CNI Fundamentals

Overview

This is a theory lab which introduces Kubernetes networking concepts with a focus on the Container Network Interface (CNI) specification and popular plugins like Calico, Flannel, and Cilium. You will learn about the challenges in Kubernetes networking, including pod communication, service discovery, and traffic routing, and discover how CNI plugins address them. Additionally, you will explore the differences between overlay and underlay network models and how Kubernetes networking is implemented efficiently.

Inside this lab

Through hands-on documentation and examples, you will:

• Understand Kubernetes' limitations in native networking and the reliance on external solutions.
• Explore the fundamentals of the Container Network Interface (CNI), its modularity, and extensibility.
• Discover the features, use cases, and functionalities of common CNI plugins like Calico, Flannel, and Cilium in facilitating Kubernetes networking.
• Compare overlay and underlay network models, such as VXLAN and BGP, with practical examples of their application.
• Analyze common networking challenges such as pod-to-pod communication, service discovery, traffic routing, and how CNI plugins help resolve these issues to provide secure and reliable networks within Kubernetes environments.

Relevant technologies

• CNI (Container Network Interface)
• Kubernetes Networking
• Networking Plugins (Calico, Flannel, Cilium)

Learning outcomes

By completing this lab, you will have a strong understanding of Kubernetes networking architecture, CNI plugins, and practical tools to configure and troubleshoot networking setups in Kubernetes clusters. Whether planning for scalability, performance, or security, this lab equips you with the foundational knowledge required for modern Kubernetes networking.