User`s guide

G-10 DL3100 User’s Guide—November 1998
G
network
An interconnection of computer systems, terminals, or data communications
facilities.
NI (Network Interface)
The point of demarcation between the customer premises and the carrier's
network, usually drawn at the network connector on the rear panel of the
Digital Link access device.
NRZ (Non-Return to Zero)
A binary encoding and transmission scheme where ÒonesÓ and ÒzerosÓ are
represented by opposite, and alternating, high and low voltages.
NRZI (Non-Return to Zero Inverted)
A binary encoding technique that inverts the signal on a ÒoneÓ and leaves the
signal unchanged for a Òzero,Ó where a change in voltage state signals a ÒoneÓ
bit and the absence of a change denotes a ÒzeroÓ bit value.
O
OOS (Out of Service)
A digital network trouble signal.
OOF (Out of Frame)
An error checking scheme. An OOF occurs when two out of four consecutive
framing bits are in error.
P
parity bit
An additional, non-informational bit appended to a group of bits indicating
that the number of ÒonesÓ in the bits group is odd or even.
parity check
A process of error checking using the parity bit.
polarity
Any condition where there are two opposing charges, such as positive and
negative.
port
The physical point of access into a computer, network or other electronic
device.
protocol
A formal set of rules governing the format, timing, sequencing and error
control of exchanged messages on a data network.