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Designing and Implementing Azure Cross-region Connectivity Between Multiple Locations

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As dependency on cloud services grows, so does the need for a reliable, low-latency network connection to the cloud. Also, some organizations and government agencies require a dedicated connection that does not pass network traffic over the public internet. Azure ExpressRoute provides a dedicated, redundant connection to Azure cloud services.  

In this course, we examine Azure ExpressRoute. Azure ExpressRoute creates a reliable, dedicated connection between an organization's on-premises environment and Microsoft Azure. We cover design considerations when planning for ExpressRoute, requirements for installing ExpressRoute, and management and troubleshooting tasks. The learning objectives for this course map to the Azure AZ-700: Designing and Implementing Microsoft Azure Networking Solutions exam.

Learning Objectives

  • Choose between provider and direct model (ExpressRoute Direct)
  • Design and implement Azure cross-region connectivity between multiple ExpressRoute locations
  • Select an appropriate ExpressRoute SKU and tier
  • Design and implement ExpressRoute Global Reach and ExpressRoute FastPath 
  • Choose between private peering only, Microsoft peering only, or both
  • Configure private peering and Microsoft peering
  • Create and configure an ExpressRoute gateway
  • Connect a virtual network to an ExpressRoute circuit
  • Recommend a route advertisement configuration
  • Configure encryption over ExpressRoute
  • Implement Bidirectional Forwarding Detection
  • Diagnose and resolve ExpressRoute connection issues

Intended Audience

  • System or network administrators with responsibilities for connecting an on-premises network to Azure
  • Anyone preparing for the Azure AZ-700: Designing and Implementing Microsoft Azure Networking Solutions exam


  • A basic understanding of networking, routing, and VPN concepts

Now that we understand the versions and options available for ExpressRoute, circuits and gateways, let's move on to Cross-region Connectivity between multiple locations. ExpressRoute connects an on-premises location to a VNet in an Azure subscription. If there's only one VNet and one subscription, the configuration is fairly straightforward. However, environments are typically a little more complex. For example, what if we add a region in another subscription? We could connect the two regions with VNet Peering.

VNet Peering is a way to connect VNets and Azure. With VNet Peering, we can connect or peer to VNets in the same region. If the VNet is in a different region, we can use Global VNet Peering to connect them. VNet Peering is used to connect VNets in the same region while Global VNet Peering is used to connect VNets in different regions. Let's add VNet Peering between the two VNets. By default, the VNets will be able to communicate with each other once they're peered and the on-premises location can pass traffic to the subscription one VNet, but the on-premises site and the subscription to VNet will not be able to communicate. 

We could enable transitive routing and add user-defined routes, but there's an easier way to establish connectivity. We can cross-connect and ExpressRoute connection to multiple VNets in Azure. This provides connectivity without forcing traffic through a single VNet. Linking both VNets to the gateway, improves latency by removing a hop in the network path. It can also propagate routing information between the subnets and ExpessRoute, providing dynamic routing information between the locations.

Let's use an example of two organizations, both have ExpressRoute connected to a VNet and an Azure subscription. These organizations merge and need to provide connectivity between the on-premises location and the Azure subscription Global VNet Peering provides connectivity between the two VNets. A network link is added between Business Inks Express route gateway and the company's subscription, as well as between company LLCs ExpressRoute gateway and the business subscription.

Together Global VNet Peering and virtual network links provide connectivity between the Vnet on the two subscriptions and the on-premises location for both subscriptions. Keep the features and limits with each Express Route SKU in mind when planning and implementing ExpressRoute cross-region connectivity. With ExpressRoute Local there's a limit of ten virtual network links and those links can only be to VNets in one or two local regions. With ExpressRoute Standard we still have the ten virtual network link limit, but those links can be to any VNet in a single geo-political location.

Finally, with ExpressRoute Premium there can be up to 100 virtual network links depending on the provision capacity of the connection. And these virtual network links can be global. For example, if we have ten virtual network links in a single geopolitical area, the standard SKU is fine. In order to add an 11th virtual network link, we need to add ExpressRoute Premium. That brings us to the end of this lecture on designing and implementing cross-region connectivity. We'll expand on this topic with ExpressRoute Global Reach next.

About the Author
Travis Roberts
Cloud Infrastructure Architect

Travis Roberts is a Cloud Infrastructure Architect at a Minneapolis consulting firm, a Microsoft MVP, MCT, and author. Travis has 20 years of IT experience in the legal, pharmaceutical, and marketing industries and has worked with IT hardware manufacturers and managed service providers. In addition, Travis has held numerous technical certifications throughout his career from Microsoft, VMware, Citrix, and Cisco.