Clarify Basic VWAN scale units and BGP ASN assignments in routing deep dive

- Added explicit note that gateway scale units are not supported in Basic Virtual WAN (AB#478924)
- Added clarifying note about intentional BGP ASN assignments in routing deep dive diagrams (AB#478925)

Co-authored-by: Copilot <[email protected]>

Author: kenwith

articles/virtual-wan/routing-deep-dive.md

@@ -27,6 +27,9 @@ All VNet and branch connections are associated and propagating to the default ro
 
 :::image type="content" source="./media/routing-deep-dive/virtual-wan-routing-deep-dive-scenario-1.png" alt-text="Diagram that shows a Virtual WAN design with two ExpressRoute circuits and two V P N branches." :::
 
+> [!NOTE]
+> In the diagrams throughout this article, each network entity is assigned a distinct BGP Autonomous System Number (ASN). VPN Branch 1 uses ASN 65501, while SDWAN Branch 4 uses ASN 65504. The different ASNs reflect the different connectivity types (site-to-site VPN vs. integrated SDWAN NVA) and follow a numbering convention based on the branch number. Other ASNs shown include 65012 for the NVA in VNet 12, 65102 for the SDWAN NVA in Hub 2, and 65001 for the ExpressRoute circuits.
+
 > [!IMPORTANT]
 > The previous diagram shows two secured virtual hubs. This topology is supported with Routing Intent. For more information, see [How to configure Virtual WAN Hub routing intent and routing policies][virtual-wan-intent].
 

articles/virtual-wan/virtual-wan-about.md

@@ -78,6 +78,9 @@ There are two types of virtual WANs: Basic and Standard. The following table sho
 
 [!INCLUDE [Basic and Standard SKUs](../../includes/virtual-wan-standard-basic-include.md)]
 
+> [!NOTE]
+> Basic Virtual WAN doesn't support adjusting gateway scale units to increase throughput. If you need higher aggregate throughput, upgrade to Standard Virtual WAN. For more information about gateway scale units, see [About Virtual WAN gateway settings](gateway-settings.md).
+
 For steps to upgrade a virtual WAN, see [Upgrade a virtual WAN from Basic to Standard](upgrade-virtual-wan.md).
 
 ## <a name="connectivity"></a>Connectivity