Jargon buster - networking glossary of terms
Access Server
Access Server, also called network access server, is a computer server that connects asynchronous devices to a LAN or WAN through network and terminal emulation software. An access server (NAS) enables an internet service provider (ISP) to provide connected customers with Internet access. An access server has interfaces to both the local telecommunication service provider such as the phone company and to the Internet backbone. The server authenticates users requesting login, usually by verifying a user name and password, and then allows requests to begin to flow between the user host and hosts (computers) elsewhere on the Internet.
back to the top
Activation
Activation in networking refers to the process of enabling a subscriber device for network access and privileges on behalf of a registered account. In computer software, activation may refer to the process of enabling a user with a valid license key the privilege to use particular software.
back to the top
Active FTP
Active FTP is an alternative FTP mode which was designed before firewalls. In active mode FTP, the client connects from a random unprivileged port (N > 1023) to the FTP server's command port, port 21. Then, the client starts listening to port N+1 and sends the FTP command PORT N+1 to the FTP server. The server will then connect back to the client's specified data port from its local data port, which is port 20.
back to the top
ADSL modem
An ADSL modem, also known as a DSL modem, is a device used to connect one or more computers to a phone line, in order to use an ADSL service. Some ADSL modems also manage the connection and sharing of the ADSL service with a group of machines, making an ADSL router or ADSL modem/router a more accurate name for the device.
back to the top
Alarm
Generally speaking, an alarm gives an audible or visual warning of a problem or condition. In networking, alarm refers to notification sent by a network monitoring system to tell network administrators or other people about possible problems in the network.
back to the top
Algorithm
Algorithm, basically, is the well-defined rule or process for arriving at a solution to a problem. In networking, algorithms commonly are used to determine the best route for traffic from a particular source to a particular destination. The queuing algorithms of routers and switches are critical to determine the speed of packet processing.
back to the top
Attenuation
Attenuation refers to decreasing in signal magnitude between two points. These points may be along a radio path, transmission line or other devices.
back to the top
B2B: Business to Business
Business to Business (B2B) refers to conducting business between two or more companies over the Internet, rather than between businesses and consumers (B2C).
back to the top
B2C: Business to Consumer
Business-to-consumer (B2C), also known as business-to-customer, refers to commercial organizations selling products and services to the end consumers over the Internet.
back to the top
Back End
Back End, in the context of a computer system, refers to a node or software program that provides services to a front end. The front end typically interfaces with users directly while the back end may communicate with other systems such as databases and other systems.
back to the top
Backbone
Backbone is the part of a network that acts as the primary path for all network traffic, which requires very high bandwidth. A backbone network of a service provider typically connects many enterprise sub networks and networks of smaller service providers. An enterprise backbone network typically connects many LANs and data centres.
back to the top
Bandwidth
Bandwidth refers to the maximum capacity of a network channel. Usually bandwidth is measured in bits per second (bps), kilo-bits per second (Kbps), mega bits per second (Mbps) or gigabits per second (Gbps). For example, Ethernet has a bandwidth of 10-, 100-, 1000 Mbps and 1 and 10 Gbps.
back to the top
Broadband
Broadband in networking and telecommunication refers to any type of transmission technique that carries several data channels over a common wire. In home networking, "broadband" usually refers to high-speed Internet access using broadband transmission technique. The mostly used broadband access technologies include DSL (over normal telephone lines), DOCSIS (over cable wires) etc. So-called broadband routers and broadband modems are network devices that support both DSL and DOCSIS.
back to the top
Broadband Network
Broadband Network is a network capable of transporting multiple services including voice, interactive full-motion video, and data simultaneously on the same physical cable over long distances. In contrast, a narrowband network can transport only traditional telephone service, electronic mail, paging services, and faxes.
back to the top
Broadband Router
Broadband router is an access router used by Small Office Home Office (SOHO) or residential customers to access the Internet via DSL or cable moderns. A broadband router typically combines the features of a traditional network switch, a firewall, and a DHCP server. A broadband router supports file sharing, Internet connection sharing, and home LAN.
back to the top
Cable
Cable is the physical transmission medium of a group of metallic conductors or optical fibres that are bound together and wrapped in a protective cover, and insulation between individual conductors/fibres and for the entire group.
back to the top
Circuit
A circuit is a communications path between two or more points among a network. A physical circuit is actually a wire or a part of a wire which connects two computer or network devices for permanently dedicated communications. A virtual circuit may be a temporarily established logic connection between two network devices for communications within certain time limit.
back to the top
Collapsed Backbone
Collapsed Backbone refers to a non-distributed backbone in which all network segments are interconnected by way of an internetworking device. A collapsed backbone might be a virtual network segment existing in a device such as a hub, a router, or a switch.
back to the top
Communication Server
Communication Servers are specially designed computer servers that provide access to resources on the network for users not directly attached to the network or that permits network users to access external resources not directly attached to the network. Communication servers typically connect asynchronous devices to a LAN or WAN through network and terminal emulation software.
back to the top
Cross Talk
Cross Talk refers to the interfering energy transferred from one circuit to another, or the unwanted information from one channel to "spill over" into an adjacent channel.
back to the top
DCE: Data Communications Equipment
Data Communications Equipment (DCE) is a device that communicates with a Data Terminal Equipment (DTE) device. The DCE provides a physical connection to the network, forwards traffic, and provides a clocking signal used to synchronize data transmission between DCE and DTE devices. Modems and interface cards are examples of DCE.
back to the top
DCN: Data Communications Network
In telecommunication, Data Communications Network (DCN) is an out-of-band network based on the configuration of telecommunication facilities for the purpose of transmitting data, as opposed to analogue signals. DCN provides connectivity between network elements and their respective operations support systems (OSS's). Its primary function is enabling the surveillance and the status of a telco/PTT network but it also facilitates network operations and management, such as provisioning, billing, planning, and service assurance.
back to the top
Dongle
In computer networking, a dongle is a short network cable that joins a PCMCIA adapter to a network cable. Dongles typically attach to either a RJ-45 connector for Ethernet networking or an RJ-11 connector for dial-up networking. Dongles tend to run no longer than about six inches.
The term "dongle" also has become popular in USB networking, referring to the USB cable that extends from a USB peripheral.
back to the top
Download
Download refers to the process of moving a file from a remote network location to a local computer. There are a few methods of doing this on the Internet. HTTP, FTP and e-mail attachments are the most common.
back to the top
Drop
A drop is a point on a multipoint channel where a connection to a networked device is made.
back to the top
Drop Cable
Drop Cable is the cable that connects a network device (such as a computer) to a physical medium such as Ethernet transceiver. The maximum length if full-spec is 47m.
back to the top
Drop-and-Insert
Drop-and-Insert is a feature that enables a single T1 access line to carry both data and voice traffic. The MAX uses a pre-allocated portion of the T1 access line to use both nailed-up and switched circuits for LAN internetworking. The remaining portion of the line can go to a PBX with a T1 interface; the PBX can access both nailed-up and switched circuits for voice purposes. Drop-and-Insert can also be used to share access line bandwidth between the MAX and equipment other than a PBX, such as a channel bank or T1 multiplexer.
back to the top
DVVI: Data, Voice, Video Integration
Data, Voice, Video Integration (DVVI) refers to providing data voice and video services over one single network. This term is often used for an Enterprise network. In the case of a Service Provider, it is often called triple play.
back to the top
Echo
Echo in computer networking is a testing technique where packets are sent to a distant node that is obligated to immediately send the packets back.
back to the top
Effective Data Transfer Rate
Effective Data Transfer Rate, usually expressed in bits (or characters, blocks, or frames), is the average number of units of data transferred per second from a source and accepted as valid by a receiver.
back to the top
Encoder
Encoder is a device (hardware, software or both) that modifies information into certain format for viewing, editing, storage and transmission. This is usually done by means of an algorithm, especially if any part is digital, while most analogue is done with circuitry. For example, software that turns uncompressed WAV (Windows) or AIFF files into compressed files, using a CODEC such as MP3 or RealAudio. A decoder is required to convert the encoded information back to its original format, if necessary.
back to the top
Encoding
Encoding is the process of converting the analogue electrical or optical signals to certain digital format for storage, manipulation, and display by a computer. Encoding also means transferring digital information from one format to another format for a specific purpose such as data compression.
back to the top
Ethernet
Ethernet is the most popular local area network (LAN) technology implemented worldwide. Ethernet was first developed in early 1970s. Basically, Ethernet includes a shared transmission medium such as a twisted pair cable or co-axial cable and a multi-port hub, bridge or switch. Computers, printers and workstations are connected to each other through the hub/switch/bridge using the cables in a star-like or a bus-like configuration. Ethernet originally supported a maximum theoretical data rate of 10 megabits per second (Mbps). Later, Fast Ethernet standards increased this maximum data rate to 100 Mbps. Today, Ethernet technology further extends peak performance up to 1Gbps and 10 Gbps.
back to the top
Ethernet hub
Ethernet Hub or repeater is a device that accepts numerous Ethernet connections from network devices and cross-connects them, making them act as a single segment. Data arriving via the receive pair of one connection is regenerated and sent out on the transmit pair to all connected devices except for the device who originated the transmission. Ethernet Hub works at the physical layer of the OSI model. If a signal comes into two ports at the same time when a collision occurs, so every attached device shares the same collision domain. Hubs support only half duplex Ethernet, providing bandwidth which is shared among all the connected devices.
back to the top
Ethernet Meltdown
Ethernet Meltdown refers to an event that causes saturation, or near saturation, on an Ethernet. It usually results from illegal or misrouted packets and typically lasts only a short time.
back to the top
Ethernet VPN
Ethernet VPN refers to a group of technologies to provide Virtual Private Network services over the Internet between the Ethernet LANs. One of the Ethernet VPN technologies is based on Virtual Private LAN Services (VLPS) and Multiprotocol Label Switching (MPLS), which provides more benefits than other alternative layer 2 or 3 VPN technologies.
back to the top
Fibre Optics
Fibre Optics is a physical method for the transmission of information (audio, video, and data) using optic fibre cable and light. Light is modulated and transmitted over high purity, hair-thin fibres of glass. The bandwidth capacity of fibre optic cable is much greater than that of conventional cable or copper wire.
back to the top
Fibre-optic Cable
Fibre-optic Cable is the physical medium capable of conducting modulated light transmission. Compared with other transmission media, fibre-optic cable is not susceptible to electromagnetic interference and is capable of higher data rates.
back to the top
Fibre Channel
Fibre Channel, also known as Fibre Channel, is a set of related physical layer networking standards for high-performance disk storage networking of corporate networks. Fibre Channel supports functions such as data backups, clustering and replication. Fibre Channel can utilize copper wiring. However, copper limits Fibre Channel to a maximum recommended reach of 30 meters. When using more expensive fibre optic cables, Fibre Channel reaches to 10 kilometres.
back to the top
Front End
Front End refers to a node or software program, such as a web browser, that requests services of a back end such as a database
back to the top
Full Duplex
Full Duplex transmission indicates the transmission of data in two directions simultaneously. For example, on a local area network with full-duplex transmission, one workstation can be sending data on the line while another workstation is receiving data. On the other hand, a half duplex transmission indicates that data transmission happens only in one direction at a time.
back to the top
Gb: Gigabit
Gigabit (Gb), approximately 1,000,000,000 bits, is a measure of computer data storage.
back to the top
GB: Gigabyte
Gigabyte (GB), approximately 1,000,000,000 bytes (one byte is 8 bits), is a measure of computer data storage.
back to the top
GBIC: Gigabit Interface Converter
Gigabit Interface Converter (GBIC) is a standard for transceivers, commonly used with gigabit Ethernet and fibre channel.
back to the top
Gbps: Gigabits per Second
Gigabits per Second (Gbps) is a measure of data transfer speed in networking. Gigabytes per Second (GBps) is eight times more than the Gigabits per Second (Gbps).
back to the top
GBps: Gigabytes per Second
Gigabytes per Second (GBps) is a measure of data transfer speed in networking. Gigabytes per Second (GBps) is eight times more than the Gigabits per Second (Gbps).
back to the top
Gigabit Ethernet
Gigabit Ethernet is a type of the Ethernet with speed tenfold over the fast Ethernet supporting a theoretical maximum data rate of 1000 Mbps. It uses shorter frames with carrier Extension. It is defined in the IEEE 802.3z and 802.3ab, supplement to the IEEE 802.3 base standards.
back to the top
Grid Network
A grid network consists of a number of computer systems connected in a grid topology. In a regular grid topology, each node in the network is connected with two neighbours along one or more dimensions. If the network is one-dimensional, and the chain of nodes is connected to form a circular loop, the resulting topology is known as a ring.
back to the top
Half-Duplex
Half-duplex is a data transmission method in which data can be transmitted in both directions on a signal carrier, but not at the same time. For example, on a local area network using a technology that has half-duplex transmission, one workstation can send data on the line and then immediately receive data on the line from the same direction in which data was just transmitted. On the other hand, full-duplex transmission implies that data are transmitted in both directions simultaneously.
back to the top
Hub
The Hub (or repeater) is a device that accepts numerous Ethernet connections from network devices and cross-connects them. Data arriving via the receive pair of one connection is regenerated and sent out on the transmit pair to all connected devices except for the device that originated the transmission.
back to the top
Hybrid network
Hybrid network is an internetwork made up of more than one type of network technology, including LANs and WANs.
back to the top
Internet Protocol
IP is the primary network protocol used on the Internet, developed in the 1970s. On the Internet and many other networks, IP is often used together with the Transport Control Protocol (TCP) and referred to interchangeably as TCP/IP.
IP supports unique addressing for computers on a network. Most networks use the IP version 4 (IPv4) standard that features IP addresses four bytes (32 bits) in length. The newer IP version 6 (IPv6) standard features addresses 16 bytes (128 bits) in length.
back to the top
Kbps / kbps, Mbps, Gbps
One kilobit per second (Kbps) equals 1000 bits per second (bps). Kbps is also written as “kbps" that carries the same meaning. Likewise, one megabit per second (Mbps) equals one million bps and one Gigabit equals one billion bps.
Network performance is best measured in bps, but sometimes numbers are given in bytes per second (Bps). Then, one KBps equals one kilobyte per second, one MBps equals one megabyte per second, and GBps equals one gigabyte per second. Many times people write KBps, for example, when they mean Kbps, and it is important to be clear on this distinction.
back to the top
LAN - Local Area Network
A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet or other WAN.
Most local area networks are built with relatively inexpensive hardware such as Ethernet cables, network adapters, and hubs. Wireless LAN and other more advanced LAN hardware options also exist.
back to the top
Modem
Traditional modems used in dial-up networking convert data between the analogue form used on telephone lines and the digital form used on computers. Standard dial-up network modems transmit data at a maximum rate of 56,000 bits per second (56 Kbps). However, inherent limitations of the public telephone network limit modem speeds to 33.6 Kbps or lower in practice.
Broadband modems that are part of cable and DSL Internet service use more advanced signalling techniques to achieve dramatically higher network speeds than traditional modems. Broadband modems are sometimes called "digital modems" and those used for traditional dial-up networking, "analogue modems." Cellular modems that establish Internet connectivity through a digital cell phone also exist.
A patch cable connects two network devices. Patch cables are typically CAT5 / CAT5e Ethernet cables linking a computer to a nearby network hub, switch or router.
back to the top
Patch Cable
Ethernet patch cables are useful to those building home computer networks and also to travellers who need wired access to Internet connections such as those provided in hotel rooms. They are normally manufactured using stranded rather than solid sheathing in order to give them pliability that reduces risk of breakage when unplugging or carrying them.
A crossover cable is a specific type of Ethernet patch cable used to directly connect two computers to each other.
Fibre optic patch cables are also commonly used in the networking. The term patch cord is sometimes used synonymously with patch cable, although patch cords are often non-network types of cables such as those for wiring stereo components.
Also Known As: patch cord
back to the top
RJ45
RJ45 is a standard type of connector for network cables. RJ45 connectors are most commonly seen with Ethernet cables and networks.
RJ45 connectors feature eight pins to which the wire strands of a cable interface electrically. Standard RJ-45 pinouts define the arrangement of the individual wires needed when attaching connectors to a cable.
Several other kinds of connectors closely resemble RJ45 and can be easily confused for each other. The RJ-11 connectors used with telephone cables, for example, are only slightly smaller (narrower) than RJ-45 connectors.
Also Known As: Registered Jack 45
back to the top
Routers
Routers are physical devices that join multiple wired or wireless networks together. Technically, a wired or wireless router is a Layer 3 gateway, meaning that the wired/wireless router connects networks (as gateways do), and that the router operates at the network layer of the OSI model.
Home networkers often use an Internet Protocol (IP) wired or wireless router, IP being the most common OSI network layer protocol. An IP router such as a DSL or cable modem broadband router joins the home's local area network (LAN) to the wide-area network (WAN) of the Internet.
By maintaining configuration information in a piece of storage called the routing table, wired or wireless routers also have the ability to filter traffic, either incoming or outgoing, based on the IP addresses of senders and receivers. Some routers allow the home networker to update the routing table from a Web browser interface. Broadband routers combine the functions of a router with those of a network switch and a firewall in a single unit.
back to the top
Server
A network server is a computer designed to process requests and deliver data to other (client) computers over a local network or the Internet.
Network servers typically are configured with additional processing, memory and storage capacity to handle the load of servicing clients. Common types of network servers include:
- Web servers
- Proxy servers
FTP servers
- Online game servers
Numerous systems use this client / server networking model including Web sites and email services. An alternative model, peer-to-peer networking enables all computers to act as either a server or client as needed.
back to the top
Switch
A network switch is a small hardware device that joins multiple computers together within one local area network (LAN). Technically, network switches operate at layer two (Data Link Layer) of the OSI model.
Network switches appear nearly identical to network hubs, but a switch generally contains more intelligence than a hub. Unlike hubs, network switches are capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately. By delivering messages only to the connected device intended, a network switch conserves network bandwidth and offers generally better performance than a hub.
As with hubs, Ethernet implementations of network switches are the most common. Mainstream Ethernet network switches support either 10/100 Mbps Fast Ethernet or Gigabit Ethernet (10/100/1000) standards.
Different models of network switches support differing numbers of connected devices. Most consumer-grade network switches provide either four or eight connections for Ethernet devices. Switches can be connected to each other, a so-called daisy chaining method to add progressively larger number of devices to a LAN.
back to the top
Telephony
The term telephony refers to the technology behind voice communications (typically, telephone networks). Telephony ordinarily involves analogue electrical signalling over copper wire.
Newer IP telephony technology converts analogue voice into digital data packets to support telecommunication over Internet Protocol networks. So-called "voice over IP" (VoIP) solutions today support IP telephony.
The deployment of Internet telephony allows both voice and data to share the same networks. The telecommunications industry is moving toward this "convergence" for largely financial reasons. However, traditional telephone networks are extremely reliable, and IP telephony must first achieve a similar level of capability before it can completely replace older telephony systems.
back to the top
USB
USB is a high-performance serial bus communication technology. Most new computers and associated peripheral devices like printers and scanners contain built-in support for this technology. USB hubs for file and printer sharing also exist. USB and FireWire are the most popular, competing standards for networking computer peripherals.
back to the top
Using USB for Local Networking
To build a USB network, simply connect USB cables to the USB ports on those devices. USB is plug and play compatible, meaning the operating system USB driver software automatically detects and configures device connections. One USB network supports up to 127 devices.
USB interfaces are backward compatible; for example, a USB 2.0 and a USB 1.1 can be networked. When two ends of a connection support different versions of USB, the link automatically runs at the lower speed of the older version.
back to the top
USB Keys
As an alternative to using USB technology for local area networking, USB keys can be used to transfer files between two devices without requiring cables. To use a USB key (also known as a memory stick), copy files from one computer onto the key, then physically carry the stick to a different computer and copy the files onto that device.
Also Known As: Universal Serial Bus
back to the top
VoIP
VoIP is a technology that allows telephone calls to be made over computer networks like the Internet. VoIP converts analogue voice signals into digital data packets and supports real-time, two-way transmission of conversations using Internet Protocol (IP).
VoIP calls can be made on the Internet using a VoIP service provider and standard computer audio systems. Alternatively, some service providers support VoIP through ordinary telephones that use special adapters to connect to a home computer network.
VoIP offers a substantial cost saving over traditional long distance telephone calls. The main disadvantage of VoIP is, like cell phones, a greater potential for dropped calls and generally lesser voice quality.
Also Known As: Voice over Internet Protocol (IP)
back to the top
VPN
A VPN utilizes public telecommunications networks to conduct private data communications. Most VPN implementations use the Internet as the public infrastructure and a variety of specialized protocols to support private communications through the Internet.
VPN follows a client and server approach. VPN clients authenticate users, encrypt data, and otherwise manage sessions with VPN servers utilizing a technique called tunnelling.
VPN clients and VPN servers are typically used in these three scenarios:
- To support remote access to an intranet
- To support connections between multiple intranets within the same organization, and
- To join networks between two organizations, forming an extranet
The main benefit of a VPN is the lower cost needed to support this technology compared to alternatives like traditional leased lines or remote access servers.
VPN servers can also connect directly to other VPN servers. A VPN server-to-server connection extends the intranet or extranet to span multiple networks.
Also Known As: virtual private network
back to the top
WAN
A WAN spans a large geographic area, such as a state, province or country. WANs often connect multiple smaller networks, such as local area networks (LANs) or metro area networks (MANs).
The world's most popular WAN is the Internet. Some segments of the Internet, like VPN-based extranets, are also WANs in themselves. Finally, many WANs are corporate or research networks that utilize leased lines.
WANs generally utilize different and much more expensive networking equipment than do LANs.
Also Known As: wide area network
back to the top
WAP - Wireless Access Points and Wireless Application Protocol
WAP - the Wireless Application Protocol - defines a network architecture for content delivery over wireless networks. Central to the design of WAP is a network stack based on the OSI model. WAP implements several new networking protocols that perform functions similar to the well-known Web protocols HTTP, TCP, and SSL.
The term "WAP" also is used to refer to wireless access points.
back to the top
Wi-Fi - Wireless Fidelity
Wi-Fi is the industry name for wireless LAN (WLAN) communication technology related to the IEEE 802.11 family of wireless networking standards.
back to the top