Azure ExpressRoute Circuit

What is an ExpressRoute Circuit?

An Azure ExpressRoute circuit is the logical representation of a physical circuit connection between your on-premises network or co-location environment and Microsoft Azure. It enables you to establish private, high-throughput, low-latency connections to Azure services, bypassing the public internet.

ExpressRoute circuits provide a reliable and secure way to extend your on-premises infrastructure into the cloud. They are a fundamental building block for hybrid cloud solutions, allowing for consistent performance and predictable network behavior.

Key Components

An ExpressRoute circuit is composed of several key elements:

• Provider: A connectivity provider that offers ExpressRoute services. You'll work with a partner to provision the physical connectivity.
• SKU: The service tier (Standard or Premium) that determines features like global reach and bandwidth.
• Bandwidth (Mbps/Gbps): The maximum data transfer rate you can achieve.
• Peering Locations: The physical locations where your network connects to the Microsoft global network.
• VLANs: Used to segment traffic within the circuit for different routing domains.
• Service Keys: Unique identifiers required for circuit provisioning and authorization.

Creating an ExpressRoute Circuit

You can create an ExpressRoute circuit using the Azure portal, Azure CLI, or Azure PowerShell. The general steps involve:

1. Choose a Connectivity Provider and Partner: Select an ExpressRoute partner and a peering location.
2. Order the Circuit: Work with your provider to order the physical circuit.
3. Create the Circuit in Azure: In the Azure portal, navigate to "ExpressRoute circuits" and click "Create".
4. Configure Circuit Details: Specify the name, region, provider, SKU, and bandwidth.
5. Obtain Service Key: Once the circuit is created in Azure, you'll get a service key.
6. Provide Service Key to Provider: Give the service key to your connectivity provider to complete the circuit provisioning on their end.
7. Configure Peering: After the circuit is provisioned, you'll configure public, private, or Microsoft peering.

Azure CLI Example (Conceptual)

az expressroute create --name MyExpressRouteCircuit \
  --resource-group MyResourceGroup \
  --location westus \
  --provider "SomeProvider" \
  --sku Standard \
  --bandwidth 1000
        

Azure PowerShell Example (Conceptual)

New-AzExpressRouteCircuit -Name "MyExpressRouteCircuit" `
  -ResourceGroupName "MyResourceGroup" `
  -Location "West US" `
  -Bandwidth (New-AzExpressRouteCircuitSkuId -Name "1Gbps" -Tier "Standard") `
  -CircuitName "MyCircuit" `
  -PeeringLocation "Washington" `
  -ServiceProviderName "SomeProvider"
        

Managing an ExpressRoute Circuit

Once your ExpressRoute circuit is established, you can manage its various aspects through the Azure portal:

• Monitoring: Track bandwidth utilization, latency, and packet loss.
• Updating Bandwidth: Increase or decrease the bandwidth of your circuit (subject to provider capabilities).
• Modifying SKU: Change the service tier if needed.
• Adding/Removing Peering: Configure or remove peering connections.
• Associating Virtual Networks: Link your virtual networks to the ExpressRoute circuit.
• Accessing Service Keys: Retrieve service keys for new connections or provider updates.
• Circuit Provisioning State: Monitor the status of your circuit (e.g., Provisioned, NotProvisioned).

Best Practices

• Redundancy: Implement redundant ExpressRoute circuits for high availability. This typically involves connecting to Microsoft's network at two different peering locations.
• Bandwidth Planning: Accurately estimate your bandwidth requirements to avoid over-provisioning (costly) or under-provisioning (performance issues).
• Monitor Performance: Use Azure Monitor and ExpressRoute-specific metrics to keep a close eye on latency, throughput, and packet loss.
• Security: Configure network security groups (NSGs) and Azure Firewall appropriately for traffic flowing over ExpressRoute.
• Partner Selection: Choose a reliable and experienced connectivity provider with good support in your desired peering locations.
• Circuit Pairing: Understand the difference between provider, peer, and Microsoft peering, and configure them according to your network design.

By understanding and effectively utilizing ExpressRoute circuits, you can build robust, high-performance hybrid cloud solutions with Azure.