What is vnet peering

Overview

Azure Virtual Network peering is a fundamental networking feature that connects two virtual networks within Azure infrastructure. When you establish peering between networks, virtual machines, databases, and other resources can communicate directly using private IP addresses, similar to resources on the same physical network. This eliminates the need for traffic to traverse the public internet or require VPN connections.

How VNet Peering Works

Peering operates at the network layer by updating routing tables in both virtual networks. When peering is established, Azure automatically adds routes that direct traffic destined for the peered network to the appropriate network interface. Resources in Network A can then reach resources in Network B by addressing them directly via their private IP addresses, without requiring gateway devices or VPN configurations.

Types of VNet Peering

• Regional Peering: Connects virtual networks within the same Azure region, offering the lowest latency and highest bandwidth
• Global Peering: Connects virtual networks across different Azure regions worldwide, enabling multi-region application architectures

Key Requirements and Limitations

Virtual networks being peered must have non-overlapping IP address spaces. For example, you cannot peer a network using 10.0.0.0/16 with another network also using 10.0.0.0/16. Additionally, peering must be configured on both sides of the connection to enable bidirectional communication. Azure supports transitive peering through User-Defined Routes (UDR), allowing traffic to flow through hub networks in hub-and-spoke topologies.

Benefits and Use Cases

VNet peering reduces latency and improves performance compared to internet-based connections. Organizations use peering for multi-tier application architectures, disaster recovery setups, shared services models, and connecting development/test environments to production networks. The private, secure connectivity also enhances security by keeping traffic off public networks.