wip: uniform

Author: mbrat2005

articles/virtual-machine-scale-sets/virtual-machine-scale-sets-networking.md

@@ -44,7 +44,14 @@ See [Azure Load Balancer and Virtual Machine Scale Sets](../load-balancer/load-b
 
 To add a scale set to the backend pool of an Application Gateway, reference the Application Gateway backend pool in your scale set's network profile. This can be done either when creating the scale set (see ARM Template below) or on an existing scale set.  
 
-### [Portal](#tab/portal1)
+### Adding Uniform Orchestration Virtual Machine Scale Sets to an Application Gateway
+
+When adding Uniform Virtual Machine Scale Sets to an Application Gateway's backend pool, the process will differ for new or existing scale sets:
+
+- For new scale sets, reference the Application Gateway's backend pool ID in your scale set model's network profile, under one or more network interface IP configurations. When deployed, instances added to your scale set will be placed in the Application Gateway's backend pool. 
+- For existing scale sets, first add the Application Gateway's backend pool ID in your scale set model's network profile, then apply the model your existing instances by an upgrade. If the scale set's upgrade policy is `Automatic` or `Rolling`, instances will be updated for you. If it is `Manual`, you need to upgrade the instances manually. 
+
+#### [Portal](#tab/portal1)
 
 1. Create an Application Gateway and backend pool in the same region as your scale set, if you do not already have one
 1. Navigate to the Virtual Machine Scale Set in the Portal
@@ -54,7 +61,7 @@ To add a scale set to the backend pool of an Application Gateway, reference the
 1. Select the target backend pool and click **Save**
 1. If your scale set Upgrade Policy is 'Manual', navigate to the **Settings** > **Instances** pane to select and upgrade each of your instances
 
-### [PowerShell](#tab/powershell1)
+#### [PowerShell](#tab/powershell1)
 
 ```azurepowershell
     $appGW = Get-AzApplicationGateway -Name <appGWName> -ResourceGroup <AppGWResourceGroupName>
@@ -84,7 +91,7 @@ To add a scale set to the backend pool of an Application Gateway, reference the
 
 ```
 
-### [CLI](#tab/cli1)
+#### [CLI](#tab/cli1)
 
 ```azurecli-interactive
 appGWName=<appGwName>
@@ -102,7 +109,7 @@ az vmss update -n $vmssName -g $vmssResourceGroup --add "virtualMachineProfile.N
 az vmss update-instances --instance-ids * --name $vmssName --resource-group $vmssResourceGroup
 ```
 
-### [ARM template](#tab/arm1)
+#### [ARM template](#tab/arm1)
 
 ```json
 "ipConfigurations": [{
@@ -120,6 +127,10 @@ az vmss update-instances --instance-ids * --name $vmssName --resource-group $vms
 --- 
 <!-- The three dashes above show that your section of tabbed content is complete. Don't remove them :) -->
 
+### Adding Flexible Orchestration Virtual Machine Scale Sets to an Application Gateway
+
+When adding a Flexible scale set to an Application Gateway, the process is the same as adding standalone VMs to an Application Gateway's backend pool--you update the virtual machine's network interface IP configuration to be part of the backend pool. This can be done either [through the Application Gateway's configuration](/azure/application-gateway/create-multiple-sites-portal#add-backend-servers-to-backend-pools) or by configuring the virtual machine's network interface configuration. 
+
 >[!NOTE]
 > Note that the application gateway must be in the same virtual network as the scale set but must be in a different subnet from the scale set.