CommScope Definitions: What Is PON?

Do you know what PON technology is? As part of our CommScope Definition blog series, we explain what PON is, how it can be deployed and why operators can benefit from deploying this technology.

What_Is_PON_imageThis blog post is part of a series called “CommScope Definitions” in which we will explain common terms in communications network infrastructure.


Passive Optical Networks  is a versatile technology that can be deployed by various network operators who want to deliver advanced voice, video and data services to their users / subscribers using fiber optic cables. PON is the most popular of the methods used to provide fiber-to-the-home (FTTH), fiber-to-the-desk (FTTD), fiber-to-the-MDU (FTTMdu), fiber-to-the-business (FTTB) and the host of other FTTx locations.

A PON fiber optic access network consists of three pieces as shown in the following diagram:

  • an optical line terminal (OLT) at the service provider’s central office (headend/hub)
  • a number of optical network units (ONUs) located near end users. If you have fiber optics coming into your home, you probably have an ONU somewhere in your house. ONUs are frequently called ONTs (optical network terminals)
  • an optical distribution network (ODN) connecting OLTs and ONUs together

So, why use PON?

Along with providing more bandwidth, PON technology reduces the amount of fiber, power and cooling required compared with point-to-point architectures. It simplifies network design and management. And even though PON is a point-to-multipoint topology, transmissions are encrypted to prevent eavesdropping, making PON an ideal solution for government, banks and other deployments requiring secure communications.

For cable operators in particular, PON differs from other fiber offerings because it bridges the gap from hybrid fiber/coax (HFC) network to a converted Ethernet/IP platform. For example, Radio Frequency over Glass (RFoG or RF PON) solutions support building out the PON fiber infrastructure—the ODN–while continuing to use the existing headend, CPE, and back office systems used today. The drawback to using an RFoG network is it has the same upstream bandwidth limitations of an HFC network. However, it eliminates future investment in infrastructure when the network evolution requires the step to a converged Ethernet/IP platform over an optical infrastructure. If customer demand calls for an increase in bandwidth to critical customers, an Ethernet Passive Optical Network (EPON) overlay can be added to the RFoG network to eliminate upstream limitations of the HFC, add additional downstream bandwidth, and off-load the HFC/DOCSIS network.

Network operators, whether for giant public networks or small private networks, must keep up with the ever-growing demand for bandwidth. Yet it is still expensive for telecom and cable operators to deploy FTTH in rural and other areas of low population density. That’s why electric power cooperatives, telecom cooperatives and municipalities are now entering the broadband operators’ arena. They are looking to provide high-speed broadband services to their subscribers in rural communities. One thing is for certain, the need for an economical, future-proof architecture is clear. Operators need solutions to deliver bandwidth and additional service options to all their users—both business and residential—and one way they are addressing this situation is by deploying PON.

Related Resources:

Passive Optical Networks

FTTx using Ethernet PON