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VLANs (Virtual Local Area Networks) Introduction

Networking Fundamentals: The 0 to Hero Guide

Lesson 30: VLANs (Virtual Local Area Networks) Introduction

As networks grow, placing all users on a single broadcast domain becomes inefficient and insecure. VLANs solve this problem by allowing a single physical switch to be logically partitioned into multiple separate broadcast domains.

What is a VLAN?

A VLAN allows network administrators to logically group ports on a switch (or across multiple switches) so that the devices in one group cannot communicate directly with devices in another group, even if they are physically connected to the same hardware.

Key Benefits:

  1. Security: Isolating sensitive data. For example, separating Guest Wi-Fi traffic from internal employee data.
  2. Performance: Reducing the size of broadcast domains means fewer broadcasts flood the entire network, improving speed.
  3. Flexibility: Users can be moved easily simply by changing their port assignment in software, rather than physically moving cables.

VLAN Traffic and Inter-VLAN Routing

  • Intra-VLAN Communication: Devices within the same VLAN communicate using Layer 2 (MAC addresses) via the switch.
  • Inter-VLAN Communication: Since VLANs are separate Layer 3 networks (separate broadcast domains), a Router or a Layer 3 Switch is required for devices in different VLANs to communicate. This process is called Inter-VLAN Routing.