What is routing preference?
Azure routing preference enables you to choose how your traffic routes between Azure and the Internet. You can choose to route traffic either via the Microsoft network, or, via the ISP network (public internet). These options are also referred to as cold potato routing and hot potato routing respectively. Egress data transfer price varies based on the routing selection. You can choose the routing option while creating a public IP address. The public IP address can be associated with resources such as virtual machine, virtual machine scale sets, internet-facing load balancer, etc. You can also set the routing preference for Azure storage resources such as blobs, files, web, and Azure DataLake. By default, traffic is routed via the Microsoft global network for all Azure services.
Routing via Microsoft global network
When you route your traffic via the Microsoft global network, traffic is delivered over one of the largest networks on the globe spanning over 160,000 miles of fiber with over 165 edge Point of Presence (POP). The network is well provisioned with multiple redundant fiber paths to ensure exceptionally high reliability and availability. The traffic engineering is managed by a software defined WAN controller that ensures low latency path selection for your traffic and offers the premium network performance.
Ingress traffic: The global BGP Anycast announcement ensures ingress traffic enters Microsoft network closest to the user. For example, if a user from Singapore accesses Azure resources hosted in Chicago, USA then traffic is entered into Microsoft global network in Singapore Edge POP and travels on Microsoft network to the service hosted in Chicago.
Egress traffic: The egress traffic follows the same principle. Traffic travels majority of its journey on Microsoft global network and exits closest to the user. For example, if traffic from Azure Chicago is destined to a user from Singapore, then traffic travels on Microsoft network from Chicago to Singapore, and exits the Microsoft network in Singapore Edge POP.
Both ingress and egress traffic stays bulk of the travel on the Microsoft global network. This is also known as cold potato routing.
Routing over public Internet (ISP network)
The new routing choice Internet routing minimizes travel on the Microsoft global network, and uses the transit ISP network to route your traffic. This cost-optimized routing option offers network performance that is comparable to other cloud providers.
Ingress traffic: The ingress path uses hot potato routing which means that traffic enters the Microsoft network that is closest to the hosted service region. For example, if a user from Singapore accesses Azure resources hosted in Chicago then traffic travels over the public internet and enters the Microsoft global network in Chicago.
Egress traffic: The egress traffic follows the same principle. Traffic exits Microsoft network in the same region that the service is hosted. For example, if traffic from your service in Azure Chicago is destined to a user from Singapore, then traffic exits the Microsoft network in Chicago and travels over the public internet to the user in Singapore.
Public IP with Routing preference choice “Microsoft Global Network” can be associated with any Azure services. However, Public IP with Routing preference choice Internet can be associated with the following Azure resources:
- Virtual machine
- Virtual machine scale set
- Azure Kubernetes Service (AKS)
- Internet-facing load balancer
- Application Gateway
- Azure Firewall
For storage, primary endpoints always use the Microsoft global network. You can enable secondary endpoints with Internet as your choice for traffic routing. Supported storage services are:
- Azure DataLake
The price difference between both options is reflected in the internet egress data transfer pricing. Routing via Microsoft global network data transfer price is same as current internet egress price. Visit Azure bandwidth pricing page for the latest pricing information.
- Routing preference is only compatible with zone-redundant standard SKU of public IP address. Basic SKU of public IP address is not supported.
- Routing preference currently supports only IPv4 public IP addresses. IPv6 public IP addresses are not supported.