Configuring and Managing Host-Based X.25 Links - Edition 5 (36939-90054)
Glossary 211
Glossary
PSN Packet-Switching Network.
Any data communication network
using packet- switching
techniques wherein data is
disassembled into packets at a
source interface and reassembled
into a data stream at a
destination interface. A public
PSN offers the service to any
paying customer.
PSS Packet-Switching System.
The national public PSN of the
United Kingdom.
PVC Permanent Virtual Circuit.
A permanent logical association
between two physically separate
DTEs that does not require call
set-up or clearing procedures.
PXP See Packet Exchange
Protocol.
Q bit Qualified bit. When set in
DATA packets the Q bit signifies
that the packet's user data is a
control signal for the remote
device, not a message for its user.
QuickVal A software program
that tests whether Network
Services are operating correctly
between nodes.
RDBS Remote Data Base Access.
A network service that allows
users to access data bases on
remote nodes.
reachable network A network
that can be accessed (with
additional internet hops possibly
required) by a particular gateway.
remote connect device
Asynchronous device that is
connected to a DTC indirectly,
using a modem and telephone
hook-up, or a PAD.
remote node A node on an
internetwork other than the node
you are currently using or
referring to.
retransmission count (N2) The
maximum number of times a
frame will be retransmitted
following the expiration of the
retransmission timer, T1.
retransmission timer (T1)
Length of time the transmitter
will wait for an acknowledgment
from the destination address
before attempting to retransmit
the frame. When choosing this
value, factors like the line speed
and maximum frame size should
be taken into account.
RFA Remote File Access. A
network service that allows users
to access files and devices on
remote nodes.
router network See
Point-to-Point.
routing The path that packets,
or fragments of a message, take
through a network to reach a
destination node.
RPM Remote Process
Management. A network service
that allows a process to
programmatically initiate and