A mathematical system used to represent negative numbers in computer systems.
ordered set
A special construct used to implement low-level networking functions. An ordered set is usually 2 or 4 bytes long. Each byte has a specific meaning, and the bytes must be transmitted in a specific order.
Organizationally Unique Identifier (OUI)
The IEEE-RAC assigned 24-bit value that is used as the first three bytes of an EUI-48 or EUI-64 address. The OUI identifies the organization that administers the remaining bits of the EUI-48 or EUI-64 address.
Parallel ATA (PATA)
A series of specifications for ATA operation on parallel bus interfaces.
parallel SCSI
A series of specifications for SCSI operation on parallel bus interfaces.
Path Maximum Transmission Unit (PMTU)
The smallest MTU along a given OSI Layer 3 end-to-end path.
phase-collapse
An iSCSI term referring to the ability to piggyback data with a SCSI command. Alternately, SCSI status may be piggybacked with data.
pluggable transceiver
A hot-pluggable transceiver.
primitive sequence
A Fibre Channel Ordered Set that is continuously transmitted under certain circumstances until the receiving device responds.
primitive signal
A Fibre Channel Ordered Set that is transmitted under certain circumstances for as long as the transmitting device deems appropriate.
protection switching
A technique employed by wide area optical technologies to transparently switch from a failed circuit to a standby circuit.
Protocol Data Unit (PDU)
An OSI layer data entity composed of a header, upper neighbor layer SDU, and optional trailer.
protocol decoder
A product that dissects frame header fields to reveal exactly what is happening on the wire.
protocol stack
Vertically stacked communication protocols representing an implementation of a layered network model.
punch card
One of the earliest media for entering commands and data into a computer. A punch card is a slip of cardstock with holes punched at specific positions (row and column) to represent data.
