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Multi-Region Deployment

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Why Multi-Region?

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Performance

User in Tokyo → Asia-Pacific Region (50ms)
vs.
User in Tokyo → US East Region (200ms)

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Compliance

• GDPR: EU data must stay in EU
• CCPA: California data preferences
• HIPAA: Healthcare data location requirements

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High Availability

US East: ❌ Down
    ↓
Automatic failover
    ↓
US West: ✅ Serving traffic

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Available Regions

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How It Works

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Automatic Routing

Client Location: London, UK
    ↓
DNS Resolution
    ↓
Nearest Region: EU West (Ireland)
    ↓
Request routed to EU West
    ↓
Low latency: ~20ms

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Data Synchronization

• Routes: Instantly synchronized
• Secrets: Replicated encrypted
• Clients: Available in all regions
• Logs: Aggregated centrally

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Region Selection

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1. Automatic (Recommended)

User → Closest Region

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2. Pinned Region

curl https://a1b2c3d4.acme.knoxcall.com/api/endpoint \
  -H "x-knoxcall-route: my-route" \
  -H "x-knoxcall-region: eu-west-1"

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3. Per-Route Region

Route: customer-data-api
Default Region: eu-west-1 (GDPR compliance)

Route: global-api
Default Region: auto (nearest)

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Setting Up Multi-Region

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Step 1: Enable Multi-Region (Enterprise)

1. Contact sales or support
2. Enable multi-region for your tenant
3. Select regions to deploy to

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Step 2: Configure Routes

1. Navigate to Routes → Select route
2. Go to Regional Configuration tab
3. Select mode:

Region Selection: Automatic
Fallback Region: us-east-1

Region Selection: Pinned
Primary Region: eu-west-1

Region Selection: Active-Active
Regions: us-east-1, eu-west-1, ap-southeast-1
Load Balancing: Geo-proximity

4. Save configuration

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Step 3: Test Regional Routing

# From US
curl https://a1b2c3d4.acme.knoxcall.com/api/test \
  -H "x-knoxcall-route: my-route" \
  -v | grep "x-knoxcall-region"

# Response header shows:
x-knoxcall-region: us-east-1

# From EU
# (Same request)
x-knoxcall-region: eu-west-1

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Data Residency Configuration

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GDPR Compliance (EU)

Route: eu-customer-data
Regions: eu-west-1, eu-west-2, eu-central-1
Data Residency: Enforce EU only
Failover: Within EU only

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US Data Residency

Route: us-customer-data
Regions: us-east-1, us-west-2
Data Residency: Enforce US only
Failover: Within US only

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Multi-Regional with Restrictions

Route: global-api
Regions: All regions
EU Traffic: Must use EU regions
US Traffic: Must use US regions
APAC Traffic: Must use APAC regions

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Failover & High Availability

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Automatic Failover

Primary: US East → ❌ Health check fails
    ↓
Traffic switches to: US West ✅
    ↓
User requests continue uninterrupted
    ↓
When US East recovers → Traffic returns

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Health Checks

• Frequency: Every 10 seconds
• Threshold: 3 consecutive failures triggers failover
• Checks:
  • API endpoint responsiveness
  • Database connectivity
  • Latency < 1000ms
  • Success rate > 95%

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Regional Status Page

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Performance Benefits

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Latency Reduction

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Global Coverage Map

      🇺🇸 US West     🇺🇸 US East
         25ms            20ms
              ╲        ╱
                ╲    ╱
                 User
                ╱    ╲
              ╱        ╲
         15ms            30ms
      🇪🇺 EU West    🇸🇬 APAC

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Monitoring Multi-Region

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Regional Metrics Dashboard

• Request volume per region
• Average latency per region
• Error rate per region
• Failover events

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Alerts

Alert: Region Degraded
Condition: Latency > 500ms for 5 minutes
Notification: Email, Slack, PagerDuty

Alert: Regional Failover
Condition: Traffic switched to backup region
Notification: Immediate SMS, Email

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Cost Considerations

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Data Transfer

• Within region: Free
• Cross-region: $0.02/GB

• Pin routes to single region when possible
• Use multi-region only for global applications

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Regional Pricing

• US Regions: Standard pricing
• EU Regions: +10% due to GDPR compliance costs
• APAC Regions: +15% due to infrastructure costs

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Best Practices

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1. Use Automatic Routing by Default

Region Selection: Automatic

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2. Pin Compliance-Sensitive Routes

Route: patient-data
Regions: us-east-1, us-west-2 (HIPAA)
Data Residency: Enforce US only

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3. Test Failover

1. Simulate region failure
2. Verify traffic switches to backup
3. Ensure data consistency

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4. Monitor Regional Performance

• Latency trends
• Error rates
• Traffic distribution

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5. Configure Appropriate Failover

Failover: Automatic, within 30 seconds
Backup regions: 2

Failover: Manual approval required

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Troubleshooting

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High latency despite multi-region

• DNS propagation (24-48 hours)
• Regional assignment correct
• Client using correct endpoint

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Requests going to wrong region

• DNS caching
• VPN routing
• Pinned region configuration

• Clear DNS cache
• Check x-knoxcall-region header
• Verify route configuration

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Failover not working

• Health checks enabled
• Backup region configured
• Failover policy active

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Next Steps