Specifications

Gateway
Gateways are points of entrance and exit from a communications
network. Viewed as a physical entity, a gateway is that node that
translates between two otherwise incompatible networks or network
segments. Gateways perform code and protocol conversion to
facilitate traffic between data highways of differing architecture.
GFP (Generic Framing
Procedure)
Defined by ITU-T G.7041, generic framing procedure allows efficient
mapping of variable length, higher-layer client signals, such as
Ethernet, over a transport network like SDH/SONET. Recently, GFP
has been extended to lower speed PDH networks.
HDLC (High-Level
Data Link Control)
A synchronous, bit-oriented link layer protocol for data transmission.
Frame Relay is an example of an HDLCbased packet protocol.
Impedance
The combined effect of resistance, inductance and capacitance on a
transmitted signal. Impedance varies at different frequencies.
Interface
A shared boundary, defined by common physical interconnection
characteristics, signal characteristics, and meanings of exchanged
signals.
IP Address
Also known as an Internet address. A unique string of numbers that
identifies a computer or device on a TCP/IP network. The format of
an IP address is a 32-bit numeric address written as four numbers
from 0 to 255, separated by periods (for example, 1.0.255.123).
Jitter
The deviation of a transmission signal in time or phase. It can
introduce errors and loss of synchronization in high speed
synchronous communications.
Laser
A device that transmits an extremely narrow and coherent beam of
electromagnetic energy in the visible light spectrum. Used as a light
source for fiber optic transmission (generally more expensive,
shorter lived, single mode only, for greater distances than LED).
Leased Line
A permanent telephone connection between two points that is
rented for exclusive use from a telecommunications common carrier.
In contrast to a normal dial-up connection, a leased line is always
active. Typically, the highest speed data connections require a leased
line connection. For example, a T1 channel is a type of leased line
that provides a maximum transmission speed of 1.544 Mbps.
Loopback
A type of diagnostic test in which the transmitted signal is returned
to the sending device after passing through all or part of a
communications link or network.
Mark
In telecommunications, this means the presence of a signal. A mark
is equivalent to a binary 1. A mark is the opposite of a space (0).
Multiplexer
At one end of a communications link, a device that combines several
lower speed transmission channels into a single high speed channel.
A multiplexer at the other end reverses the process. Sometimes
called a mux. See Bit Interleaving/Multiplexing.