Cilium vs OVN-Kubernetes

Cilium is an open-source, cloud-native system for providing, securing, and observing network connectivity between workloads using eBPF. Its networking capabilities include CNI, Layer 4 load balancing, Cluster Mesh, kube-proxy replacement, BGP, service mesh, Gateway API, IPv6, host firewall, and ingress. Network policies can enforce identity-aware rules from L3 through L7, including DNS- and HTTP-aware filtering. Security features include runtime protection and transparent encryption of managed host and endpoint traffic using IPsec, WireGuard, or ztunnel; ztunnel support is marked beta. For visibility, Cilium lists service maps, metrics and tracing export, network flow logs, and protocol visibility. Hubble, built on Cilium and eBPF, provides visibility into service communication and behavior. Documentation describes Prometheus and Grafana integrations and Kubernetes support for services including GKE, AKS, EKS, OpenShift, RKE, k3s, and Alibaba ACK. Its container image requires AMD64 or AArch64 hosts running Linux kernel 5.10 or later, or an equivalent kernel such as 4.18 on RHEL 8.10. For environments above 500 nodes, the quick installation guide directs readers to large-environment guidance or specific datapath modes.

OVN-Kubernetes is a free, open-source networking solution and CNI-conformant plugin for Kubernetes, built on OVN and Open vSwitch. It handles pod IP allocation and interfaces, GENEVE overlays, Kubernetes Services, EndpointSlices, network policies, and IPv4/IPv6 dual-stack clusters. OVN ACLs enforce NetworkPolicy, AdminNetworkPolicy, and EgressFirewall rules; EgressIP, EgressService, and EgressQoS govern outbound traffic. Pods can join multiple networks, and the project also supports multicast, traffic shaping, BGP route advertisements, and SmartNIC or DPU offload. For KubeVirt, it provides persistent IPs during live migration; Hybrid Overlay enables mixed Windows and Linux networking. Deployment documentation covers Kind, Helm, DPU acceleration, kubeadm, and source builds. Requirements depend on OVN, nft, Multus, CNI, and Kubernetes versions; the master branch lists Kubernetes 1.33 or newer. Secondary User Defined Networks currently lack north-south traffic and core Kubernetes Services support. AdminNetworkPolicy APIs remain alpha and may change before stable v1.