Broadband FAQ
ADSL (Asymmetric Digital Subscriber Line)
ADSL is a data communications technology that allows for the faster transfer of data across standard copper telephone lines than a conventional dial up modem can manage. ADSL provides a high speed, always on connection that can carry both data and voice. The term asymmetric is used because the data being carried along the line moves faster one way than the other. In other words, downloading is faster the uploading.» Also known as: Broadband, DSL
ATM (Asynchronous Transfer Mode)
This is a way of transferring voice, video and data over a high-speed network.Attenuation
The loss of the broadband signal as it makes its way from your exchange to your home, attenuation can be caused by the distance between you and the exchange, or poor quality cables. It is measured in decibels (dB).Bandwidth
Bandwidth is the amount of data that can be transmitted over your broadband connection during a period of time. The more bandwith that is available, the more data that can be transferred during that time, and the faster your data (such as a webpage, or a film trailer) will download to your computer.Bit
All data held in digital format is stored and processed as a stream of ones and zeroes. Each individual 0 or 1 is a bit - the word bit can be read as an abbreviation of Binary digIT.Broadband
Broadband is a faster version of the internet that works at higher speeds because of an increased bandwidth. The most commonly used form is ADSL (Asymmetrical Digital Subscriber Line) which is an upgraded home telephone line that remains connected so there is no need to dial it up each time and you can make phone calls while using the internet. Broadband can also be obtained through cable TV or satellite.Byte
A unit of data, a byte is made up of 8 bitsCHAP (Challenge Handshake Authentication Protocol)
CHAP is an authentication scheme used by Point to Point Protocol (PPP) servers to validate the identity of remote clients. CHAP periodically verifies the identity of the client by using a three-way handshake. This happens at the time of establishing the initial link, and may happen again at any time afterwards.Contention
This describes the maximum number of users sharing the bandwidth on the broadband connection between your local exchange and your broadband provider. Standard contention ratios are 50:1 and 20:1. If you had a 50:1 connection ratio it would mean that at any one time you would never be sharing your bandwidth with more than 49 other users. Therefore, the lower the contention rate the better.DACS (Digital Access Carrier System)
DACS provides two direct exchange lines over one cable pair.Dial-Up
A basic form of Internet connectivity established over a standard telephone line. Typical associated with mere 56kps speeds and dialling tone noises upon connection.» Also known as: Narrowband
Downstream
This refers to data that goes from the Internet to your computer.DSL (Digital Subscriber Line)
See ADSLDSLAM (Digital Subscriber Loop Access Multiplexer)
The device that aggregates many ADSL circuits to the BT network by multiplexing traffic onto one or more trunk lines.Exchange
The service area that your connection is associated with. For example if you are unable to receive broadband where you live it is because you are not within range of a broadband exchange.Extranet
An extranet is essentially an intranet that can be accessed by computers outside the network but is not available to the general public.Gigabyte
A unit of data, a gigabyte is made up of 1024 megabytes» Also known as: GB, Gigs
Intranet
This is a private network/site set up for a subset of authorised users, often in a corporate environment.IP (Internet Protocol)
This enables information to be routed from one network to another. The information is sent in packets and then reassembled into information when it reaches its destination.ISDN (Integrated Services Digital Network)
A service that is between dial up and ADSL in terms of speed. It is mostly used in geographic areas that do not have the infrastructure to accommodate ADSL and an average connection speed would be 128kbps.ISP (Internet Service Provider)
A company that offers its customers access to the Internet.» Also known as: Internet Provider
Kilobit
A unit of data, a kilobit is made up of 1024 bits.» Also known as: Kb
Kilobyte
A unit of data, a kilobyte is made up of 1024 bytes.» Also known as: KB
LAN (Local Area Network)
This stands for Local Area Network and refers to a network confined to a confined area.Latency
Latency refers to the delay caused by the time it takes for data to travel between communicating devices, eg two computers playing an online game. A fast, effective network needs low latency and high bandwidth. With a high latency network, data takes longer to be transmitted and this can adversely affect the performance of applications that require a fast response to operate effectively.LLU (Local Loop Unbundling)
When a provider rents space from the exchange and then sells its own services on the line.MAC (Migration Authorisation Code)
Allows you to migrate from one broadband provider to another.Megabyte
A unit of data, a megabyte made up of 1024 kilobytes, and is eight times a megabit» Also known as: MB
Microfilter
A micro filter acts as a splitter and plugs into your telephone socket. This reduces interference on fax or telephone calls when a broadband connection is present by splitting the normal line frequencies into one band for telephone use and another for broadband use.» Also known as: Filter
Modem
This is an acronym derived from the words modulator and demodulator by taking the mo and dem from the words. A modem is a piece of hardware that is used to connect computers to the Internet.NAT (Network Address Translation)
This is a system often used on routers to provide access for multiple computers on a network through one 'real' IP addresses assigned by their ISP. The router stores the internal 'private' network IP address, the destination IP address and port number in a routing table so when data returns the NAT can match the them up and forward the traffic correctly.NTE (Network Terminating Equipment)
Packet
A packet is a unit of data transmitted from one device on a network to another. Data you send and receive over the Internet is broken into packets for transmission.» Also known as: Datagream, Frame
PING (Packet Internet Groper)
When a message is sent to another computer and the command waits for a response. This is a method often used to check if a network is reachable.PoP (Point of Presence)
POTS (Plain Old Telephone Service)
PPP (Point to Point Protocol)
PPPoA (PPP over ATM)
PPP over ATM is the standard delivery method for ADSL servers.PPPoE (PPP over Ethernet)
PVC (Permanent Virtual Circuit)
PVCC (Permanent Virtual Circuit Connection)
RADIUS (Remote Authentication Dial In User Service)
RADSL (Rate Adaptive Digital Subscriber Line)
This is an improved broadband technology, which extends the reach of the current copper wire telephone system from 3.5 km to 5.5km from a DSL exchange. This means that more users can benefit from ADSL as the reach is extended.RAS (Remote Access Server)
Router
A router is a device that connects a local area network (LAN) to a wide area network (WAN) such as the Internet and handles the task of routing messages between the two networks. A number of computers can be configured to share a router and hardware firewalls are often incorporated as standard.SDSL (Symmetric Digital Subscriber Line)
A form of connectivity that allows more data to be sent over existing copper telephone lines at rates up to 3Mbps. With SDSL the upstream and downstream is identical hence the symmetric definition. Due to this fact, this form of broadband is popular with business users.SSB (Service Selection Baring)
Streaming
Allows the user to watch/listen to a download as the download commences in the background. This is most common with live streaming, such as with commentary from sports events, etc.Switch
Synchronisation Speed
The speed at which your ADSL modem or router communicates with the BT Exchange. This is always higher than the speed at which data will actually be downloaded over the connection. The sync rate is determined by your phone line's characteristics, such as line length and quality. The shorter the line and the better the quality the faster the line will sync.» Also known as: Line Rate, Synch, Sync