Fibre Channel infrastructure

SAN-switch with optical FC connectors installed.Fibre Channel switches can be divided into two classes. These classes are not part of the standard, and the classification of every switch is a marketing decision of the manufacturer:

Directors offer a high port-count in a modular (slot-based) chassis with no single point of failure (high availability).

Switches are typically smaller, fixed-configuration (sometimes semi-modular), less redundant devices.

A fabric consisting entirely of one vendor is considered to be homogeneous. This is often referred to as operating in its "native mode" and allows the vendor to add proprietary features which may not be compliant with the Fibre Channel standard.

If multiple switch vendors are used within the same fabric it is heterogeneous, the switches may only achieve adjacency if all switches are placed into their interoperability modes. This is called the "open fabric" mode as each vendor's switch may have to disable its proprietary features to comply with the Fibre Channel standard.

Some switch manufacturers offer a variety of interoperability modes above and beyond the "native" and "open fabric" states. These "native interoperability" modes allow switches to operate in the native mode of another vendor and still maintain some of the proprietary behaviors of both. However, running in native interoperability mode may still disable some proprietary features and can produce fabrics of questionable stability.

June 30, 2011

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