It is used in optical transmitter and receiver of wired television and communication network as round head or screw socket.

FC, Fiber Channel
Developed in 1998, FC is initially used in SAN and primarily to improve transmission bandwidth of hard disk protocol as well as focus on quickness, efficiency and reliability of data transmission. Till late 1990s, FA SAN is widely used in a large scale. FA possesses its own protocol layering including ? FC-0:, ? FC-1:, ? FC-2:, ? FC-4: and ? FC-3:.

The main part of FA is actually FC-2 among which part from FC-0 to FC-2 is called as FC-PH, namely physical layer. FC transmits mainly via FC-2; therefore, FC is also called as Layer 2 protocol or Ethernet-like protocol. According to diverse connecting and addressing methods, FC supports three topologies: ? PTP is generally used in DAS setting; ? FC-AL adopts FC-AL arbitration mechanism usually employing Token method; ? FC-SW is the way operating on switching SAN. FC-SW could connect in any type avoiding many defects of arbitrated loop. Nevertheless, switching mode or FC switchboard supporting switch fabric is required.