Fibre Channel Primer

34 Fibre Channel: Connection to the Future
ULP MAPPING: FC-4
FC-4 defines interoperable implementations of Fibre Channel for
standard protocols, audio/video, or applications like real-time
computing. Each Fibre Channel implementation is specified in a
separate FC-4 document.
Fibre Channel allows both network and channel protocols to be
concurrently transported over the same physical interface. The
following protocols are currently specified or proposed as FC-4s
(proprietary protocols are also possible and permitted):
l Small Computer System Interface (SCSI)
l Internet Protocol (IP)
l Intelligent Peripheral Interface (IPI)
l High Performance Parallel Interface (HiPPI) Framing Protocol
l Link Encapsulation (FC-LE) using International Standard (IS)
IS8802.2
l Single Byte Command Code Set Mapping (SBCCS) to implement
ESCON
®
and block multiplex interfaces
l Audio Video Fast File Transfer and Real Time Stream Transfer
l Real-time, embedded avionics
FC-4 maps protocols to the FC-PH physical and signaling
standard. Through mapping rules, a specific FC-4 describes how ULP
processes of the same FC-4 type interoperate. A networking example
of an active ULP process is the transfer of an IS8802-2 PDU from
one FC node to another. A channel example of a ULP process is a
SCSI operation between a channel and a disk drive.
Fibre Channel implementation is accomplished in hardware,
providing faster throughput. Typically, channel protocols follow a
command/data/status paradigm. Each of these information categories
has different attributes and requires separate processing. However,
the processing of each category is common for all protocol types.
Common definitions of these information categories allow common
implementations in hardware. Fibre Channel’s hardware
implementation eliminates compute cycles for I/O processing, making
servers, workstations, and storage systems more efficient.
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