So, guys, we have discussed the problems of Lance.
Now let us discuss what are VLANs and how Vlan will help us to resolve the problems which are due to
local area networks.
So VLANs help remove the positional constraint or immobility, right?
So we allow different hosts which are connected to the same network that is physical wire to reside
in a different subnets.
So for example, Vlan will allow host D that is this host to be present in subnet X while host E and
F could reside in a subnet Y, while all the host is still sit behind the same l3 router interface.
Right.
So there is no need to move the host x to another interface of an L3 router.
All of them can be placed in different subnets using the concept of Vlan without actually changing their
physical positions.
So one of the primary goal of Vlan is to place the host in different subnets without actually recabling
the network.
So here you can see that the host D is placed in subnet X, whereas host E and F are placed in subnet
Y, and we have not changed the physical position of any of these hosts.
Right.
So Vlan allows logical grouping of host by virtue of their functions rather than by virtue of their
position.
Right.
So in case of local area networks, different hosts or machines were placed in the same subnet by virtue
of their physical position.
Right.
But in case of virtual LANs, different hosts or machines are grouped together in the same subnet by
virtue of their functions.
Right.
So note the difference between LAN and VLANs.
So you can see in this diagram the host, E and F could be the employees of the testing team, whereas
Host D could be the employee of development team, Right.
So they perform logically different functions and therefore using the concept of VLANs, they can be
placed in different subnets.
But note that host machine D and host machine F could be present adjacent to each other or next to each
other.
So your friends sitting by your side could be connected to a different subnet altogether.
Right.
So you can see that host machine D is a part of subnet X and host machine F is a part of subnet Y,
yet physically they are in close proximity with each other.
So don't be surprised when you see your friend sitting by your side, but your friend is connected to
a different subnet altogether and you are connected to a different subnet.
So this is achieved using the concept of VLANs.
So going forward, you can see that this diagram actually captures the entire essence of VLANs.
Right.
Sit wherever you want in the building and you can always connect to the subnet you want.
Right.
So you can see in this diagram that host A and host B are seated on first floor and second floor.
Yet they are connected to the same subnet.
Right.
And the same goes with host C and host D, so there is no need to go to floor number X only to connect
to the subnet s.
Right.
We saw that this was the constraint that was imposed by local area networks, but with VLANs there is
no such need.
All subnet sits behind the same router interface.
That is, you save the real estate of an L3 router.
Right.
You don't need you don't need multiple physical interface of an L3 router to serve different subnets.
So according to this diagram, how many different subnets are there?
There are five different subnets because there are five VLANs, but still only one physical interface
of L3 router is consumed.
Right.
So if there was no concept of VLANs, then we would have to consumed five interfaces of an L3 router.
Right.
So with VLANs, it is possible that a testing team engineer can sit by the side of development engineer
while both stay connected to their respective subnets.
So this is the diagram that actually captures the entire functionality of virtual local area networks.
So to summarize, the lens actually allows the positional flexibility to host or machines.
You can sit wherever you want in the building.
You can always connect to the subnet you want.
Right.
So going forward, we have just seen a major problem which villains can solve, and that is the problem
of mobility and security, right?
Villains is a layer two concept and is implemented by layer two device called switch.
So remember, villains is a layer two concept, and it is the L2 device that is Switch, which implements
the Vlan.
Let us now understand how can we create VLANs using L2 switch and see what other problems it can solve?
Yes, there are more benefits of VLANs and we will see.
What are those benefits of VLANs when we will dive deep into the study of VLANs?
By now.
You must have got some idea about virtual local area networks and more.
We will understand when we shall see VLANs in action.
So let's begin with the Vlan concepts and guys, fasten your seat belts.