Monitoring networks with subnets and VLANs

3 min


Guide to deploying Domotz to monitor networks with subnets and VLANs

How many Domotz agents should I use on networks with subnets and VLANs?

How should I install an agent?

I get these questions a lot which is why I thought it would be useful to write up a quick guide on monitoring networks with subnets and VLANs. This guide covers how to install our monitoring software in different types of networks. We’ll cover a variety of setups and use cases.

To determine the best way to set up a new network with Domotz, answer these two questions and you’ll be on your way.

  • How many subnets does my client have?
  • Are any of these subnets VLANs?

Once you’ve determined the set-up of your client’s network, you can jump ahead to the most relevant section of this article.

One subnet, no VLANs

This case covers a network structured on a single subnet (with a maximum of /22 subnet mask – 255.255.252.0), wired or wireless where all devices are reachable on Layer 2.

If your client has a /16 network Domotz also supports this.
If you need to enable /16 network scans, contact our support team at support@domotz.com.

A network configured with one subnet and no VLANs is the most common case scenario when dealing with local area networks.

For example, 192.168.1.0/24 (255.255.255.0) is a classic class C network.

In the case of a network with one subnet and no VLANs, you can monitor all your devices with Domotz, you would need only one Domotz Agent.

Monitoring networks with subnets and VLANs

Two or more (routed) subnets, no VLANs

Networks that are structured on two or more subnets that can be reached through a router or a VPN are covered here.

For example 192.168.1.0/24 and 192.168.2.0/24.

In this scenario, you have two options to deploy Domotz software.

Option no. 1 (advised)
You deploy two Domotz Agents, one agent per network.

Option no. 2 (alternative)
You deploy only one Domotz Agent in one network and you add your other network defined as a “Private subnet” in Domotz.

Limitations (on 192.168.2.0 – the private subnet):

  • Device identification (type/brand/model) only IP address is not available
  • No Network Topology
  • Configuration management and other integrations cannot be used

Option 2 is not available in the connected VPN is not use a private IP addressing scheme. In other words, if it’s using a non-RFC 1918 compliant name, then this option is not available. Learn more here.

Learn more about how to add a “Private Subnet” in your Domotz Agent.

Monitoring networks with two or more Subnets (VLANs)

This guide covers a network with two or more additional VLANs defined on a managed switch.

Let’s assume that your client has tree VLANs:

  • 192.168.1.0/24 (managing vlan – untagged)
  • 192.168.20.0/24 (VLAN 20 – vlan tag/id 20)
  • 192.168.30.0/24 (VLAN 30 – vlan tag/id 30)
  • 192.168.40.0/24 (VLAN 40 – vlan tag/id 40)

In this scenario, you only need one Domotz agent to monitor all your VLANs

Monitoring networks with two or more Subnets (VLANs)

The VLAN configuration you use in Domotz depends on the operating system the Agent is installed on. If you need to configure VLANs we advise you to install the Linux Agent or to purchase a Domotz Box because they are VLAN ready.

Learn all about configuring VLANs in Domotz in this guide.

Monitoring networks with two or more Subnets that are reachable from a Server with multiple Network Interface Cards.

A network with two or more subnets that can be reached in layer 2 from a single location even if they are located in separate switches.

This scenario involves the server with multiple network interface cards.

Each of them is configured with a static IP address suitable for monitoring each subnet. Afterward, they are attached to the corresponding network appliance.

In this case, a single Domotz agent is installed on the server and it will be able to monitor all the subnets connected to its network interfaces cards.

Server with multiple network interface cards

Further information on monitoring networks with subnets and VLANs

If you have any further questions don’t hesitate to write to us at support@domotz.com.

Learn more about configuring VLANs and installing your Domotz agent.

Learn more about how to make a network topology diagram and the top reasons to use network monitoring software.

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