Merge pull request #251709 from rvandenbedem/patch-4

Private ASN processing clarification

Author: v-dirichards

articles/azure-vmware/concepts-network-design-considerations.md

@@ -3,7 +3,7 @@ title: Concepts - Network design considerations
 description: Learn about network design considerations for Azure VMware Solution
 ms.topic: conceptual
 ms.service: azure-vmware
-ms.date: 6/26/2023
+ms.date: 9/15/2023
 ---
 
 # Azure VMware Solution network design considerations
@@ -24,7 +24,8 @@ For AS-Path Prepend, consider the following:
 
 > [!div class="checklist"]
 > * The key point is that you must prepend **Public** ASN numbers to influence how Azure VMware Solution routes traffic back to on-premises. If you prepend using _Private_ ASN, Azure VMware Solution will ignore the prepend, and the ECMP behavior above will occur. Even if you operate a Private BGP ASN on-premises, it's still possible to configure your on-premises devices to utilize a Public ASN when prepending routes outbound, to ensure compatibility with Azure VMware Solution.
-> * Both or all circuits are connected to Azure VMware Solution through ExpressRoute Global Reach.
+> * Design your traffic path for private ASNs after the public ASN to be honored by Azure VMware Solution. The Azure VMware Solution ExpressRoute circuit doesn't strip any private ASNs that exist in the path after the public ASN is processed.
+> * Both or all circuits are connected to Azure VMware Solution through Azure ExpressRoute Global Reach.
 > * The same netblocks are being advertised from two or more circuits.
 > * You wish to use AS-Path Prepend to force Azure VMware solution to prefer one circuit over another.
 > * Use either 2-byte or 4-byte public ASN numbers.

articles/azure-vmware/faq.yml

@@ -202,7 +202,7 @@ sections:
           The only way to connect to Azure VMware Solution through ExpressRoute is for your environment and the on-premises ExpressRoute-carrier partners/ISPs support 4-byte ASN or have backward compatibility from 4-byte to 2-byte ASN in the BGP prefix ASN path advertisement.        
 
           > [!NOTE]
-          > Currently, private ASN (64512 - 65534) prepending from a customer on-premises environment isn't supported by Azure VMware Solution. This scenario might lead to intermittent connection drops from on-premises to Azure VMware Solution.
+          > Currently, private ASN (64512 - 65534) prepending from a customer on-premises environment isn't supported by Azure VMware Solution. This scenario might lead to intermittent connection drops from on-premises to Azure VMware Solution. Also design your traffic path for private ASNs after the public ASN to be honored by Azure VMware Solution. The Azure VMware Solution ExpressRoute circuit doesn't strip any private ASNs that exist in the path after the public ASN is processed.
 
       - question: What network IP address planning is required to incorporate private clouds with on-premises environments?
         answer: A private network /22 address space is required to deploy an Azure VMware Solution private cloud. This private address space shouldn't overlap with other virtual networks in a subscription or with on-premises networks.