Optical fiber supports greater distances than copper. Unshielded twisted-pair Category 5 copper cables must be less than 100 meters in length, which is strictly due to signal attenuation. Copper-based Gigabit Ethernet is even more restrictive in terms of transmission length segments. But fiber optic cables can carry signals up to 2 kilometers over multimode fiber and 100 kilometers over singlemode fiber before signal degradation becomes a limiting factor. This length restriction on the media is typically the rationale for moving to a fiber optic backbone.
Optical fiber is far more scalable than copper.
Moreover, the life span of a fiber optic based LAN or WAN with multimode fiber is at least fifteen years and for singlemode fiber it may even go up to thirty years. Fiber optical transmission systems offer higher bandwidth services and high transmitting speeds as well as a more efficient transmission mode. Furthermore, optical fiber easily supports extremely high speed and capacity. Today's telecommunications and network service providers can cost-justify installing optical fiber links to connect to the periphery of remote user sites that serve scores or hundreds of customers. In other words, the bottleneck between the business users and the service provider is often the local loop access, which has primarily been the copper wire used for telephony.