Subnets vs VLANs

Hello everyone, in this video we're going to talk 
about the difference between subnets and VLANs.   Now both of these do the same thing, they are 
both used to separate or break down a network   into smaller networks. And the main reasons for 
doing this is to make a network perform better,   to add security to a network, and to make a 
network more manageable. However both subnets   and VLANs do these things using different methods. 
Subnets separate networks physically, while VLANs separate networks virtually.

So let's talk about subnets first. Subnet stands for sub network.   A subnetwork is a smaller network within a larger 
network. And subnets are created by using routers.  So for example let's look at a small local area 
network that's typically used in a small business.   So here we have some computers connected to 
a switch. Now when these computers want to   communicate with other computers on this network, 
they will first send out a broadcast over the   entire network and every computer that's connected 
to this switch will receive the broadcast.

This is   known as a broadcast domain. Now this wouldn't 
be a problem on a small network like this   with only a few computers. But if this business got 
larger and more computers were added, the amount of   broadcast traffic would increase and flood the 
network with data, potentially causing a slowdown.   Now one way to prevent this is by creating sub 
networks or subnets, which is known as subnetting.   Creating subnets will separate and physically 
break down this network into smaller networks   and they are broken down and separated by using 
routers. And by doing this, this would alleviate   the problem of excess of traffic because 
broadcasts do not go past routers, broadcasts   only stay within a network. So as you can see,
the subnets are separated by routers and each   of these subnets has their own broadcast domain 
which will not interfere with the other networks.   Another reason for separating a network is 
for security.

So for example let's say that a   business has three departments, such as sales, I.T.,
and service. And in each of those departments are   servers that contain sensitive data that no one 
in the other departments are allowed to access.   Now if this network was kept like this, meaning one 
big network, where all the devices are connected   using a switch, well that means that everyone 
in all the departments are able to see all the   computers and servers in the other departments.
So the network administrator needs to isolate   the network traffic between the departments. 
So that sales doesn't see traffic from I.T,   I.T.

Doesn't see traffic from service, and so on. 
And once again since there are three departments   the administrator can break down this network 
into three subnets using routers. So that each   department has their own network. So now the 
network traffic from the different departments   stay within their network and each department 
can only see their own computers and servers.   They are not able to see the other devices in 
the other departments. Now a VLAN will do the   same thing. A VLAN or virtual local area network 
will also break down and separate a network, but it   will do it virtually. VLANs are created on a VLAN 
enabled switch. The ports on the VLAN switch can   be configured to separate network traffic without 
using routers. So back to our business example with   three departments, so if you as an administrator 
wanted to break down and separate this network   into three smaller networks according to their 
department, there's no need to move the computers   and cables or add additional routers.

All we have 
to do is configure three VLANs on the switch.   So we'll configure four ports on the VLAN switch for 
the sales department. And then we'll call this VLAN 1  and then we'll plug all the devices from the 
sales department into these ports. And then we'll   configure another four ports on the switch for 
the service department and then we'll call this   VLAN 2 and then we'll plug all the devices from 
the service department into these ports.  And then we'll configure four ports for the I.T. department and then we'll call this VLAN 3 and then we'll   plug all the devices from the I.T. department into 
those ports. And once that is complete, these are   now three separate networks with three separate 
broadcast domains. Each department can only see   their own network traffic and their own devices 
because the network traffic is separated between   the departments using VLANs.

So this is why VLANs 
are so popular with medium to large businesses   because they can separate networks without adding 
routers, firewalls, cables, moving equipment around,   or configuring IP addresses. They can just 
separate networks virtually by using VLANs   So guys if you never worked with VLANs before 
there's only so much you can learn from a video   I recently purchased a small VLAN switch from my 
home and configured several VLANs as a refresher   for this video. It's a great way to learn and see 
how VLANs work. And if you're interested in getting   one I'll put a link in the description below of 
this video of the one I purchased. So I want to   thank everyone for watching this video. Please 
subscribe and I will see you in the next video..