Azure CNI Overlay: Scalable Pod Networking

Azure CNI Overlay provides scalable pod networking without consuming VNet IP addresses for each pod, solving IP exhaustion issues in large clusters.

Traditional vs Overlay Networking

Traditional Azure CNI assigns VNet IPs to pods, limiting scale. Overlay mode uses a separate address space for pods.

Enabling Overlay Mode

az aks create \
    --resource-group myResourceGroup \
    --name myAKSCluster \
    --network-plugin azure \
    --network-plugin-mode overlay \
    --pod-cidr 192.168.0.0/16

Configuration

# Node configuration
nodeConfig:
  networkPlugin: azure
  networkPluginMode: overlay
  podCIDR: 192.168.0.0/16
  serviceCIDR: 10.0.0.0/16

Benefits

• Larger pod address space
• Reduced VNet IP consumption
• Better scalability
• Maintained Azure integration

Migration Considerations

# Check current network mode
az aks show --resource-group myRG --name myAKS --query networkProfile

Summary

Azure CNI Overlay solves IP exhaustion challenges while maintaining Azure network integration, enabling larger AKS deployments.

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References:

• Azure CNI Overlay
• AKS Networking