What does OLT and ONT mean in this alphabet soup called Optical LAN?

by | Mar 21, 2023 | Blog

What does OLT and ONT mean in this alphabet soup called Optical LAN?

Acronyms like OLT, ONT, PON, and OLAN can appear to be a stirred-up bowl of alphabet soup. All these abbreviations make it hard to easily digest all the wonderful things that Optical LAN delivers. So, for those of you who are hungry to learn more about this technology, let’s dip our spoons in, lift out these acronyms one by one, and get a better understanding of their ingredients.

The Optical Line Terminal (or OLT) and Optical Network Terminal (or ONT) are both components used in fiber optic networks leveraged by both service providers and enterprise customers. The main difference between the two is their location in the network and their function. To be clear, this blog will focus on the enterprise application of Optical LAN (OLAN) inside buildings and across extended campuses.

An OLT is a device that is usually located in the main data center for enterprise deployment. The OLT serves as the “brain” providing control of the far-reaching Passive Optical Network (PON). It is responsible for transmitting data signals across the network over fiber optic cables. The OLT also receives data signals from these same endpoints. Since it has visibility across the entire network and all the connected devices, it can orchestrate strict traffic management, network access controls, and even dynamic bandwidth allocation in real-time. The fact that it has centralized intelligence and management makes it incredibly simple, scalable, sustainable, stable, and secure. For example, it is an industry-leading architecture for drastically reducing security gaps, shrinking a network’s attack surface, and implementing Zero Trust Architecture.

On the other side of the equation are the ONTs that are connected by fiber optic cabling and can be mounted long distances away – even miles! An ONT’s main function is to convert the optical signal transmitted over the fiber optic cable into an electrical signal that can be used by the connected end devices, such as computers, phones, wireless access points, IP surveillance cameras, or any connected endpoint in a Smart Building. ONTs are simple optical-to-electrical (and vice versa) media converters. It has no local management interface, so there is little reason for human touch – this is why IT staff gain operational efficiencies with OLAN. The ONT also performs other functions, such as managing the quality of the signal, and can deliver Power over Ethernet (PoE) to the powered devices. Even better yet, they come in different sizes, with multiple connector choices and they can be mounted anywhere – rack mounted in a telecommunications closet, in a ceiling or floor zone box, hidden inside walls or cubical furniture, and on top or below desks.

All these acronyms do make for a confusing recipe for this bowl of alphabet soup. Yet, you do not want to let this technology just sit there and get cold, so dig in and enjoy its benefits! It is a better way to build and operate networks that tastes great and is less filling (on the pocketbook).

To get a simple education on this technology, we invite you to visit our Optical LAN tutorial website resources, where you will find an explainer video, quick facts, a high-level solution summary, and frequently asked questions. Plus, we encourage you to join our social media channels, such as Facebook, LinkedInTwitter, Instagram, and YouTube.


John Hoover, Tellabs Marketing Director
John Hoover
Director of Marketing
John Hoover is a Marketing Director at Tellabs and 2024 Board Chair of the Association for Promoting Optical LAN (APOLAN). Over the past 20 years, John has influenced industry milestones such as early passive optical network deployments, video implementations, wireless and more recently enterprise Passive Optical LAN adoption.