The node protection device that shunts the optical signal is called the fiber optic distribution box. From the Access Node the Feeder Network is based in a number of Feeder routes and cables that interconnects the FDTs in a ring topology to provide network resiliency. What is an OLT? Definition: An Optical Line Terminal (OLT), also called. FTTH networks, which bring high-speed internet directly to residential areas, are composed of several key elements. These include the Optical Line Terminal (OLT), pivotal in initiating the fiber optic signal; the Optical Distribution Frame (ODF), which organizes and manages connections; and the. When you stream high-definition movies, attend video conferences, or download large files, a sophisticated piece of technology called the Optical Line Terminal (OLT) plays a crucial role in delivering seamless internet connectivity.