Glossary Co-Cz

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  • Coating: A material put on a fiber during the drawing process to protect it from the environment.
  • Coaxial Cable: A type of electrical cable in which a signal central wire that carries the signal is surrounded by insulation & then a complete metal shield. Ethernet, thinnet & RG62 cables are examples.
  • Coaxial Connector: A connector that has coaxial construction & is used with coaxial cable.
  • Code: A set of unambiguous rules specifying the way in which data may be represented.
  • Coil Effect: The inductive effect exhibited by a spiral-wrapped shield, especially above audio frequencies.
  • Collapsed Backbone: A local area network configuration wherein bridging & routing functions are located at the main cross-connect & accessed via optical fiber (usually 2 or 4). Concentrators (twisted pair to fiber) remain at the horizontal cross-connects.
  • Collision: The result of simultaneous transmission by two DTEs on a shared bus. Both DTEs must re-transmit the data (one at a time or taking turns).
  • Collision Detect: A signal that one or more stations are contending with the local station's transmission. The signal is sent by the physical layer to the data link layer on an Ethernet/IEEE 802.3 node.
  • Collision Domain: See Segment
  • Color Code: A color system for wire or circuit identification by use of solid colors, traces, braids, surface printing, etc.
  • Comite Consultatif International de Telegraphique et Telephonique: (CCITT) French for "International Telephone & Telegraph Advisory Council." It's an organization that plays a major role in the United National International Telecommunications Union (ITU). The CCITT is responsible for making technical recommendations about communications systems worldwide. Every four years, CCITT updates the standards.
  • Common Carrier: Public transmission link such as the Bell or General Telephone systems
  • Common Management Information Protocol: (CMIP) the network management protocol defined by the OSI specifications. CMIP is used to convey CMIS defined operations over an OSI network.
  • Common Management Information Services: (CMIS) The portion of the OSI network management specification which defines the management services available to a network management system. CMIS works with CMIP.
  • Communications Control Unit: (CCU) A computer attached to a host & dedicated to performing data communications functions. Its purpose is to enable the host to perform other tasks. A CCU is also called a "Front End Processor"
  • Communications Server: An intelligent device (a computer) providing communications functions; an intelligent, specially configured node on a local area network, designed to enable remote communications access & exit for LAN users.
  • Community Antenna Television: (CATV) Cable Television; data communications based on radio frequency (RF) transmission, generally using 75 ohm coaxial cable as the transmission medium; communications via coaxial cable where multiple frequency divided channels allow mixed transmissions to be carried simultaneously; broadband.
  • Compaction: See Compression
  • Composite Cable: Cable containing more than one gauge size or a variety of circuit types, e.g. pairs, triples, quads, coaxials etc.
  • Composite Link: The line or circuit connecting a pair of multiplexers or concentrators; the circuit carrying multiplexed data.
  • Compression: Any of several techniques that reduce the number of bits required to represent information in data transmission or stage (thus conserving bandwidth and/or memory), in which the original form of the information can be reconstructed; also called "compaction".
  • Computer Emergency Response Team: (CERT) The CERT was formed by DARPA in November 1988 in response to the Internet worm incident. CERT exists to facilitate Internet-wide response to computer security events involving Internet hosts & to conduct research targeted at improving the security of existing systems. They maintain an archive of security-related issues on their FTP server
  • Concentrator: A communications device that allows a shared transmission medium to accommodate more data sources than channels currently available within the transmission medium.
  • Concentric Stranding: A group of uninsulated wires twisted together & containing a center core with subsequent layers spirally wrapped around the core to form a single conductor.
  • Conditioning: The addition of equipment to improve ("tune") the transmission characteristics of a dedicated voice grade telephone line. Conditioning is done to allow for an increase in transmission speed (Bit rate) without increasing the error rate.
  • Conductivity: Any material that allows electrons to flow measured by the voltage applied.
  • Conductor: A material that offers little resistance to the flow of electrical current.
  • Conduit: A raceway of circular cross-section of the type permitted under the appropriate electrical code.
  • Configuration Management: A network management function defined by the International Standards Organization (ISO). It involves installing, reinitializing & modifying hardware & software.
  • Connecting Hardware: A device providing mechanical cable terminations.
  • Connection: A term used in the networking environment to describe the path between two devices. A connection allows the exchange of information between two or more devices. Equivalent terms are session & circuit.
  • Connection-Oriented: Refers to a protocol which uses virtual circuits; the nodes which are the endpoint of the connection, or circuit, maintain state control information. This allows them to correlate each packet with previously received packets to provide error-free, loss-less packet delivery.
  • Connectionless Service: A protocol or service which does not require that a virtual circuit be established between the endpoints: each packet is processed independently. All commonly used LAN's provide connectionless service as the basic packet delivery service mechanism.
  • Console: The terminal used to configure network devices at boot or start up time.
  • Contention: A situation when multiple users compete for a transmission channel within a multiplexed digital facility.
  • Continuity Check: A test performed on a length of finished wire or cable to determine if the electrical current flows continuously throughout the length. Each conductor may also be checked against each other to ascertain that no shorts exist.
  • Control Cable: A cable used for remote control operation of any type of electrical power equipment.
  • Control Signals: A category of signals in a DTE to DCE interface specification. These signals control the data transmission.
  • Coordinating Committee for Intercontinental Research Networks: (CCIRN) A committee that provides a forum for North American & European network research organizations to cooperate & plan.
  • Core: Typically made out of glass, the core is the light conducting central portion of the optical fiber. It has a higher refractive index than the cladding.
  • Coupling: The transfer of energy between two or more cables or components of a circuit.
  • Coupling Loss (fiber optic): Signal losses due to small differences in numerical aperture, core diameter, core concentricity & tolerances in splicing connectors when two fibers are aligned. Also known as splicing loss & transfer loss.
  • Coverage: The calculated percentage which defines the completeness with which a metal braid covers the underlying surface. The higher percentage of coverage, the greater the protection against external interference.
  • CPU: See Central Processing Unit
  • CRC: See Cyclic Redundancy Check
  • Cross-connect: A facility for the interconnection & termination of cabling.
  • Crossover: Conductor which runs through the cable & connect to a different pin number at each end.
  • Crosstalk: The unwanted electrical currents in conductors caused by electromagnetic or electrostatic coupling from other conductors, or, the signal on 1 pair leaks or jumps onto & adjacent pair. It is measured in decibels (dB). Crosstalk must be at least 10 dB greater than the total cable loss.
  • CRT: See Cathode Ray Tube
  • CSA: See Canadian Standards Association
  • CSMA: See Carrier Sense Multiple Access
  • CSMA/CD: See Carrier Sense Multiple Access/Collision Detection
  • CSU: See Channel Service Unit
  • Current Loop: Method of interconnecting terminals & transmitting signals a mark (binary1) is represented by current on the line, & a space(binary 0) is represented by the absence of current.
  • Cut-through: Technique for examining incoming packets whereby an Ethernet switch looks only at the first few bytes of a packet before forwarding or filtering it. This process is faster than looking at a whole packet, but also allows some bad packets to be forwarded.
  • CXC: Coaxial Cable.
  • Cyberspace: The "world of computers & the society that gathers around them," as referred to by William F. Gibson in his fantasy novel "Neuromancer." It now loosely refers to the online world & even more loosely to the Internet.
  • Cyclic Redundancy Check: (CRC) An error-detecting code appended to a packet to help the receiver determine if errors were introducing during transmission. The CRC is specialized checksum computed over the entire packet & added to the packet by transmitters LAN controller hardware, & is checked for correctness by the receiving station's hardware. Use of the CRC allows the LAN MAC layer to guarantee a very low probability of incorrectly delivering a corrupted packet. Crossed Pinning: Cable configuration that allows two DTE devices or two DCE devices to communicate.
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