Installation manual

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Appendix B Glossary
Some terms used in the Fibre Channel industry are defined below. More information is available through the ATTO
Technology website (
www.attotech.com ), the Fibre Channel Industry Association, Cern, the Storage Area
Networking Industry Association (
www.snia.org ), and the Fibre Channel Consortium.
Term Definition
ANSI American National Standards Institute.
arbitrate The process of selecting one L_Port from a collection of ports which ask for use of the
arbitrated loop at the same time.
arbitrated loop A loop topology (FC-AL) in which two or more ports are interconnected, but only two
ports can communicate at one time. Low-cost solution which may or may not use hubs
and switches.
autonegotiation A process when hardware senses and automatically responds depending on
configuration.
BER Bit Error Rate: a measure of transmission accuracy; the ratio of bits received in error to
bits sent.
bit The smallest unit of data a computer can process: a single binary digit, either 0 or 1.
bus A collection of unbroken signal lines used to transmit information from one part of a
computer system to another. Taps on the lines connect devices to the bus.
Byte An ordered set of 8 bits.
channel A Point-to-Point link which transports data from one point to another.
CPU Central Processing Unit: the portion of the computer which performs computations.
CRC Cyclic Redundancy Check: an error-correcting code which calculates a numeric value
for received and transmitted data. If no error has occurred during transmission, the
CRC for both received and transmitted data should be the same.
destination
address
A value in the frame header of each frame which identifies the port in the node where
the frame is being sent.
device driver A program which allows a microprocessor to direct the operation of a peripheral device.
DMA Direct Memory Access: a way to move data from a storage device directly to RAM
without using the CPU’s resources.
DMA bus master Allows a peripheral to control the flow of data to and from system memory by block as
opposed to allowing the processor to control the data by bytes (PIO or programmed
I/O).
fabric A Fibre Channel switch or two or more Fibre Channel switches interconnected to
physically transmit data between any two N_Ports on the switch or switches.
FC Fibre Channel.
F_port A port in the Fibre Channel fabric where a N_port may attach.
FL_port A port in the Fibre Channel fabric where a NL_port may attach in an arbitrated loop.
frame An indivisible unit for transfer of information in Fibre Channel.
frame header The first field in the frame containing the address and other control information about
the frame.
full duplex A communication protocol which allows transmission in both directions at the same
time.
half duplex A communication protocol which allows transmission in both directions, but only one
direction at a time.
host A processor, usually a CPU and memory, which communicates with devices over an
interface.
initiator device A component which originates a command.