Traffic Manager subnet override using Azure PowerShell

Traffic Manager subnet override allows you to alter the routing method of a profile. The addition of an override directs traffic based upon the end user's IP address with a predefined IP address range to endpoint mapping.

How subnet override works

When subnet overrides are added to a traffic manager profile, Traffic Manager first checks if there's a subnet override for the end user's IP address. If one is found, the user's DNS query is directed to the corresponding endpoint. If a mapping isn't found, Traffic Manager falls back to the profile's original routing method.

The IP address ranges can be specified as either CIDR ranges (for example, 1.2.3.0/24) or as address ranges (for example, 1.2.3.4-5.6.7.8). The IP ranges associated with each endpoint must be unique to that endpoint. Any overlap of IP address ranges among different endpoints causes the profile to be rejected by Traffic Manager.

There are two types of routing profiles that support subnet overrides:

• Geographic - If Traffic Manager finds a subnet override for the DNS query's IP address, it routes the query to the endpoint whatever the health of the endpoint is.
• Performance - If Traffic Manager finds a subnet override for the DNS query's IP address, it only routes the traffic to the endpoint if it's healthy. Traffic Manager falls back to the performance routing heuristic if the subnet override endpoint isn't healthy.

Prerequisites

• An Azure account with an active subscription. Create a trial subscription.
• For this guide you need an App Service and a Traffic Manager profile. To learn more, see Create a Traffic Manager profile.

If you choose to install and use PowerShell locally, this article requires the Azure PowerShell module version 5.4.1 or later. Run Get-Module -ListAvailable Az to find the installed version. If you need to upgrade, see Install Azure PowerShell module. If you're running PowerShell locally, you also need to run Connect-AzAccount -Environment AzureChinaCloud to create a connection with Azure.

Create a Traffic Manager subnet override

To create a Traffic Manager subnet override, you can use Azure PowerShell to add the subnets for the override to the Traffic Manager endpoint.

Add IP Address range to Endpoint

1. Retrieve the Traffic Manager endpoint:

   To enable the subnet override, retrieve the endpoint you wish to add the override to and store it in a variable using Get-AzTrafficManagerEndpoint.

   Replace the Name, ProfileName, and ResourceGroupName with the values of the endpoint that you're changing. In this example we use the endpoint name myAppServicePlan and the profile name myTrafficManagerProfile.

   
   $TrafficManagerEndpoint = Get-AzTrafficManagerEndpoint -Name "myAppServicePlan" -ProfileName "myTrafficManagerProfile" -ResourceGroupName "MyResourceGroup" -Type AzureEndpoints
   
   

2. Add the IP address range to the endpoint:

   To add the IP address range to the endpoint, you'll use Add-AzTrafficManagerIpAddressRange to add the range.

   
   ### Add a range of IPs ###
   Add-AzTrafficManagerIPAddressRange -TrafficManagerEndpoint $TrafficManagerEndpoint -First "1.2.3.4" -Last "5.6.7.8"
   
   ### Add a subnet ###
   Add-AzTrafficManagerIPAddressRange -TrafficManagerEndpoint $TrafficManagerEndpoint -First "9.10.11.0" -Scope 24
   
   ### Add a range of IPs with a subnet ###
   Add-AzTrafficManagerIPAddressRange -TrafficManagerEndpoint $TrafficManagerEndpoint -First "12.13.14.0" -Last "12.13.14.31" -Scope 27
   
   

Update Endpoint

Once the ranges are added, use Set-AzTrafficManagerEndpoint to update the endpoint.

Set-AzTrafficManagerEndpoint -TrafficManagerEndpoint $TrafficManagerEndpoint

Remove IP address range from Endpoint

1. Retrieve the Traffic Manager endpoint:

   To enable the subnet override, retrieve the endpoint you wish to add the override to and store it in a variable using Get-AzTrafficManagerEndpoint.

   Replace the Name, ProfileName, and ResourceGroupName with the values of the endpoint that you're changing.

   
   $TrafficManagerEndpoint = Get-AzTrafficManagerEndpoint -Name "myAppServicePlan" -ProfileName "myTrafficManagerProfile" -ResourceGroupName "MyResourceGroup" -Type AzureEndpoints
   
   

2. Remove the IP address range from the endpoint:

   
   ### Remove a range of IPs ###
   Remove-AzTrafficManagerIpAddressRange -TrafficManagerEndpoint $TrafficManagerEndpoint -First "1.2.3.4" 
   
   ### Remove a subnet ###
   Remove-AzTrafficManagerIpAddressRange -TrafficManagerEndpoint $TrafficManagerEndpoint -First "9.10.11.0" 
   
   ### Remove a range of IPs with a subnet ###
   Remove-AzTrafficManagerIpAddressRange -TrafficManagerEndpoint $TrafficManagerEndpoint -First "12.13.14.0" 
   
   

Update Endpoint

Once the ranges are removed, use Set-AzTrafficManagerEndpoint to update the endpoint.

Set-AzTrafficManagerEndpoint -TrafficManagerEndpoint $TrafficManagerEndpoint

Next steps

Learn more about Traffic Manager traffic routing methods.

Learn about the Subnet traffic-routing method