What is a LAN? For beginners

What is a LAN?

When I first got into the IT world, there were a lot of concepts I had to wrap my mind around. A lot of the training ground started with getting certifications like the Network+ or the CCNA. I knew I wanted a career in networking at that time, and certifications were the best options to get started. A LAN would be one of the first concepts I learned.

What is a LAN? A LAN is an acronym for Local Area Network. It is a concept which local devices are separated from other devices connection to the internet. One clear example is a home network is a LAN, as it connects to the internet in another way than another home network.

Some can confuse LAN as being separated by a particular hardware, in some case it is. But it is more of a logical division from one local network to another. It’s probably most helpful to show by example.

Home LAN Examples

A popular example of a LAN Network is a home network. Your Apple TV, Macbook, Windows Desktop, iPhones and Android may all share a connection to your home router (wireless and wired). This is a LAN because your router is giving each of these devices access to the internet through the same path.

In the corporate world, the idea of LAN Network can get more abstract. But before I get there, I’m hoping to clear up the concept of LAN at home.

Another LAN example is your 4G/5G or whatever XG connection you may have through your cell phone provider. Let’s say you have half of your devices going through your home router, and you have half of your devices going through your 4G mobile phone hotspot. This mobile phone creates another LAN environment in your house.

Just because all of your devices are in the same local area, does not mean it is part of the same LAN. One LAN is divided from another LAN based on the logical separation of the path it takes to get to the outside world.

In the above home examples, you’ll now have two LANs (Local Area Networks):

  1. Home Router LAN – This LAN makes up of the devices that are currently connected to the router. All of these devices share the same path to the outside world through the Home Router.
  2. Mobile Phone Hotspot LAN – Although your devices are in the same local area, this is not the same LAN as your Home Router. All devices that are connected to the Mobile Phone Hotspot becomes a separate LAN. Why? It is in the same LAN as the Mobile Phone Hotspot, because it shares the same path to the outside world. It is not in the same LAN as the Home Router because it does not share the Home Router’s path to the outside world.

Now if you take a device from the Home Router LAN, and connect it to the Mobile Phone Hotspot LAN, your device will no longer by in the original LAN but in the Mobile Hotspot LAN.

Okay, I think the idea of the home network LAN should be pretty clear at this point. Just remember, the LAN separation is more logically based than it is physically based.

Corporate LAN

On the other side of the home network, are places like the corporate world. This is less understood as the infrastructure is not as common for everyone. The idea of a local area network being a logical separation to the outside world remains the same. Except in the corporate world we would usually add another layer of abstraction called virtualization.

In our home example we used a mobile hotspot and a home router to separate one local area network from the other. In the corporate world, this can still happen. But the larger the company is, creating a hardware device to separate every local area network just doesn’t scale. That’s why local area networks are virtualized while using the same hardware: as this allows for greater scalability. 

Virtual LAN (VLAN)

First off, why would you want to have separate Local Area Networks in the same corporate environment? After all, when at home we can usually get away with just one LAN. The answer is security and management.

When a corporate network is separated into LANs, communication within LANs have to have permission from their outside environment to talk. For example, you can divide LANs between the sales department and the technology department. That way sales can’t see what they won’t need to see with the technical infrastructure resources.

Other times it’s to separate one kind of network traffic from the other. You may want to separate your Data from your Voice LAN. That way you can prioritize the speeds of Voice to not drop phone calls.

The examples start to expand pretty quickly from here. Instead of having one hardware device to separate each LAN, the concept of virtualization came into play. Within hardware called ‘layer 3 switches’ the LANs become Virtual LANs aka VLANs.

Layer 3 switches can create and accommodate thousands of Virtual LANs for a corporate environment.

What is a LAN and WAN?

There’s a certain set of technologies and protocols that are limited to LANs that allow people every day use of the internet. In the corporate world, LAN will also allow access to local devices in the same network like a database for instance. The key word in what makes LAN different from a WAN is Local. LAN allows Local access for people’s every day use of the internet or local devices. WAN on the other hand is the medium which LAN may use to get to the world wide web.

WAN stands for Wide Area Network. It is basically the highway of the internet. In WAN, we have a different set of protocols and technologies – largely due to the greater amount of traffic pointing needs. In LAN, I’ve mentioned switching technologies or Layer 3 Switches, in WAN there is a greater use of hardware devices called routers.

Although switches can also function similarly to routers, routing protocols is largely referenced in the WAN world. To move traffic from one side of the world to another side of the world, requires information to be passed off from one location to another. The automatic way this is done is by leveraging routing protocols.

In short, WAN is usually separated in large geographical areas; and LAN is a local gateway to the internet.

Related Questions

What is a LAN used for?

A LAN is used to connect a local network for communication with each other and to the internet. It can also be separated within a corporate environment for security and manageability. Security in that it can limit communication between one department or device type from others. Manageability in that it can make sure enough data is allocated for priority traffic.

What is a LAN example?

The best example for a LAN is your home network. By definition a LAN are a group of devices that share the same network path. This network path allows communication between devices as well. In a home network, you can find mobile devices, desktops, video game systems, etc that are all connected to the same router. The router provides the same path to all of these devices that allows them travel along the same path to the outside world.

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