Arbitrated loop

It allowed connection of many servers and computer storage devices without using then very costly Fibre Channel switches.

The cost of the switches dropped considerably, so by 2007, FC-AL had become rare in server-to-storage communication.

The hub on the other hand, while maintaining a logical ring, allows a star topology on the cable level.

Fibre Channel hubs therefore have another function: They provide bypass circuits that prevent the loop from breaking if one device fails or is removed.

If a device is removed from a loop (for example, by pulling its interconnect plug), the hub’s bypass circuit detects the absence of signal and immediately begins to route incoming data directly to the loop’s next port, bypassing the missing device entirely.