add migration sectin due to cris

Author: Justin

articles/aks/load-balancer-standard.md

@@ -14,9 +14,9 @@ ms.author: zarhoads
 
 # Use a Standard SKU load balancer in Azure Kubernetes Service (AKS)
 
-To provide access to your applications in Azure Kubernetes Service (AKS), you can create and use an Azure Load Balancer. A load balancer running on AKS can be used as an internal or an external load balancer. An internal load balancer makes a Kubernetes service accessible only to applications running in the same virtual network as the AKS cluster. An external load balancer receives one or more public IPs for ingress and makes a Kubernetes service accessible externally using the public IPs.
+To provide access to applications via Kubernetes services of type `LoadBalancer` in Azure Kubernetes Service (AKS), you can use an Azure Load Balancer. A load balancer running on AKS can be used as an internal or an external load balancer. An internal load balancer makes a Kubernetes service accessible only to applications running in the same virtual network as the AKS cluster. An external load balancer receives one or more public IPs for ingress and makes a Kubernetes service accessible externally using the public IPs.
 
-Azure Load Balancer is available in two SKUs - *Basic* and *Standard*. By default, the *Standard* SKU is used when you create an AKS cluster. Using a *Standard* SKU load balancer provides additional features and functionality, such as larger backend pool size and Availability Zones. It's important that you understand the differences between *Standard* and *Basic* load balancers before choosing which to use. Once you create an AKS cluster, you cannot change the load balancer SKU for that cluster. For more information on the *Basic* and *Standard* SKUs, see [Azure load balancer SKU comparison][azure-lb-comparison].
+Azure Load Balancer is available in two SKUs - *Basic* and *Standard*. By default, the *Standard* SKU is used when you create an AKS cluster. Using a *Standard* SKU load balancer provides additional features and functionality, such as a larger backend pool size and Availability Zones. It's important that you understand the differences between *Standard* and *Basic* load balancers before choosing which to use. Once you create an AKS cluster, you cannot change the load balancer SKU for that cluster. For more information on the *Basic* and *Standard* SKUs, see [Azure load balancer SKU comparison][azure-lb-comparison].
 
 This article assumes a basic understanding of Kubernetes and Azure Load Balancer concepts. For more information, see [Kubernetes core concepts for Azure Kubernetes Service (AKS)][kubernetes-concepts] and [What is Azure Load Balancer?][azure-lb].
 
@@ -27,10 +27,19 @@ If you don't have an Azure subscription, create a [free account](https://azure.m
 If you choose to install and use the CLI locally, this article requires that you are running the Azure CLI version 2.0.74 or later. Run `az --version` to find the version. If you need to install or upgrade, see [Install Azure CLI][install-azure-cli].
 
 ## Before you begin
+
 This article assumes you have a AKS cluster with the *Standard* SKU Azure Load Balancer. If you need an AKS cluster, see the AKS quickstart [using the Azure CLI][aks-quickstart-cli] or [using the Azure portal][aks-quickstart-portal].
 
 The AKS cluster service principal needs also permission to manage network resources if you use an existing subnet or resource group. In general, assign the *Network contributor* role to your service principal on the delegated resources. For more information on permissions, see [Delegate AKS access to other Azure resources][aks-sp].
 
+### Moving from a Basic SKU Load Balancer to Standard SKU
+
+If you have an existing cluster with the Basic SKU Load Balancer, there are important behavioral differences to note when migrating to use a cluster with the Standard SKU Load Balancer.
+
+For example, making blue/green deployments to migrate clusters is a common practice given the `load-balancer-sku` type of a cluster can only be defined at cluster create time. However, *Basic SKU* Load Balancers use *Basic SKU* IP Addresses which are not compatible with *Standard SKU* Load Balancers as they require *Standard SKU* IP Addresses. When migrating clusters to upgrade Load Balancer SKUs, a new IP address with a compatible IP Address SKU will be required.
+
+For more considerations on how to migrate clusters, visit [aka.ms/aks/migrate](https://aka.ms/aks/migrate) to view a list of important topics to consider when migrating. The below limitations are also important behavioral differences to note when using Standard SKU Load Balancers in AKS.
+
 ### Limitations
 
 The following limitations apply when you create and manage AKS clusters that support a load balancer with the *Standard* SKU:
@@ -39,9 +48,10 @@ The following limitations apply when you create and manage AKS clusters that sup
     * Provide your own public IPs.
     * Provide your own public IP prefixes.
     * Specify a number up to 100 to allow the AKS cluster to create that many *Standard* SKU public IPs in the same resource group created as the AKS cluster, which is usually named with *MC_* at the beginning. AKS assigns the public IP to the *Standard* SKU load balancer. By default, one public IP will automatically be created in the same resource group as the AKS cluster, if no public IP, public IP prefix, or number of IPs is specified. You also must allow public addresses and avoid creating any Azure Policy that bans IP creation.
-* When using the *Standard* SKU for a load balancer, you must use Kubernetes version 1.13 or greater.
+* When using the *Standard* SKU for a load balancer, you must use Kubernetes version `1.13 or greater`.
 * Defining the load balancer SKU can only be done when you create an AKS cluster. You cannot change the load balancer SKU after an AKS cluster has been created.
-* You can only use one load balancer SKU in a single cluster.
+* You can only use one type of load balancer SKU (Basic or Standard) in a single cluster.
+* *Standard* SKU Load Balancers only support *Standard* SKU IP Addresses.
 
 ## Configure the load balancer to be internal