X25AM Configuration and Management Manual

Glossary
X25AM Configuration and Management Manual—523424-004
Glossary-8
process
divided into a primary substation and a secondary substation. See also secondary
station.
process. When a program on a NonStop Kernel operating system is being executed, it is
called a process.
program. Set of coded instructions residing on a disk.
protocol. Set of rules for assembling, sending, and receiving data.
PSDN. See packet-switching data network (PSDN).
PTP protocol. Process-to-process protocol. For X25AM, PTP is used by the X25AM
process when it exchanges data with a remote device.
public data network (PDN). A network providing (among other possible services) packet-
switching services to the public.
point-to-point. A data-link configuration between only two stations. The X.25 standard
supports only point-to-point communications. In other types of communications, such
as SNA or BSC, it is possible to have multipoint configurations. In multipoint
configurations, one station is designated as a supervisor that controls multiple tributary
stations.
PVC. See permanent virtual circuit (PVC).
QLLC. Qualified Logical-Link Control protocol. A link-level IBM protocol that serves as an
X.25 interface for attaching SNA devices to packet-switching networks.
REJ. Reject. Link-level control frame or packet-level packet. As a packet, it requests the
retransmission of data.
restart packet. Packet sent by the network when a call is restarted.
RNR. Receiver not ready. Link-level frame or packet-level packet. As a packet, it
acknowledges the receipt of data and requests that packet transmission be halted.
RPOA. Registered private operating agency. Network provider providing some degree of
public service.
RR. Receiver ready. Link-level frame or packet-level packet. As a packet, it acknowledges
the receipt of data and requests that packet transmission continue.
RS-232. An industry standard defining the physical characteristics of the cable and 25-pin
connectors used for connecting DTE and DCE.
RS-422/449. An industry standard defining the physical characteristics of the cable and the
37-pin and 9-pin connectors used for connecting DTE and DCE.
SABM. Set asynchronous balanced mode. Link-level frame used for call connection.