title: Optical line termination
text: # Optical line termination
  
  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. It provides two main functions:
  
  * 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.
  * to coordinate the multiplexing between the conversion devices on the other end of that network (called either optical network terminals or optical network units).
  
  The diagram below depicts an OLT within a fiber-optic network.
  
  ## Features
  
  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.
  