Glossary
PCI (Peripheral Component Interconnect) bus ◆
PDU (Protocol Data Unit) ◆ Data in a
PHY (Physical Layer) ◆ Layer 1 of the OSI model. Defines and handles 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 implementation of the PCI bus specification.
POTS (Plain Old Telephone Service) ◆ Conventional voice grade service and cabling infrastructure.
PPP
PPP/MP
PPP.
PRI (Primary Rate Interface) ◆ A type of ISDN service that offers 23
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
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.
iSPAN PRI PCI ISDN Users Guide | 139 |