VLANS on Home Networks

vlans-home-network-iconIn 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.

standard-switch-broadcasts

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.

VLAN-switch

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.

You will need to choose which devices to use to implement your VLAN and the VLAN mode to use.

VLANs are supported on routers (not all) and on network switches.

On routers the VLANS have different IP subnets.

VLAN Modes

Most devices will support multiple VLAN modes.

The TP link smart switch(TL-SG105E) supports three modes:

  1. MTU VLAN (Multi-Tenant Unit VLAN)
  2. Port Based VLAN
  3. 802.1Q VLAN

which mode you need to use will depend on your network requirements.

MTU VLAN (Multi-Tenant Unit VLAN)

This uses a shared uplink port that is normally connected to the Internet.

The other ports can send and receive data on the uplink port but not between each other as shown in the schematic below:

VLAN-MTU-Schematic

This is very easy to configure as all you really need to do is choose the uplink port (shared port) and enable it.

For example it can be used to:

  • Create an isolated guest network.
  • create an Isolated smart home network.

The schematic below shows the basic layout:

Guest network Vlans

 

Port Based VLANS

In this mode a VLAN can consist of several ports but a port can only exist on one VLAN.

It is used when you want to create an isolated network.

A possible configuration is shown in the schematic below:

VLANs-Using-Port-Mode

In this configuration devices on VLAN 1 can access device connected to ports 1,2 and 3 but not devices connected to ports 4,5 (VLAN 2).

Devices connected to ports 4,5 (VLAN 2 ) can connect to each other and have no internet connection, and cannot connect to devices on VLAN 1

802.1Q VLAN

This is the most flexible mode but also the most difficult one to configure.

The IEEE 802.1Q protocol defines a new format for the Ethernet data frame by inserting a VLAN tag in the data frame data frame as shown in the schematic below:

VLAN-frame

Tagging is used when you have multiple VLAN switches and a distributed VLAN.

As an example imagine you had devices in the living room connected to a smart switch and devices in a home office connected to a second smart switch.

Now you want some devices in the living room to be on the same VLAN.

Because they are physically connected to two different switches you will need to used tagging.

Because this is more complex I will cover it in its own tutorial at a later date but TP-Link include it as an example here.

For this tutorial we will take an example of a single switch with no tagging and configure two VLANs (main and guest ) with both VLANs able to connect to the Internet.

The following schematic is a modified schematic taken from the tplink site here.

vlan-802.1Q

Although we have only two networks (guest and main) we require 3 VLANs.

As port 1 connects the switch to the router all ports need access to this port and so we configure VLAN1 as the default to include all ports.

VLAN2 is the main network and we will use ports 1,2 and 3. VLAN3 is the guest network with ports 1,4 and 5.

tplink-vlan-ports

Now the not very obvious configuration is the PVID settings which must be done for this to work the PVID must match the VLAN ID.

tplink-PVID-settings

TP-Link Router Configuration for Guest Network

This is the configuration I use for a guest network on my home network.

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.

tp-link-archer-router-vlan

This is a schematic of my home network using the TP-link router..

Home-Network-Schematic

Notes:

  • 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
  • The basement VLAN has its own WAP

The DHCP server on the router is automatically configured to assign addresses on the new subnet as shown below:

tplink-vlan-router-dhcp

Home Network VLAN Testing

The easiest way of testing is using the ping command.

You should not be able to ping machines on different VLANs.

ping-fail-vlan

Simple Home network Design Example

Example 1

You have lodgers or a guest house and want to isolate guest machines from your main network but give them access to the Internet.

Your router doesn’t support VLANs and guest Wi-Fi doesn’t have the range. You cannot change the router and both the guest and main network need Wi-Fi access

Solution

You will need a VLAN capable switch to split the network. You will also need to Wireless access points and shouldn’t use the WI-Fi provided by the main router.

A schematic is show below:

example-1-solution

The above solution can be achieved using 802.1Q VLAN or MTU VLAN modes on the switch.

Quick Questions

Referring to the schematic for solution 1 above.

Q1- If you connect a device to the main Wi-Fi router using Wi-Fi will you be able to ping a devices on the guest and main network? Yes or No.

Q2. Will a device on the main network be able to ping a device on the main network? Yes or No.

Q3: The main router also has 3 spare Ethernet ports. Can you use them?

Q4 On what device do you think the DHCP server is located?

Answers

A1 Yes

A2 Yes

A3 If you do it will not be secure.

A4 The main router

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.

tp-link-switch-vlan

Summary

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.

Terms Used in this Tutorial

broadcast traffic– traffic that is end to all hosts(devices) on an network. Many network services rely on this type of traffic e.g ARP and DHCP.

ARP– protocol used to resolve obtain the MAC address of a device using and iP address.

DHCP– Protocol for obtaining an IP address. See Understanding DHCP on Home Networks

Related Tutorials and Resources

Please Let me Know if you found it Useful
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16 comments

  1. Good article. However, I would be very suspect of TP-Link networking equipment. TP-Link is a Chinese based company. Swim at your own risk.

  2. Thank you for the write-up. I suspect you might have typo in question 2 at the end (“Will a device on the main network be able to ping a device on the main network? Yes or No.”) I believe the answer to that question is “YES” (not “NO”). However a ping from main to guest will not succeed.

  3. Under ‘implementing examples 1 and 2’ you have a typo under the diagram – they are both labelled “VLAN 1” when the second is supposed to be VLAN 2.

  4. Hi Steve,

    Thank you for this wonderful explanation. I do have a TP-link router as well.

    My objective is to create a VLAN for a home lab and seperate it from my main network (192.168.1.1/24). I have configured the interface grouping and enabled the group isolation with my home lab’s network (192.168.2.1/24) on LAN1 interface.

    I’m hosting an ESXi server on 192.168.2.2 and I want to be able to access the ESXi management portal from a dedicated deivce on my main network. Is there a way to do this on this router?

    Thank you,

    Oliver

  5. Hi, I have a GS116Ev2 switch, trunked to pfSense and also unifi AP. Need to know why DHCPDISCOVER broadcasts are being sent to two of my four VLANs and not just one VLAN that the discover came from. Seems like the switch is sending out two two VLANs. Any one have any ideas? Thank you

  6. hi i’ve followed this through and can’t get it to work at all. I have two vlans 1 and 10 on an hpv1910 48g switch, and i’m using a virginmedia superhub for access. I’ve set both vlans to have a common physical port as a hybrid port that connects by cable directly to the superhub. each vlan has been set to have an ip address , respectively 192.168.0.2 for vlan 1 and 192.168.1.1 for vlan 10. The superhub is the default gateway at 192.168.0.1 . at this point, any clients plugged into vlan 1 by default works fine with full access to the internet and each other. No access to clients in vlan10 , as expected – all good. However, clients in vlan 10 cannot connect to the internet at all. From what you have said above this should just start working but it doesn’t -what could I be doing wrong? is this because the superhub from virginmedia is not vlan aware in any shape way or form and is what i’m trying to achieve effectively impossible?

  7. Hi,
    I am trying to setup a home network that I can do the following:
    1. Main network
    2. Kids network ( guest network) with parental control
    3. Vlan – for smart devices (security reason)
    4. Cottage network- for guests

    Question:. All the smart devices require wifi access. How does vlan utilize the wifi network? How do I ensure the security ?

    If I implemented what you wrote above. Will it accomplish my goal of 4 networks that can be parental controlled separately?

    1. Yes most routers offer guest network ability which is for guests not the kids and would be Wi-Fi only. The parental control for the kids can be done on the device address rather than the network address.

  8. Hi there,

    I’m hoping you can help me.

    My setup:
    I have the following devices as part of my network:
    2x TP Link access points (EAP225 and EAP255)
    1x Virgin media superhub / router – internet access
    1x 16 port TP link unmanaged switch
    1x 8 port TP link unmanaged switch
    1x 5 port managed switch (TP link SG105E)

    On the WiFi access points, I configured them to broadcast three WiFi networks:
    IoT (for all my IoT devices)
    Guest (for guests)
    Home network (everything else that doesn’t fall into the two above)

    My requirement:
    I have a few devices plugged into both the 8 port and 16 port switches and I’m happy for them to be on ‘Home network’. The other IoT devices and guests connect in via the APs and I would like for them to be separate VLANs.

    The issue:
    I just want to set up the VLANs on the switch and bind the WiFi networks on the APs to those VLANs (i.e. VLAN ID 2 = Iot, VLAN ID 3 = guest, VLAN ID 1,4,5 = home network).
    I can’t figure out how to do this using the web based configuration on the SG105E – getting confused between MTU, port based, 801.2q etc..)
    Can you help?

  9. This is great. I wanted to know why and how to utilize VLAN in my home network. I just purchased a refurbished Cisco 3750 and want to put it my network. I am assuming that my modem/router from Spectrum/ATT/Comcast etc. would plug into on port on the switch.

    So I can configure on port on the switch to be available to many VLANs?

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