A simple rule is that each device needs two cores—one for sending and one for receiving data. Dual fiber modules use two fibers. The total number of cores for a 1pc fiber patch cable is calculated as the number of. The secret lies in fiber optic technology, and understanding the basics—1-core, 2-core, Single Mode (SM), and Multi-mode (MM)—is key to mastering this field. Let's break down these terms in simple, clear language with practical examples. When selecting fiber, the first step is to determine single mode or multimode, and. The number of optical cores in an optical fiber is the total number of equipment interfaces multiplied by 2, plus 10% to 20% of the spare quantity, and if the communication mode of the equipment has serial communication and equipment multiplexing, you can reduce the number of cores.