Skip to main content

Understanding VLANs in Kubernetes

04/08/2024

Introduction

In modern cloud-native environments, Kubernetes has become the de facto standard for container orchestration. Networking within Kubernetes is crucial for ensuring that pods, services, and external resources can communicate efficiently and securely. VLANs (Virtual Local Area Networks) offer a way to segment network traffic, providing improved security and performance. This blog post will explore how VLANs can be implemented in a Kubernetes cluster using Calico, a popular networking and network security solution.

What is a VLAN?

A VLAN is a method of creating separate, isolated networks on the same physical infrastructure. Each VLAN is identified by a unique VLAN ID, allowing devices within the same VLAN to communicate as if they were on the same physical network while being isolated from devices in other VLANs.

Why Use VLANs?

  1. Improved Security: Isolating traffic within a VLAN ensures that sensitive data is only accessible to authorized devices.
  2. Enhanced Performance: Reducing broadcast domains can alleviate network congestion and improve overall performance.
  3. Simplified Management: VLANs provide a structured way to manage network segments, making it easier to control and troubleshoot.

Introducing Calico

Calico is an open-source networking and network security solution for containers, virtual machines, and native host-based workloads. It provides a rich set of features, including IP address management, network policy enforcement, and integration with various Kubernetes network setups. Calico supports VLANs, allowing you to segment your Kubernetes network efficiently.

Implementing VLANs in Kubernetes with Calico

Here’s a step-by-step guide to implementing VLANs in your Kubernetes environment using Calico.

Prerequisites

  • A running Kubernetes cluster.
  • Administrative access to the cluster.
  • Basic understanding of Kubernetes networking and Calico.

Step 1: Install Calico

First, ensure Calico is installed in your Kubernetes cluster. You can install Calico by applying the manifest provided by Project Calico.

sh
kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml

Step 2: Configure Calico to Use VLANs

Calico needs to be configured to understand and use VLANs. This involves setting up a BGP (Border Gateway Protocol) configuration and defining the VLANs.

  1. Configure BGP Peering: Ensure that your Calico nodes are properly configured for BGP peering. This allows Calico to handle routing between nodes and VLANs efficiently.
  2. Define VLANs in Calico Configuration: You can specify VLANs in the Calico IPAM configuration.

Create a Calico IPAM configuration that includes VLANs. For example:

yaml
apiVersion: crd.projectcalico.org/v1
kind: IPPool
metadata:
name: default-vlan-pool
spec:
cidr: 192.168.100.0/24
ipipMode: Never
vxlanMode: Never
natOutgoing: true
vlan: 100

Apply this configuration:

sh
kubectl apply -f calico-vlan-pool.yaml

Step 3: Create a NetworkPolicy for VLAN

To ensure that only specific pods or namespaces use the VLAN, create a NetworkPolicy in Calico.

yaml
apiVersion: crd.projectcalico.org/v1
kind: NetworkPolicy
metadata:
name: vlan-policy
namespace: default
spec:
selector: all()
types:
- Ingress
- Egress
egress:
- action: Allow
destination:
nets:
- 192.168.100.0/24
ingress:
- action: Allow
source:
nets:
- 192.168.100.0/24

Apply this NetworkPolicy:

sh
kubectl apply -f vlan-network-policy.yaml

Step 4: Deploy a Pod on the VLAN

Finally, deploy a pod that will use the VLAN. Ensure the pod specification includes the necessary annotations to use the Calico VLAN configuration.

yaml
apiVersion: v1
kind: Pod
metadata:
name: vlan-pod
namespace: default
annotations:
cni.projectcalico.org/ipAddrs: "[\"192.168.100.10\"]"
spec:
containers:
- name: nginx
image: nginx

Apply this pod configuration:

sh
kubectl apply -f vlan-pod.yaml

Conclusion

Implementing VLANs in a Kubernetes cluster using Calico can enhance your network’s security, performance, and manageability. By following the steps outlined in this guide, you can effectively segment your network traffic and leverage the powerful networking features that Calico offers. This setup ensures a robust and secure network architecture tailored to your organizational needs.

By understanding and implementing VLANs with Calico in your Kubernetes environment, you can achieve a higher level of control and efficiency in your network infrastructure. Happy networking!

Close Menu