What is a Passive Optical Network?

The PON, or passive optical network, is a network structure that carries optical fiber cabling and the resulting signaling to within a short distance of the point of termination. Rather than relying on a network composed of multiple switching interfaces to carry the signal, the passive optical network employs a structure that may require not more than a couple of switch points. There may be one switch to allow a sender to jump onto the network and another switch to allow the signal to jump off the network just prior to reaching an end user. A passive optical network may be structured in several different configurations, depending on the individual application and system limitations.

There are essentially three different passive optical network configurations in common use to day. One configuration is referred to as a fiber-to-the-curb or FTTC. This application takes the signaling to a facility that is literally located outside the business or home. A connection from the end-user is run to interact with the switch and thus allow the signal to complete the journey.

A fiber-to-the-building or FTTB moves one step further in the process of terminating the signal than the FTTC manages. With this application of a passive optical network, the signal remains on the network until it enters the building. It is at that point that the signal comes off the originating network and terminates on a local area network that is connected with one or more of the businesses physically located in the building.

A third type of passive optical network is the fiber-to-the-home or FTTH. This type of network connectivity carries the signal directly into a switch co-located with the home and requires nothing more for termination than a connection to a device that is capable of receiving the transmission.

The “passive” is a passive optical network calls attention to the fact that the signaling process does not require any additional power sources in order to keep moving to the point of termination. The signal is simply passing through the network and will follow a logical flow until it reaches the end user.

When employed in a stand-alone system, a passive optical network allows for easy transmission of date to various points along the network. Each end user is allocated a fixed amount of bandwidth for both sending and receiving data. An administrator can make adjustments in the allowed amount of bandwidth, based on the total capacity of the network and the individual needs of each end user. In addition, the administrator can configure the network to connect with an outside system, such as a cable hookup or traditional phone line in order to allow the flow of data in and out of the network from outside users.