The number of fiber cores is mainly related to the device interface of the fiber connection and the communication mode of the device. Made from either high-quality. Common fiber cores include 1 core, 2 cores, 6 cores, 8 cores, etc. When selecting fiber, the first step is to determine single mode or multimode, and. Before we dive into the details, let's briefly explain what fiber cores are. Fiber optic cables consist of multiple thin strands of glass or plastic, known as “cores. ” These cores carry the data signals via light.