How Kubernetes Builds Networking on Top of Containers

Author

Govardhana M K
January 22, 2026

TechOps Examples

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🧠 DEEP DIVE USE CASE

How Kubernetes Builds Networking on Top of Containers

Networking is what makes or breaks a Kubernetes system. You can have perfectly written code and well-sized nodes, but if networking is misunderstood, everything from service discovery to scaling starts to fail in subtle ways.

Before we move further, we need to clearly understand two fundamental layers: Application Network Layers, Container Network Layers

1. Application Network Layers

This is the basic networking stack every Kubernetes application sits on.

  • Cloud / Bare Metal Infrastructure

    • Physical or virtual machines

    • Provides the real network cables, NICs, routing, and IP reachability

  • Kubernetes Cluster

    • Manages nodes and workloads

    • Ensures networking keeps working as applications scale or move

  • Container

    • Runs the application in an isolated network space

    • Assigns IPs, ports, and localhost to the application

  • Code

    • Your application logic

    • Opens ports and sends or receives network traffic

2. Container Network Layers

This is how containers create a private network environment that Kubernetes later connects together.

  • IPC Namespace

    • Controls shared memory and message queues

    • Prevents unintended cross-container communication

  • Network Namespace

    • Defines the container’s network stack

    • Own IP address, interfaces, and routing table

  • PID Namespace

    • Isolates processes inside the container

    • Network-related processes see only container PIDs

  • Hostname Namespace

    • Sets the container’s hostname

    • Used by applications for identification

  • Mount Namespace

    • Controls filesystem and socket visibility

    • Scopes network files to the container

  • Container

    • Runs the application inside these namespaces

    • Presents a complete, private network environment

Note: A container is just a Linux process, and every “layer” you see is a Linux namespace boundary drawn around it.

How Pods Communicate

A Pod groups one or more containers and provides a shared networking context.

  • Each Pod is assigned a unique IP address

  • All containers within a Pod share the same network namespace

  • Containers inside a Pod communicate using localhost

  • Communication across Pods happens using Pod IP addresses

  • Kubernetes ensures Pod-to-Pod connectivity across nodes

Containers share networking within a Pod, while Pods communicate using routable IPs.

Note: Networking in Kubernetes is defined at the Pod level, not the container level.

The next step is understanding how container networking itself works before Kubernetes adds its abstractions.

  1. Containers Networking on a Single Host

  2. Containers Networking Across Multiple Hosts

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