T1 American standard 1544 kbit/s
 E1 European standard 2048 kbit/s
 T2 American standard 6 Mbit/s (4 x T1, exotic)
 E2 European standard 8 Mbit/s (4 x E1, exotic)
 E3 European standard 34 Mbit/s (4 x E2)
 T3 American standard 45 Mbit/s (7 x T2, used a lot)
 OC-1 American standard 51 Mbit/s (SONET, verpakt 1 T3)
 E4 European standard 140 Mbit/s (4 x E3)
 OC-3 American standard 155 Mbit/s (SONET, 3 x OC-1)
 STM-1 European standard 155 Mbit/s (SDH snelheid = OC-3)
 STM-4 European standard 622 Mbit/s (4 x STM-1)
 STM-16 European standard 2488 Mbit/s (16 x STM-1; 2,5 Gbit/s)
 STM-64 European standard 9952 Mbit/s (16 x STM-1; 10 Gbit/s)

 Japanners kennen wel de T1 maar multiplexen in een andere hiërarchie
 naar 32 Mbit/s en 96 Mbit/s. Formeel zijn er geen American
 standards boven T3, in de praktijk zijn er veel proprietary
 transmissiesystemen gebouwd in de jaren tachtig tot 1,8 Gbit/s.
 In Europa zijn ook nog 565 Mbit/s (4 x E4) veelvuldig ingezet.

 SONET/SDH is midden jaren tachtig op de rails gezet
 om de wildgroei te temmen en voor de hogere snelheden
 wereldstandaarden te definiëren. In de praktijk is dat
 pas redelijk gelukt op snelheden van 155 Mbit/s en hoger
 en dan in hoofdzaak op de optische interfaces (die zijn identiek).

 De American SONET-standards volgen dezelfde hiërarchie als SDH,
 dus OC-12 = 622 Mbit/s, OC-48 = 2,5 Gbit/s, OC-192 = 10 Gbit/s

 Toekomst:
 STM-256 en/of OC-768 40 Gbit/s (2001 of 2002)

 Optisch: DWDM golflengte-multiplexen
 Wordt geleverd in kanalen, per kanaal 2,5 Gbit/s of 10 Gbit/s
 16 kanalen 40 Gbit/s  (officiële standard ITU)
 32 kanalen 80 Gbit/s  (Lucent Wavestar 80G)
 40 kanalen 100 Gbit/s (Ciena)
 96 kanalen 240 Gbit/s (Ciena)
 ook
 16 kanalen 160 Gbit/s
 40 kanalen 400 Gbit/s (Lucent Wavestar 400G, prototypes beschikbaar)
 128 kanalen 1,28 Tbit/s (Pirelli-TeraMux)
 160 kanalen 1,6 Tbit/s (OPTera/Nortel)

=====================================================================

backbone

The top level of a hierarchical network. The main pipes along which
data is transferred. The "Internet backbone" is sometimes referred to, though it doesn't exist.


bandwidth

1. The amount of information or data that can be sent
over a network connection in a given period of time.
Bandwidth is usually stated in bits per second (bps),
kilobits per second (kbps), or megabits per second (mps).
2. The technical meaning is generalized in hacker slang.
Individuals are said to be "high bandwidth" if they are able
to process large volumes of information in short periods of time.


baud

The speed of a modem. Specifically, the number of times per second
a communications channel changes the carrier signal it sends on the
phone line. A 2400-baud modem changes the signal 2400 times a second.

Baud is often confused with bits per second (bps).
They are technically different measurements!


bit

Short for binary digit, the basic unit of computer storage.
All computer information is ultimately represented as bits.
Computer processing capability is evaluated by the number of bits
handled at once.
Personal computers utilize 8-, 16-, 32-, or 64-bit microprocessors.

Stands for binary digit. A bit is either on or off and is represented by "1" or "0". A collection of bits are put together to form a byte.


Bits

A bit is the smallest unit of data in a computer.
A bit has a single binary value, either 0 or 1.
Although computers usually provide instructions that can test
and manipulate bits, they generally are designed to store data
and execute instructions in bit multiples called bytes!
In most (!) computer systems, there are eight bits in a byte.
The value of a bit is usually stored as either above or below
a designated level of electrical charge in a single capacitor
within a memory device. 


bit rate

The speed of a digital transmission, measured in bits per second.


bps (bits per second)

The speed at which data bits are transmitted
over a communications medium, such as a transmission wire
or a modem. Common PC modem speeds are 28,800 and 14,400 bps.
Often expressed in thousands of bits (kilobits) per second.

Abbreviation for bits per second. A measurement of the number
of bits of information that can be sent over a network connection.


byte

A group of 8 bits. Usually the smallest addressable unit of
information in a data memory storage unit. A single 8-bit byte
can describe 256 different binary numbers or values,
which is important in discussions of color palette,
pixel depth, and audio sample depth.
Usually each byte stores one character. 

A collection of bits to form a binary number.
The size of bytes varies from system to system.
On the original home computers, bytes were composed of 8 bits.
Now many computers operate with bytes that are 32 bits long. 

In most computer systems, a byte is a unit of information
that is eight bits long. A byte is the unit most computers use
to represent a character such as a letter, number, or typographic
symbol (for example, "g", "5", or "?"). A byte can also hold a string
of bits that need to be used in some larger unit for application
purposes (for example, the stream of bits that constitute
a visual image for a program that displays images). 


data

Plural of datum, a piece of information. Generally, information
of any type, but especially any information in a computer.


data rate

The amount of data or bits of information transmitted or moved
in a certain time period, usually expressed as bits or bytes
per second. In reference to .asf files, the amount of data
that must transmit in a given second for the whole file to be heard.
For a file to transmit completely and smoothly, its data rate
must be less than the bandwidth of its target network.


download

To transfer data from a larger "host" system to a smaller
"client" system's hard drive or other local storage device.


Ethernet

Ethernet is the most widely-installed local area network technology. 
Now specified in a standard, IEEE 802.3, Ethernet was originally
developed by Xerox and then developed further by Xerox, DEC, and Intel.
An Ethernet Local Area Network (LAN) typically uses coaxial cable
or special grades of twisted pair wires (TP, UTP mostly).
The most commonly installed Ethernet systems are called 10BASE-T
and provide transmission speeds up to 10 Mbps. Devices are connected to the cable and compete for access using a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol.


Fast Ethernet 

Fast Ethernet is an upgraded standard for connecting computers
into a local area network (LAN). It works just like regular
Ethernet except that it can transfer data at a peak rate of 100 mbps.
Also referred to as 100BaseT, fast Ethernet is more expensive
and less common than its slower 10BaseT sibling.


K

Kilo-. Informally, 1,000. Technically, 1,024, so
64 K is actually 65,536.
Uppercase "K" is often used for kilobyte,
lowercase "k" for kilobit.


KB (kilobyte)

1,024 bytes. Approximately equivalent to
half a sheet of paper's worth of typing, double spaced.


Kb (kilobit)

1,024 bits. Also kb. 


Kbps (kilobits per second)

The common measurement of Internet bandwidth and
data transmission rates.
Refers to transmission speed of 1,024 bits per second. 

In the U.S., Kbps stands for thousands of bits per second
and is a measure of bandwidth (the amount of information
that can flow in a given time) on a data transmission medium
such as twisted-pair copper cable or coaxial cable.
On coaxial cable, bandwidth may also be in the
Mbps (millions of bits or megabits per second) range
and, on optical fiber, in the
Gbps (billions of bits or gigabits per second) range. 


Mbps (Megabits per second)

Equivalent to one million bits per second. 

Mbps stands for millions of bits per second and is a measure
of bandwidth (the total information flow over a given time)
on a data transmission medium such as twisted-pair copper cable,
coaxial cable, or optical fiber. Depending on the medium and the
transmission method, bandwidth may also be in the Kbps (thousands
of bits or kilobits per second) range or the Gbps (billions
of bits or gigabits per second) range


Megabyte (Mb or MEG)

As a measure of computer processor storage and real and
virtual memory, a megabyte (abbreviated
Mb) is 2 to the 20th power bytes, or
1,048,576 bytes in decimal notation. 


modem (modulator, demodulator)

A device that you connect to your computer and to a phone line
to allow communication with other computers through the phone system.
Modems convert the computer's digital signals into analog waves
that can be transmitted over standard voice telephone lines.
Modem speeds are measured in bits per second (bps),
also sometimes expressed as kilobits (thousands of bits) per second.


palette

In 8-bit images or displays, only 256 different can be displayed
at any one time. This collection of 256 colors is called the palette.
In 8-bit environments, all screen elements must be painted with the
colors contained in the palette. The 256 color combination
is not fixed—palettes can and do change frequently.
But at any one time, only 256 colors can be used to describe
all the objects on the screen or image

pixel depth

The number of bits of color information per pixel.
On a computer monitor, each pixel may be represented
by a variable number of bits that are used to describe
the color of the pixel. Pixel depth determines how many
different colors are available. This table shows the relationship:

Pixel Depth Available Colors 
2-bit black ½ white
4-bit 16 colors 
8-bit 256 colors 
16-bit 65,356 colors 
24-bit 16,700,000+ colors 


resolution

1. The number of pixels in a file. When applied to digital video
or images, it refers to the three-dimensional measure of the frame
or image composition. Expressed as a series of three numbers, such
as 320 X 240 X 24, where the first number is the horizontal width in
pixels, the second number is the vertical height in pixels, and the
third number is the number of bits describing the color of each pixel
(pixel depth). 
1. The width and height of the video window or computer monitor display,
in pixels. Also screen resolution. 


sample depth

Bits per sample. The number of bits used to record a single sample
of audio, usually 8-bit (256 values) or 16-bit (65,536 values).
A higher sample depth results in a more accurate representation
of the original signal and higher-quality sound. Compare sample rate.


sample rate

The number of samples taken of a signal per unit time, usually
expressed as samples per second. The higher the sample rate,
the more digital sound data that is recorded, resulting in
higher-quality sound and a more accurate recording.
Typical sample rates are 8 kHz, 11 kHz, 22 kHz, and 44.1 kHz.
CD-quality audio is recorded at 44.1 kHz. Also sample frequency.
Compare sample depth. 


stream

v. To transmit multimedia files which begin playing upon arrival
of the first packets, without needing to wait for all the data to arrive.
To send data in such a way as to simulate real-time delivery of
multimedia. The flow of streaming multimedia.
In NetShow, this stream is a common format (ASF) that can be rendered
by Microsoft Media Player. The data output by NetShow Server is a stream.
adj. streamed, streaming Files or multimedia that stream.
For example, an ASF is a streaming file containing streamed media.


T1

A leased-line connection capable of carrying data at 1.544 Mbps,
T-1 is currently the fastest speed commonly used to connect networks
to the Internet. At maximum theoretical capacity, a T-1 line
could move a megabyte in less than 10 seconds.


T3

A leased-line connection capable of carrying data at 44.736 Mbps,
T-3 is currently the fastest possible Internet connection.
Equivalent in bandwidth to 28 T1s. T3 is sometimes called
a 45-meg circuit.

10BaseT 

The most common form of Ethernet is called 10BaseT,
which denotes a peak transmission speed of 10 mbps
using copper twisted-pair cable. Ethernet is a standard 
for connecting computers into a local area network (LAN).


Baudrate

Snelheid van datatransmissie gerekend in bytes per seconde,
huidige modems ondersteunen veelal 14k4, of 28k8, dus 14.400,
of 28.800 bits per seconde.


Bit

Representatie van 0 of 1 in de computer, kleinste rekeneenheid
voor gegevens op computers. 8 bits vormen samen 1 byte.


Bps (bytes per second)

Voor stroomsnelheden van datatransmissie wordt gerekend in bytes
per seconde aldus ontstaat de volgende reeks: Bps, Kps, Mps, Gps.


Byte

Kom uit de reeks Byte, Kilobyte, Megabyte, Gigabyte.
Een Byte is acht bits voorafgegaan door een start bit
en beeindigd door een eindbit, de tussenliggende acht bits
worden gebruikt om karakters op te bouwen, of om andere gegevens
in op te slaan. Voor stroomsnelheden wordt gerekend
in bits per seconde aldus ontstaat de volgende reeks:
Bps, Kps, Mps, Gps.


Data

Informatie en communicatie is samengesteld uit data,
dit zijn verzamelingen bytes in bestanden.


Datatransmissie

Overdracht van data tussen verschillende computers.
Snelheid van communicatie wordt gemeten in bytes per seconde
en wordt ook wel baudrate genoemd.


Gb of Gigabyte

Kom uit de reeks Byte, Kilobyte, Megabyte, Gigabyte.
Een Byte is acht bits voorafgegaan door een start bit
en beeindigd door een eindbit, de tussenliggende acht bits
worden gebruikt om karakters op te bouwen, of om andere gegevens
in op te slaan. Voor stroomsnelheden wordt gerekend
in bits per seconde aldus ontstaat de volgende reeks:
Bps, Kps, Mps, Gps.


Gbs (Gigabytes per second)

Een Gb per seconde. Voor stroomsnelheden van datatransmissie,
wordt gerekend in veelvouden van bytes per seconde,
aldus ontstaat de volgende reeks: Bps, Kps, Mps, Gps.


Kb of Kilobyte

Kom uit de reeks Byte, Kilobyte, Megabyte, Gigabyte.
Een Byte is acht bits voorafgegaan door een start bit
en beeindigd door een eindbit, de tussenliggende acht bits
worden gebruikt om karakters op te bouwen,
of om andere gegevens in op te slaan.
Voor stroomsnelheden wordt gerekend in bits per seconde
aldus ontstaat de volgende reeks: Bps, Kps, Mps, Gps.


Kbs (Kilobyte per second)

Een Kb per seconde. Voor stroomsnelheden van datatransmissie,
wordt gerekend in veelvouden van bytes
per seconde aldus ontstaat de volgende reeks: Bps, Kps, Mps, Gps.


Mb of Megabyte

Kom uit de reeks Byte, Kilobyte, Megabyte, Gigabyte.
Een Byte is acht bits voorafgegaan door een start bit
en beeindigd door een eindbit, de tussenliggende acht bits 
worden gebruikt om karakters op te bouwen, of om andere gegevens
in op te slaan. Voor stroomsnelheden wordt gerekend in bits per seconde
aldus ontstaat de volgende reeks: Bps, Kps, Mps, Gps.

Een Kb per seconde. Voor stroomsnelheden van datatransmissie,
wordt gerekend in veelvouden van bytes per seconde
aldus ontstaat de volgende reeks: Bps, Kps, Mps, Gps.


Mbs (Megabyte per second)

Een Kb per seconde. Voor stroomsnelheden van datatransmissie,
wordt gerekend in veelvouden van bytes per seconde
aldus ontstaat de volgende reeks: Bps, Kps, Mps, Gps.

Smileys and the likes, update 1998