A 4-core fiber optic cable consists of four individual fiber strands, typically two for transmitting (Tx) and two for receiving (Rx). This guide covers everything you need to know about 4 core fiber, including its internal structure, TIA standard color coding, and how to choose the right type. This guide will help you understand the process and best practices for achieving seamless communication. The number of. The total number of cores for a 1pc fiber patch cable is calculated as the number of branches multiplied by the number of cores per branch (if there are no branches, the number of branches = 1).