ctive of this project is to compare Istio and Cilium scalability, several constraints make a direct comparison difficult.</p><h3 id=layer-4-isnt-always-layer-4>Layer 4 Isn’t always Layer 4</h3><p>While Istio and Cilium both offer L4 policy enforcement, their APIs and implementation differ substantially. Cilium implements Kubernetes NetworkPolicy, which uses labels and namespaces to block or allow access to and from IP Addresses. Istio offers an AuthorizationPolicy API, and makes allow and deny decisions b