Telephone and Network Glossary
Telephone and Network Glossary
100BASE-T4/100BASE-TX/100BASE-FX
100BASE-x – this refers to the type of actual wire used to carry 100 megabit/second Ethernet traffic. The -T refers to twisted-pair cable (-T4 uses all 8 wires [4 pairs] of a typical CAT5 cable, whereas -TX uses only 4 wires) and –FX refers to fiber-optic cable. The term BASE means that the wires are used to carry Ethernet and nothing else.
10BASE-2/10BASE-5/10BASE-F/10BASE-36/10BASE-T
10BASE-x – this refers to the type of actual wire used to carry 10 megabit/second Ethernet traffic. The –2, -5 and –36 refer to coaxial cable, -T refers to twisted-pair cable and –F refers to fiber-optic cable. The term BASE means that the wires are used to carry Ethernet and nothing else.
Asynchronous Digital Subscriber Line – a residential-grade high-speed Internet connection delivered over telephone lines and sometimes satellite. Data transfer from the Internet is much faster than data transfer to the Internet, hence the "asynchronous" part of the name. Also see SDSL.
Bridge – this is a network device that transparently connects two separate physical network segments. Unlike a router, which intelligently examines network traffic and forwards it in the appropriate direction, a bridge simply passes all the data back and forth and hence is a "dumber" device than a router. In a DSL scenario if you have a bridge, then your computer’s IP address is the real thing, whereas with a router it probably is a non-routable address.
Category 1/3/5/6 – a specification for the type of copper wire (most telephone and network wire is copper) and jacks. The number (1, 3, 5, etc) refers to the revision of the specification, and in practical terms refers to the number of twists inside the wire (or the quality of connection in a jack). CAT1 is typically telephone wire. This type of wire is not capable of supporting computer network traffic and is not twisted. CAT3, CAT5 and CAT6 are network wire specifications. This type of wire can support computer network and telephone traffic. For higher network speeds (100Mbps plus) you must use CAT5 wire, but for 10Mbps CAT3 will suffice. CAT3 and CAT5 cable is actually 4 pairs of twisted copper wires, and CAT5 has more twists per inch than CAT3. CAT6 wire was originally designed to support gigabit Ethernet (although there are forthcoming standards that will allow gigabit transmission over CAT5 wire). It is similar to CAT5 wire, but contains a physical separator between the 4 pairs to further reduce EM interference.
Competitive Local Exchange Carrier – in relation to DSL, this will be the network provider that your ISP is using. Covad Communications is an example of a CLEC.
Central Office – the local office of your telephone company where all neighborhood telephone wires terminate. Your DSL network provider must have a presence at this location to be able to provide you with DSL service. DSL service also depends on your distance from the CO.
Customer Premise Equipment -- this refers to the telephone/networking equipment located on your premises (house, office, etc). Each telephone in your home is an example of a CPE, and so is the DSL modem.
Digital Subscriber Line – a high-speed Internet connection delivered over telephone lines and sometimes satellite. Comes in two flavors: ADSL and SDSL.
Digital Subscriber Line Access Multiplexer – a device located in your local telephone company’s CO that receives the DSL signals from your home and translates them into the format that is compatible with standard network equipment, such as switches and routers.
Electromagnetic Interference – when metal wires carry electrical signals of any strength (telephone and network data is actually very weak electrical signals), they generate a magnetic field. Similarly, whenever a wire is present inside a magnetic field, electrical current is generated in the wire. This means that two electrical wires next to each other can interfere with each other, because the magnetic field created by one wire can affect the electrical current in the other wire. The stronger the electrical current, the stronger the magnetic field and the more interference the wire generates. EM interference becomes problematic in telephone and network wires because of the weak nature of the signals that usually travel them and because of the great distances the signals must usually go.
Ethernet – is the most common type of LAN technology in the world. It was originally developed by Xerox and then further refined in conjunction with Digital Equipment Corporation (now part of Compaq, soon to be Hewlett-Packard) and Intel. Ethernet comes in a variety of speeds, ranging from 10 megabits/second to 1 gigabit/second. Other types of LAN technologies include AppleTalk, most commonly found on Apple and Macintosh networks and Token-Ring, which came out of IBM.
Incumbent Local Exchange Carrier – the local phone company that serves your neighborhood and actually owns the wires (Verizon, Pacific Bell, etc.).
Internet Protocol Address – every computer on the Internet is assigned a unique address known as an IP address. IP addresses consist of 4 numbers separated by a period and look similar to this: 192.11.33.1 Depending on your service, you will either be assigned a permanent (static) address or your computer will obtain an address automatically every time you turn it on. There is a certain range of IP addresses that are designed as not routable on the Internet. All Internet routers are programmed to ignore any data with these special IP addresses. This is done to more securely separate an internal network from the Internet. The following are non-routable IP addresses: 10.anything, 172.16.anything and 192.168.anything.
Internet Service Provider -- the company who provides you with internet services, such as a mail account. This company is also responsible for assigning you an IP address and providing technical support.
Local Area Network — the part of any network that is physically local to you. A home network is a LAN. In your workplace, the LAN is the entire network at your office, but does not include the networks from other offices that you may be connected to. In DSL terms, this will be whatever network equipment you have connected on your side of the DSL modem. Also see WAN.
Media Access Control Address – this is a unique hardware address that is physically embedded into every NIC.
MODulator/DEModulator – a device that allows computers to communicate over telephone wires, whether it be a dial-up connection or a DSL connection. A modem takes digital data, consisting of 1s and 0s and transforms it into the same type of electrical signals as a telephone does with your voice. Dial-up modems use an audible frequency range, so if you ever pick up the phone while dialed up, you will hear the data going back and forth (although you certainly won’t be able to understand it!). DSL modems use a frequency range outside of human hearing, which is one of the things that makes it possible to be on the phone and use DSL over the same wires simultaneously.
Main Point Of Entry – a telephone company term that refers to the point where telephone cables enter your premises. If you live in a condo or apartment building, this will usually be in a basement or some type of storage room or closet. If you live in a house, this will often be in a box on an outside wall. The local phone company will need access to this during their phase of the installation.
Network Address Translation – a technique by which several computers can share the same real IP address. This is performed either on a device that is capable of NAT, such as a DSL router, or on a computer that has NAT software installed (such as WinRoute).
Network Interface Card – this is a card that installs inside your computer (many newer computers have this built-in, as do many new laptops). The NIC is what allows a computer to communicate with other computers over a network. NICs are not aware of anything relating to protocols, browsers or other such software. Their job is to take data packets and send them on. Every NIC in the world has a unique MAC address. NICs are specific to the type of network you are running, such as Ethernet, token-ring, etc. Ethernet NICs can communicate at several different speeds. The most standard are 10Mbps (megabits per second) and 100Mbps. When buying a NIC, look carefully to see what speed it can talk at. Some NICs are only capable of communicating at 10 and some at only 100. There are NICs that are capable of communicating at either 10 or 100Mbps. A 10Mbps only NIC will not be able to talk to a 100Mbps only NIC. The technology coming on the horizon is 1Gbps (gigabits per second). For DSL purposes 10Mbps is all you will need, but be sure to check with the hardware specifications of your DSL modem, since it may require a 100Mbps NIC.
Registered Jack-11 – the official name for a standard telephone jack/plug. This jack is capable of supporting 6 wires, but typical telephone installations and cables only use 4 (even though a telephone line is only 2). (Simple jack addition)
Registered Jack-14 – the official name for a standard telephone jack/plug that carries 2 phone lines. If you ever look at a 2-line telephone, you’ll probably notice that the jack for line 1 is actually labeled line 1/line2, meaning that if you plugged that into a properly wired RJ-14 jack, you would only need one wire to connect both phone lines.
Registered Jack-45 – the official name for a standard network jack/plug. This jack is capable of supporting 8 wires, and in most network installations it is fully wired, even though standard Ethernet only requires 4 wires. This jack is different in size from RJ-11 and RJ-14. A RJ-11 or 14 plug could be plugged into a RJ-45 jack, but not vice-versa. This means that if you wanted to, you could use RJ-45 jacks for telephone.
Router – a device that directs (routes) data between two different networks. A router is essentially a mini-computer, because it has a processor and an operating system. It intelligently examines data and sends it the best way possible to reach its intended destination. A router always has its own IP address. In the case of DSL, if you are given a router (basically a combination router and DSL modem), then your assigned IP address will be programmed into the router for you, and your computer will probably have a private, non-routable IP address that is not valid on the real internet. The router will then perform NAT (Network Address Translation) to allow you to get out to the Internet.
Synchronous Digital Subscriber Line -- a business-grade high-speed Internet connection delivered over telephone lines and sometimes satellite. Data transfer from the Internet is the same speed as data transfer to the Internet, hence the "synchronous" part of the name. Also see ADSL.
Transmission Control Protocol/Internet Protocol – this is the protocol (language, in human terms) that is used to communicate over the Internet and many home and corporate networks. Technically these are 2 separate protocols, with IP providing the underlying data transmission, and TCP using IP. Data is sent over a network in small chunks, called packets. TCP is what is used to ensure that all of your data gets to its destination intact, because IP, by design, makes no guarantees about anything, except that it will try to send the packets out. It is the job of TCP to make sure that all the packets are delivered in the correct sequence.
Twisted Pair – this refers to the actual physical appearance of network wire. CAT3, CAT5 and CAT6 wire consists of 4 pairs of wires. The two wires in a pair are twisted together throughout the entire length of the wire. The twists decrease EM interference and allow data to travel a greater distance.
Wide Area Network – this is the connection between two or more LANs. In DSL terms, this is basically everything that starts from the telephone-side of your DSL modem on, including the entirety of the Internet.
This glossary was written by Sergey Polak, a computer programmer and network engineer. He has a BS in Computer Science, is a Microsoft Certified Professional and has over 9 years experience in the field.
