VNet Peering Concepts

Vnet Peering

Vnet Peering is used to provide connectivity between two or more Virtual networks in Azure. Traffic between Virtual machine via VNet Peered network uses Microsoft backbone infrastructure.  

Network traffic between Peered Virtual network is private and No public Internet, Gateways, or Encryption is required for communication between Virtual Network.

Below are two types of Vnet Peering:

• Virtual Network Peering: It is used to connect virtual Network within same Azure Region.
• Global Virtual Network Peering: It is used to connect Virtual network across Azure Regions.

Below are benefits of using Virtual Network Peering (Local or Global):

• It provides Low -latency, High-bandwidth connection between resources in different Virtual networks.
• It provides reliable data transfer between virtual network across Azure Subscription, Azure Active Directory tenants, deployment Models, and Azure Regions.
• Azure resource Manager can also be used to create Virtual peer Network.

Vnet Peering Connectivity

When Virtual Network are peered, resources in each Virtual Peered network can talk to each other directly using Azure Backbone Infrastructure.

Network Latency between Virtual Machines in peered network in the same region is same as the latency within a single virtual network.

For Security, a NSG (Network Security Group) can be configured in either virtual network to block access to other virtual network or subnets. By default, Full Connectivity is Open between Virtual Peered network.

Vnet Peering Service Chaining

Service chaining is used to direct traffic from one Virtual network to a Virtual Appliance or Gateway in a Peered network through User-Defined Routes.

In-Order to enable Service-Chaining, you should configure the user-defined routes that points to virtual machine in peered Virtual Network as a next Hop IP address. Here you can’t route between Virtual Network with user-defined route that specifies an Azure Express Route gateway as next Hop type.

User defined routes could also point to Virtual network gateway to enable Service chaining.

Using this concept , a Hub and Spoke network can also be deployed , where HUB network hosts infrastructure components like Network Virtual appliance or VPN gateway. All the Spoke Virtual Network can then peer with the hub Virtual network and traffic from Spoke Virtual Network traverse to HUB via Network Virtual appliance or VPN gateway and then to Spoke Virtual Network.