About ExpressRoute FastPath

ExpressRoute virtual network gateway is designed to exchange network routes and route network traffic. FastPath is designed to improve the data path performance between your on-premises network and your virtual network. When enabled, FastPath sends network traffic directly to virtual machines in the virtual network, bypassing the gateway.

Requirements

Circuits

FastPath is available on all ExpressRoute circuits.

Gateways

FastPath still requires a virtual network gateway to be created to exchange routes between virtual network and on-premises network. For more information about virtual network gateways and ExpressRoute, including performance information and gateway SKUs, see ExpressRoute virtual network gateways.

To configure FastPath, the virtual network gateway must be either:

  • Ultra Performance
  • ErGw3AZ

Limitations

While FastPath supports most configurations, it doesn't support the following features:

  • UDR on the gateway subnet: FastPath doesn't honor UDRs configured on the gateway subnet. FastPath traffic bypasses any next-hops determined by UDRs configured on the gateway subnet.

  • Basic Load Balancer: If you deploy a Basic internal load balancer in your virtual network or the Azure PaaS service you deploy in your virtual network uses a Basic internal load balancer, the network traffic from your on-premises network to the virtual IPs hosted on the Basic load balancer will be sent to the virtual network gateway. The solution is to upgrade the Basic load balancer to a Standard load balancer.

  • Private Link: If you connect to a private endpoint in your virtual network from your on-premises network, the connection will go through the virtual network gateway.

Public preview

The following FastPath features are in Public preview:

VNet Peering - FastPath will send traffic directly to any VM deployed in a virtual network peered to the one connected to ExpressRoute, bypassing the ExpressRoute virtual network gateway.

Private Link - Private Link traffic sent over ExpressRoute FastPath will bypass the ExpressRoute virtual network gateway in the data path. This preview is available in the following Azure Regions.

  • Australia East
  • East Asia
  • East US
  • East US 2
  • North Central US
  • North Europe
  • South Central US
  • South East Asia
  • UK South
  • West Central US
  • West Europe
  • West US
  • West US 2
  • West US 3

This preview supports connectivity to the following Azure Services:

  • Azure Cosmos DB
  • Azure Key Vault
  • Azure Storage
  • Third Party Private Link Services

Note

Private Link pricing will not apply to traffic sent over ExpressRoute FastPath during Public preview. For more information about pricing, check out the Private Link pricing page.

See How to enroll in ExpressRoute FastPath features.

Available in all regions.

Next steps

To enable FastPath, see Link a virtual network to ExpressRoute.