In this beginner’s guide on networking, we will learn some basics of Optical Networks. After that, we will take a look at the differences between Active and Passive Optical Networks. Finally, we will see what is an ONT.
Introduction
If we take a look at the modern internet infrastructure, optical fibers are an essential part. They are the backbone of today’s communication systems, be it telephone, internet, or even cable TV. The amount of data that we stream, download, or exchange daily is huge. As the number of users is increasing, so is the demand for faster and higher bandwidth connectivity. As a result, the whole communications infrastructure transitioned (or is gradually transitioning) from traditional copper-based cables (co-axial or twisted pair) to fiber optic cables. Optical Fibers offer very high bandwidth when we compare them to copper cables. Also, using fiber optics, the number of users in a network is very high than what it can reach in the traditional system. Even with these benefits, early optical fibers are primarily used for long-distance networks, between access nodes, and only in metro regions. Things started to change as ISPs (Internet Service Providers) saw the benefits of cost and complexity (or the lack thereof) and started investing in Fiber To The Home (FTTH) connectivity. There are other FTTX (where X can be a Building, Curb, Premises, etc.) types but the essential thing here is that optical fiber is easily available to the end user.
Active And Passive Optical Networks
In a typical network infrastructure, an Access Node or Access Network is a system that acts as an intermediary between the actual “Internet” and the individual user. We can divide Access Nodes based on the type of connectivity they use (or offer) i.e., Wired Access Networks and Wireless Networks. Wired Access Networks are suitable for long-distance deployment due to their higher bandwidth and wider reach. In the initial days, most wired connectivity was based on coaxial cables due to low cost and ease of installation. But with the increase in demand for higher bandwidths and faster speeds, the use of optical fibers is on the rise. We can divide Optical Access Networks into two types:
Active Optical Network (AON) Passive Optical Network (PON)
In an Active Optical Network, the Central Office (CO) or the Optical Line Terminal (OLT) acts as the central network terminal. It connects directly to multiple end users with the help of active switches or routers. Each end-user has a special device known as Optical Network Terminal (ONT) or Optical Network Unit (ONU). Every ONT gets its own optical fiber connection to the switch. A Passive Optical Network, on the other hand, is a type of point-to-multipoint connection (P2MP). Each ONT shares the network with other ONTs using Splitters.
What Is An ONT?
In the previous section, we saw a bunch of interesting network terminology. Irrespective of Active or Passive Optical Network layout, they both have ONT at the end user. So, what is an ONT? If you are familiar with optical fiber communication, they use light to transmit data. This is okay for node-to-node communication but what about the end user? We need some sort of electrical signals so that our networking devices and equipment can use them to transmit or receive. This is what an ONT does. It converts the optical signals from the OLT to proper electrical signals so that we can use simple copper cables (coaxial or twisted pair) in our homes with our computers, Wi-Fi Routers, Switches, etc. An Optical Network Terminal or ONT translates the optical signals from the OLT to electrical signals and also vice-versa i.e., it converts the electrical signals from our internal network to optical signals before transmitting them to the OLT. We need ONTs for both Active Optical Networks (AON) as well as Passive Optical Networks (PON) as they both use optical fibers for last-mile connectivity. If this approach seems familiar, that is because we use a similar setup with our telephone (DSL) or Cable Internet connections. There, we use ADSL Modems and Cable Modems to separate voice or TV data from digital data. Just like our Modems need electricity to work, we also have to provide electricity to ONTs.
Do I Need An ONT? Where Is ONT Installed?
Let us answer the first question. You need ONT if you are planning to install a fiber network in your home. Your ISP (Internet Service Provider) usually installs it for you and most of the time, you don’t need to worry about its installation or other issues. Depending on your situation i.e., an independent house or an apartment, and also how your ISP works, they will install the ONT at a convenient location where you have a proper power supply and also wiring cables after installation. Some common places where ONTs are typically installed are: near the service entrance, garage, basement, or someplace outside the home. The installation technician will inspect the premises and suggest an ideal position for the ONT. In the case of apartments, there can be two types of ONT devices. In the first type, each flat in the apartment gets its own ONT. But in the second type, the entire apartment building gets a slightly larger and more complex ONT and from this ONT each flat gets its internet cable, usually some form of twisted pair (CAT5, CAT 5E, CAT6, or CAT6A).
Conclusion
With the demand for high-speed internet increasing day by day, the implementation of FTTH (Fiber To The Home) is becoming popular. At first, optical fiber connectivity is limited to metros and urban settings but nowadays, it is expanding to slightly remote places as well. In a typical FTTH connection, an optical fiber comes from your ISP’s Access Node and terminates at your home. Since Optical Fibers use light (Infrared or Laser) to transmit the data, end users cannot use this without converting it into electrical signals. This is the job of an ONT or Optical Network Terminal. In this guide, we saw some basics of fiber networking. After that, we saw different types of connections between the Access Node and the end user. Finally, we understood what is an ONT and how important it is for modern optical fiber communication. Comment * Name * Email * Website
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