Understanding Container Network Interface (CNI) in Kubernetes

Infrastructure engineer and Kubernetes ingress-Nginx maintainer James Strong joins host Robert Blumen to discuss the Kubernetes networking layer. The discussion draws on content from Strong’s book on the topic and covers a lot of ground, including: the Kubernetes network's use of different IP ranges than the host network; overlay network with its own IP ranges compared to using expanded portions of the host network ranges; adding routes with kernel extension points; programming kernel extension points with IP tables compared to eBPF; how routes are updated as the host network gains or loses nodes, the use of the Linux network namespace to isolate each pod; routing between pods on the same host; routing between pods across the host network; the container-network interface (CNI); the CNI ecosystem; differences between CNIs; choosing a CNI when running on a public cloud service; the Kubernetes service abstraction with a cluster-wide IP address; monitoring and telemetry of the Kubernetes network; and troubleshooting the Kubernetes network.

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