Interphase Tech iSPAN - Manual (Page 226)

206 Interphase Corporation
PMC (PCI Mezzanine Card) ◆ A daughter-card form factor imple-
mentation of the PCI bus specification.
POTS (Plain Old Telephone Service) ◆ Conventional voice grade
service and cabling infrastructure.
PPP (Point-to-Point Protocol) ◆ A dial-up protocol that allows a
computer to use TCP/IP networking to connect remote access devices,
such as modems, to the Internet or other TCP/IP based networks.
PPP/MP (Point-to-Point Protocol/Multilink Protocol) ◆ See Multi-
link PPP .
PRI (Primary Rate Interface) ◆ A type of ISDN service that offers 23
B-channels at 64 Kbps and one D-channel at 64 Kbps (23B+D). In
Europe, PRI provides for 30 B-channels and two D-channels
(30B+1D).
Private Line ◆ Synonym for a leased line. Dial voice line that does
not terminate at the voice private automatic branch exchange or that
does not appear on other sets in a key system.
Protocols ◆ A set of rules that define how different computer sys-
tems and other devices interoperate with each other.
PSTN ◆ Public Switched Telephone Network.
PVC (Permanent Virtual Circuit) ◆ A logical link whose endpoints
and class of service are defined by network management.
For Frame Relay, analogous to an X.25 permanent virtual circuit, a
PVC consists of the originating frame relay network element address,
originating data link control identifier, terminating frame relay net-
work element address, and termination data link control identifier.
Originating refers to the access interface from which the PVC is initi-
ated. Terminating refers to the access interface at which the PVC stops.
Many data network customers require a PVC between two points.
QLLC (Qualified Logical Link Control) ◆ An X.25 protocol that
allows the transfer of data link control information between two
adjoining SNA nodes that are connected through an X.25 packet-
switching data network. The QLLC provides the qualifier Q bit in X.25
data packets to identify packets that carry logical link protocol infor-
mation.
Q.921 ◆ This is the link layer protocol for ISDN.
Q.931 ◆ This is the network layer protocol for ISDN. Q.931 was
developed for out-of-band call control.