Merge pull request #295789 from wtnlee/vnetrouting

criupdate

Author: prmerger-automator[bot]

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

@@ -88,9 +88,19 @@ You can specify the following next hop types when you create a UDR:
 
     You can define a route with 0.0.0.0/0 as the address prefix and a next hop type of virtual appliance. This configuration allows the appliance to inspect the traffic and determine whether to forward or drop the traffic. If you intend to create a UDR that contains the 0.0.0.0/0 address prefix, read [0.0.0.0/0 address prefix](#default-route) first.
 
-* **Virtual network gateway**: Specify when you want traffic destined for specific address prefixes routed to a virtual network gateway. The virtual network gateway must be created with the type **VPN**. You can't specify a virtual network gateway created as the type **ExpressRoute** in a UDR because with ExpressRoute, you must use BGP for custom routes. You can't specify virtual network gateways if you have virtual private network (VPN) and ExpressRoute coexisting connections either. You can define a route that directs traffic destined for the 0.0.0.0/0 address prefix to a route-based virtual network gateway.
-
-   On your premises, you might have a device that inspects the traffic and determines whether to forward or drop the traffic. If you intend to create a UDR for the 0.0.0.0/0 address prefix, read [0.0.0.0/0 address prefix](#default-route) first. Instead of configuring a UDR for the 0.0.0.0/0 address prefix, you can advertise a route with the 0.0.0.0/0 prefix via BGP if the [BGP for a VPN virtual network gateway](../vpn-gateway/vpn-gateway-bgp-resource-manager-ps.md?toc=%2fazure%2fvirtual-network%2ftoc.json) is enabled.
+* **Virtual network gateway**: User-defined routes with next hop type Virtual Network Gateway allow you to route traffic to a Virtual Network's gateway. A Virtual Network has a single gateway that is automatically set by the underlying software-defined networking platform based on your deployment. User-defined routes with next hop Virtual Network Gateway are supported only when the Virtual Network's gateway is a **VPN gateway (and not ExpressRoute, RouteServer or Virtual WAN hub router)**.  
+   * For Virtual Networks with a VPN Gateway, ExpressRoute Gateway and/or Route Server:
+      * If RouteServer is deployed in a VNET, RouteServer is set as the Virtual Network's gateway.
+      * If VPN Gateway and ExpressRoute Gateway are deployed in the same VNET (without RouteServer), ExpressRoute Gateway is set as the Virtual Network's gateway.  
+      * If either an VPN Gateway or ExpressRoute Gateway is the only gateway in the VNET (without RouteServer), the deployed gateway is the Virtual Network's gateway.
+   * For Virtual Networks peered to another Virtual Network with gateways or RouteServer and the "Use the remote virtual network's gateway  or Route Server" setting is **enabled**:
+      * If RouteServer is deployed in the peered VNET, the remote RouteServer is set as the Virtual Network's gateway.
+      * If VPN Gateway and ExpressRoute Gateway are deployed in the peered VNET (without RouteServer), the remote ExpressRoute Gateway is set as the Virtual Network's gateway.  
+      * If either an VPN Gateway or ExpressRoute Gateway is the only gateway in the peered VNET (without RouteServer), the remote gateway is set as the Virtual Network's gateway.
+   * For Virtual Networks connected to a Virtual WAN hub:
+      * The Virtual Network's gateway is always set to the Virtual WAN hub router.
+
+      On your premises, you might have a device that inspects the traffic and determines whether to forward or drop the traffic. If you intend to create a UDR for the 0.0.0.0/0 address prefix, read [0.0.0.0/0 address prefix](#default-route) first. Instead of configuring a UDR for the 0.0.0.0/0 address prefix, you can advertise a route with the 0.0.0.0/0 prefix via BGP if the [BGP for a VPN virtual network gateway](../vpn-gateway/vpn-gateway-bgp-resource-manager-ps.md?toc=%2fazure%2fvirtual-network%2ftoc.json) is enabled.
 
 * **None**: Specify when you want to drop traffic to an address prefix, rather than forwarding the traffic to a destination. Azure might show **None** for some of the optional system routes if a capability isn't configured. For example, if you see that **Next hop IP address** shows **None** and **Next hop type** shows **Virtual network gateway** or **Virtual appliance**, it might be because the device isn't running or isn't fully configured. Azure creates system [default routes](#default) for reserved address prefixes with **None** as the next hop type.
 * **Virtual network**: Specify the **Virtual network** option when you want to override the default routing within a virtual network. For an example of why you might create a route with the **Virtual network** hop type, see [Routing example](#routing-example).