Fibre Channel overview

Fibre Channel (FC) is the high-reliability transport built for storage area networks (SANs) — connecting servers to storage arrays with low latency and lossless delivery.

Why it is different from Ethernet

• Lossless by design — a buffer-credit flow-control scheme means frames are not dropped under congestion, which storage traffic depends on.
• Purpose-built fabric — hosts use HBAs (Host Bus Adapters) and connect through FC switches into a switched fabric.

Topologies

• Point-to-point — two devices directly.
• Switched fabric — the usual case: many hosts and storage ports through FC switches.

Transceivers

FC links use the same optical module families as Ethernet — SFP+ for up to 16GFC, SFP28 for 32GFC, and QSFP for the multi-lane 128GFC — but with FC-specific optics designated SW (short wave, 850 nm MMF) or LW (long wave, 1310 nm SMF). Rates are covered in Fibre Channel speeds.

A module built for Fibre Channel reports FC rates in its memory; CodingBox decodes those capability fields like any other.

Further reading

• FC protocol basics — FC-0 to FC-4, port types, WWN/FCID, FLOGI/PLOGI/PRLI, classes of service, zoning.
• FC port diagnostics — porterrshow and MDS counters mapped to causes, slow drain, sfpshow, D_Port.