Merge pull request #209318 from KapilAnanth-MSFT/patch-3

(AzureCXP) fixes Transit Routing requirement

Author: prmerger-automator[bot]

articles/expressroute/expressroute-howto-coexist-resource-manager.md

@@ -34,7 +34,7 @@ The steps to configure both scenarios are covered in this article. This article
 ## Limits and limitations
 * **Only route-based VPN gateway is supported.** You must use a route-based [VPN gateway](../vpn-gateway/vpn-gateway-about-vpngateways.md). You also can use a route-based VPN gateway with a VPN connection configured for 'policy-based traffic selectors' as described in [Connect to multiple policy-based VPN devices](../vpn-gateway/vpn-gateway-connect-multiple-policybased-rm-ps.md).
 * **ExpressRoute-VPN Gateway coexist configurations are not supported on the Basic SKU**.
-* **If you want to use transit routing between ExpressRoute and VPN, the ASN of Azure VPN Gateway must be set to 65515.** Azure VPN Gateway supports the BGP routing protocol. For ExpressRoute and Azure VPN to work together, you must keep the Autonomous System Number of your Azure VPN gateway at its default value, 65515. If you previously selected an ASN other than 65515 and you change the setting to 65515, you must reset the VPN gateway for the setting to take effect.
+* **If you want to use transit routing between ExpressRoute and VPN, the ASN of Azure VPN Gateway must be set to 65515 and Azure Route Server should be used.** Azure VPN Gateway supports the BGP routing protocol. For ExpressRoute and Azure VPN to work together, you must keep the Autonomous System Number of your Azure VPN gateway at its default value, 65515. If you previously selected an ASN other than 65515 and you change the setting to 65515, you must reset the VPN gateway for the setting to take effect.
 * **The gateway subnet must be /27 or a shorter prefix**, (such as /26, /25), or you will receive an error message when you add the ExpressRoute virtual network gateway.
 * **Coexistence in a dual-stack vnet is not supported.** If you are using ExpressRoute IPv6 support and a dual-stack ExpressRoute gateway, coexistence with VPN Gateway will not be possible.