A basic guideline is that each device typically requires two cores: one for sending and one for receiving data. 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. How Many Cores Do You Need?Long-haul and submarine: These routes typically use very few physical fibers — often a single fiber pair — because each pair carries huge capacity via DWDM and advanced Coherent optics. “Future-proof” doesn't mean buying. The number of cores you choose directly impacts the capacity and flexibility of your network. Common fiber cores include 1 core, 2 cores, 6 cores, 8 cores, etc.