In the computer storage field, a Fibre Channel switch is a network switch compatible with the Fibre Channel (FC) protocol. It allows the creation of a Fibre Channel fabric, that is currently the core component of most storage area networks (SAN). The fabric is a network of Fibre Channel devices which allows many-to-many communication, device name lookup, security, and redundancy. FC switches implement zoning, a mechanism that disables unwanted traffic between certain fabric nodes.
A Fibre Channel director is, by current convention, a switch with at least 128 ports. It does not differ from a switch in core FC protocol functionality. The term itself initially soaked from old ESCON technology.
Fibre Channel switches may be deployed one at a time or in larger multi-switch configurations. SAN administrators typically add new switches as their server and storage needs grow, connecting switches together via fiber optic cable using the standard device ports. Some switch vendors now offer dedicated high-speed stacking ports to handle inter-switch connections (similar to existing stackable Ethernet switches), allowing high-performance multi-switch configurations to be created using fewer switches overall.
http://en.wikipedia.org/wiki/Fibre_Channel_switch