Ethernet over fibre is a networking technology that delivers Ethernet bandwidth ranging up to using optical fibre lines. Such wired transmission methods extend connectivity over long distances up to , support higher bitrates and provide far greater immunity from electromagnetic interference (EMI) than electrical connections. Copper-based Ethernet connections are generally limited to a maximum length of or less, a maximum speed of , and they are more easily affected by surrounding EMI.
Ethernet over fibre has emerged as a preferred medium in situations that require long-distance communication, high speeds or a high level of immunity from electromagnetic interference (EMI). With fibre-optic cables, data can be transmitted over much greater distances compared to copper-based Ethernet cable.
Ethernet over fiber-optic cable has been a technology with specifications dating back to the mid 1980s (10BASE-F). Initially, fibre-optic cables were primarily used to connect repeaters when the distance between them exceeded the limitations of ThickNet cable. The initial specification, known as Fibre-optic inter-repeater link (FOIRL), outlined the process of linking two repeaters using fibre-optic cable, allowing for connections of up to in length. With the disappearance of half-duplex connections and improvements in fibre-optic communication, distances and data rates increased greatly.