While single-mode fiber (SMF) dominates long-distance and carrier-grade infrastructure, multimode fiber remains the most cost-efficient and practical choice for enterprise buildings, campus networks, and modern data centers. Multi-mode optical fiber is a type of optical fiber mostly used for communication over short distances, such as within a building or on a campus. This guide explains the five generations of multimode fiber - OM1, OM2. Many engineers assume multimode fiber should have disappeared from modern data centers once high-speed single-mode optics became widely available. At first glance, this assumption appears logical. With the prices being nearly the same for both transceivers. This is made possible by its relatively large core diameter, typically 50 or 62.