AATM: Asynchronous Transfer Mode.
ATM refers to the protocol which uses fixed length packets called cells to
transfer information.
AS/400: The AS/400 is a middle-size
server designed for small businesses and departments in large enterprises
and its operating system is called the OS/400. The product is now
known as the i-Series.
B
B-Channel: Bearer Channel. With ISDN, the B-Channel
carries the data.
Backbone: A backbone generally carries
the heaviest traffic. It is a larger transmission line that carries data
gathered from smaller lines that interconnect with it. A backbone may
connect LANs, WANs or a combination of both.
BRI: Basic
Rate Interface. A type of ISDN service which comes with two B- Channels at
64 Kbps each and a D-Channel at 16 Kbps.
Bridge: A devise
that connects a local area network to another local area network that uses
the same protocol (for example, Ethernet or token ring). A bridge decides
whether a message from you to someone else is going to the local area
network in your building or to someone on the local area network in
another building across the street. A bridge looks at each message on a
LAN, "passing" those known to be within the same LAN, and forwarding those
known to be on the other interconnected LAN.
Broadband:
Broadband provides multiple channels of data over a single communications
medium, typically using some form of multiplexing.
C
Cells: Fixed size packets that carry your data
information over a cell relay network such as ATM. Each cell contains 53
bytes. In comparison, frame packets are variable
lengths.
CICS: Customer Information Control System is an
online transaction processing program.
Central Office: C.O.
It generally refers to the telephone company's switching equipment or the
building in which the switching equipment is housed. The C.O. is located
in your town or in a nearby town.
CIR: This generally
refers to a frame relay network and the guaranteed bandwidth/speed that
Verizon (Bell Atlantic) will provide over a PVC.
Client:
The client is a computer that relies on the server to fulfill certain
functions.
Client-Server Architecture: In a LAN where
computers are either servers or clients. Clients depend on the server. The
server is usually a much more powerful computer.
D
D-Channel: Delta Channel. With ISDN the D-Channel is
used for signaling only.
DID: Direct Inward Dialing. A
feature that allows an outside caller to dial a phone number that will
ring directly to a specific party instead of calling a main phone number.
Each workstation is assigned a direct phone number.
DLCI:
Data Link Connection Identifier. This is a Frame Relay term which defines
an address field in a frame packet.
DSL: Digital
Subscriber Line. This is a generic term and refers to all types of Digital
Subscriber Lines. It runs over your existing copper telephone lines (POTS)
and offers extremely high transmission rates, up to 8 Mbps. DSL is
distance sensitive and a DSL user must be with 12,000 to 15,000 feet of
the telephone company's Central Office.
Digital: Refers to
the use of a binary code (ones and zeros) to represent information as
opposed to an analog signal (waves).
E
E-commerce: Electronic Commerce. Buying and selling
products and services on-line via the Internet.
Ethernet:
The physical layer that allows Ethernet devices to communicate over
coaxial or twisted pair cable. Ethernet is 10 Megabits per second
and is the foundation for FAst Ethernet(100) and Gigabit
Ethernet(1000). 10G is under development at this time and uses the
same fundamental design as the first Ethernet specification.
F
Fast Ethernet: 100Base-T Ethernet running at 100
Megabits per second, 10 times faster than 10Base-T
Ethernet
Fractional T-1: Refers to a data transmission speed
between 56 Kbps and 1.54 Mbps. Channels are typically 64k in
size.
Frame Packet: A block of data grouped into variable length
frames, which are transmitted through a Frame Relay
network.
Frame Relay: A network usually maintained by a
local phone company where businesses can connect to multiple locations via
a single physical connection. Frame Relay can connect 2 or more
branch offices to a central office, for example. Frame Relay is an
affordable way to link offices in a secure way. Traffic passing on
Frame Relay is kept private, and is not exposed to the Internet.
G
Gigabit: One thousand million bits or 649
T-1s. When applied to Ethernet, GigE is 10 times faster than
100Base-T Fast Ethernet.
H
HDSL: High-bit-rate-Digital Subscriber Line (DSL).
Bandwidth is symmetrical, or equal in both directions of the data
transmission, unlike ADSL which provides a higher download than upload
speed.
Hub: In data communications world, a hub is kind of
like a central meeting place where data arrives from one or more
directions and is forwarded out in one or more other directions. Generally
a hub includes some kind of switch. Some times the switch could also be
the hub, the hub is the place where data comes together and the switch
decides how and where data is send. Not to make things to confusing but a
switch can also include a router.
I
ISDN: Integrated Services Digital Network. A service
which runs over existing telephone lines. (POTS). There are two types of
service: Basic Rate Interface (BRI) and Primary Rate Interface (PRI).
BRI includes two B-Channels and a D-Channel. The B-Channels can be used
for data, voice, and video. The D-Channel is used for signaling. PRI has
23 B-Channels and a D-Channel. Each B-Channel can transmit at 64
Kbps.
IPX: Inter-network Packet Exchange is a networking
protocol from Novell that connects NetWare clients and
servers.
ISP: Internet Service Provider. A company from
which you purchase access to the Internet.
J
Jack: In telecommunications, the jack is where the
data or voice line terminates within your building. "I plugged my phone
into the jack on the wall." Types of jacks include the RJ11 (mostly used
for analog voice, fax, modem lines), the RJ45 and the RJ48 (mostly used
for high speed digital data lines such as T-1s), etc.
K
Kb: Kilobyte. 1,024 bytes. "We used to get 40 Kbps
with our analog line internet connection, but now that we have a digital
ISDN line, we get 128 Kbps speed instead."
L
LAN: A Local Area Network is comprised of two or
more computers, which share resources, such as printers and
software.
LATA: In the telecommunications industry, the US
is divided into LATA's (local access and transport area) which are covered
by one or more local telephone companies. The local telephone companies
are also referred to as local exchange carriers. A LATA may have one or
more area codes.
M
Mainframe: This is a type of computer that is
associated with centralized rather than distributed
computing.
Mbps: Megabytes per second. 1,048,576 bytes per
second. "Our T-1 provides us with a speed of 1.54
Mbps."
Multiplexing: Multiplexing is sending multiple
signal streams of information on a carrier at the same time in the form of
a single signal. At the other end of the transmission it is recovered and
separated. Analog signals are commonly multiplexed using
frequency-division multiplexing, in which the carrier bandwidth is divided
into sub-channels of different frequency widths, each carries a signal at
the same time. Digital signals are commonly multiplexed using
time-division multiplexing, in which the multiple signals are carried over
the same channel in alternating time slots.
N
Network: A Local Area Network, LAN, ties together
printers, servers, routers, and PCs. The network of a long distance
company ties together their switches and POPs. The internet is a public
network that ties together millions of computers via routers and switches.
See also WAN.
NNI: Network to Network Interface. A term
used in conjunction with Frame Relay and describes the connection between
two public Frame Relay networks.
O
OC Levels: Optical Carrier Levels (OCx), a set of
signal rate multiples for transmitting digital signals on optical fiber.
The base rate (OC-1) is 51.84 Mbps. OC-2 runs at twice the base rate, OC-3
at three times the base rate, and so forth. Planned rates include OC-1,
OC-3 (155.52 Mbps), OC-12 (622.08 Mpbs), and OC-48 (2.488 Gbps). ATM makes
use of some of the Optical Carrier levels.
On-line: Turned
on, connected and ready to receive and send data.
Optical
Fiber: Optical fiber (or "fiber optic") is a transmission medium
associated with the transmission of information as light pulses along a
glass or plastic wire or fiber. Optical fiber carries a lot more
information than copper wire and is usually not subject to electromagnetic
interference and the need to retransmit signals. Most of Verizon's
inter-office telephone lines are now of optical
fiber.
OPX: Off Premise Extension. A dedicated phone line
between two physical points purchased from your local phone company. This
allows a branch office to access all of the features of your main
location's PBX.
P
PBX: Private Branch Exchange. A switching device
located at your company, which allows you to transfer calls, make
conference calls, or call another extension within your company,
etc.
Peer-to-Peer Architecture: A relatively simple LAN in
which all computers have similar capabilities and share information, as
opposed to a client-server environment in which the computers depend on
other dedicated, more powerful computers (a server) to perform most
functions.
POP: Point of Presence.
POTS:
Plain Old Telephone Service. It refers to the telephone lines that most
homes and businesses have.
PRI: Primary Rate Interface. A
type of ISDN service that includes 23 B-Channels and a
D-Channel.
Protocol: In the data world, we require a set
of rules for communicating that two or more end stations use. Protocols
provide these rules of data communication. All end points must agree on
the same protocol. TCP/IP is a protocol.
PVC: Permanent
Virtual Connection. A logical path that is software defined in a public
network by a carrier within a packet-switched network such as Frame Relay.
The actual pathway through the packet-switched network may change due to
routing around downed or busy connections, providing advantages over a
simple point to point data circuit which has no routing ability to avoid
congestion.
Q
QoS: Quality of Service. A subjective term used to
measure the "quality of service" of a product or service offered by a
carrier. Also used in reference to certain products specifically, such as
ATM. ATM is a "quality of service" product since it provides different
levels of quality depending on which type of data you want to transmit,
such as voice, data or video. You need a higher quality of service
(constant stream of data) if you want to transmit video, than if you do if
you want to send and receive intermittent data ("bursty" stream of data).
R
Router: Can connect LANs and WANs. Routers are the
"gateway" that allows network traffic pass from one LAN to another.
All connections to the Internet pass through a router to reach the
ISP. Routers can re-route traffic over secondary routes in the event
a primary route goes down. TCP/IP (The Internet protocol), and IPX
are examples of routable protocols.
S
SDLC: Synchronous Data Link Control is a
transmission protocol that was developed by IBM in the 1970s to replace
IBM's binary synchronous (BSC) protocol.
Server: A
computer that is accessed by other computers (clients) to share resources.
The server is usually the most powerful computer in a
LAN.
Server-based Computing: Using Microsoft Terminal
Services and Citrix Metaframe, PC applications are "served" by powerful,
centralized application servers to client computers. The
applications run on the server's CPU and resources and are not dependent
on the client for processing.
SNA: Systems Network Architecture
is a proprietary IBM architecture for network computing within an
enterprise. With the advent of multi-enterprise network computing, the
Internet, and TCP/IP, IBM is finding ways to combine its own SNA within
the enterprise with TCP/IP for applications in the larger
network.
Switch: A device that opens or closes circuits to
select paths for data or voice to travel through.
T
T-1: High speed connection with a transmission rate
of 1.54 Megabytes per second.
T-3: High speed connection
with a transmission rate of about 28 T-1's or 45 Megabytes per
second.
Time-Division Multiplexing: In this type of
multiplexing numerous signals are combined on a single communications line
or channel. Each signal is broken up into many segments, each having very
short length.
TCP/IP: An open protocol, which means that
it isn't tied to any one particular hardware or software vendor. Just
about any vendor's hardware or software can work with TCP/IP. In contrast,
both NetWare and Windows NT Server like to use their own protocols, which
were developed by Novell and Microsoft, respectively.
TCP/IP
works with whatever network cabling you already have installed. Thus, you
can run TCP/IP on your existing Ethernet network cables.
TCP/IP doesn't
conflict with NetWare or Windows NT Server protocols. Thus, you can run
NetWare, Windows NT Server, and TCP/IP networks together, over the same
cables, at the same time.
To build a TCP/IP network, all you need to
add are software drivers to the computers that you want to participate in
the TCP/IP network. You don't have to purchase special network cards or
other hardware.
Trunks: A special phone line used in conjunction
with PBXs purchased from your local telephone company to supply you with
dial-tone.
U
Upload: The transmission of data from your computer
to another computer, as opposed to "download" which is the receiving of
data to your computer from another computer.
V
VPN: Virtual Private Network. Uses a shared public
data network (Frame Relay, Internet) as the medium to communicate between
multiple locations that can be separated by long distances. This tends to
be a less expensive option than dedicated leased data circuits.
W
WAN: Wide Area Network. A network that interconnects
remote computers or remote site LANs via dedicated telecommunications
circuits using Frame Relay, ATM, Wireless, or other data communications
technologies.
WEP: Wired Equivalency Protocol. A
weak security standard designed to secure data passed over wioreless
networks usually using the 802.11b standard.
