CNI

Overview

CNI (Container Network Interface) is a standard set of tools that provides networking capabilities to containers in a Kubernetes cluster. Simply put, CNI is an abstraction layer that helps Kubernetes manage and configure networking for pods (a collection of containers sharing the same network) in a flexible and efficient way.

How does CNI work?

When you create a new pod, Kubernetes calls CNI to create a network interface for that pod. The CNI plugin performs the following tasks:

• Assign IP address: Assign a unique IP address to the pod.

• Routing configuration: Set up routing rules that allow communication between pods,...

Additionally, the connections work as follows:

• Connecting within the same VPC : Nodes within the same VPC will connect directly to each other.

• Connecting between different VPCs : Use VPC Peering to connect nodes between different VPCs.

• Connect to external infrastructure: Use networking solutions such as site-to-site VPN or Direct Connect to connect from nodes in VPC to external infrastructures (On Cloud, On-premise).

This helps maintain a continuous, flexible, and secure network infrastructure in a multi-cloud or hybrid-cloud environment.

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Comparison between CNI plugins

Currently, VKS is providing 3 popular CNI plugins: Calico Overlay, Cilium Overlay, Cilium VPC Native Routing. In which:

• Calico Overlay : Uses overlay model through tunneling ( IP-in-IP ). Compatible with many infrastructures but performance can be affected by tunnel overhead .

• Cilium Overlay : Also uses the overlay model but has strong integration with eBPF , which improves performance, security, and scalability.

• Cilium VPC Native Routing : Uses eBPF and no overlay required , leveraging the routing capabilities of the VPC infrastructure, providing the best performance and scalability.

When to use Calico Overlay : simple to use, does not require too high performance.

When to use Cilium Overlay : simple to use, does not require too high performance but requires intensive monitoring (Hubble).

When to use Cilium VPC Native Routing : high performance requirements, easy connectivity to external systems , and in-depth monitoring needs (Hubble).