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.
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.
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.
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.
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.
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.
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.
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.
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.
Drop
A drop is a point on a multipoint channel where a connection to a networked device is made.
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.
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.
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.
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.
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.
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.
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.
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.
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.