Specifications

Frame
A logical grouping of information sent as a link-layer unit over a
transmission medium. The terms packet, datagram, segment, and
message are also used to describe logical information groupings.
Framing
At the physical and data link layers of the OSI model, bits are fit
into units called frames. Frames contain source and destination
information, flags to designate the start and end of the frame,
plus information about the integrity of the frame. All other
information, such as network protocols and the actual payload of
data, is encapsulated in a packet, which is encapsulated in the
frame.
Full Duplex
A circuit or device permitting transmission in two directions
(sending and receiving) at the same time.
FXO (Foreign Exchange
Office)
A voice interface, emulating a PBX extension, as it appears to the
CO (Central Office) for connecting a PBX extension to a
multiplexer.
FXS (Foreign Exchange
Subscriber)
A voice interface, emulating the extension interface of a PBX (or
subscriber interface of a CO) for connecting a regular telephone
set to a multiplexer.
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.
Half Duplex
A circuit or device capable of transmitting in two directions, but
not at the same time.
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).
J1
Digital interconnection protocol similar to T1 and E1 used in Japan.
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).
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.