Azure ExpressRoute Global Reach: Overview and Configuration Example

Azure ExpressRoute Global Reach extends the capabilities of Azure ExpressRoute to enable private connectivity between geographically dispersed locations. It facilitates communication between on-premises networks connected to ExpressRoute circuits in different geopolitical boundaries. Here's a detailed overview of Azure ExpressRoute Global Reach along with a configuration example:

Features of Azure ExpressRoute Global Reach:

1. Global Network Connectivity:

   • Enables private connectivity across global ExpressRoute circuits, allowing communication between on-premises locations in different regions.

2. Private Peering:

   • Utilizes private peering to establish private connections between on-premises networks, maintaining privacy and security.

3. Transitive Routing:

   • Supports transitive routing, allowing traffic to flow through multiple ExpressRoute circuits to reach the destination.

4. Hub-and-Spoke Topology:

   • Facilitates the creation of hub-and-spoke network architectures for centralized connectivity and traffic control.

5. Centralized Management:

   • Provides centralized management of ExpressRoute connections and circuits through the Azure Portal.

Configuration Example:

Let's configure Azure ExpressRoute Global Reach between two ExpressRoute circuits in different regions:

1. ExpressRoute Circuit Setup:

   • In the Azure Portal, navigate to the "ExpressRoute circuits" section.
   • Create ExpressRoute circuits for each on-premises location. Ensure that each circuit is associated with a different geopolitical region.

2. Provider Configuration:

   • Coordinate with the ExpressRoute service provider to configure the necessary settings for each ExpressRoute circuit.

3. Create Private Peering:

   • In the configuration of each ExpressRoute circuit, set up private peering with the respective on-premises network.
   • Ensure that the IP addresses used for the private peering are unique and do not overlap.

4. Enable ExpressRoute Global Reach:

   • In the configuration of each ExpressRoute circuit, enable ExpressRoute Global Reach.
   • Specify the peer's AS number and the connection key provided by the ExpressRoute service provider.

5. Hub-and-Spoke Topology (Optional):

   • If deploying a hub-and-spoke architecture, configure one ExpressRoute circuit as the hub and the others as spokes.
   • Ensure that transitive routing is allowed for traffic to flow through the hub to reach other spokes.

6. Routing Considerations:

   • Configure routing on on-premises routers to route traffic through the ExpressRoute circuits appropriately.

7. Transitive Routing (Optional):

   • Test transitive routing by sending traffic between on-premises locations connected to different ExpressRoute circuits.

8. Monitor Connectivity:

   • Monitor connectivity using Azure Network Watcher or other monitoring tools to ensure that traffic flows as expected.

9. Centralized Management:

   • Manage and monitor all ExpressRoute circuits and connections centrally through the Azure Portal.

10. Clean Up Resources:

    • Once done, clean up resources by deleting the ExpressRoute circuits or specific resources as needed.