Knowledge Base on Azure ExpressRoute

What is Azure ExpressRoute?

Azure ExpressRoute is a service provided by Microsoft that creates a dedicated, private connection between an organization’s on-premises infrastructure and Microsoft Azure. Unlike public Internet-based connections, ExpressRoute ensures higher security, reliability, and faster transfer speeds, making it ideal for enterprise workloads, hybrid cloud scenarios, and large-scale data transfer.

How Does ExpressRoute Work?

1. Private Connectivity: ExpressRoute enables private communication by connecting your on-premises network directly to Azure via a service provider. It avoids using the public Internet, reducing latency and increasing security.
2. ExpressRoute Circuit: An ExpressRoute circuit is the logical connection established between your organization and Azure. This circuit handles the data flow between your infrastructure and Azure resources, such as virtual networks (VNets), storage, or Microsoft services like Office 365.
3. Routing via BGP: ExpressRoute uses Border Gateway Protocol (BGP) to dynamically exchange routing information between your network and Azure, ensuring efficient and redundant traffic flow.
4. Redundancy: Each ExpressRoute connection is set up with redundant physical links to ensure high availability and reliability.
5. ExpressRoute Peerings: You can configure different types of peerings based on your needs:

What is an ExpressRoute Circuit?

An ExpressRoute circuit is the backbone of the connection. Think of it as the bridge between your data center and Azure.

How an ExpressRoute Circuit Works:

1. The circuit establishes a private link between your network and Azure, bypassing the public Internet.
2. Traffic flows through a service provider's private MPLS (Multiprotocol Label Switching) network or another dedicated infrastructure.
3. The connection terminates at an ExpressRoute location (a Microsoft data center or partner facility).
4. Routing is managed via BGP, allowing dynamic exchange of routes between on-premises networks and Azure.

Technical Details:

• Bandwidth options range from 50 Mbps to 10 Gbps.
• Redundant paths are included to prevent a single point of failure.
• Supports global connectivity by linking to multiple Azure regions through Microsoft's private backbone.

What is an ExpressRoute Gateway?

The ExpressRoute Gateway is a component within an Azure Virtual Network (VNet) that facilitates communication between your VNet and an ExpressRoute circuit. It acts as the bridge between the private connection and Azure services.

Key Features of the ExpressRoute Gateway:

• Deployed in a gateway subnet within your VNet.
• Supports private peering for direct access to Azure resources like VMs, storage, or databases.
• Dynamically exchanges routes with your on-premises network using BGP.
• Offers high availability with built-in redundancy.

ExpressRoute Gateway SKUs:

Azure offers several performance options:

1. Standard: Best for moderate workloads.
2. High Performance: For larger data transfer needs.
3. Ultra Performance: Designed for maximum throughput and lowest latency.

What is Direct ExpressRoute?

Direct ExpressRoute provides a dedicated physical connection between your organization and Microsoft’s global network, bypassing third-party service providers. It is an advanced option tailored for organizations with high bandwidth requirements or sensitive data transfer needs.

How Direct ExpressRoute Works:

1. You purchase physical ports in increments of 10 Gbps or 100 Gbps.
2. The connection is established at an ExpressRoute location, where your infrastructure connects directly to Microsoft’s network.
3. The connection includes two redundant ports for reliability.
4. BGP is used to manage traffic routes dynamically between your network and Azure.

Key Features of Direct ExpressRoute:

• Direct access to Microsoft’s private backbone, avoiding service providers.
• High bandwidth and low latency, suitable for demanding workloads.
• Enhanced control over connection management and routing.

Use Cases:

• Massive data transfers, like backups or migrations.
• Enterprises with strict compliance and security requirements.
• Global organizations with high-performance needs.

Benefits of Using Azure ExpressRoute

1. Enhanced Security: By avoiding the public Internet, ExpressRoute minimizes exposure to potential threats and ensures data integrity.
2. High Performance: Offers low latency and consistent performance, ideal for real-time workloads like financial trading or video streaming.
3. Scalability: Flexible bandwidth options allow scaling as your needs grow.
4. Global Connectivity: A single ExpressRoute circuit can connect to multiple Azure regions worldwide, leveraging Microsoft’s private backbone.
5. Reliability: Built-in redundancy ensures uptime and fault tolerance for mission-critical applications.

Key Differences: ExpressRoute Circuit vs. Gateway vs. Direct ExpressRoute

Deployment Steps for ExpressRoute

1. Set Up ExpressRoute Circuit: Work with an ExpressRoute partner to create a circuit and connect your on-premises network to an Azure region.
2. Deploy Gateway Subnet: Create a subnet called GatewaySubnet in your VNet.
3. Deploy an ExpressRoute Gateway: Use the Azure portal, CLI, or PowerShell to deploy the gateway.
4. Link the Circuit to the Gateway: Associate the ExpressRoute circuit with the gateway to route traffic between your on-premises network and Azure.
5. Configure Routing: Set up BGP to dynamically exchange routes between your infrastructure and Azure.

Conclusion

Azure ExpressRoute provides a secure, reliable, and high-performance way to connect your on-premises resources to Microsoft Azure. Whether using standard circuits through service providers or leveraging Direct ExpressRoute for direct access, it supports hybrid cloud strategies, large-scale data transfers, and latency-sensitive applications.