What Is The Container Network Interface (CNI)?

The Container Network Interface (CNI) is a framework for dynamically configuring network resources. It makes use of Go-written libraries and specifications. The plugin standard specifies an interface for configuring the network, assigning IP addresses, and maintaining connectivity to many hosts.

When used with Kubernetes, CNI connects smoothly with the Kubelet, allowing for the use of an over or underlay network to automatically configure the network between pods. These networks encapsulate network activity behind a virtual interface, such as Virtual Extensible LAN (VXLAN). Serves as networks are physical networks made up of switches and routers.

Once you’ve defined the network configuration type, the container runtime determines which network the containers join. The runtime adds the interface to the container namespace using the CNI plugin and distributes the linked subnetwork routes using the IP Address Management (IPAM) plugin.

CNI supports Kubernetes networking and is compatible with other Kubernetes-based container management solutions, including OpenShift. CNI uses software-defined networking (SDN) to unify container communication between clusters.

What Is Container Network Interface (CNI) ?

Controlling networks within Kubernetes clusters is mostly dependent on the Container Network Interface (CNI). CNI is an important component of the Kubernetes environment that allows easy networking and communication between containers and other networks. Let’s briefly discuss the Container Network Interface (CNI).

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What Is The Container Network Interface (CNI)?

The Container Network Interface (CNI) is a framework for dynamically configuring network resources. It makes use of Go-written libraries and specifications. The plugin standard specifies an interface for configuring the network, assigning IP addresses, and maintaining connectivity to many hosts....

CNI Architecture

A simple plugin-based architecture drives CNI. The CNI plugins are called by the container runtime (like Docker) for setting up the network environment when a pod is created in Kubernetes. The plugins can be created using several different programming languages and use standard input and output to communicate with the container runtime. To set up networking for containers, they make use of the Linux networking stack....

Why Is Kubernetes CNI Used?

The technologies around Linux-based containers and container networking are always changing to support applications that operate in a variety of situations. The Cloud-Native Computing Foundation (CNCF) launched CNI, a project that describes how Linux container network interfaces should be set up....

How To Implement CNI?

Let’s look at an example of a Kubernetes cluster running multiple pods to get a better understanding of CNI. Suppose for the moment that we want to assist with how two pods, A and B, connect....

CNI Based on Network Models

Network models that are both encapsulated or unencapsulated can be used to implement CNI networks. A model that is encapsulated is called XLAN, but an unencapsulated model is called Border Gateway Protocol (BGP)....

Encapsulated Networks

This concept supports many Kubernetes nodes and encapsulates a logical Layer 2 network using an existing Layer 3 network topology. Because Layer 2 networks are separated routing distribution is not required. Larger IP packages and better processing are provided at an affordable cost as the IP header produced by the overlay encapsulation contains the IP package....

Unencapsulated Networks

A Layer 3 network is provided by this model to route packets between containers. No separate Layer 2 network or overhead exists, but Kubernetes workers pay the cost of managing any necessary route distribution. To connect the Kubernetes workers, a network protocol is used, and BGP is used to provide pods with routing information. Docker or another container engine is the part of the pod that handles communication with workloads....

Conclusion

In addition, CNI provides an adaptive and flexible approach for handling networking requirements. Additionally, the plugins help in managing tasks like creating network routes for containers and assigning IP addresses. However, you must consider certain requirements and guidelines in order to work with the container runtime and establish a smooth connection with outside networks....

Container Network Interface (CNI) – FAQ’s

Why CNI is required in Kubernetes?...