Azure VPN Gateway Best Practices

Table of Contents

Introduction

Azure VPN Gateway provides a secure and reliable way to connect your on-premises networks to your Azure virtual networks. Implementing best practices is crucial for ensuring optimal performance, availability, security, and cost-effectiveness. This document outlines key recommendations for designing, configuring, deploying, and managing your Azure VPN Gateway.

Planning and Design

Choosing the Right Gateway SKU

The SKU of your VPN Gateway significantly impacts performance, features, and cost. Consider the following when selecting a SKU:

  • Throughput: Estimate your required bandwidth for site-to-site and point-to-site connections. SKUs range from Basic (lower throughput) to VpnGw4 (very high throughput).
  • Connection Count: Determine the maximum number of tunnels you expect to establish. Higher SKUs support more connections.
  • Features: Some SKUs offer advanced features like VNet-to-VNet connections, ExpressRoute gateway integration, and active-active configurations.
  • Cost: SKUs vary in pricing. Choose a SKU that meets your needs without over-provisioning. You can upgrade your SKU if requirements change.
Recommendation: Start with a SKU that meets your current needs and monitor performance. Plan for potential future growth and select a SKU that allows for easy scaling.

Connection Types

Azure VPN Gateway supports several connection types. Choose the type that best suits your scenario:

  • Site-to-Site (S2S) VPN: Connects your on-premises network to your Azure VNet using an IPsec/IKE VPN tunnel.
  • Point-to-Site (P2S) VPN: Connects individual devices (laptops, desktops) to your Azure VNet. Useful for remote access.
  • VNet-to-VNet: Connects two or more Azure VNets securely over the Azure backbone.
  • ExpressRoute: A dedicated private connection between your on-premises network and Azure. Can be combined with VPN Gateway for hybrid connectivity.

Ensure your on-premises VPN devices are compatible with Azure VPN Gateway. Refer to the Azure VPN device compatibility list for supported models and configurations.

IP Addressing

Proper IP address planning is critical to avoid conflicts and ensure seamless connectivity.

  • Gateway Subnet: The VPN gateway must reside in a dedicated subnet named 'GatewaySubnet'. This subnet cannot contain any other resources.
  • Address Space: Ensure that the IP address spaces of your on-premises networks and Azure VNets do not overlap.
  • Public IP Address: The VPN gateway requires a public IP address. Consider using a static public IP address for stability.
Tip: Design your VNet address spaces carefully to allow for future expansion of subnets and services.

Configuration and Deployment

Tunnel Types and Encryption

Azure VPN Gateway supports two main tunnel types for S2S connections:

  • Route-based VPN: More flexible, uses IKEv2 and supports dynamic routing protocols (BGP). Recommended for most scenarios.
  • Policy-based VPN: Older, uses IKEv1, and requires static XOR policies. Less flexible and has limitations.

For encryption and integrity, Azure VPN Gateway supports various algorithms and protocols. Ensure you configure strong encryption algorithms (e.g., AES256) and hashing algorithms (e.g., SHA256) for optimal security.

Example: Using PowerShell to set up a Route-based VPN connection:

New-AzVirtualNetworkGateway -Name "MyVpnGateway" -ResourceGroupName "MyResourceGroup" -Location "East US" `
    -GatewayType Vpn -VpnType RouteBased -GatewaySku VpnGw1 -VpnClientAddressPool "10.2.0.0/24" `
    -EnableBgp $true -PublicIpAddress "myVpnGatewayPublicIp" -IpAddresses 10.0.0.4

Routing and BGP

Border Gateway Protocol (BGP) is highly recommended for managing routes between your on-premises network and Azure. BGP simplifies route management, enables dynamic route exchange, and supports complex network topologies.

  • Enable BGP on your VPN Gateway and your on-premises routers.
  • Configure ASNs (Autonomous System Numbers) for your networks.
  • Ensure correct route advertisement and propagation.

If not using BGP, you'll need to manually configure static routes on your VPN gateway, which can be cumbersome for larger deployments.

High Availability and Redundancy

Azure VPN Gateway offers several options for high availability:

  • Active-Standby: The default configuration. One gateway instance is active, and the other is on standby. If the active instance fails, the standby instance takes over.
  • Active-Active: Two gateway instances are active simultaneously. This provides higher availability and increased throughput. Requires a dedicated public IP address for each instance.
  • Zone Redundancy: Deploy your gateway across Availability Zones for resilience against datacenter failures. This is available for certain SKUs and regions.
High Availability: For production workloads, consider active-active or zone-redundant configurations to minimize downtime.

Monitoring and Management

Continuous monitoring is essential for maintaining the health, performance, and security of your VPN Gateway.

Logging and Auditing

Enable diagnostic settings for your VPN Gateway to collect logs related to:

  • Connection events (established, disconnected)
  • Tunnel status
  • Routing information
  • Errors and warnings

Send these logs to Azure Monitor Logs (Log Analytics), Storage Accounts, or Event Hubs for analysis and auditing.

Performance Monitoring

Monitor key performance metrics:

  • Data In/Out: Track bandwidth utilization.
  • Tunnel Throughput: Monitor the actual data transfer rates per tunnel.
  • Packet Drop Rate: High packet drops can indicate network congestion or configuration issues.
  • CPU/Memory Usage: Ensure the gateway is not overloaded.

Use Azure Monitor dashboards to visualize these metrics.

Alerting

Configure Azure Monitor alerts based on critical metrics or log events:

  • Alert when a VPN connection goes down.
  • Alert on high packet drop rates.
  • Alert on gateway CPU utilization exceeding a threshold.
  • Alert on specific error messages in logs.
Proactive Alerts: Set up alerts to be notified of potential issues before they impact users.

Security Considerations

Firewall Rules and Network Security Groups (NSGs)

While VPN Gateway provides a secure tunnel, it's important to implement proper network security controls within your Azure VNets.

  • Use NSGs to filter traffic to and from subnets connected via the VPN gateway.
  • Define rules that allow only necessary traffic from your on-premises network to your Azure resources.
  • Consider using Azure Firewall for more advanced centralized network security.

Threat Protection

Integrate VPN Gateway with other Azure security services:

  • Azure Security Center: Provides security recommendations and threat detection for your Azure resources.
  • Azure DDoS Protection: Protects your VPN Gateway endpoints from Distributed Denial of Service attacks.
Layered Security: Implement a layered security approach, combining VPN encryption with network access controls.

Performance Optimization

Throughput Considerations

VPN Gateway throughput is influenced by:

  • Gateway SKU: Higher SKUs offer greater throughput capacity.
  • Encryption Algorithms: Stronger encryption can consume more CPU resources, potentially impacting throughput.
  • Packet Size: Smaller packets incur more overhead.
  • Number of Tunnels: A single gateway has a maximum aggregate throughput.
  • On-premises Network Bandwidth: Your on-premises link is often a bottleneck.

Monitor throughput closely and scale up your gateway SKU or optimize your on-premises network as needed.

Latency Mitigation

While VPN Gateway inherently adds some latency, you can mitigate it by:

  • Choosing the Right Region: Deploy your VPN Gateway in an Azure region geographically close to your on-premises location or your users.
  • Optimizing Network Path: Ensure your on-premises network path to the internet is efficient.
  • Using Azure Virtual WAN: For complex hub-and-spoke architectures, Virtual WAN can optimize routing and potentially reduce latency.

Conclusion

By following these best practices, you can establish a robust, secure, and high-performing Azure VPN Gateway solution. Regularly review your configuration, monitor performance, and stay updated with Azure's evolving capabilities to ensure your hybrid connectivity meets your business demands.