Merge pull request #3740 from ManikaDhiman/md-l3-tweak

Note about routing consideration using L3

Author: v-regandowner

azure-local/concepts/gateway-overview.md

@@ -5,7 +5,7 @@ author: AnirbanPaul
 ms.author: anpaul
 ms.topic: overview
 ms.service: azure-local
-ms.date: 10/22/2024
+ms.date: 07/16/2025
 ms.custom: kr2b-contr-experiment
 ---
 # What is Remote Access Service (RAS) Gateway for Software Defined Networking?
@@ -72,6 +72,9 @@ If you plan to deploy L3 Gateway connections with BGP routing, make sure to conf
 - update-source: This specifies the source address for BGP updates, that is L3 VLAN. For example, VLAN 250.
 - ebgp multihop: This specifies more hops are required since the BGP neighbor is more than one hop away.
 
+> [!NOTE]
+> When using BGP with an L3 peer IP in a different subnet from the BGP router, you must configure a static /32 route in the L3 connection. For example, if the L3 peer is 15.0.0.1 and the BGP peer is 25.0.0.1, add a route with destination 25.0.0.1/32 and next hop 15.0.0.5 (L3 IP).
+
 ### Dynamic routing with BGP
 
 BGP reduces the need for manual route configuration on routers because it's a dynamic routing protocol, and automatically learns routes between sites that are connected by using site-to-site VPN connections. If your organization has multiple sites that are connected using BGP-enabled routers, such as RAS Gateway, BGP allows the routers to automatically calculate and use valid routes to each other in case of network disruption or failure.