EKS networking with VPC CNI in AWS - Step-by-Step Execution

Process Flow - EKS networking with VPC CNI

Create VPC with subnets

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Deploy EKS Cluster

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Install VPC CNI Plugin

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Assign ENIs and IPs to Pods

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Pods get IPs from VPC subnet

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Pods communicate using VPC networking

This flow shows how an EKS cluster uses the VPC CNI plugin to assign real VPC IP addresses to pods, enabling native VPC networking.

Execution Sample

AWS

eksctl create cluster --name my-cluster --region us-west-2 --nodes 2
kubectl apply -f aws-vpc-cni.yaml
kubectl get pods -n kube-system
kubectl describe pod <pod-name>

This sequence creates an EKS cluster, installs the VPC CNI plugin, and checks pod networking details.

Process Table

Step	Action	Resource Created/Modified	Result/State Change
1	Create VPC with public and private subnets	VPC, Subnets	VPC ready with subnets for EKS
2	Create EKS cluster with nodes	EKS Cluster, EC2 Nodes	Cluster active, nodes registered
3	Install AWS VPC CNI plugin	DaemonSet aws-node	Pods get ENIs and IPs from VPC
4	Pods start with VPC IP addresses	Pod ENIs	Pods have IPs from VPC subnet range
5	Pods communicate over VPC network	Network traffic	Pod-to-pod traffic uses VPC routing
6	Check pod IP assignment	kubectl describe pod	Pod IP matches VPC subnet IP
7	Cluster scales nodes	New EC2 nodes	New nodes get ENIs, pods get IPs
8	Exit	N/A	All pods use VPC IPs, native networking enabled

💡 Pods have IPs assigned from VPC subnets, enabling native VPC networking; no further steps needed.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
VPC	None	Created with subnets	Same	Same	Same
EKS Cluster	None	Created	Same	Same	Same
Nodes	None	Created	Same	Same	Scaled as needed
VPC CNI Plugin	Not installed	Not installed	Installed as DaemonSet	Running on nodes	Running
Pod IPs	None	None	None	Assigned from VPC subnet	Assigned from VPC subnet

Key Moments - 3 Insights

Why do pods get IP addresses from the VPC subnet instead of a separate range?

Because the VPC CNI plugin assigns ENIs and IPs directly from the VPC subnets, pods use real VPC IPs, as shown in execution_table step 4.

What happens if the VPC CNI plugin is not installed?

Pods will not get VPC IPs and will use Kubernetes default networking, losing native VPC integration, as seen by the absence of step 3 and 4 in execution_table.

How does scaling nodes affect pod IP assignment?

New nodes get ENIs attached and pods on them get IPs from the VPC subnet, maintaining native networking, as shown in step 7.

Visual Quiz - 3 Questions

Look at the execution_table, at which step do pods start receiving IPs from the VPC subnet?

A Step 3

B Step 4

C Step 2

D Step 5

💡 Hint

Check the 'Result/State Change' column for when pods get IPs from VPC subnet.

According to variable_tracker, what is the state of the VPC CNI Plugin after Step 3?

A Not installed

B Running on nodes

C Installed as DaemonSet

D Scaled as needed

💡 Hint

Look at the 'VPC CNI Plugin' row under 'After Step 3' column.

If the cluster scales nodes, what happens to pod IP assignment according to execution_table?

A Pods get IPs from the VPC subnet as before

B Pods lose IPs

C Pods get IPs from a new subnet

D Pods share IPs

💡 Hint

See step 7 in execution_table about scaling nodes and pod IPs.

Concept Snapshot

EKS networking with VPC CNI:
- Pods get real VPC IPs via ENIs
- VPC CNI plugin runs as DaemonSet
- Pods use VPC routing for communication
- Enables native AWS networking features
- Scales with nodes attaching ENIs
- Requires VPC with proper subnets

Full Transcript

This visual execution shows how Amazon EKS uses the VPC CNI plugin to assign real VPC IP addresses to pods. First, a VPC with subnets is created. Then, an EKS cluster with nodes is deployed. The VPC CNI plugin is installed as a DaemonSet on the nodes. This plugin assigns Elastic Network Interfaces (ENIs) and IP addresses from the VPC subnets directly to pods. As a result, pods communicate over the native VPC network. When the cluster scales, new nodes get ENIs and pods on them receive IPs from the same VPC subnet range. This setup enables pods to have native AWS networking capabilities. The execution table and variable tracker detail each step and state change, clarifying common confusions about pod IP assignment and plugin installation.