Introduction

• Understand ExpressRoute service tiers — Local, Standard, and Premium — and how they differ in geographic reach and route limits.
• Learn how to select the best peering location to minimize latency and maximize application performance.
• Determine the right circuit type and billing model (metered vs. unlimited) and choose appropriate bandwidth for your traffic profile.

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ExpressRoute service tiers — quick comparison

• Local circuits are generally lower cost but do not provide access to Azure regions outside the peering location.
• Standard circuits provide intra-geopolitical-region access (e.g., within North America or within Europe).
• Premium circuits are required when you need cross-geopolitical-region reach (for example, connecting to Azure regions across continents) and when you require higher route capacity.

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Choosing an optimal peering location

• Proximity to your network edge and primary user base — choose the closest peering location to your traffic sources or sinks to minimize round-trip latency.
• Carrier presence and transport fabric — verify your service provider/carrier has an active presence in the peering location and supports cross-connects at acceptable cost.
• Azure resource placement — align peering locations with the regions where your critical Azure services and virtual networks reside.
• Redundancy and resilience — design for multiple peering locations (active/active or active/passive) to avoid single points of failure.
• Costs and contractual constraints — include cross-connect fees, data transfer charges, and carrier circuit costs when comparing locations.
• Compliance and data residency — ensure the peering choice does not inadvertently cause data to traverse regions with restricted regulatory requirements.

• Map your major on-premises egress points and nearest colocation facilities.
• Confirm carrier availability and pricing for each candidate peering site.
• Measure or estimate latency to the Azure region(s) from candidate peering locations.
• Plan at least two diverse peering sites for high availability if SLA and workload requirements demand it.

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Circuit type, bandwidth options, and billing model

• Bandwidth offerings: Providers often offer a range of bandwidths — from small Mbps tiers up to 100 Gbps. Choose based on peak and sustained throughput needs and future growth.
• Billing model:
  • Metered data: You pay for the circuit plus egress/ingress metered data. Suitable when traffic volumes are variable and lower overall.
  • Unlimited (unmetered) data: Flat-rate billing for data transfer on the circuit. Useful when you have predictable, high-volume transfers.
• Service-level differences between carriers: Not all bandwidth tiers and billing models are available at every peering location or through every connectivity provider.

• Measure current and projected traffic profiles (peak, average, and burst) and use those metrics to model monthly costs for each billing option.
• If you anticipate growth or heavy cross-region replication, evaluate Premium circuits and unlimited data plans to avoid unpredictable egress fees.
• Confirm provider-specific bandwidth availability — some providers cap maximum bandwidth per location or require special ordering for very high speeds (e.g., 40/100 Gbps).

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Design checklist (concise)

1. Inventory workloads and map traffic patterns to Azure regions.
2. Choose the minimal service tier that satisfies reachability and route limits (Local → Standard → Premium).
3. Select peering locations closest to traffic sources with confirmed carrier presence.
4. Decide on metered vs. unlimited based on traffic predictability and cost modeling.
5. Plan redundancy: multiple circuits/peering locations and diverse paths.
6. Validate security boundaries, compliance requirements, and egress cost implications.
7. Test latency and throughput before final cutover; run pilot workloads if feasible.

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Links and references

• Azure ExpressRoute overview
• Choose an ExpressRoute circuit
• Azure networking documentation