How It Works - ZyXEL Communications P-3202HN-Ba User Manual

How It Works

There are no active components in the PON backbone that require power. Light
impulses move from point A to point B with nothing inbetween to facilitate it other
than optical physics. Although the devices at the point of origin and the point of
termination undoubtedly require power, the network itself does not.
Figure 120 An example of Passive Optical Networking
In this example, the PON consists of: one or more Optical Line Terminals (OLTs)
located at the service provider's central office (A) to convert and transmit data; a
network of fiber optical cables to passively carry the data (B); and one or more
Optical Network Units (ONUs) at the subscriber end to receive the data (C).
PON Development
As a technology, PON has been around for quite some time although it was initially
unusable for network communications.
One of the original improvements made to it was Asynchronous Transfer Method
PON (ATM PON, more commonly called APON). The benefit of using a well
established networking protocol (such as ATM in this case) to enhance the fiber
network is that it is usually backwards-compatible with an existing Wide Area
Network (WAN). Unfortunately, ATM has fallen out of favor due to its relative
complexity and the rapid rise in popularity of the Internet Protocol (IP), which is
both less complex and more cost effective due to the ubiquitousness of the
hardware that supports it. A more robust off-shoot of APON offering faster
transmission speeds is Broadband PON (BPON).
IAD User's Guide
A
C
B
Appendix A Passive Optical Networks
241