Fibre Channel Primer

24 Fibre Channel: Connection to the Future
The three FC-PH levels are defined as follows:
l FC-0 – Covers the physical characteristics of the interface and
media, including the cables, connectors, drivers (ECL, LEDs, short-
wave lasers, and long-wave lasers), transmitters, and receivers.
l FC-1 – Defines the 8B/10B encoding/decoding and transmission
protocol used to integrate the data with the clock information
required by serial transmission techniques.
l FC-2 – Defines the rules for the signaling protocol and describes
transfers of data frames, Sequences, and Exchanges.
FC-PH completed its first public review in January 1993, the
second review began in October 1993, and the standard was approved
in November 1994. The three levels are described in detail in the
following sections.
PHYSICAL INTERFACE AND MEDIA: FC-0
The lowest level, FC-0, specifies the physical link of the channel.
Fibre Channel operates over various physical media and data rates.
Fibre Channel’s approach ensures maximum flexibility, allowing
existing cable plants and a number of different technologies to be
used to meet a wide variety of system requirements.
As an example, with Fibre Channel, a single-mode fibre can
enter a building and a multimode fibre can be used for the vertical
distribution inside, with copper drops to individual workstations. For
short distances, Fibre Channel uses twinax copper connections. 100
MBps of effective transfer rate is possible with a line speed of
1.0625 Gbaud. Fibre optic extensions to 2.125 and 4.25 Gbaud are
already approved. A representative FC-0 link is shown in Figure 4.2.
Three connector types are generally available. Fibre optic
connectors are usually provided via Dual SC connectors. Copper
connections can be provided through standard DB-9 connectors or
the more recently developed HSSDC connectors.
Fibre Channel products may include a fixed embedded copper
or fibre optic interface or may provide a media independent interface.
Three media independent interfaces are available.
l Gigabaud Link Modules (GLMs) include the serializer/deserializer
(SERDES) function and provide a 20-bit parallel interface to the