===== What issue does Global Reach solve =====

**ExpressRoute Global Reach** often causes confusion, because it’s not the same as ExpressRoute into **vWAN** or VNet peering.  

==== The Problem Without Global Reach ====
  * If you have **two ExpressRoute circuits** in different peering locations (e.g., one in London, one in Frankfurt) connected to your **on-premises datacenters**, they are **not automatically connected** to each other.
  * By default:
    * London DC ↔ Azure (via ER circuit 1)  
    * Frankfurt DC ↔ Azure (via ER circuit 2)  
    * **But London DC ↔ Frankfurt DC cannot talk directly** via Microsoft’s backbone.
  * If you need those two datacenters to exchange traffic, you’d normally have to **backhaul through your own WAN** or build additional connectivity (VPN, MPLS, SD-WAN, etc.).

==== What Global Reach Does ====
  * **ExpressRoute Global Reach** lets you **connect two (or more) on-premises sites together** via the Microsoft backbone, **through their ER circuits**.
  * So, your **London on-premises site can talk directly to Frankfurt on-premises site**, riding Microsoft’s private backbone instead of your own WAN.

==== Benefits ====
  * Eliminates the need for a separate WAN/MPLS link between sites.  
  * Reduces latency (uses Microsoft’s global backbone).  
  * Simplifies routing: both sites learn each other’s prefixes via ER BGP.  
  * Still keeps Azure reachable via both ER circuits.

==== Summary ====
**ExpressRoute Global Reach solves the problem of connecting your own on-premises datacenters (in different geographic locations) to each other over Microsoft’s private backbone, using their respective ExpressRoute circuits.**

===== Sources for ExpressRoute Global Reach =====

==== Official Microsoft Documentation ====
  * **ExpressRoute Documentation**  
    The main portal for all things related to ExpressRoute, including Global Reach.  
    Link: https://docs.microsoft.com/ro-ro/azure/expressroute/

  * **ExpressRoute Global Reach Overview**  
    Detailed explanation of how Global Reach connects on-premises environments via Microsoft’s private backbone.  
    Link: https://docs.microsoft.com/ro-ro/azure/expressroute/expressroute-global-reach

  * **Tutorial: Peer On-Premises Environments to Azure VMware Solution**  
    Practical guide showing how to use Global Reach to connect on-premises networks to Azure VMware Solution.  
    Link: https://docs.microsoft.com/vi-vn/azure/azure-vmware/tutorial-expressroute-global-reach-private-cloud