Connecting Virtual Networks (VNets)
This document outlines common scenarios and best practices for connecting Azure Virtual Networks (VNets) to each other. Connecting VNets is a fundamental aspect of building scalable and secure cloud architectures on Azure, enabling resources in different VNets to communicate privately and securely.
Why Connect VNets?
- Resource Isolation: Separate environments for development, testing, and production.
- Regional Expansion: Extend your network across multiple Azure regions for high availability and disaster recovery.
- Application Tiers: Create layered application architectures where different tiers reside in separate VNets.
- Data Sovereignty: Meet regulatory requirements by keeping data within specific geographical regions.
- Mergers & Acquisitions: Integrate existing Azure networks from different organizations.
Connectivity Options
Azure offers several robust methods for connecting VNets:
VNet Peering
Description: VNet peering connects two Azure VNets directly, allowing resources in each VNet to communicate with each other as if they were on the same network. This is a non-transitive connection, meaning VNet A peered with VNet B, and VNet B peered with VNet C, does not imply VNet A can communicate with VNet C.
Use Cases:
- Connecting VNets within the same region.
- Connecting VNets across different Azure regions (Global VNet Peering).
- Enabling secure, low-latency communication between application tiers.
Key Features: High bandwidth, low latency, no gateways required, private IP addressing.
VNet-to-VNet VPN Gateway
Description: This method uses Azure VPN Gateway to establish a secure, encrypted connection between two VNets. This is particularly useful when you need to extend your on-premises network to Azure or connect VNets that are not in the same region and don't support direct peering, or when advanced routing is needed.
Use Cases:
- Connecting VNets when VNet peering is not suitable (e.g., needing transitive routing via a hub VNet).
- Connecting VNets that require specific security policies or firewalling between them.
- When existing VPN infrastructure is already in place.
Key Features: Site-to-site VPN, encryption, can handle more complex network topologies.
Azure Virtual WAN
Description: Virtual WAN is a networking service that brings together Azure networking, security, and routing capabilities into a single operational interface. It provides optimized and automated VNet-to-VNet connectivity and VNet-to-on-premises connectivity.
Use Cases:
- Large-scale, hub-and-spoke network architectures.
- Connecting many VNets and remote sites in a centralized and managed way.
- Leveraging integrated security features like Azure Firewall.
Key Features: Centralized management, optimized routing, scalable connectivity, integrated security services.
Designing Your VNet Connectivity
When designing your VNet connectivity strategy, consider the following:
- Latency and Bandwidth Requirements: VNet peering generally offers the lowest latency.
- Transitivity: If you need transitive routing, consider VNet-to-VNet VPNs or Virtual WAN.
- Scale: For a large number of VNets, Virtual WAN simplifies management and routing.
- Security: Implement Network Security Groups (NSGs) and Azure Firewall to control traffic flow between VNets.
- Cost: Evaluate the costs associated with VPN gateways or Virtual WAN services against VNet peering.
By leveraging these Azure networking features, you can build sophisticated and interconnected cloud environments tailored to your specific application and business needs.
Next Steps:
- Learn more about VNet Peering configuration.
- Explore setting up VNet-to-VNet VPN gateways.
- Discover the benefits of Azure Virtual WAN.