Add GWSubnet BGP update

Author: jaredr80

articles/virtual-network/virtual-networks-udr-overview.md

@@ -118,7 +118,7 @@ An on-premises network gateway can exchange routes with an Azure virtual network
 
 When you exchange routes with Azure using BGP, a separate route is added to the route table of all subnets in a virtual network for each advertised prefix. The route is added with *Virtual network gateway* listed as the source and next hop type. 
 
-ER and VPN Gateway route propagation can be disabled on a subnet using a property on a route table. When you exchange routes with Azure using BGP, routes are not added to the route table of all subnets with Virtual network gateway route propagation disabled. Connectivity with VPN connections is achieved using [custom routes](#custom-routes) with a next hop type of *Virtual network gateway*. For details, see [How to disable Virtual network gateway route propagation](manage-route-table.md#create-a-route-table).
+ER and VPN Gateway route propagation can be disabled on a subnet using a property on a route table. When you exchange routes with Azure using BGP, routes are not added to the route table of all subnets with Virtual network gateway route propagation disabled. Connectivity with VPN connections is achieved using [custom routes](#custom-routes) with a next hop type of *Virtual network gateway*. **Route propagation should not be disabled on the GatewaySubnet. The gateway will not function with this setting disabled.** For details, see [How to disable Virtual network gateway route propagation](manage-route-table.md#create-a-route-table).
 
 ## How Azure selects a route
 

includes/vpn-gateway-gwudr-warning.md

@@ -9,4 +9,4 @@
  ms.author: cherylmc
  ms.custom: include file
 ---
-User defined routes with a 0.0.0.0/0 destination and NSGs on the GatewaySubnet **are not supported**. Gateways created with this configuration will be blocked from creation. Gateways require access to the management controllers in order to function properly.
+User defined routes with a 0.0.0.0/0 destination and NSGs on the GatewaySubnet **are not supported**. Gateways created with this configuration will be blocked from creation. Gateways require access to the management controllers in order to function properly. [BGP Route Propagation](https://docs.microsoft.com/en-us/azure/virtual-network/virtual-networks-udr-overview#border-gateway-protocol]) should be set to "Enabled" to ensure functionality of the gateway. If this is disabled, the gateway will not functionality.