Path selection with Azure Route Server

Azure Route Server allows you to control traffic to route through your SDWAN NVA over the Internet to your on-premises network. In this article, we'll talk about how Azure Route Server enables path selection which allows you to configure your SNWAN NVA to have a routing preference when communicating with your on-premises network.

How does it work?

Diagram of Azure Route Server and a SDWAN with Internet routing IP.

Cold potato routing

When you deploy an SDWAN NVA in the same virtual network as the Azure Route Server it is configured with a Microsoft network IP address. Traffic path to your on-premises will use the Microsoft global network and exits the Microsoft network closest to the destination. The routing from your on-premises will enter the Microsoft network closest to the user on the return path. This method of routing is performance optimize, therefore providing the best possible experience at a cost.

Hot potato routing

As a way to optimize for cost, a second method of routing is introduce by assigning your SDWAN NVA with an Internet IP. When traffic is routed to your on-premises, it will exit the Microsoft network in the same region the service is hosted. Then it will route through the Internet using the ISP's network. The routing from on-premises will enter Microsoft network closest to the hosted service region. This method of routing will provide the best overall price when completing a task such as transferring large amount of data.

How to enable routing preference?

When creating a new Public IP address, select Internet as the Routing preference. Then assign the public IP address to the SDWAN NVA.

Screenshot of the Internet routing preference for a public IP address.

Microsoft recommends implementing a connectivity solution using both the Microsoft network and the Internet to provide your environment with an extra layer of resiliency.

Next steps