Merge pull request #267725 from duongau/eroverview

ExpressRoute - Overview (add resiliency section)

Author: prmerger-automator[bot]

articles/expressroute/expressroute-introduction.md

@@ -46,6 +46,12 @@ Microsoft uses BGP, an industry standard dynamic routing protocol, to exchange r
 
 Each ExpressRoute circuit consists of two connections to two Microsoft Enterprise edge routers (MSEEs) at an [ExpressRoute Location](./expressroute-locations.md#expressroute-locations) from the connectivity provider or your network edge. Microsoft requires dual BGP connections from the connectivity provider or your network edge – one to each MSEE. You might choose not to deploy redundant devices/Ethernet circuits at your end. However, connectivity providers use redundant devices to ensure that your connections are handed off to Microsoft in a redundant manner.
 
+### Resiliency
+
+Microsoft has multiple ExpressRoute peering locations in many geopolitical regions. In order to provide resiliency, Microsoft recommends that you connect to ExpressRoute in two peering locations. The maximum resiliency is achieved by connecting to two ExpressRoute circuits in different ExpressRoute locations. Standard resiliency is achieved by connecting to one ExpressRoute circuit with redundant connections. The Azure portal provides a guided experience to help you create a resilient ExpressRoute configuration. For Azure PowerShell, CLI, ARM template, Terraform, and Bicep, you can achieve maximum resiliency by creating a second ExpressRoute circuit in a different ExpressRoute location and connecting to it. For more information, see [Create maximum resiliency with ExpressRoute](expressroute-howto-circuit-portal-resource-manager.md?pivots=expressroute-preview).
+
+:::image type="content" source="./media/expressroute-howto-circuit-portal-resource-manager/maximum-resiliency.png" alt-text="Diagram of maximum resiliency for an ExpressRoute connection.":::
+
 ### Connectivity to Microsoft cloud services
 
 ExpressRoute connections enable access to the following services: