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In this video let's talk about VLAN settings.

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Remember, when it comes to VLANs, you need

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to route the traffic between the VLANs,

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otherwise your devices aren't going to be able to communicate.

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So let's pretend I have two VLANs, one called IT

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and one called HR.

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Even though both IT and HR are connected to switch one

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and switch two physically, they can't communicate

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with each other until I route traffic

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between them using a router.

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Also, if you're going to have devices in the same VLAN,

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they need to be in the same logical subnet.

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So in this example, all of my clients are part

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of the IT VLAN

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and they should be using the same subnet of 192.168.1.0/24.

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And all of my HR VLAN clients should use their own subnet,

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something like 192.168.2.0/24.

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So let's take a look at this using a basic

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network logical diagram.

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Here we see one IT client and one HR client.

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Each one is assigned an IP address in a slash 24 network.

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The IT client is assigned to the IT subnet

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of 192.168.10/24 in VLAN 100,

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and the HR client is going to be assigned to 192.168.2.0/24

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as its network in VLAN 200.

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To simplify this topology, I left out all the other IT

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and HR clients, but there could be 50

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or 60 of these connected there as well either

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to switch one or two.

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It really doesn't matter for our purposes as long

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as they're configured into the proper VLAN.

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Now, as this is a logical diagram

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and how we see it set up here, IT client cannot communicate

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to the HR client and neither

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of those clients can communicate with the internet.

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Why is that?

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Alright, I want you to pause the video here

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and I'm going to count to five

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and I want you to come back and give me the answer.

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1, 2, 3, 4, 5, all right, you're back.

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Did you figure out the issue?

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Well, this issue is all going to come down to the fact

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that there are not gateways for the IT

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or HR clients to communicate with.

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Notice in this logical topology, we only have one router,

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and that router has an interface IP

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of 10.0.0.1 in the 10.0.0.0/24 network.

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This means it's the default VLAN, VLAN 1

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and its network isn't on the same logical network

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as either the IT or HR VLANs.

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So for us to allow the IT

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and HR clients to communicate, they're going to need a place

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to route traffic between switch one and switch two.

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Then to allow both of them to communicate with the internet,

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we need to connect them to a new router that's connected

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to the internet as well.

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Now, our easiest and cheapest solution in this case would be

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to remove the connection between switch one and switch two.

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Then we can connect switch one to router one

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and assign it a new interface on an IP address

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in the IT VLAN.

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We could also connect switch two directly to router one

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and assign it interface with the HR VLAN.

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Now we can use router one to route traffic between VLAN 100,

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the IT VLAN, and VLAN 200, the HR VLAN,

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and we can route both of those VLANs out

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to the internet going through router one as well.

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So remember, if you start having devices

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that can't communicate with each other, like one

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of the IT clients can't communicate with one

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of the HR clients, it could be an

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improper VLAN configuration.

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Make sure you check your configuration

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and if there's a proper routing setup

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between the different VLANs,

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because the number one cause of issues when you're dealing

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with VLANs that will communicate is people aren't

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routing the traffic right.

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Another common mistake people make when dealing

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with VLANs is simply that they don't use them.

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Now, if you don't use VLANs, all

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of your traffic will end up in the default VLAN, VLAN 1.

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When this occurs, you're going to have a really large

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single broadcast domain.

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For example, if you have a server

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that's operating in VLAN 1, the default VLAN,

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it can experience slow load types

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because there's too many devices located inside VLAN 1

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and the number of broadcasts are going to slow

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down the entire VLAN.

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Instead, this server, which currently has an untagged port,

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and therefore it's assigned to VLAN 1 by default,

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should be added to the server VLAN with the other servers.

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This will segregate them from all the other client VLANs

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and increase their speed dramatically.