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Multi-Region and Multi-Set Architectures in Azure

Multi-Region and Multi-Set Architectures in Azure

Multi-region and multi-set architectures are essential for building resilient, scalable, and globally distributed systems—especially for mission-critical workloads or multi-tenant SaaS platforms. These designs leverage Azure Virtual Networks (VNets) for connectivity and resiliency.

🌍 Multi-Region Architecture with VNets

🔧 Purpose

To ensure geo-redundancy, disaster recovery, and low-latency access across different Azure regions.

🧠 Key Components

  • Hub-and-Spoke Topology per Region: Each region has a hub VNet (with NVAs, Route Servers, etc.) and multiple spoke VNets for workloads.
  • Global VNet Peering: Connects hub VNets across regions for secure, low-latency communication.
  • Azure Route Server + BGP: Enables dynamic route propagation between NVAs across regions.
  • ExpressRoute or VPN Gateways: Optional for hybrid connectivity to on-premises networks.

📈 Benefits

  • Centralized routing and security policies
  • Automatic adaptation to topology changes
  • High availability and failover across regions

🧩 Multi-Set Architecture (Availability Sets + Scale Sets)

🔧 Purpose

To improve fault tolerance and scalability within a single region or across multiple regions.

🧠 Key Components

  • Availability Sets: Distribute VMs across fault and update domains to avoid single points of failure.
  • Virtual Machine Scale Sets (VMSS): Automatically scale VMs based on demand with built-in load balancing.
  • Zonal Deployment: Use Availability Zones for stronger fault isolation across datacenter zones.

📈 Benefits

  • SLA-backed uptime (99.95% with Availability Sets, 99.99% with Zones)
  • Elastic scaling for web tiers, APIs, or compute nodes
  • Redundancy across hardware and update cycles

🔗 Combined Architecture: Multi-Region + Multi-Set

Example Setup:

  • Region A (East US):
    • Hub VNet with Route Server and NVA
    • Spoke VNets with VMSS for web apps
    • Availability Sets for backend services
  • Region B (West Europe):
    • Same topology mirrored
    • Peered hubs via Global VNet Peering
    • NVAs exchange routes via BGP tunnels (IPsec or VXLAN)

Failover Strategy

  • DNS-based traffic routing (Azure Traffic Manager or Front Door)
  • Active/Active or Active/Passive NVA setup using AS path prepending
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