ADTRAN Express L1.5, Руководство пользователя

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Glossary
114 Express L768/L1.5 User Manual 61202192L1-1
netmask
A 32-bit bit mask which shows how an Internet address is to be divided into
network, subnet, and host parts. The netmask has ones in the bit positions in
the 32-bit address which are to be used for the network and subnet parts, and
zeros for the host part. The mask should contain at least the standard network
portion (as determined by the address's class), and the subnet field should be
contiguous with the network portion.
non-ISDN line
Any connection from a CPE to a SPCS that is not served by D-Channel signal-
ling.
non-ISDN trunk
Any trunk not served by either SS7 or D-Channel signalling.
NT1
Network Termination 1. A unit that provides physical and electromagnetic
termination of the U-interface 2-wire transmission line, converts between Lay-
er 1 formats used at the U- and T- reference points, and performs some main-
tenance functions.
phase jitter
In telephony, the measurement in degrees out-of-phase that an analog signal
deviates from the reference phase of the main data-carrying signal. Often
caused by alternating current components in a telecommunications network.
point-to-point protocol (PPP)
An implementation of TCP/IP which is intended for transmission using tele-
phone lines. PPP provides router-to-router and host-to-network connections
over both synchronous and asynchronous circuits.
poison routes
Routes which have an infinite metric which to other routers means the net-
work for the route is inaccessible.
PRA
Primary Rate Access. Connects high-capacity CPE, such as PBXs, to the net-
work. In the US, this is composed of twenty-three 64 kbps channels and one
64 kbps D-channel. Also known as Primary Rate Interface (PRI).
RFC1490
Request for Comments document which describes an encapsulation method
for carrying network interconnect traffic over a Frame Relay backbone.
RIP
Routing Information Protocol. A protocol used to exchange routing informa-
tion among a set of computers connected by a LAN. RIP uses hop counts as a
routing metric.