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A - H
ADSL Asymmetric Digital Subscriber Line. This is a DSL line where the upload and download speeds differ - typically the download speed is faster than the upload speed. e.g. download at 512 kbs and upstream will be at 256 kbs. Sufficient for most users.
ATM Asynchronous Transfer Mode - an international standard for data transmission in which multiple service types (voice, video, data etc.) are conveyed in fixed-length (53-byte) 'cells'.
BLUETOOTH - is similar to wireless in that it provides wireless access and networking capabilities. However, Bluetooth exists mainly for short distance (localized) networking and device connectivity. See detailed FAQ answer also.
BROADBAND – the technology of using the whole available bandwidth of the transmission medium, in this case, copper telephone cable.
BT Central The name of the circuit used to connect the ADSL broadband ISP into the BT network - typically available in speeds from 2Mbit/s up to 622Mbit/s
CAT5 category 5 Cable. Used in networking.
CBT Constant Bit Rate.
CHAP Challenge Handshake Authentication Protocol.
CONTENTION – refers to the number of people who share the same local loop as yourself. This means that the higher the contention rate, the slower the ADSL network will become at peak periods. However for most people a higher contention rate (at a cheaper cost will suffice). You can always upgrade if you have problems. See also detailed FAQ answer
CRC Cyclic Redundancy Check.
CROSSOVER CABLE – type of Ethernet cable required to connect a PCs NIC directly to a router rather than a hub. This was required during BT’s ADSL trials but is no longer required because the NTE equipment (for the Ethernet variant) now has a built-in hub.
DACS - Digital Access Carrier System. DACS is a system that BT uses to split a standard telephone line into two separate lines. This is usually done when there are capacity problems at an exchange. This may have been put on your line a long time ago and it is nothing to do with your ADSL service. It probably means you have very slow internet connections currently - typically less than 30kbs. It will need to be removed before you can receive Broadband.
DHCP - Dynamic Host Configuration Protocol. A process by which a machine assigns a single IP address to a PC on a network. This IP address is taken from a 'pool' of addresses. The PC would be set up to receive its IP address 'dynamically' via its networking settings. This system allows easy administration of a network since individual addresses are not 'tied' to a particular machine. Together with the concept of a 'lease' whereby a time is specified for the duration of that IP address, it becomes possible to administer a network where there are more machines than available IPs in the pool.
DMZ = humorous reference to "Demilitarized Zone". A router normally stops incoming Internet traffic from getting on your network, unless the traffic is in response to one of your computers or when using port forwarding. But instead of discarding the incoming traffic or using port forwarding, you can send incoming traffic to one computer on your network by establishing a "Default DMZ Server". This avoids you having to figure out what ports an Internet application wants — by throwing all ports open for that computer. For regular network operation, NETGEAR recommends you do not use a DMZ. A computer with DMZ loses firewall protection, and is exposed to exploits from the Internet. If compromised, your own computer can attack the rest your network. Instead of DMZ, use port forwarding.
DNS Domain Name Server or Domain Name System.
DSL Digital Subscriber Line. This is a method of transmitting data over standard telephone lines - in the UK a variant called ADSL is most common for providing broadband access.
DSLAM – Digital Subscriber Loop Access Multiplexer. Located at the BT exchanges, these are what your ADSL modem connects to and is the device that connects many ADSL circuits to the BT network by multiplexing traffic onto one or more trunk lines
ETHERNET – the technology commonly used to network PCs (also referred to as 10BaseT or 100BaseT)FDDI (Fiber Distributed Data Interface) is a set of ANSI and ISO standards for data transmission on fiber optic lines in a local area network (LAN) that can extend in range up to 200 km (124 miles). The FDDI protocol is based on the Token Ring protocol. In addition to being large geographically, an FDDI local area network can support thousands of users. FDDI is frequently used on the backbone for a wide area network (WAN).
Firewall Essentially a firewall is a traffic cop standing between two separate networks (usually your network and the Internet) analysing the data packets wishing to pass from one network to the other. A firewall will prevent the packets from crossing unless they are explicitly permitted to do so. Firewall rules can be quite complex - usually based on the packet source, destination and type of traffic.
HTML Hyper Text Markup Language - web pages are typically written in HTML. If you are designing web pages yourself you often have little need to actually know the HTML language as there are many WYSISYG (what-you-see-is-what-you-get) web design programs like Microsoft Frontpage, Macromedia Dreamweaver, Adobe GoLive etc. available. |
I - P - definitions
IP - Internet Protocol. All machines on a single network require a unique IP address in order to communicate with one another. An IP address is divided into a network part, which must be the same on any one network, and a host portion, which must differ.
ISDN Integrated Services Digital Network. ISDN is a digital dialup service often used where broadband access is not currently available. Typically available in 64kbit/s single channel or 128kbit/s dual channel (bonded) variants. A single ISDN channel is 'roughly' twice the speed of a normal modem but still only a fraction of the speed of ADSL broadband.
Kbit/s Kilobits per second. Also Kbs or Kbps
LAN Local Area Network. It is a group of computers and associated devices that share a common communications line or wireless link and typically share the resources of a single processor or server within a small geographic area (for example, within an office building). Usually, the server has applications and data storage that are shared in common by multiple computer users. A local area network may serve as few as two or three users (for example, in a home network) or as many as thousands of users (for example, in an FDDI network). Major local area network technologies are: Ethernet, Token Ring, FDDI
LCP Link Control Protocol.
L2TP Layer 2 Tunneling Protocol.
LOCAL LOOP – refers to the telephone network between your location and the nearest BT exchange.
LSS Limited Service Selection - the ability for an ADSL broadband user to connect to multiple BT Central communication links.
Mbit/s Megabits per second. Also Mbs or Mbps
MODEM Modulator-demodulator - a device or program that enables a computer to transmit data over analogue telephone lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analogue waves. A modem converts between these two forms.
MSO Major Service Outage.
MSF Major Service Fault.
MTU Maximum Transmittable Unit - this is the maximum amount (in bytes) of data sent in each data packet - some people experiencing lower than expected download performance 'may' improve this by altering the MTU.
NAT - Network Address Translation. The name given to the process whereby one IP (Internet Protocol) address is mapped (or translated) to another. This generally occurs when a globally valid IP address is mapped to an IP on a private (internal) network. The benefits of this are several. Firstly it becomes possible to connect many machines to the Internet with only a single Static IP address. It also 'hides' the actual addresses of the internal machines, since to the outside world, all the machines share the same IP address - the network looks like a single machine. 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.
NIC – Network Interface Card (Ethernet card, 10BaseT card) that is installed in your PC in order to connect to a local area network.
NTE – Network Terminating Equipment – the BT equipment installed at you location. Refers to the USB modem in the case of a single USB installation or combined modem/router/hub in the case of the Ethernet installation.
PBX Private Branch Exchange.
PLT - Powerline Technology. Similar to DSL - a radio signal 1.6MHz-30MHz is carried on copper cables of a power network point to point or point to multipoint. When enabled a modem is plugged into any mains socket and links to the PC via Ethernet or USB. Speeds currently up to 4.5Mbps. In trial in Scotland and Winchester.
PORT Software ports are numbered connections that a computer uses to sort types of network traffic. A port may support incoming traffic, outgoing traffic, or both. A few services, such as FTP (on port 21), and HTTP (on port 80), are assigned by default to open ports where operating systems can easily find them easily. When a port is opened a service is assigned to it, for example, an online game. By default, most of a router's ports are closed so that traffic cannot flow through them to your LAN. Do not open ports unless they will be used, since open ports are a security risk.
POTS Plain Old Telephone System.
PPP Point to Point Protocol.
PPPoA PPP over ATM (the standard delivery method for ADSL servies).
PPPoE PPP over Ethernet.
PSTN – Public Switched Telephone Network. The telephone network used for telephony services.
PVC Permanent Virtual Circuit. |
R - Z
RADIUS Remote Authentication Dial-In User Service.
RADSL Rate Adaptive Digital Subscriber Line (also described as 'rate adaption'). This is a variant of ADSL that extends the maximum distance from your exchange by adjusting the upstream bandwidth based on line quality. RADSL increases the maximum distance supported from 3.5 to around 5.5 kilometres. This now means that typically 90% of people connected to an ADSL enabled exchange can get a broadband service. This option is only available on the 500Kbit/s services and due to the increased circuit length the maximum upload speed 'may' be lower than a normal ADSL circuit. It allows broadband data services to be carried on conventional copper pair telephone cables, with the rate adapting to the line conditions. The capacity provided depends on the distance between the subscriber's premises and the local telephone exchange; RADSL broadband provides higher capacities for subscribers who are closer to the exchange, with lower rates for subscribers who are further away. Speeds are typically 512kbps downstream.
RIPE Réseaux IP Européens. RIPE was setup to oversee the administrative and technical co-ordination necessary to enable the efficient operation of a European IP network. See: www.ripe.net for more details.
ROUTER will link two different networks together, and allow controlled access betweent the two. In the ADSL sense, this means linking you to an ADSL ISP network, and your home network. Generally for home use the router takes the ISP assigned IP address and through some magic shares this with multiple computers.
Next bit is routers with a built in ADSL Modem (best option usually) and those without one (the later are called cable/DSL routers, and need you to buy an Ethernet ADSL modem to connect to an ADSL line.
SDSL is SYMMETRICAL Digital Subscriber Line (DSL) and is a service that provides equal bandwidth speeds for both uploads and downloads. Originally developed in Europe, SDSL was one of the earliest forms of DSL to not require multiple telephone lines. SDSL possesses all of the common characteristics of DSL, including an "always on" combination of voice and data services, availability limited by physical distance, and high speed access compared to analog modems. SDSL currently supports data rates up to 3,088 Kbps. SDSL is available in some areas - not ours.
SMDS Symetric Multi-Megabit Data Service.
SPLITTER - device that splits the available bandwidth of the copper cable into two or more sections, on for analogue voice transmission, the other for digital data communication.
SWITCH has just enough intelligence to connect several computers together physically. All the computers are on the same network.
TCP/IP Transmission Control Protocol/Internet Protocol - the 'language' of the Internet
Token Ring network is a local area network in which all computers are connected in a ring or star topology and a bit- or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time. The Token Ring protocol is the second most widely-used protocol on local area networks after Ethernet.
USB – Universal Serial Bus - Universal Serial Bus technology means that your computer will be able to connect to the very high speeds of ADSL without slowing down the data (USB can potentially support speeds of 12megabits/per second). USB connectivity is also replacing many of the previous connections for printers, keyboards, mice, etc. Connection type used to connect most ADSL modems to the computer.
VCI Virtual Channel Identifier.
VDSL – Very High Bit Rate digital subscriber line.
VIRTUAL PATH - Since BT's introduction of the Home 1000 (1Mbps) service, a number of users have found their speeds to be less than satisfactory. The main cause of this has been determined to be 'Virtual Path' congestion. IPStream VP status - This tells you the status of the "Virtual Paths" on your exchange. This can be either Red, Amber or Green. If your exchange is Red or Amber then you may find that at peak times your speed may degrade. You should also find an VP upgrade date attached for your exchange if this is the case.
VOIP Voice Over IP. Already available and BT is moving to this over the next 5 years.
VPI Virtual Path Identifier.
VPN Virtual Private Network. This allows a secure, encrypted connection between two points over the Internet.
WAN Wide Area Network is a geographically dispersed telecommunications network. The term distinguishes a broader telecommunication structure from a local area network (LAN). A wide area network may be privately owned or rented, but the term usually connotes the inclusion of public (shared user) networks. An intermediate form of network in terms of geography is a metropolitan area network (MAN).
WIMAX - Worldwide Interoperability for Microwave Access. WiMax networks have a theoretical range of up to 30miles with data transfer of up to 70Mbps.
WIRELESS - Many people are turning to 'wireless' access for their broadband services to provide location flexibility in their homes or offices. There are several different standards – see detailed FAQ answer also. Likely to become a serious broadband option in future. |
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