Kubernetes Service Mesh vs eBPF Networking: Cilium vs Calico Explained

Kubernetes networking has historically been split across two layers: the Container Network Interface (CNI), which handles pod-to-pod connectivity and network policy, and the service mesh, which adds application-layer features like mutual TLS, traffic routing, and observability. For years the common architecture looked like this: A CNI plugin such as Calico provided basic network connectivity and Layer 3/4 policy. A service mesh like Istio added Layer 7 features using sidecar proxies injected into every pod. The rise of eBPF-based networking has started to collapse these layers. Modern CNIs such as Cilium — and Calico's newer eBPF dataplane — can enforce policy, capture telemetry, and perform traffic management directly in the Linux kernel without sidecar proxies. That shift raises a new architectural question for platform teams: if the network layer can already provide identity, encryption, and observability, do you still need a service mesh at all? Most teams add a service mesh becaus