Cabletron Systems MMAC-Plus 9F116-01, User Manual, Page: 409 / 420

Glossary Glossary-7
P
Packet
is a group of data and control signals transmitted as a composite whole across a
packet-switching network.
Packet Switching
is the breaking up of data into smaller pieces and the transmission of these pieces over
a network via X.25.
PAD
stands for “packet assembler/disassembler,” which allows a non-X.25 device to access
an FRX/FRM, by converting its protocol to the X.25 packet mode protocol, and vice
versa. FRX4000, FRX6000, and FRM support integral async, SNA, and BSC PADs.
PDN
stands for “public data network,” which is a network operated by common carriers or
telecommunications administrations for the purpose of providing data transmission
capabilities to the public.
Physical DCE/DTE
see “DCE” and “DTE.”
Port
is the entry or exit point for node traffic.
Protocol
is an agreement on format, meaning, and relative timing of information exchanged
between two communications devices.
PU
stands for “physical unit,” which is an IBM referenced to any SNA host or terminal
device.
Public Data Network
see “PDN.”
PVC
stands for “permanent virtual circuit,” which is a permanent logical connection
between two subscribers, analogous to a leased line. Transmission of packets on a
PVC needs no call setup or call clearing.
Q
QLLC
is “Qualified Logical Link Control,” which is a method of encapsulating SNA traffic
for transmission over X.25.