Choosing the right Container Network Interface (CNI) is crucial for cluster networking, security, and performance. Here's how the major options stack up.
| CNI | Type | Pros | Cons |
|---|---|---|---|
| Calico | L3 | Strong network policies, eBGP support, high scalability, production-ready | Complex initial setup |
| Cilium | L7 | eBPF performance, L7 policies, built-in observability, can replace kube-proxy | Steeper learning curve |
| Flannel | Overlay | Simple, easy setup, small footprint, lightweight | Limited policies, VXLAN overhead |
| Weave Net | Overlay | Automatic mesh, encryption, simple config, multi-host routing | Performance at scale |
| AWS VPC CNI | Native | AWS integration, ENI per node, native VPC performance | AWS-only, higher cost |
| Azure CNI | Native | Azure integration, VNet integration, IP prefix support | Azure-only |
| Antrea | L3 | Open vSwitch-based, strong policies, VMware backing | Less mature ecosystem |
| Kube-router | L3 | Built-in kube-proxy replacement, BGP, IPVS | Fewer enterprise features |
| OVN (OVS) | L3 | Rich features, NAT, QoS, load balancing, Neutron backing | Complex, resource-heavy |
| Kube-OVN | L3 | OVN-based, subnet management, QoS, floating IP | Newer, smaller community |
| Multus | Multi-Net | Multiple network interfaces per pod, CRD-based | Requires other CNIs, additional setup |
| Canal | Hybrid | Combines Flannel overlay + Calico policies | Flannel limitations apply |
| Romana | L3 | Calico-like, route aggregation, no overlay needed | Less active development |
| Contiv | L3/L7 | Cisco-backed, VLAN/VXLAN support, policy engine | Complex setup |
| Terway | Native | Alibaba Cloud integration, ENI support, high performance | Alibaba-only |
| Aliyun CNI | Native | Alibaba Cloud VPC integration, elastic network interfaces | Alibaba-only |
| Submariner | Multi-Cluster | Cross-cluster networking, VPN-based, KubeFed compatible | Requires broker setup |
| Kilo | Overlay | WireGuard encryption, edge-friendly, multi-cluster | Smaller ecosystem |
Key Considerations:
- Performance: Native CNIs (AWS/Azure/Alibaba) > eBPF (Cilium) > L3 (Calico) > Overlay (Flannel/Weave)
- Security: Cilium & Calico lead with L7 policies and identity-based security
- Simplicity: Flannel, Weave, Canal for quick setups
- Enterprise: Calico, Cilium, Antrea for production at scale
- Multi-Cloud: Calico, Cilium (work anywhere)
- Multi-Cluster: Submariner, Kilo for cross-cluster connectivity
Quick Recommendation:
- Startups/Simple: Flannel or Weave
- Production/Security: Cilium or Calico
- Cloud-Native: Use the cloud provider's native CNI
- Multi-Cluster: Submariner + Calico/Cilium
