Section 4 C Terms Flashcards
1
Q
Cable
A
The transmission media of a network.
2
Q
Cable Range
A
Range of network numbers that is valid for use by nodes on an extended AppleTalk network. The cable range value can be a single network number or a contiguous sequence of several network numbers. Node addresses are assigned based on the cable range value.
3
Q
Cache
A
A group of memory locations set aside for temporary storage ofdata, especially frequently-used data or data needing high speedretrieval by the CPU.
4
Q
Call Admission Control
A
Traffic management mechanism used in ATM networks thatdetermines whether the network can offer a path with sufficient bandwidth for a requested VCC.
5
Q
Call Priority
A
Priority assigned to each origination port in circuit-switched systems. This priority defines the order in which calls are reconnected. Call priority also defines which calls can or cannot be placed during a bandwidth reservation.
6
Q
Call Setup Time
A
The time required to establish a switched call between DTE devices.
7
Q
CAM
A
Content-addressable memory. See associative memory.
8
Q
Card
A
A circuit board that plugs into a computer’s bus to extend the computer’s capability.
9
Q
Carrier
A
Electromagnetic wave or alternating current of a single frequency, suitable for modulation by another, data-bearing signal.
10
Q
Case Insensitive
A
Referring to a system in which upper case letters are not differentiated from their lower case form.
11
Q
Case Sensitive
A
Referring to a system in which upper case letters are differentiated from their lower case form.
12
Q
Category 1 Cabling
A
One of five grades of UTP cabling described in the EIA/TIA-586 standard. Category 1 cabling is used for telephone communications and is not suitable for transmitting data. Compare with Category 2 cabling, Category 3 cabling, Category 4 cabling, and Category 5 cabling. See also EIA/TIA-586 and UTP.
13
Q
Category 2 Cabling
A
One of five grades of UTP cabling described in the EIA/TIA-586 standard. Category 2 cabling is capable of transmitting data at speeds up to 4 Mbps. Compare with Category 1 cabling, Category 3 cabling, Category 4 cabling, and Category 5 cabling. See also EIA/TIA-586 and UTP.
14
Q
Category 3 cabling
A
One of five grades of UTP cabling described in the EIA/TIA-586 standard. Category 3 cabling is used in 10Base T networks and can transmit data at speeds up to 10 Mbps. Compare with Category 1 cabling, Category 2 cabling, Category 4 cabling, and Category 5 cabling. See also EIA/TIA-586 and UTP.
15
Q
Category 4 cabling
A
One of five grades of UTP cabling described in the EIA/TIA-586 standard. Category 4 cabling is used in Token Ring networks and can transmit data at speeds up to 16 Mbps. Compare with Category 1 cabling, Category 2 cabling, Category 3 cabling, and Category 5 cabling. See also EIA/TIA-586 and UTP.
16
Q
Category 5 cabling
A
One of five grades of UTP cabling described in the EIA/TIA-586 standard. Category 5 cabling is used for running CDDI and can transmit data at speeds up to 100 Mbps Compare with Category 1 cabling, Category 2 cabling, Category 3 cabling, and Category 4 cabling. See also EIA/TIA-586 and UTP.
17
Q
Catenet
A
Network in which hosts are connected to diverse networks, which themselves are connected with routers. The Internet is a prominent example of a catenet.
18
Q
CATV
A
Cable television. Communication system where multiple channels of programming material are transmitted to homes using broadband coaxial cable. Formerly called Community Antenna Television.
19
Q
CBDS
A
Connectionless Broadband Data Service. European high-speed, packet-switched, datagram-based WAN networking technology. Similar to SMDS.
20
Q
CBR
A
Constant bit rate. QOS class defined by the ATM Forum for ATM networks. CBR is used for connections that depend on precise clocking to ensure undistorted delivery.
21
Q
CCITT
A
Consultative Committee for International Telegraph and Television and Telephone. International organization responsible for the development of communications standards. Now called the ITU-T.
22
Q
CCS
A
Common Channel Signaling. Signaling system used in telephone networks that separates signaling information from user data. A specified channel is exclusively designated to carry signaling information for all other channels in the system
23
Q
CD
A
Carrier Detect. Signal that indicates whether an interface is active. Also, a signal generated by a modem indicating that a call has been connected.
24
Q
CDDI
A
Copper Distributed Data Interface. Implementation of FDDI protocols over STP and UTP cabling. CDDI transmits over relatively short distance (about 100 meters), providing data rates of 100Mbps using a dual-ring architecture to provide redundancy. Based on the ANSI Twisted-Pair Physical Medium Dependent (TPPMD) standard.
25
CDEV
The designation of a Control Panel Device in Macintosh System 6and earlier (obsolete).
26
CDPD
Cellular Digital Packet Data. Open standard for two-way wireless data communication over high-frequency cellular telephone channels. Allows data transmissions between a remote cellular link and a NAP. Operates at 19.2 Kbps.
27
CDVT
Cell delay variation tolerance. Parameter defined by the ATM Forum for ATM traffic management. In CBR transmissions, determines the level of jitter that is tolerable for the data samples taken by the PCR.
28
CEDI
Cayman Encapsulated DDP in IP. An Apple Talk tunneling protocol developed by Cayman.
29
Cell
The basic unit for ATM Switching and multiplexing. Cells contain identifiers that specify the data stream to which they belong. Each cell consists of a 5-byte header and 48 bytes of payload. See also cell relay.
30
Cell Relay
Network technology based on the use of small, fixed-size packets, or cells. Because cells are fixed-length, they can be processed and switched in hardware at high speeds. Cell relay is the basis for many high-speed network protocols including ATM, IEEE802.6, and SMDS.
31
Cells Per Second
Abbreviated cps.
32
Cellular Radio
Technology that uses radio transmissions to access telephone-company networks. Service is provided in a particular area by a low-power transmitter.
33
Centrex
AT&T PBX that provides direct inward dialing and automatic numbering identification of the calling PBX.
34
CEPT
Conférence Européenne des Postes et des Télécommunications. Association of the 26 European PTTs that recommends communication specifications to the ITU-T.
35
CERTnet
California Education and Research Federation Network. TCP/IP network, based in Southern California, that connects hundreds of higher-education centers internationally while also providing Internet access to subscribers. CERFnet was founded in 1988 by the San Diego Supercomputer Center and General Automics and is funded by the NSF.
36
Chaining
SNA concept in which RUs are grouped together for the propose of error recovery.
37
Channel
1. A communication path. Multiple channels can be multiplexed over a single cable in certain environments. 2. In IBM, the specific path between large computers (such as mainframes) and attached peripheral devices.
38
Channel-attached
Pertaining to attachment of devices directly by data channels (input/output channels) to a computer.
39
Channelized E1
Access link operating at 2.048 Mbps that is subdivided into 30 B-channels and 1 D-channel, Supports DDR, Frame Relay, and X.25. Compare with channelized T1.
40
Channelized T1
Access link operating at 1.544 Mbps that is subdivided into 24 channels (23 B-channels and 1D-channel) of 64 Kbps each. The individual channels or groups of channels connect to different destinations. Supports DDR, Frame Relay, and X.25. Also referred to as fractional T1. Compare with channelized E1.
41
CHAP
Challenge Handshake Authentication Protocol. Security feature supported on lines using PPP encapsulation that prevents unauthorized access. CHAP does not itself prevent unauthorized access, it merely identifies the remote end. The router or access server than determines whether that user is allowed access. Compare to PAP.
42
Character
1. A symbol such as a letter, number or punctuation mark that canbe arranged to represent higher units of meaning, such as wordsand sentences. 2. The group of bits that represents such a symbol.
43
Chat Script
String of text that defines the login "conversation" that occurs between two systems. Consist of expect-send pairs that define the string that the local system expects to receive from the remote system and what the local system should send as a reply.
44
Cheapernet
industry term used to refer to the IEEE 802.3 10Base2 standard or the cable specified in that standard. Compare with Thinnet. See also 10Base2, Ethernet, and IEEE 802.3.
45
Checksum
The result of a mathematical operation that uses the binary representation of a group of data as its basis, usually to check the integrity of the data.
46
Choke Packet
Packet sent to a transmitter to tell it that congestion exists and that it should reduce its sending rate.
47
CICNet
Regional network that connects academic, reserach, nonprofit, and commercial organizations in the Midwestern United States. Founded in 1988, CICNet was a part of the NSF NET and was funded by the NSF until the NSFNET dissolved in 1995. See also NSFNET.
48
CICS
Customer Information Control System. IBM application subsystem allowing transactions entered at remote terminals to be processed concurrently by user applications.
49
CIDR
Classless interdomain routing. Technique supported by BGP4 and based on route aggregation. CIDR allows routers to group routes together in order to cut down on the quantity of routing information carried by the core routers. With CIDR, several IP networks appear to networks outside the group as a single, larger entity.
50
CIR
Committed information rate. The rate at which a Frame Relay network agrees to transfer information under normal conditions, averaged over a minimum increment of time. CIR, measured in bits per second, is one of the key negotiated tariff metrics.
51
Circuit
1. Any electrical pathway. 2. An arrangement of electrical andelectronic devices and the conductive paths between them.
52
Circuit Group
Grouping of associated serial lines that link two bridges. If one of the serial links in a circuit group is in the spanning tree for a network, any of the serial links in the circuit group can be used for load balancing. This load-balancing strategy avoids data ordering problems by assigning each destination address to a particular serial link.
53
Circuit Switching
Switching system in which a dedicated physical circuit path must exist between sender and receiver for the duration of the "call." Used heavily in the telephone company network. Circuit switching can be contrasted with contention and token passing as a channel-access method, and with message switching and packet switching as a switching technique.
54
Classic IP Over ATM
Specification for running IP over ATM in a manner that takes full advantage of the features of ATM. Defined in RFC 1577. Sometimes called CIA.
55
CLAW
Common Link Access for Workstations. Data link layer protocol used by channel-attached RISC System/6000 series systems and by IBM 3172 devices running TCP/IP off-load. CLAW improves efficiency of channel use and allows the CIP to provide the functionality of a 3172 in TCP/IP environments and support direct channel attachment. The output from TCP/IP mainframe processing is a series of IP datagrams that the router can switch without modifications.
56
Client
Node or software program (front-end device) that requests services from a server. See also back end, front end and server.
57
Client/Server
A type of relationship between two computers where the two havedifferent roles in the relationship. Typically, the client computerdrives the relationship and uses a resource of the servercomputer.
58
CLNP
Connectionless Network Protocol. OSI network layer protocol that does not require a circuit to be established before data is transmitted. See also CLNS.
59
CLNS
Connectionless Network Service. OSI network layer service that does not require a circuit to be established before data is transmitted. CLNS routes messages to their destinations independently of any other messages. See also CLNP.
60
CLP
Cell loss priority. Field in the ATM cell header that determines the probability of a cell being dropped if the network becomes congested. Cell with CLP = 0 are insured traffic, which is unlikely to be dropped. Cells with CLP = 1 are best-effort traffic, which might be dropped in congested conditions in order to free up resources to handle insured traffic.
61
Clock
1. A component in a computer that provides a timing pulse forother components. 2. The timing pulse of a network transmission.
62
Cluster controller
1. Generally, an intelligent device that provides the connections for a cluster of terminals to be data link. 2. In SNA, a programmable device that controls the input/output operations of attached devices. Typically, an IBM 3174 or 3274 device.
63
CMI
Coded mark inversion. ITU-T line coding technique specified for STS-3c transmissions. Also used in DS-1 systems.
64
CMIP
Common Management Information Protocol.
65
CMIS
Common Management Information Services. OSI network management service interface created and standardized by ISO for the monitoring and control of heterogeneous networks. See also CMIP.
66
CMNS
Connection-Mode Network Service. Extends local X.25 switching to a variety of media (Ethernet, FDDI, Token Ring). See also .
67
CMT
Connection management. FDDI process that handles the transition of the ring through its various states (off, active, connect, and so on), as defined by the ANSI X3T9.5 specification.
68
CO
Central office. Local telephone company office to which all local loops in a given area connect and in which circuit switching of subscriber lines occurs.
69
Coaxial cable
An electrical cable in which the conductors share a common axis.
70
CODEC
Coder-decoder. Device that typically uses PCM to transform analog signals into a digital bit stream and digital signals back into analog.
71
Coding
Electrical techniques used to convey binary signals.
72
Collapsed Backbone
Nondistributed 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.
73
Collision
In Ethernet, the result of two nodes transmitting simultaneously. The frames from each device impact and are damaged when they meet on the physical media. See also Collision domain.
74
Collision Avoidance
A Media Access Control (MAC) method in which any node maytake control of the network after taking certain steps to insure thatthe cable is not in use or about to be used by another node.
75
Collision Detection
A MAC method in which any node may take control of the network when it is not in use by another node. While transmitting, stations continue to listen for incoming signals (collisions) and emit a jamming signal to notify all other stations of the collision.
76
Collision Domain
In Ethernet, the network area within which frames that have collided are propagated. Repeaters and hubs propagate collisions; LAN switches, bridges and routers do not. See also collision.
77
Common Carrier
Licensed, private utility company that supplies communication services to the public at regulated prices.
78
Communication
Transmission of information.
79
Communication Controller
In SNA, a subarea node (such as an IBM 3745 device) that contains an NCP.
80
Communication Server
Communications processor that connects asynchronous devices to a LAN or WAN through network and terminal emulation software. Performs only asynchronous routing of IP and IPX. Compare with access server.
81
Communications Line
The physical link (such as wire or a telephone circuit) that connects one or more devices to one or more other devices.
82
Community
In SNMP, a logical group of managed devices and NMSs in the same administrative domain.
83
Community String
Text string that acts as a password and is used to authenticate messages sent between a management station and a router containing a SNMP agent. The community string is sent in every packet between the manager and the agent.
84
Companding
Contraction derived from the opposite processes of compression and expansion. Part of the PCM process whereby analog signal values are logically rounded to discrete scale-step values on a nonlinear scale. The decimal step number is then coded in its binary equivalent prior to transmission. The process is reversed at the receiving terminal using the same nonlinear scale. Compare with compression and expansion. See also a-law and mu-law.
85
Component
An indivisible unit of functionality, usually embodied in hardware.
86
Compression
An alteration performed on a unit of information intended to increase it density during storage of transmission.
87
Concentrator
A synonym for a multi-port repeater that may also perform bridging and routing functions.
88
Conductor
The current-carrying component of a transmission cable, typically a copper wire.
89
Configuration Management
One of five categories of network management of OSI networks. Configuration management subsystems are responsible for detecting and determining the state of a network. See also account management, fault management, performance management, and security management.
90
Congestion
Traffic in excess of network capacity
91
Connection-Oriented
In data networks, a type of computer relationship in which the network equipment constructs a circuit between the two devices for the duration of their relationship. Once the circuit is established, the devices pass information back and forth through the circuit without regard to their physical addresses. The circuit may be physical or virtual.
92
Connectionless
A type of relationship between two devices where each information packet must contain the address of the partner device. Connectionless communication allows a message to be sent from one end point to another without prior arrangement, and has very low overhead, but cannot guarantee that there will be no loss, error insertion, mis-delivery, duplication, or out-of-sequence delivery of the packets.
93
Connectivity
A term referring to the ability of a device to trade data and shareresources with other devices of a similar and dissimilar typethrough electronic means including serial and parallel connections, networking and telecommunications.
94
Connector
A device that establishes a physical connection between oneconductor or circuit and another.
95
CONP
Connection-Oriented Network Protocol, OSI protocol providing connection-oriented operation to upper-layer protocols.
96
Console
In SNMP (Simple Network Management Protocol), a software program that has the capability of interacting with an agent, including examining or changing the values of the data objects in the agent's Management Information Base (MIB).
97
Contention
A network access method where all the devices on the network have equal changes of gaining control of the network at any time. Includes avoidance (CSMA/CA) access methods.
98
Control Panel
In the Macintosh, a software application that has the ability to control an aspect of system configuration, such as the pixel depth of the monitor (Monitors), the choice of network type (Network), etc.
99
Convergence
The speed and ability of a group of internetworking devices running a specific routing protocol to agree on the topology of an internetwork after a change in that topology.
100
Conversation
In SNA, an LU 6.2 session between two transaction programs.
101
Core Gateway
The primary routers in the Internet.
102
Core Router
In a packet-switched star topology, a router that is part of the backbone and that serves as the single pipe through which all traffic from peripheral networks must pass on its way to other peripheral networks.
103
COS
1. Class of service. Indication of how an upper-layer protocol requires that a lower-layer protocol treat its messages. In SNA subarea routing, COS definitions are used by subarea nodes to determine the optimal route to establish to given session. A COS definition comprises a virtual route number and a transmission priority field. Also called TOS (type of service). 2. Corporation for Open Systems. Organization that promulgates the use of OSI protocols through conformance testing, certification, and related activities.
104
COSINE
Cooperation for Open Systems Interconnection Networking in Europe. European project financed by the European Community (EC) to build a communication network between scientific and industrial entities in Europe. The project ended in 1994.
105
Cost
Arbitrary value, typically based on hop count, media bandwidth, or other measures, that is assigned by a network administrator and used to compare various paths through an internetwork environment. Cost values are used by routing protocols to determine the most favorable path to a particular destination: the lower the cost, the better the path. Sometimes called path cost. See also routing metric.
106
Count to Infinity
Problem that can occur in routing algorithms that are slow to converge, in which routers continuously increment the hop count to particular networks. Typically, some arbitrary hop-count limit is imposed to prevent this problem.
107
CP
Control point. In SNA networks, element that identifies the APPN networking components of a PU 2.1 node, manages device rresources, and can provide services to other devices. In APPN, CPs are able to communicate with logically adjacent CPs by way of CP-to-CP sessions. See also EN and NN.
108
CPCS
Common part convergence sublayer. One of the two sublayers of any AAL. The CPCS is service-independent and is further divided into the CS and the SAR sublayers. The CPCS is responsible for preparing data for transport across the ATM network, including the creation of the 48-byte payload cells that are passed to the ATM layer. See also AAL, ATM layer, CS, SAR, and SSCS.
109
CPE
Customer premises equipment. Terminating equipment, such as terminals, telephones, and modems, supplied by the telephone company, installed at customer sites, and connected to the telephone company network.
110
CPI-C
Common Programming Interface for Communications. Platform-independent API developed by IBM and used to provide portability in APPC applications. See also APPC.
111
CPS
Cells per second.
112
CPU
Central Processing Unit. The main processor in the computer's configuration that handles processing tasks or directs auxiliary processors (coprocessors) to perform them.
113
CPU bound
A computing activity or network interaction whose speed is limited by the speed at which the CPU can perform the necessary computing tasks.
114
Crash
An abrupt termination or computing activity caused by an error. In many instances, the computer becomes completely unusable and must be restarted before activity can resume.
115
CRC
Cyclic Redundancy Check. A method of insuring data integrity where a calculation is performed using the binary representation of the data itself as the basis of the calculation. The CRC is the numerical result of this calculation and is held separately from the data. The integrity of the data is checked by calculating a newCRC. If the two CRC's match, then there is a high degree of confidence that the data has not changed.
116
CREN
Corporation for Research and Educational Networking. The result of a merger of BITNET and CSNET. CREN is devoted to providing Internet connectivity to its members, which include the alumni, students, faculty, and other affiliates of participating educational and research institutions, via BITNET III. See also BITNET, BITNET III, and CSNET.
117
Crosstalk
In electronic signaling, an error condition caused when the signal from one circuit causes a disturbance to the signal of the nearby circuit..
118
CS
Convergence sublayer. One of the two sublayers of the AAL CPCS, responsible for padding and error checking. PDUs passed from the SSCS and appended with a 8-byte trailer (for error checking and other control information) and padded, if necessary, so that the length of the resulting PDU is divisible by 48. These PDUs are then passed to the SAR sublayer of the CPCS for further processing. See also AAL, CPCS, SAR, and SSCS.
119
CSA
Canadian Standards Association. Agency within Canada that certifies products that conform to Canadian national safety standards.
120
CSLIP
Compressed Serial Link Internet Protocol. Extension of SLIP that, when appropriate, allows just header information to be sent across a SLIP connection, reducing overhead and increasing packet throughput on SLIP lines. See also SLIP.
121
CSMA/CD
Carrier sense multiple access collision detect. Media-access mechanism wherein devices ready to transmit data first check the channel for a carrier. If no carrier is sensed for a specific period of time, a device can transmit. If two devices transmit at once, a collision occurs and is detected by all colliding devices. This collision subsequently delays retransmissions from those devices for some random length of time. CSMA/CD access is used by Ethernet and IEEE 802.3.
122
CSNET
Computer Science Network. Large internetwork consisting primarily of universities, research institutions, and commercial concerns. CSNET merged with BITNET to form CREN.
123
CSNP
Complete sequence number PDU. PDU sent by the designated router in an OSPF network to maintain database synchronization.
124
CSU
Channel service unit. Digital interface device that connects end-user equipment to the local digital telephone loop. Often referred to together with DSU, as CSU/DSU. See also DSU.
125
CTS
1. Clear To Send. Circuit in the EIA/TIA-232 specification that is activated when DCE is ready to accept data from DTE. 2. Common transport semantic. Cornerstone of the IBM strategy to reduce the number of protocols on networks. CTS provides a single API for developers of network software and enables applications to run over APPN, OSI, or TCP/IP.
126
CUT
Control Unit Terminal.
127
Cut-through Packet Switching
Packet switching approach that streams data through a switch so that the leading edge of a packet exits the switch at the output port before the packet finishes entering the input port. A device using cut-through packet switching reads, processes, and forwards packets as soon as the destination address is looked up, and the outgoing port determined. Also known as on-the-fly packet switching. Contrast with store and forward packet switching.
