Router Charts

Router Charts

Router Ranker

Router Ranker

Router Chooser

Router Chooser

NAS Charts

NAS Charts

NAS Ranker

NAS Ranker

More Tools

More Tools

LAN & WAN Features

Introduction

What is a VLAN? Is it some sort of highly expensive technology or virtual reality? Not at all. VLANs are relatively simple, yet they offer a wide variety of options and capabilities to improve your network.

VLAN, or Virtual LAN, is a technology that enables dividing a physical network into logical segments at Layer 2. Functionally, VLANs enable a network administrator to partition a network into separate, independent networks. There are many reasons to separate a network into VLANs, and numerous options to consider.

While a useful technology for small LANS, VLANs are often deployed in large networks, too. In larger networks, VLANs are sometimes used to join physically separate LANs or LAN segments into a single logical LAN.

The goal of this article is to explain and discuss VLANs, including why you should consider using VLANs in a smaller network. I'll also walk through a configuration example showing how to configure a VLAN-aware switch to create separate LAN segments.

VLANs and Switches

If you have more than one device on your network, you probably have a switch. A switch is a simple device that operates at Layer 2 of the OSI model, forwarding data frames from one device to another based on their hardware or MAC (Media Access Control) address. The basic Layer 2 switch does not care or know about IP addresses, which operate at Layer 3.

Your switch may be a few ports built into your router, it may be a small unmanaged (non-configurable) switch such as the D-Link DGS-2205 shown in Figure 1. Or you may have a more advanced switch with VLAN capability, possibly referred to as a managed, "smart" or multilayer switch. Larger networks usually have multiple switches at numerous locations.

D-Link switch

Figure 1: D-Link switch without VLAN capability

As stated, switches pass data from one device to another based on their MAC addresses. The key question is, how does the switch know which MAC address is located on which port?

Even the simplest switch has a "learning ability" to read the MAC address of the devices connected, and store those MAC addresses in a table in memory. Switches "learn" by examining the source MAC address of every frame received. New MAC addresses learned on received frames are added to a table, creating in the switch's memory a mapping of MAC addresses to switch ports.

More LAN & WAN

Top Performing Routers

AC3200
AC2350
AC1900
AC1750
AC1200

Top Performing NASes

1 drive
2 drives
4 drives
6 drives
8 drives

Over In The Forums

  • Asuswrt-Merlin 378.51 Beta 1 is out
    Highlights of this release: * Official support for the *RT-N16 is being dropped*. This last model based on SDK5 requires too much efforts to...
  • 2 SSID - 1 VPN and 1 ISP
    So I am trying to achieve the ability to have 1 SSID for a VPN and 1 SSID for Internet using just my ISP. One of the SSID's will be from the Guest...
  • Need to replace WNR3000v3 advice please?
    This Netgear is crapping out, even after flashing with dd-wrt. I am looking at supporting G and N devices but with 2 kids I have a ton of devices...
  • [bugreport] IPv6 broken in 378.50
    After flashing new firmware, doing factory reset and reconfiguring router from scratch i've met the fact IPv6 stop working. Here is diagnosis: ...
  • Guest network authentication methods
    Hi, I am using the Merlin firmware (3.0.0.4.378.50_0) on an Asus RT-AC56U. I am setting up an old laptop for a friend. It has no LAN but an old...