A simple rule is that each device needs two cores—one for sending and one for receiving data. However, if your equipment supports serial communication or allows device. A 4 Core Optical Cable is a fiber optic cable that contains four individual optical fibers within a single protective outer jacket. Each fiber is capable of independent data transmission. Future-proofing: Consider potential future growth in connected devices. The number of cores you choose directly impacts the capacity and. For example, if you have three optical fiber access switches, you need to have three cores.