In the early days of networking splitting a network into segments required a router.
VLANS or Virtual LANS is a technology that allows you to split a home network into segments using low cost switches.
Generally a switch will send broadcast traffic to all connected ports, and will allow devices connected on any port to communicate with any other device.
VLANS were created in order to reduce the amount of broadcast traffic on a network.
However on home networks they are used mainly to improve network security.
If we consider a switch with 8 ports as shown in the schematic below.
A broadcast sent from a device attached to any port will be sent to all ports.
In addition any device attached to any port can communicate with any other device attached to any port.
This becomes problematic when you have untrusted devices with access to your network or as in the case of home automation you have IOT devices that are possibly vulnerable to attack.
However with a VLAN capable switch it is possible to restrict broadcasts and to control which devices can communicate with each other.
This makes it possible to design a more secure home network.
If we now take out 8 port switch and split it into two VLANs which we call VLAN1 and VLAN2 as shown below.
In this configuration we effectively have created two independent networks. Devices connected to VLAN1 cannot communicate with devices that are connected to VLAN2 and vice versa
VLAN Uses on A Home network
The main use is for security where you want to isolate certain machines from the main network. Here are two usage examples that should make it clearer.
Simple Design Examples
You have lodgers or a guest house and want to isolate guest machines from you main network but give them access to the Internet.
You have IOT devices e.g and want to isolate them from you main network, but need them to be accessible from the Internet.
Implementing Examples 1 and 2
To implement both examples 1 and 2 we require a VLAN capable switch which we split into 2 VLANS.
1 VLAN will be for our Home devices VLAN1 and the other for our IOT devices or for guest access (VLAN2).
One port of the switch will be common to both VLANs and connects to our router. This is shown in the schematic below.
In the above illustration Port 1 is common to VLAN1 and VLAN2 and is connected to the router to give both VLANs access to the Internet.
Devices connected to ports 2,3,4,5 can communicate directly with other i.e you can ping them.
They can also access the Internet, but they cannot connect to devices connected to ports 6,7,8.
Devices connected to ports 6,7,8 can communicate directly with other i.e you can ping them.
They can also access the Internet, but they cannot connect to devices connected to ports 2,3,4,5.
TP-Link Router Configuration
My TPlink Router also supports VLANS and so I connect my guest network which is in the basement to LAN1 (port1) and assign it to its own VLAN.
There is no option to assign a Wan Interface as it automatically is allowed.
This is a schematic of my home network using the TP-link router..
- The Wi-Fi router is on the main network VLAN.
- The Router assigns a different subnet to the second VLAN. The main network uses 192.168.1.0 and the basement VLAN uses 192.168.2.0
Switches With VLAN Support
Usually if the switch is labelled as a smart switch or managed switch it will have VLAN support but you should read the description to be sure.
Below is screen shot from Amazon of a TP-link switch (£30) that supports VLANs.
VLANs provide an excellent and low cost method of greatly improving you home network security and should be considered if you share your network with guests, and or have IOT devices connected to your Network.
Related Tutorials and Resources
- How To Segment A Small LAN Using Tagged VLANs
- VLAN How To: Segmenting a small LAN
- Private VLANs -Wiki
- Basic Home Networking course