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Kubernetes is a great orchestator for containers. But it does not manage network for Pod-to-Pod communication. This is the mission of Container Network Interfaces (CNI) plugins which are a standardized way to achieve network abstraction for container clustering tools (Kubernetes, Mesos, OpenShift, etc.) But here is the point: what are the differences between those CNIs? Which one has the best performance? Which one is the leanest? This article is showing the results of a benchmark I’ve conducted on 10Gbit/s network.

When it comes to Kubernetes networking, Calico is widely used. One of the main reasons being its ease of use and the way it shapes up the network fabric. Calico is a pure L3 solution, where packets are routed in just the same manner as your regular Internet. Each node (eg. VM) acts like a vRouter, which means tools like traceroute, ping, tcpdump, etc just work as expected! Whether the packet is flowing from one container to another or container to another node (or vice-versa), its just treated as a flat network route (L3 hops).