Skip to main content
In this lesson we explain Azure ExpressRoute: Microsoft’s service for creating a private, dedicated connection between on‑premises networks and Azure. Unlike VPNs that traverse the public internet, ExpressRoute uses private circuits (or Microsoft’s backbone) to deliver enterprise-grade throughput, predictable latency, and higher reliability for hybrid and cloud-first architectures. ExpressRoute is commonly used to extend enterprise WANs into Azure, accelerate large data transfers, and support latency-sensitive, mission-critical workloads.

​
Key capabilities

CapabilityDescriptionBenefit
Layer 3 routed connectivity with BGPUses industry-standard BGP for dynamic routing and redundancy between customer edge and Microsoft edge.Fast failover and scalable routing for enterprise networks.
Peering optionsPrivate Peering for Azure Virtual Networks; Microsoft Peering for Azure PaaS and Microsoft 365 services.Flexible connectivity to VNet resources and Microsoft services with separate routing.
Global reach & PremiumA single circuit can reach multiple regions in a region group; ExpressRoute Premium expands reachable regions and routes.Simplifies multi-region connectivity and supports multinational architectures.
ExpressRoute Global ReachConnects on‑premises sites through Microsoft’s backbone to create private on‑prem to on‑prem tunnels.Enables Azure to act as a WAN hub for inter-datacenter connectivity.
Scalable bandwidth (Direct available)Circuits from tens of Mbps to multiple Gbps — up to 100 Gbps with ExpressRoute Direct.Meets high-throughput requirements for migrations and large-scale data transfer.
Billing modelsUnmetered (fixed) and metered (pay-per-GB) plans available.Choose predictable costs or usage-based billing depending on workload.

​
Why organizations choose ExpressRoute

  • Predictable performance and lower latency for latency-sensitive or mission-critical systems (SAP, ERP, real-time analytics).
  • Secure, high-throughput data transfer for large migrations, backups, or continuous bulk replication.
  • Seamless extension of enterprise MPLS WANs into Azure for hybrid applications, disaster recovery, and central management.
  • Regulatory or compliance requirements that mandate private connectivity instead of public internet transit.

​
How it fits into architecture

A typical ExpressRoute deployment includes the following components:
  1. Customer edge routers (on‑premises) that peer with a connectivity provider or Microsoft at a co-location/Exchange facility.
  2. An ExpressRoute circuit provisioned between the customer and Microsoft edge routers.
  3. An ExpressRoute gateway deployed in an Azure virtual network (select the gateway type = ExpressRoute) to connect Azure resources to the circuit.
Conceptually this looks similar to a site‑to‑site VPN topology, but the underlying transport is a private circuit or Microsoft backbone rather than the public internet. When creating the gateway in Azure, choose ExpressRoute as the gateway type to establish the dedicated connection and enable BGP sessions to exchange routes.
A network diagram of an Azure ExpressRoute setup showing on-premises computers and a gateway connecting via local edge routers to an ExpressRoute circuit and Microsoft edge routers, which link into an Azure virtual network containing an ExpressRoute gateway, web tier, and management subnet. A red banner highlights the challenge "02 High-Capacity Hardware Needs," noting the demand for enterprise-grade, high-throughput routers on customer premises.

​
Operational considerations and challenges

  • Third‑party coordination: Provisioning usually involves telcos, co‑location providers, or Microsoft partners. Plan for lead times, change windows, and joint testing.
  • Hardware requirements: Customer-premises equipment (CPE) must support BGP, required VLAN tagging, high interface throughput, and optional MPLS integration for WAN scenarios.
  • Network design: Careful IP addressing, route filtering, ASN planning, advertisement limits, and redundancy design are essential for performance and security.
  • SLA and availability: ExpressRoute circuits offer redundancy; to meet high-availability targets (for example, 99.95% or better) design with diverse circuits and paths.
  • Cost and billing model selection: Choose unmetered vs metered based on expected data transfer patterns to control costs.
ExpressRoute deployments typically require coordination with service providers and enterprise‑grade network equipment (BGP-capable edge routers and sufficient throughput). Account for procurement lead times, cabling, and support contracts during planning.

​
When to use ExpressRoute

  • Production workloads that require predictable latency and guaranteed throughput.
  • Large-scale migrations, high-throughput backups, or ongoing bulk data transfers to/from Azure.
  • Hybrid topologies where multiple datacenters and Azure require secure, private connectivity.
  • Regulatory or compliance scenarios that disallow transit over the public internet.

​
Summary

ExpressRoute is the right choice when you need a private, high-performance, and reliable link between on‑premises networks and Azure. It provides Layer 3 connectivity with BGP, flexible peering for VNets and Microsoft services, global reach via Premium or Direct options, scalable bandwidth, and multiple billing models. Successful deployments require careful network design, appropriate CPE, and usually coordination with connectivity providers or Microsoft partners.

​
References

Watch Video