What is passive optical LAN?

POL, or Passive Optical LAN, is a network infrastructure that is more powerful and at a fraction of the complexity, space, energy and costs of a traditional copper-based LAN. Instead of structured cabling with various levels of cables, routers and switches, it uses fiber-optic cables to deliver voice and data.

Passive Optical LAN simplifies the network setup since it shifts the network intelligence to one central point, the Optical Line Terminal (OLT). It centralises the management of all far-reaching edge devices, the Optical Network Terminal (ONT). There are no active elements between OLT and ONT. POL requires less cable and hardware and uses light to transmit data.

Optical LAN is a future-proof and high capacity always-on network for in-building and campus connectivity as well as mobile backhauling. It can cover distances of up to 20 kilometers eliminating the need for telecoms closets, switches and power every 100 meters. It consumes less energy and can thus be qualified as a truly green solution.

What components are used in Passive Optical LAN?

Optical Line Terminal (OLT)

The optical line terminal sits in the main distribution frame (MDF) or datacentre. It’s connected to the core switch and converts optical signals from the various splitters back into electrical ones so the core router can work with them.

An optical line terminal helps provide capabilities like redundant switching and power, and it may—depending on the manufacturer and model—include features like ethernet bridging, end-user authentication, VLAN and security filtering.

Passive Optical Splitter (POS)

A passive optical splitter splits the optical signal from the optical line terminal into different branches that are connected to the optical network terminals. They’re called passive splitters because you don’t need to power them. A passive optical splitter can handle a variety of different split ratios, like 1:8, 1:16, 1:32, 2:8, 2:16 and 2:32.

Optical Network Terminal (ONT)

The optical network terminal sits user-side, where it converts electrical signals from endpoints into optical ones and vice versa. It acts as a translator for endpoints, just like computers and IP telephones use electrical signals to “talk” to the outside world.

Optical network terminals are small devices that can be mounted in various places, like racks, ceilings, walls or desks. Depending on the model and manufacturer, they have different sets of ports and features. Discover the different power considerations of ONTS in a passive optical LAN.

When do you need Passive Optical LAN?

Passive Optical LAN drastically simplifies your LAN and gives you more speed and data throughput overall. The latter is needed to address the ever-increasing number of devices tied to your local network. And let’s not forget the equally exploding use of cloud services. Cloud services gobble up so much bandwidth that they can grind traditional LANs to a halt.

Another upside is that you need less cable, fewer devices and less power. So overall, it brings down costs and speeds things up.