ZyXEL Communications Prestige 724, User Manual

Page: 81 / 87

Prestige 724 G.SHDSL CSU/DSU
Glossary M
Port (H/W)
An interface on a computer for connecting peripherals or devices to the computer. A
printer port, for example, is an interface that is designed to have a printer connected to
it. Ports can be defined by specific hardware (such as a keyboard port) or through
software.
POTS Plain Old Telephone Service is the analog telephone service that runs over copper
twisted-pair wires and is based on the original Bell telephone system. Twisted-pair
wires connect homes and businesses to a neighborhood central office. This is called
the local loop. The central office is connected to other central offices and long-
distance facilities.
PPP
Point to Point Protocol. PPP encapsulates and transmits IP (Internet Protocol)
datagrams over serial point-to-point links. PPP works with other protocols such as
IPX (Internetwork Packet Exchange). The protocol is defined in IETF (Internet
Engineering Task Force) RFC 1661 through 1663. PPP provides router-to-router,
host-to-router, and host-to-host connections.
Protocol A “language” for communicating on a network. Protocols are sets of standards or
rules used to define, format and transmit data across a network. There are many
different protocols used on networks. For example, most web pages are transmitted
using the HTTP protocol.
PSTN
Public Switched Telephone Network was put into place many years ago as a voice
telephone call-switching system. The system transmits voice calls as analog signals
across copper twisted cables from homes and businesses to neighborhood COs
(central offices); this is often called the local loop. The PSTN is a circuit-switched
system, meaning that an end-to-end private circuit is established between caller and
callee.
PVC
Permanent Virtual Circuit. A PVC is a logical point-to-point circuit between
customer sites. PVCs are low-delay circuits because routing decisions do not need to
be made along the way. Permanent means that the circuit is preprogrammed by the
carrier as a path through the network. It does not need to be set up or torn down for
each session.
ras This is the name of the firmware on the ZyXEL device. Renaming may be necessary
when uploading new firmware to the device.
RBOC Regional Bell Operating Company. There are currently seven regional telephone
companies that were created by the AT&T divestiture.
RFC An RFC (Request for Comments) is an Internet formal document or standard that is
the result of committee drafting and subsequent review by interested parties. Some
RFCs are informational in nature. Of those that are intended to become Internet
standards, the final version of the RFC becomes the standard and no further
comments or changes are permitted. Change can occur, however, through subsequent