Filter
Top Products
Glossary
iSPAN PRI PCI ISDN Users Guide 139
PCI (Peripheral Component Interconnect) bus ◆ A high-performance
multiplexed address and data bus. Supporting 32-bit with optional 64-
bit data transfers, the PCI bus is intended to be an interconnect between
peripheral controllers, peripheral add-in boards, and processor/mem-
ory systems. The PCI bus operates at up to 66 MHz, providing burst
transfer rates up to 264 MBps 32 bits wide, or up to 528 MBps 64 bits
wide.
PDU (Protocol Data Unit) ◆ Data in a highly-structured format for the
purpose of transmission. Frame, packet, and PDU are equivalent in
most contexts.
PHY (Physical Layer) ◆ Layer 1 of the OSI model. Defines and han-
dles the electrical and physical connections between systems. The
Physical layer can also encode data in a form that is compatible with
the medium (coaxial, twisted pair, fiber, and so on).
PMC (PCI Mezzanine Card) ◆ A daughtercard form factor implemen-
tation of the PCI bus specification.
POTS (Plain Old Telephone Service) ◆ Conventional voice grade ser-
vice and cabling infrastructure.
PPP (Point-to-Point Protocol) ◆ A dial-up protocol that allows a com-
puter 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).
Protocols ◆ A set of rules that define how different computer systems
and other devices interoperate with each other.
PSTN (Public Switched Telephone Network)
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.
RAI (Remote Alarm Indication) ◆ PRI alarm, also known as Yellow
signal. This alarm indicates a carrier failure.
RBOC (Regional Bell Operating Company) ◆ There are seven
regional telephone companies that were created by the AT&T divesti-
ture: Nynex, Bell Atlantic, Bell South, Southwestern Bell, US West,
Pacific Telesis and Ameritech.