Global Load Balancing: Architecture Guide for Multi-Region Deployments

Global load balancing is the key to delivering low-latency, high-availability applications worldwide. This guide covers the architecture, implementation, and operational considerations for routing users to the optimal backend—whether that's the nearest region, the healthiest endpoint, or a specific deployment.

What is Global Load Balancing?

Global load balancing distributes traffic across multiple geographic regions or data centers. Unlike regional load balancers that work within a single location, global load balancers make routing decisions at the internet edge based on:

DNS-Based vs. Anycast Global Load Balancing

There are two fundamental approaches to global load balancing, each with tradeoffs:

DNS-Based Global Load Balancing

DNS-based GLB returns different IP addresses based on the resolver's location or health of backends:

Pros: Works with any backend, no special infrastructure required
Cons: Slow failover, clients may cache DNS, resolver location != client location

Anycast Global Load Balancing

Anycast GLB uses a single IP address advertised from multiple edge locations:

Pros: Instant failover, accurate proximity routing, DDoS absorption
Cons: Requires edge infrastructure (cloud provider or CDN)

Cloud Provider Global Load Balancing Services

AWS Global Accelerator

Global Accelerator provides Anycast IP addresses that route traffic to AWS edge locations, then through AWS's private backbone to your regional endpoints:

# Terraform example: Global Accelerator
resource "aws_globalaccelerator_accelerator" "main" {
  name            = "my-global-accelerator"
  ip_address_type = "IPV4"
}

resource "aws_globalaccelerator_listener" "https" {
  accelerator_arn = aws_globalaccelerator_accelerator.main.id
  protocol        = "TCP"
  port_range {
    from_port = 443
    to_port   = 443
  }
}

resource "aws_globalaccelerator_endpoint_group" "us_east" {
  listener_arn                  = aws_globalaccelerator_listener.https.id
  endpoint_group_region         = "us-east-1"
  health_check_interval_seconds = 10
  threshold_count               = 3
  traffic_dial_percentage       = 50

  endpoint_configuration {
    endpoint_id = aws_lb.us_east.arn
    weight      = 100
  }
}

Google Cloud Load Balancing

GCP's HTTP(S) Load Balancing is Anycast by default with a single global IP:

Azure Front Door

Azure Front Door provides global HTTP load balancing with edge caching:

Cloudflare Load Balancing

Cloudflare offers load balancing across their 300+ edge locations:

Health Checking Strategies

Health checks are critical for global load balancing—they determine when to remove unhealthy backends:

Health Check Types

Health Check Best Practices

// Example: Comprehensive health check endpoint
app.get('/health', async (req, res) => {
  const checks = {
    database: await checkDatabase(),
    cache: await checkRedis(),
    timestamp: Date.now()
  };
  
  const healthy = checks.database && checks.cache;
  res.status(healthy ? 200 : 503).json(checks);
});

Routing Policies

Geoproximity Routing

Route users to the nearest region based on geographic location:

Latency-Based Routing

Route based on measured latency rather than geography:

Weighted Routing

Distribute traffic by percentage across regions:

Failover Routing

Primary/secondary configuration for disaster recovery:

Multi-Region Architecture Patterns

Active-Active

                 ┌─────────────────┐
                 │  Global LB      │
                 └────────┬────────┘
            ┌────────────┼────────────┐
            ▼            ▼            ▼
     ┌──────────┐ ┌──────────┐ ┌──────────┐
     │ US-East  │ │ EU-West  │ │ APAC     │
     │ (Active) │ │ (Active) │ │ (Active) │
     └──────────┘ └──────────┘ └──────────┘

Learn more: Active-Active vs Active-Passive

Active-Passive

                 ┌─────────────────┐
                 │  Global LB      │
                 └────────┬────────┘
                          │
            ┌─────────────┴─────────────┐
            ▼ (100%)                    ▼ (0%)
     ┌──────────┐              ┌──────────┐
     │ US-East  │              │ US-West  │
     │ (Active) │              │ (Standby)│
     └──────────┘              └──────────┘

Session Persistence Across Regions

Maintaining user sessions across global infrastructure requires careful design:

Options

Cost Considerations

For cost optimization strategies, see our cost optimization framework.

Key Takeaways

Need Global Load Balancing Architecture?

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