Demystifying passive optical network architecture: everything you need to know

In this Vitex Talks white board video, we’ll discuss the basic components of PON, also known as passive optical network, architecture. The basics include the OLT (optical line terminal), ONT (optical network terminal) or ONU (optical network unit), and ODN (optical distribution network). These components work together to deliver triple play services, for instance, and in most fiber-to-the-home services.

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(0:00-0:25) Intro
(0:26-1:57) Basic PON architecture
(1:58-2:37) What is in the network?
(2:38-3:52) Why is it important?
(3:53-5:00) Downstream vs upstream in PON
(5:01-5:58) Conclusion

Products Mentioned

PON Transceivers

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Hey everybody, this is Craig from Vitex and today we’re going to shine some light on PON. So if you work in broadcast or you’ve done anything with fiber to the home or really fiber to anywhere, you may have had some questions on what’s PON and what are some of the components in it. Well, today you’re in luck because we’re going to talk about that.

Basic PON architecture

So basic PON architecture has three major components that we’re going to talk about. Okay.

So the first one is our OLT. So this is in our central office. This is our optical line terminal. So the information is coming through here into the network and it’s going to terminate on where our users are, right?

On our ONT or our ONU, and that’s just the optical network terminal or the optical network unit. So these kind of reside in like houses, businesses, campus centers, hospitals, anywhere the end user is.

So what brings these two components together? That’s what’s in the network. So a lot of these services such as triple play services where you combined video, data, voice, to a fiber to the home setup they run through the ODN. So what is that? That’s our optical distribution network. And this is where some of our main focus is going to be because that’s really at the center of what we’re talking about.

Yes, it’s important to understand how our terminals and our end units, they will actually be sending and receiving all the information and they’re going to house things such as the transceivers, which we’re going to talk about in another video. But today we want to really focus on what’s in the network.

What is in the network?

So there’s three main things that make up this network, right?

So one, we have our fiber cables, two, we’re going to have any of our connectors such as patch panels or just mating connectors or adapters. And then the third major component is our splitters, which if you kind of think of it without how the PON is split across multiple users, it really wouldn’t be something that would be effective, an effective type of architecture.

Why is it important?

So when we look at this network, how does it all come together and why is it important? So one of the main concerns when we talk about passive networks, we want to think about power consumption, what actually goes into powering all of this setup.

So let’s just go through together a little bit of math, right? So we’re going to kind of look at our network, we’re going to add some of these things up. All right, so we take this to the square and 256 and then we want to cube that. And then once we go through all of those different things, we get our result of zero watts. When we… It’s a passive network, it actually doesn’t require any active component. So when these two duke it out, the passive and the optical active networks, that’s the major difference. All of these components inside the network, they’re all passive, they don’t require any active DC connections to actually power them, which is really awesome because that helps us on cost, it helps us on quality, helps us on durability, it helps with the whole lifespan of this product that it doesn’t require any of this maintenance that goes with an active optical network. So on this area, when these two fight together, PON definitely has a clear advantage of that.

Downstream vs upstream in PON

So the next question a lot of people think about is, “Yeah, it’s great I’m getting these things to my home, but keep hearing about these different streams,” right? Not video streams or your Netflix streams, but downstream versus upstream. “So where am I in that pipeline?” So just to kind of help you visualize this, think of, you know, mountain stream, right? So as the stream is running down, we have our house, okay? Maybe I’m not the best drawer, but hopefully everybody gets a picture of that. So all the information is coming down this stream to us. And everybody knows about this magical cloud, right? What’s all up in the cloud? So well, you can also think about it this way. Data comes down from the cloud to us, the end user, and we want to send something back, we send it up. So it’s the same thing in our stream analogy. Data is coming down and data is going up. So no matter where you are, being part of a PON network can totally help you when you’re trying to do applications that are involved in fiber to the home.


So we hope this was helpful for you. One of the things we want to hear from you is what kind of questions you have as you’re doing different kind of broadband or building out your network. You can reach us here in our New Jersey office. If you want to send a comment either through this video, when you like it or post a comment or send us an email, if we pick your comment to actually answer your question, I’m going to go ahead and buy you a cup of coffee. So start those questions off and we’ll look forward to getting them and answering them. So until next time, see you then.

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