An optical line termination (OLT), also called an optical line terminal, is a device which serves as the service provider endpoint of a passive optical network. ... to perform conversion between the electrical signals used by the service provider's equipment and the fiber optic signals used by the passive optical network.

OLTs include the following features:

• A downstream frame processing means for receiving and churning an asynchronous transfer mode cell to generate a downstream frame, and converting a parallel data of the downstream frame into a serial data thereof.

• A wavelength division multiplexing means for performing an electro/optical conversion of the serial data of the downstream frame and performing a wavelength division multiplexing thereof.

• An upstream frame processing means for extracting data from the wavelength division multiplexing means, searching an overhead field, delineating a slot boundary, and processing a physical layer operations administration and maintenance (PLOAM) cell and a divided slot separately.

• A control signal generation means for performing a media access control (MAC) protocol and generating variables and timing signals used for the downstream frame processing means and the upstream frame processing means.

• A control means for controlling the downstream frame processing means and the upstream frame processing means by using the variables and the timing signals from the control signal generation means.

Introduction to GPON

What Is GPON

PON is a point to multi-point (P2MP) passive optical network. GPON, a type of PON technology, is defined by ITU-T Recommendation G.984.x. Figure 2-1 shows a GPON network.

• The optical line terminal (OLT) is an aggregation device located at the central office (CO) for terminating the PON protocol.

• Optical network units (ONUs)/Optical network terminal (ONTs) are located on the user side, providing various ports for connecting to user terminals. The OLT and ONUs communicate with each other through the optical distribution network (ODN).

• The ODN is composed of passive optical components (POS), such as optical fibers, and one or more passive optical splitters. The ODN provides optical channels between the OLT and ONUs. It interconnects the OLT and ONUs and is highly reliable.

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https://en.wikipedia.org/wiki/Optical_line_termination

https://support.huawei.com/enterprise/en/doc/EDOC1000078313?section=j003&topicName=introduction-to-gpon

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