidth is limited by internet connection and VPN Gateway SKU.
• Azure ExpressRoute:
  • Purpose: Creates a private, dedicated, high-bandwidth connection, bypassing the public internet.
  • Use Cases: Mission-critical applications, large data transfers, or scenarios requiring predictable performance and low latency.
  • Performance: Offers higher bandwidth (up to 100 Gbps) and lower latency.
  • Security: Traffic remains on a private connection, enhancing security.
  • Cost: Generally more expensive than VPN Gateway.
• Redundancy: Design for high availability by deploying redundant VPN Gateways or ExpressRoute circuits.

⚠️ Common Pitfall: Relying on a single ExpressRoute circuit for a mission-critical workload without a backup. A single physical link is a single point of failure. Best practice is to have a redundant ExpressRoute circuit or a backup VPN Gateway connection.

Key Trade-Offs:

• Performance/Security (ExpressRoute) vs. Cost/Flexibility (VPN): ExpressRoute offers superior, consistent performance and security but comes with higher costs and longer setup times. A VPN is cheaper and faster to deploy but relies on the public internet, leading to variable performance.

Reflection Question: How does strategically choosing between Azure VPN Gateway (for secure internet-based tunnels) and Azure ExpressRoute (for private dedicated connections) fundamentally enable hybrid connectivity solutions, balancing performance, security, and cost requirements for diverse on-premises and cloud communication needs?