Glossary of ISP Related Terms

Often too many people get confused with all the definitions, here we have explained in easy to understand terms.

ADSL
Asymmetric Digital Subscriber Line - asymmetric meaning it's faster downstream than upstream.

ASAM
Advanced Services Access Manager -Whether you have a DSLAM or ASAM in your exchange doesn't really matter. They do the same thing. See DSLAM's as well.

ATM
Asynchronous Transfer Mode - a method of encapsulation which is capable of many virtual circuits. With these, providers (ISP's) can split an ATM connection (155Mbit or 622Mbit) up into many connections. ATM isn't just used for DSL but in the case of DSL it's used to provision each customer.

Broadband
Digital technologies that offer consumers a single way to access voice, high-speed data services, video services, and interactive information delivery services.

Bandwidth
How much information you can send through a connection. Usually measured in bits-per-second (bps), kilobytes-per-second (Kbps), or megabytes-per-second (Mbps). A full page of English text is about 16,000 bits. A fast modem can move about 15,000 bits in one second.

bit
A binary digit. The unit of information that can take on one of two values, such as true or false or zero or one.

browser
Software that allows you to "surf " the Internet. Netscape, Mosaic, and Internet Explorer are examples of Web browsers. A browser provides an easy to use interface for accessing the information on the World Wide Web.

byte
The smallest addressable unit of digital storage larger than a bit and smaller than a word. A byte now consists of eight bits.

Cable Modem
A cable modem is a device that enables you to hook up your PC to a local cable TV line and receive data at about 1.5 Mbps. A cable modem can be added to or integrated with a set-top box that provides your TV set with channels for Internet access.

CPE
Customer Premises Equipment, the term that describes the equipment used on the customer end of a connection, for example your DSL modem/router or cable modem.

Dedicated Line
A communications circuit or channel for the exclusive use of a particular subscriber. For example, dedicated lines are used for computers when large amounts of data need to be moved between two points.

dial-up
A connection to the Internet or private network that uses a modem connected to your computer and a normal phone line. The connection speed is limited to 56kbps. This is the standard type of Internet connection for home use.

DSL
Digital Subscriber Line. DSL is a method for moving data over regular phone lines. A DSL circuit is much faster than a regular phone connection, and the wires coming into the subscriber's premises are the same (copper) wires used for regular phone service. DSL uses previously unused frequencies of the line so that a user may connect to the Internet and talk on the phone at the same time. xDSL refers to different variations of DSL, such as ADSL, HDSL, SDSL, VDSL and RDSL.

DSLAM
Digital Subscriber Line Access Multiplexer – They are placed in DSL enabled Telecomm exchanges, when your modem syncs up and the DSL light comes on, it means you are connected. When data travels down your connection, it goes from the CPE -> DSLAM -> RAN -> ISP

ERX
Edge Routing Exchange. See RAN.

Ethernet
A very common method of networking computers in a LAN. Ethernet will handle about 10,000,000 bits-per-second and can be used with almost any kind of computer.

FireWall
A combination of hardware and software that separates a LAN into two or more parts for security purposes. Often used to separate an in-house LAN from the Internet.

HDSL
High bit-rate Digital Subscriber Line that delivers T1 speeds. This requires two lines at present.

IDSL
DSL transferred at 128Kbps on regular copper lines. This uses ISDN transmission coding, but no form of dial-up.

IP Address
Every machine that is on the Internet has a unique IP number - if a machine does not have an IP number, it is not really on the Internet. Most machines also have one or more Domain Names that are easier for people to remember.

IPNet
Telecommunications backhaul networks for carrying traffic from the customer to the ISP, i.e. carrying traffic from RAN's to ISP's.

ISDN
Integrated Services Digital Network. Is a digital network with higher speed than found on the traditional telephone network. Even though ISDN uses existing phone lines, it does require specialized equipment. Because the network is all digital it can easily send voice, data, and video over the same line simultaneously.

ISP
Internet service provider. Where you get your Internet service.

LAN
A LAN (Local Area Network) is a computer network that spans a relatively small area. Most LANs are confined to a single building, connecting two or more computers.

Modem
Modulator-demodulator. A device that converts digital signals into analog signals and enables computers to receive data over telephone networks.

Ping or Latency
A ping measures the time in milliseconds that it takes for a packet to travel from your computer to a remote computer and back to you again. Just because you can't ping a given host, quite a lot of providers are beginning to filter ICMP (pings come under this protocol) traffic because it is commonly used to attack hosts and wastes a lot of bandwidth. Many providers also give low priority to ping (ICMP) traffic which may mean your ping at a command line isn't very good, but in say a game, things may be fine.

RAN
Regional Access Node. These aggregates many DSLAM's connections and then feed the data to an ISP.

RDSL = RADSL
Rate-Adaptive Digital Subscriber Line. The DSL equipment senses the speed limitations of the customer's phone line and adjusts the rate downward accordingly from some maximum.

Router
This is your connection between networks for DSL service. It keeps packets flowing from everywhere, directing traffic according to programmed routing tables.

RTT
Round Trip Time - the time it takes in milliseconds for a packet to go from A to B and back again. See ping.

SDSL
Symmetrical Digital Subscriber Line - symmetrical meaning the same speed up and down.

SMTP
Simple Mail Transfer Protocol. The main protocol used to send electronic mail on the Internet.

Streaming
Unlike downloading (where you save a complete file locally before you are able to play it) streaming allows you to play a file as it is being downloaded.

T1
A leased-line connection capable of carrying data at 1,544,000 bits-per-second.

TCP/IP
Transmission Control Protocol/Internet Protocol. The protocol defines a common set of rules and signals that computers on the network use to communicate.

Units

There is a major difference between UPPER and lowercase

MB = Mega Bytes
Mb = Mega bits
kB = Kilo Bytes
kb = Kilo bits

There is 8 bits to a Byte, 8 kb = 1 kB

VDSL
Very High Bit Rate Digital Subscriber Line. An asymmetric DSL that delivers from 13 to 52 megabits per second downstream bandwidth and 1.5 to 2.3 megabits per second upstream.

WAN
Wide Area Network. A computer network which connects LANs or single computers in different geographic areas together.

Wi-Fi
A wireless network equipment certification that ensures certain levels of performance, compatibility and features are available. Based on the IEEE 802.11b standard, more information is available at Wi-Fi.org.