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56K Dialup
One of the cheapest and most popular ways for a home user to access the Internet, this kind of
connection uses standard telephone lines to link your desktop to the Internet.The term 56K refers to a new generation of modems that improve the speed
of communication between personal computers and the Internet. The previous
speed standard of v.34 provided communication at speeds as high as 33,600
bits per second (bps). The new 56K modems increase that speed to a theoretical
maximum of 57,600 or 56Kbps. In the past, two different technologies
emerged enabling 56K communication: K56flex and x2. They have been replaced
by a new, international standard for 56K data communications known as
v.92.
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A
ADSL
Asymmetric Digital Subscriber Line: Modems attached to twisted pair
copper wiring that transmit from 1.5Mbps to 9Mbps downstream (to the
subscriber) and from 16Kbps to 800Kbps upstream, depending on line distance.
ADSL Lite
A lower data rate version of Asymmetric Digital Subscriber Line (ADSL)
technology.
Analog
A signal that can take on any value in a range. Contrast with Digital.
Asymmetrical
Offering different data rates in the upstream and downstream directions,
where upstream is the direction from the end-user to the network, and
downstream is the direction from the network to the user.
ATM
A connection-oriented, packet-like switching technology that utilizes
virtual channels instead of dedicated circuits to carry data in fixed-length
(1 cell = 53 bytes) over a broadband network.
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B
Bandwidth
- The information carrying
capacity of a channel. Expressed in hertz (e.g., kHz or MHz) for analog
transmission media and in bits per second (e.g., kbps, Mbps) for digital
transmission media.
- The width of a channel's
passband (e.g., the bandwidth of a channel with a 300 to 3400 Hz passband
is 3100 Hz, or 3.1 kHz).
Bridge Unit
In telecommunications networks, a bridge is a product that connects
a local area network (LAN) to another local area network that uses the
same protocol (for example, Ethernet or Token Ring). A bridge examines
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 (or
LANs).
Broadband
A term for high-speed, high-capacity Internet and data connections.
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C
Cable Modem
A device that attaches between a PC and an analog cable TV distribution
plant that can modulate and demodulate user data onto/from the cable
plant. It allows cable TV companies to provide data transmission capabilities
to customers over existing infrastructure.
CAP
Carrier-less Amplitude/Phase (CAP) modulation; incoming data modulates
a single carrier that is then transmitted down a telephone line. The
carrier itself is suppressed before transmission (it contains no information,
and can be reconstructed at the receiver), hence the adjective "carrier-less." CAP and DMT are two modulation systems currently on the market for ADSL.
CDSL
Consumer Digital Subscriber Line (CDSL) is a proprietary technology
trademarked by Rockwell International.
Channel
A transmission path between two points. The term channel usually refers
to a one-way path, but when paths in the two directions of transmission
are always associated, the term channel can refer to this two-way path.
CPE
Customer Premises Equipment - Any equipment provided by the customer
at their premises.
Customer Self-Install
(CSI)
Customer Self-Install uses customer-installed low-pass microfilters
for each line analog device (typically telephones, fax machines, etc)
to filter out any DSL signal noise from your voice service, allowing
both voice and data to share common inside wiring. The filters are placed
between the analog devices and the phone jack(s) and do not require
any tools for installation.
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D
Data
A formal representation of raw material from which information is constructed
via processing or interpretation.
DHCP
Dynamic Host Configuration Protocol. DHCP lets a network administrator
supervise and distribute IP addresses from a central point, and automatically
sends a new address when a computer is plugged into a different place
in the network.
DMT
Discrete Multi-Tone (DMT) multicarrier modulation uses 256 QAM modulation
tones simultaneously to create the ADSL signal. DMT is the basis of
ANSI Standard T1.413, and has the support of other world standards bodies.
CAP and DMT are two modulation systems currently on the market for ADSL.
Downstream
Downstream refers to "host to end-user" (receive, download) direction.
DSL
A telecommunications line that provides a fast, permanent connection to the Internet. DSL uses the
copper wiring found in almost every home and office. Special hardware attached at both ends of the
line allows data to transmit at a far greater speed than standard telephone wiring can. It also
provides a constant connection to the Internet, 24/7, so there is no need to dial-in to an ISP each
time you want to get online. A DSL line is also convenient because you only need one line to carry
both voice and data signals (in other words, you don't have to get a second phone line with DSL).
DSL is similar to ISDN in that they both operate over existing copper telephone lines and require
short runs to a central office. (The reason why DSL is not yet available in many areas is because
of the distance from a central office.) DSL provides higher speeds than ISDN, but with DSL, the
connection speeds vary. Many people prefer the fixed speed of an ISDN (or a T1, for that matter).
Connection speeds for DSL typically range from 512 Kbps to 8192 Kbps downstream and 128 to 2084 Kbps
upstream. There are several types of DSL, most common are:
ADSL (Asymmetric DSL, where you can download faster than upload)
SDSL (Symmetrical DSL, where download and upload speeds are similar)
IDSL (ISDN DSL, which is DSL over an ISDN line)
DSL Gateway
DSL Gateways are made up of DSL network equipment, housed in specialized
buildings, that enable residential and business customers to receive
DSL Internet Service who previously had been located too far from their
central switching office to get the service. In effect, they act as
miniature central offices that are able to deliver DSL Internet Service
beyond the standard 14,000 foot limit of a traditional central office.
DSLAM
Digital Subscriber Line Access Multiplexer. Specifically, a device which
takes a number of ADSL subscriber lines and concentrates these to a
single ATM line.
DSL Modem
Short for MOdulator-DEModular, this hardware device converts ATM cells
to Ethernet packets and visa-versa in the use of DSL.
Dynamic IP Addressing
An IP address is assigned to the customer for their current session
or some other ISP-specified amount of time. The alternate to a dynamic
IP address is a Static IP address.
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E
EtherLoop
EtherLoop is currently a proprietary technology from Nortel, short for "Ethernet Local Loop."
Ethernet Connection
A high speed direct connection to a network where an Ethernet network
interface card (NIC) is installed so that the user can access any host
connected to the network.
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F
Firewall
A security device that controls access from the Internet to a local
network.
Frame Relay
A packet interface protocol that adheres to the ANSI/ITU-T standard. Frame relay has a few advantages
over ISDN. For one thing, you can purchase frame relay lines in increments between 56K and 1.5 Mbps
(equivalent to a T1 connection). Since frame relay is designed for data transfer only, it's not well
suited for video conferencing or any other voice application.
Frame relay is sometimes confused with a leased line. Both are primarily used to extend a local area
network (LAN) between business branches, but a leased line is a dedicated line (permanently connected
between sites), whereas frame relay uses the telephone company's shared network on an as-needed basis.
Full Duplex
Refers to the transmission of data in two directions simultaneously.
In full-duplex mode, data you transmit does not appear on your screen
until it has been received and sent back by the other party. This enables
you to validate that the data has been accurately transmitted.
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H
HDSL
High Bit-rate Digital Subscriber Line (HDSL) technology is generally
used as a substitute for T1/E1.
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I
IDSL
ISDN-based DSL technology developed originally by Ascend Communications.
Info-tainment
A combination of traditional elements of video, film, graphics, animation,
music, audio, and text for the purposes of providing information and/or
entertainment. Often characterized by hyperlinks among the various media.
Integrated T-1
Integrated T1 service is just what the name implies, voice and data traffic on the same T1. A T1 has
24 channels (23 with a PRI) to work with, you can divide up the load according to your needs. for
example, your company may have 10 phone lines. The PRI (on hold to avert dropped calls) can allocate
10 DS-0 lines for Voice, and 14 DS-0 lines for Internet. In this example, your company could handle
10 simultaneous calls while surfing the web at a speed of 896 KBPS. Just a quick note: If 14 users
are online for data, the 896 k "pipe" will slow down per user. Total bandwidth divided by the number
of connections will reduce access speed per user. Normally this is not an issue. If the KPS varies
per connection, this in not a service issue - the bandwidth adjusts to the number of connections.
Internet
The globally interconnected collection of IP protocol based networks.
Intranet
A corporate network that uses an IP network structure, together with
Web servers and browsers. Intranets are generally used to provide information
such as benefits plans, etc. to corporate employees in an easily accessible
fashion.
IP
Internet Protocol
IP Video
An encoding mechanism that is used to transmit motion video clips over
an IP network.
IP Voice
A technology that enables voice traffic to be transmitted over any network
that uses IP (the Internet Protocol), including LANs, WANs, and the
Internet.
ISDN
Integrated Services Digital Network: A completely digital telecommunications network for carrying
voice, data, images, and video at high speed by sending digitally-encoded signals. ISDN provides
end-to-end digital service and can work on the copper wiring phone lines found in most homes and
businesses today. One ISDN line supports data rates of 64K, most telephone companies will offer
two lines, called B-Channels, which can be used on their own or can be bonded together to give a
transfer speed of 128K per second.
ISP
Internet Service Provider
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K
kbps
Kilobits (or thousands of bits) per second. When used in reference to
transmission rates, the prefix kilo means exactly one thousand.
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L
LAN
Local Area Networks - A network of interconnected computers that is
distinguished by its small geographical size (typically measured in
meters), privately owned, high-speed (usually measured in megabits per
second), and low error rate (typically 1 bit in a trillion).
Line Card
A line card is a circuit pack which sends signals from the Central Office
to equipment used on the customer's premises. These signals provide
the intelligence needed to make terminal equipment work.
Load Coil
A metallic, doughnut shaped device used on local loops to extend their
reach. Load coils severely limit the bandwidth in digital communications.
Local Loop
The local loop is a 2-wire non-loaded copper wire pair with no bridged
taps. The local loop is terminated at the customer's premises on a standard
network interface which is supplied by either the customer or a vendor.
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M
Mbps
Megabits (or millions of bits) per second. When used in reference to
transmission rates, the prefix mega means exactly one million.
Microfilters
The microfilter is used to protect the DSL signal from being contaminated
by any signal noise from your voice service, allowing both voice and
data to share common inside wiring.
Modem
Originally short for modulator/demodulator, modem has become common
usage. An electronic device that modulates an analog carrier, enabling
digital information to be sent over analog transmission facilities.
MSO
Multiple service operator synonymous with cable provider.
Multilink
A protocol standard that provides higher Internet access speeds and greater bandwidth than a standard
56K dialup connection. Multilink uses two modems to connect to the Net simultaneously, at double the
speed of a single modem. It requires two modems, a phone line, a multilink dial-up account, and a PC
running Windows 98 (or higher) or Windows NT; also, your ISP must have the necessary hardware and
software to support this service.
Multiplexing
Transmitting several messages simultaneously on the same circuit or
channel.
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N
NAP
Network Access Point (NAP) is a high-speed interconnection service that
gives Internet Service Providers access to the new Internet infrastructure.
Narrowband
Traditionally, a channel with bandwidth less than or equal to one voice-grade
line. With advances in network technology, narrowband has come to be
associated with any channel operating at less than 1.544Mbps, such as
Narrowband ISDN (NISDN). Contrast with Broadband and Wideband.
Network Interface
Card (NIC)
A expansion board you insert into a computer so the computer can be
connected to a network. Most NICs are designed for a particular type
of network, protocol, and media, although some can serve multiple networks.
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P
PC Card
Term used for laptop NIC cards
POTS
Plain Old Telephone Service - Basic analog telephone service with no
frills or special facilities.
POP
Point of Presence - The point within a Local Access and Transport Area
(LATA) at which the Interexchange Carrier (IEC) establishes itself.
The POP provides the IEC with LATA access and enables the Local Exchange
Carrier (LEC) to access inter-LATA services. Also, the consolidation
point in a local calling area where traffic is routed to an Internet
Service Provider (ISP).
PPPoE
Point to Point Protocol over Ethernet. PPPoE is software that works
with a NIC to simulate a dial-up session and allows dynamic IP address
assignment.
Private Line
A Private Line is a dedicated digital route through a telecommunication network. It is the typical
method that companies use to connect their local networks to a broader corporate WAN. The Internet
is fundamentally a collection of Private Lines. The definition of Private Lines covers almost all
physical WAN interconnect lines such as ISDN, T1, T2, T3, etc.
Private Branch Exchange
(PBX)
A PBX is a private telephone switch that provides switching (including
a full set of switching features) for an office or campus. PBXs often
use proprietary digital-line protocols, although some are analog-based.
PSTN
Public Switched Telephone Network - The dial-up, circuit-switched telephone
network.
PVC
Private Virtual Circuit (PVC) is a point-to-point circuit from the customer
premise equipment to either their Internet Service Provider (ISP) or
Enterprise Network.
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R
RADSL
Rate Adaptive Digital Subscriber Line (RADSL) technology is any rate
adaptive DSL modem, but may specifically refer to a proprietary modulation
standard designed by Globespan Semiconductor.
Repeater
In telecommunication networks, a repeater is a device that receives
a signal on an electromagnetic or optical transmission medium, amplifies
the signal, and then retransmits it along the next leg of the medium.
Repeaters overcome the attenuation caused by free-space electromagnetic-field
divergence or cable loss. A series of repeaters make possible the extension
of a signal over a distance. In addition to strengthening the signal,
repeaters also remove the "noise" or unwanted aspects of the signal.
Router
A device that routes data between networks using IP addressing. Routers
provide firewall security.
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S
SDSL
Symmetric Digital Subscriber Line (SDSL) technology is a 2-wire implementation
of HDSL.
SOHO
Small Office Home Office. A category of remote users.
Splitter
A device that separates the ADSL signal into the voice and data components.
More generally a device that separates signal components based on their
frequency content. A filter which separate high frequency (ADSL) and
low frequency (POTS) signals at both the end user and central office
end points.
Static IP Addressing
An assigned IP address used to connect to the Internet The IP address
stays with the customer's computer. Common needs for static IP include:
web or email server hosting, virtual private networks (VPN), and remote
connection to secure corporate networks or some external applications.
The alternate to a Static IP address is a Dynamic IP address.
Switch
A device that can establish communication channels between end-users.
A circuit switch provides dedicated paths to communicating entities;
a store and forward switch shares paths on a statistically multiplexed
basis.
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T
T-1
A leased line connection capable of carrying data at a very high speed (as in 1,544,000 bps
or 1.544 Mbps). At maximum theoretical capacity, a T1 line could move a megabyte in less than
10 seconds but that is still not enough bandwidth for full-screen, full-motion video (for which
you need at least 10,000,000 bps). T1 is the fastest telephone trunk line commonly used to connect
networks to the Internet.
T-3
An extremely fast high-bandwidth connection (similar to a T1 but even faster), capable of
transferring data at 44,736,000 bps (or 44.21 Mbps). This is more than enough speed to provide
full-screen, full-motion video. T3 lines are most commonly used by ISPs and large networks.
Telco
The telephone operating company or the local provider of telephone service.
TN
Telephone Number
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U
Upstream
Upstream refers to "end-user to host" (transmit, upload) direction.
The direction from an end-user to the network.
USB
Universal Serial Bus or Port, connection port on a computer that is
universally compatible with many types of devices, such as, printers,
speakers, mouse, etc. Can support speeds of up to 12Mbps.
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V
v.90
An international standard for 56K data communications.
v.92
A new, international standard for 56K data communications. This standard
increases the upload speed, allows a data call to be put on hold to
take an inbound voice call, and shortens the time to make a connection.
VDSL
Very High Bit-rate Digital Subscriber Line (VDSL) technology is proposed
for shorter local loops, perhaps up to 3000 ft. It provides 13 - 53Mbps
downstream and 1.5 - 2.3Mbps upstream.
Virtual Circuit (VC)
Interface between Access Node and network. May have multiple physical
connections although may also carry all signals across a single physical
connection.
VPN
Virtual Private Network. A secure private network that uses the public telecommunications infrastructure to transmit data.
In contrast to a much more expensive system of owned or leased lines that can only be used by one
company, VPNs are used by enterprises for both extranets and wide area intranets. Using encryption
and authentication, a VPN encrypts all data that passes between two Internet points, maintaining
privacy and security. In order to take advantage of a VPN service, you will need a static IP number,
a dedicated connection to the Internet, and a router (or switch) that supports VPN protocol.
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W
WAN
Wide area network.
Wideband
Variously defined. The term wideband is often used to describe a digital
transmission facility operating at speeds in excess of 1.544Mbps. It
is also used in the analog domain to describe a channel with a large
bandwidth (e.g., "the CATV industry offers a collection of wideband
channels")
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X
XDSL
Refers to the family of digital subscriber line technologies, such as
ADSL, HDSL, IDSL, RADSL, SDSL and VDSL. |
