An optical network terminal (ONT), sometimes also known as an ONU (optical network unit), is a device utilised for optical fibre-based telecommunications. They work in a similar way to a modem but instead of using a traditional digital/analogue transmission method they use fibre optic cables to bring a fibre-optic internet connection to your home or business.
The terms ONT and ONU are sometimes used interchangeably, however there are some subtle differences to the usage of each that you need to know before establishing your own network.
In this guide, we discuss what is an optical network terminal, how it differs from an ONU, and how this will affect your network setup. We also answer some frequently asked questions as well as discuss key phrases used when using an ONT.
Topics covered
- What is the difference between an ONT and ONU
- What does ONT stand for?
- What does an ONT do?
- Why is an ONT useful?
- Is an ONT different from a router?
- Do I need to use a modem with an ONT?
- How does an ONT work?
- Where should I install an ONT?
- What does ONU stand for?
- What does an ONU do?
- How does an ONU work?
- Other useful terminology
- What is FTTH?
- What is FTTB?
- What is a PON?
- What is an OLT?
- Building your own network using an ONT
What is the difference between an ONT and ONU?
Both ONTs and ONUs complete a similar role in telecommunications. They form part of a PON (Passive Optical Network), which uses signals sent from an ISP (Internet Service Provider) to an end user over fibre-optic cables. The use of ONT or ONU changes depending on where the technology is utilised. For example, ONTs tend to be used for home telecommunication and provide fibre optic cables directly in the user’s home, whereas an ONU tends to stop outside a user’s building and is used for business networks.
In addition to this ONT and ONU are given names by two different telecom standard bodies, even though they are sometimes used interchangeably. ONT is the terminology used by the ITU (International Telecommunications Union) and ONU is used by the IEEE (Institute of Electrical and Electronics Engineers).
What does ONT stand for?
ONT stands for Optical Network Terminal.
What does an ONT do?
Usually, an Optical Network Terminal is installed in a customer’s premises and is used for home computing. They form part of an FTTH network where the ONT delivers fibre optical cables directly into a user’s home allowing them to create a home network. These devices may have a wide range of connectivity options such as ethernet ports, telephone and Wi-Fi ports.
Why is an ONT useful?
Unlike traditional broadband connectors, an Optical Network Terminal brings fibre-optic cables directly into a user’s premises rather than the standard COAX cables used for a normal broadband connection. Traditional broadband terminals would usually only take fibre cables to a nearby routing box, at which point copper cables would carry the signal inside the property to the broadband terminal. Because fibre internet cables can transmit signals at a higher speed than standard copper phone lines, users are capable of receiving a high speed internet signal, which delivers a more consistent internet connection.
Is an ONT different from a router?
Yes, an Optical Network Terminal is a separate piece of hardware to your Wi-Fi router. It brings the fibre cables into your home, at which point you can connect your router to it to establish your home wireless network or setup.
Do I need to use a modem with an ONT?
No, you don’t. Your modem is used to convert digital signals (1’s and 0’s) to an analogue radio frequency (RF) which then sends packets of information through a cable. A modem at the receiving end then converts the analogue signal back to digital again. Because an ONT operates using fibre-optic cables, you do not need to convert the digital signal into analogue, therefore making a modem redundant.
How does an optical network terminal work?
An ONT utilises infrared light pulses which get transmitted through fibre-optic cables to send and receive information. Unlike a traditional modem which needs to convert the digital signals generated by your computer into an RF signal, the ONT sends infrared light pulses directly to the ISP via the fibre optic cables. This process is incredibly efficient as multiple signals can be sent at once, making vast internet speed differences versus traditional broadband connectivity.
Where should I install an ONT?
As the Optical Network Terminal will be the main access point of the fibre cables into your home, there are several key factors to consider before an engineer installs your ONT. Ideally, it should be:
- Placed on an internal wall.
- Located in a central point in your home, so that your router (which will be connected to the ONT) can serve as many areas as possible.
- Away from appliances which may cause, electrical interference. Although these will not directly affect the ONT, they may affect the router connected to it.
- Somewhere you’re most likely to use the internet e.g. a home office or living room.
- Close to areas where it’s likely you will have devices that need a lot of data e.g. smart TVs.
- Near a power socket. The ONT requires a separate power source.
What does ONU stand for?
ONU stands for Optical Network Unit.
What does an ONU do?
An Optical Network Unit operates in a very similar way to an ONT, in the sense that it delivers fibre-optic cables to a premises or building. However, an ONU is usually used within an FTTB network meaning the unit will be placed outside, which means the connection stops outside the building. From there a connection is established with other network devices, sometimes including ONTs to build out further networks in various offices.
How does an ONU work?
An ONU functions in the same way as an Optical Network Unit. Fibre-optic cables are installed directly to the premises where the internet is required. It uses infrared pulses to communicate directly with the ISP and can send multiple signals at once at high speeds. Unlike an ONT, the ONU is usually placed outside of a business and will often form part of an FTTC (Fibre to the curb) or FFTB network. From the ONU, users need to create an onward connection to their other network devices, in some cases, this can be an ONU.
Other useful terminology
There are several other key pieces of terminology that are used when discussing the use of an ONT or ONU. We’ve compiled a list of some frequently asked questions below.
What is FTTH?
FTTH stands for Fibre To The Home and covers the process of delivering fibre optic cables directly from an ISP (Internet Service Provider) into a customer’s premises using an optical network terminal. At which point the user can create a home network by connecting a gateway device or router. Using FTTH usually gives customers a faster connection than traditional broadband, because the fibre cables connect directly to the ISP meaning there is less reliance on copper cables which can’t support the higher bandwidth.
What is FTTB?
FTTB stands for Fibre To The Building. In an FTTB setup, fibre optic cables are installed outside of a building and then connected to a local distribution point via an ONU. The connection can then be separated and directed to different customers within that building using ethernet, Wi-Fi or other interfaces.
What is a PON?
PON stands for Passive Optical Network. It’s the overarching architecture used by telecom providers to bring internet through fibre cabling. Many PONs nowadays operate a Gigabit PON (GPON), a combined system that utilises both ATM (Asynchronous Transfer Mode) for voice transport and Ethernet for data transport, meaning it can achieve high download and upload speeds.
What is an OLT?
OLT stands for Optical Line Terminal. This device is located at the internet service provider’s office and acts as an endpoint interface between their network and the PON.
Building your own network using an Optical Network Terminal
Now that we’ve discussed the main principles of ONTs and ONUs, you may start thinking about how you could use them to grow your own business network. TXO has years of experience refurbishing telecom network equipment, and we can give you great support when it comes to creating your network. We are also experts in maintaining and repairing many different types of network equipment, so if you’re considering replacing or upgrading your set up contact us to find out how we can help.
