In this video let's talk about VLAN settings.
Remember, when it comes to VLANs, you need
to route the traffic between the VLANs,
otherwise your devices aren't going to be able to communicate.
So let's pretend I have two VLANs, one called IT
and one called HR.
Even though both IT and HR are connected to switch one
and switch two physically, they can't communicate
with each other until I route traffic
between them using a router.
Also, if you're going to have devices in the same VLAN,
they need to be in the same logical subnet.
So in this example, all of my clients are part
of the IT VLAN
and they should be using the same subnet of 192.168.1.0/24.
And all of my HR VLAN clients should use their own subnet,
something like 192.168.2.0/24.
So let's take a look at this using a basic
network logical diagram.
Here we see one IT client and one HR client.
Each one is assigned an IP address in a slash 24 network.
The IT client is assigned to the IT subnet
of 192.168.10/24 in VLAN 100,
and the HR client is going to be assigned to 192.168.2.0/24
as its network in VLAN 200.
To simplify this topology, I left out all the other IT
and HR clients, but there could be 50
or 60 of these connected there as well either
to switch one or two.
It really doesn't matter for our purposes as long
as they're configured into the proper VLAN.
Now, as this is a logical diagram
and how we see it set up here, IT client cannot communicate
to the HR client and neither
of those clients can communicate with the internet.
Why is that?
Alright, I want you to pause the video here
and I'm going to count to five
and I want you to come back and give me the answer.
1, 2, 3, 4, 5, all right, you're back.
Did you figure out the issue?
Well, this issue is all going to come down to the fact
that there are not gateways for the IT
or HR clients to communicate with.
Notice in this logical topology, we only have one router,
and that router has an interface IP
of 10.0.0.1 in the 10.0.0.0/24 network.
This means it's the default VLAN, VLAN 1
and its network isn't on the same logical network
as either the IT or HR VLANs.
So for us to allow the IT
and HR clients to communicate, they're going to need a place
to route traffic between switch one and switch two.
Then to allow both of them to communicate with the internet,
we need to connect them to a new router that's connected
to the internet as well.
Now, our easiest and cheapest solution in this case would be
to remove the connection between switch one and switch two.
Then we can connect switch one to router one
and assign it a new interface on an IP address
in the IT VLAN.
We could also connect switch two directly to router one
and assign it interface with the HR VLAN.
Now we can use router one to route traffic between VLAN 100,
the IT VLAN, and VLAN 200, the HR VLAN,
and we can route both of those VLANs out
to the internet going through router one as well.
So remember, if you start having devices
that can't communicate with each other, like one
of the IT clients can't communicate with one
of the HR clients, it could be an
improper VLAN configuration.
Make sure you check your configuration
and if there's a proper routing setup
between the different VLANs,
because the number one cause of issues when you're dealing
with VLANs that will communicate is people aren't
routing the traffic right.
Another common mistake people make when dealing
with VLANs is simply that they don't use them.
Now, if you don't use VLANs, all
of your traffic will end up in the default VLAN, VLAN 1.
When this occurs, you're going to have a really large
single broadcast domain.
For example, if you have a server
that's operating in VLAN 1, the default VLAN,
it can experience slow load types
because there's too many devices located inside VLAN 1
and the number of broadcasts are going to slow
down the entire VLAN.
Instead, this server, which currently has an untagged port,
and therefore it's assigned to VLAN 1 by default,
should be added to the server VLAN with the other servers.
This will segregate them from all the other client VLANs
and increase their speed dramatically.