A Fibre Channel Arbitrated Loop (FC-AL) is a high-speed Fibre Channel (FC) topology in which FC ports use arbitration to establish a point-to-point circuit and prevent multiple ports from sending frames at the same time.
In a Fibre Channel topology, devices are connected in a one-way ring. When ports in a loop topology have information to transmit, they must send out an arbitration signal to decide which port can use the channel. The port in control of the channel then sends an "open" signal to the destination port and transmits its data. Since all the ports in a loop are connected, every port will see and pass along the data -- but ignore the data unless it is addressed to that particular port.