Browsing: C
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CA |
See
congestion
avoidance.
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cable |
Transmission medium of copper
wire or optical fiber wrapped in a protective cover.
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cable
range |
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.
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cable
television |
See
CATV.
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caching
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Form of replication in which information learned during a previous transaction is used to process later transactions.
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California
Education and Research Federation Network |
See
CERFnet.
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call
admission control
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Traffic management mechanism
used in ATM networks that determines whether the network can
offer a path with sufficient bandwidth for a requested VCC.
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call
priority |
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. See also
bandwidth
reservation.
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call
setup time |
The time required to establish
a switched call between DTE devices.
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CAM |
Content-addressable
memory. See
associative
memory.
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Canadian
Standards Association |
See
CSA.
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carrier |
Electromagnetic wave or
alternating current of a single frequency, suitable for
modulation by another, data-bearing signal. See also
modulation.
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Carrier
Detect |
See
CD.
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carrier
sense multiple access collision detect |
See
CSMA/CD.
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Catalyst
1600 Token Ring Switch |
Cisco Token Ring switch that
offers full-duplex dedicated LAN segments to individual
servers and other workstations that require high-speed
switching access. The Catalyst 1600 provides up to 12
switched Token Ring interfaces and low latency switching
between servers and clients across a backbone.
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Catalyst
5000 |
Cisco modular switching system
that allows connection to Ethernet, CDDI, FDDI, and ATM LANs
and backbones. The Catalyst 5000 switch performs
store-and-forward packet switching and allows the user to
dedicate 10- or 100-Mbps connections to existing LAN
segments or high-performance end stations.
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Catalyst
Workgroup Switch |
Series of Cisco workgroup
switches that enhance the network performance of Ethernet
client/server workgroups. The Catalyst Workgroup Switch
integrates software enhancements for network management and
provides a 100-Mbps interface to servers and dedicated
Ethernet-to-desktop workstations.
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Catchment
areas |
Zone that falls within area
that can be served by an internetworking device such as a
hub.
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Category
1 cabling |
One of five grades of UTP
cabling described in the EIA/TIA-568B 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-568B
and
UTP.
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Category
2 cabling |
One of five grades of UTP
cabling described in the EIA/TIA-568B 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-568B
and
UTP.
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Category
3 cabling |
One of five grades of UTP
cabling described in the EIA/TIA-568B 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-568B
and
UTP.
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Category
4 cabling |
One of five grades of UTP
cabling described in the EIA/TIA-568B 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-568B
and
UTP.
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Category
5 cabling |
One of five grades of UTP
cabling described in the EIA/TIA-568B 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-568B
and
UTP.
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catenet |
Network in which hosts are
connected to diverse networks, which themselves are
connected with routers. The Internet is a prominent example
of a catenet.
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CATV |
Cable television.
Communication system where multiple channels of programming
material are transmitted to homes using broadband coaxial
cable. Formerly called Community Antenna Television.
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CBDS |
Connectionless
Broadband Data Service. European high-speed,
packet-switched, datagram-based WAN networking technology.
Similar to SMDS. See also
SMDS.
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CBR |
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. Compare with
ABR
(available bit rate),
UBR,
and
VBR. |
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CCITT |
Consultative Committee
for International Telegraph and Telephone.
International organization responsible for the development
of communications standards. Now called the ITU-T. See
ITU-T.
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CCS |
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.
See also
SS7.
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CD |
Carrier Detect.
Signal that indicates whether an interface is active. Also,
a signal generated by a modem indicating that a call has
been connected.
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CDDI |
Copper Distributed
Data Interface. Implementation of FDDI protocols
over STP and UTP cabling. CDDI transmits over relatively
short distances (about 100 meters), providing data rates of
100 Mbps using a dual-ring architecture to provide
redundancy. Based on the ANSI Twisted-Pair Physical Medium
Dependent (TPPMD) standard. Compare with
FDDI.
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CDDI/FDDI
workgroup concentrator |
See
Cisco
Workgroup Concentrator. |
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CDP |
Cisco Discovery Protocol. Media- and protocol-independent
device-discovery protocol that runs on all Cisco-manufactured
equipment including routers, access servers, bridges, and switches.
Using CDP, a device can advertise its existence to other devices and
receive information about other devices on the same LAN or on the
remote side of a WAN. Runs on all media that support SNAP, including
LANs, Frame Relay, and ATM media.
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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.
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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. See also
CBR and
PCR.
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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.
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cell delay variation tolerance |
See
CDVT.
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cell line card |
See
CLC.
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cell loss priority |
See
CLP.
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cell payload scrambling |
Technique used on the LightStream 2020 ATM switch to maintain
framing on some medium-speed edge and trunk interfaces.
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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, IEEE 802.6, and
SMDS. See also
cell.
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cells per second |
Abbreviated cps.
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Cellular Digital Packet Data |
See
CDPD.
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cellular radio |
Technology that uses radio transmissions to access telephonecompany
networks. Service is provided in a particular area by a low-power
transmitter.
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CEMAC |
Circuit emulation access card. T1 or E1 circuit emulation
card in the LightStream 2020 ATM switch. See also
access card.
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central office |
See
CO.
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Centrex |
AT&T PBX that provides direct inward dialing and automatic number
identification of the calling PBX.
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CEPT |
Conférence Européenne des Postes et des Télécommunications.
Association of the 26 European PTTs that recommends communication
specifications to the ITU-T.
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CERFnet |
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 Atomics and is funded by
the NSF.
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CFRAD |
See
Cisco FRAD.
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CGS |
Compact Gateway Server. Cisco midrange multiprotocol router
designed for medium to small regional and district environments. The
CGS is a 2-slot router that supports up to four interfaces (all of
the same type).
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chaining |
SNA concept in which RUs are grouped together for the purpose of
error recovery.
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Challenge Handshake Authentication Protocol |
See
CHAP.
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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. |
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channel-attached |
Pertaining to attachment of devices directly by data channels
(input/output channels) to a computer.
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Channel Interface Processor |
See
CIP.
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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.
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channelized T1 |
Access link operating at 1.544 Mbps that is subdivided into 24
channels (23 B-channels and 1 D-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.
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channel service unit
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See
CSU.
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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 then determines whether that user is allowed access. Compare
to
PAP.
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chat script |
String of text that defines the login "conversation" that occurs
between two systems. Consists 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.
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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.
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checksum |
1.) Method for checking the integrity of transmitted data. A
checksum is an integer value computed from a sequence of octets
taken through a series of arithmetic operations. The value is
recomputed at the receiving end and compared for verification. 2.)
Calculated checksum of the header and data fields.
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choke packet |
Packet sent to a transmitter to tell it that congestion exists and
that it should reduce its sending rate.
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CIA |
See
classical IP over ATM.
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CICNet |
Regional network that connects academic, research, nonprofit, and
commercial organizations in the Midwestern United States. Founded in
1988, CICNet was a part of the NSFNET and was funded by the NSF
until the NSFNET dissolved in 1995. See also
NSFNET.
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CICS |
Customer Information Control System. IBM application
subsystem allowing transactions entered at remote terminals to be
processed concurrently by user applications.
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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. See also
BGP4.
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CIO |
Cisco Information Online. Online service available to Cisco
customers that provides electronic services and online information
relating to Cisco products. CIO services include product
information, software updates, release notes, technical tips,
configuration notes, brochures, and download offerings. |
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CIP |
Channel Interface Processor. Channel attachment interface
for Cisco 7000 series routers. The CIP is used to connect a host
mainframe to a control unit, eliminating the need for an FEP for
channel attachment.
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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. See also
Bc.
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circuit |
Communications path between two or more points.
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circuit emulation access card |
See
CEMAC.
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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.
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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.
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Cisco 1000 |
Any of the Cisco 1000 series LAN Extenders and routers. The Cisco
1000 series are easy-to-install, inexpensive, multiprotocol access
products designed for small offices and other remote sites. The
Cisco 1000 series includes an ISDN router, an asynchronous router,
and LAN extenders. See also
LAN Extender.
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Cisco 2500
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Any of the Cisco 2500 series routers and access servers, including
single LAN routers; mission-specific, low-end routers; router/hub
combinations; access servers; and dual LAN routers. The Cisco 2500
is designed for small offices and other remote sites and runs the
Cisco IOS software. Sometimes called the Cisco Access Server 2500
series.
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Cisco 4000 |
Any of the Cisco 4000 series routers designed for a wide variety of
network computing environments. The Cisco 4000 series routers run
the Cisco IOS software and can be optimized for particular
environments with custom configurations.
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Cisco 5100 |
Cisco data communications platform that combines the functions of a
Cisco access server with analog and digital modems, CSUs, and T1
channel banks. The Cisco 5100 is optimized for high-speed modem
access and is well-suited for dial-up applications, including host
access, electronic mail, file transfer, and dial-in access to a LAN.
Also known as the Cisco Access Server 5100.
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Cisco 7000 |
Any of the Cisco 7000 series of routers (the Cisco 7000 or the Cisco
7010), a high-end router platform that supports a wide range of
network interfaces and media types and is designed for use in
enterprise networks. Cisco 7000 series routers run the Cisco IOS
software and support online software reconfiguration, OIR, fast
boot, environmental monitoring, self-diagnostics, redundant power
supplies, and Flash memory.
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Cisco 7500 |
Any of the Cisco 7500 series of routers, a high-end multiprotocol
router platform designed for use in enterprise networks. Cisco 7500
series routers run the Cisco IOS software and implement a
distributed multiprocessor architecture consisting of the CyBus, the
RSP, and the VIP. See also
CyBus,
RSP, and
VIP. |
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Cisco Access Server 2500 |
See
Cisco 2500.
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Cisco Access Server 5100 |
See
Cisco 5100.
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ciscoBus controller |
See
SP.
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Cisco Discovery Protocol |
See
CDP.
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Cisco Extended Bus |
See
CxBus.
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Cisco FRAD |
Cisco Frame Relay access device. Cisco product that
supports Cisco IOS Frame Relay SNA services and can be upgraded to
be a full-function multiprotocol router. The Cisco FRAD connects
SDLC devices to Frame Relay without requiring an existing LAN.
However, the Cisco FRAD does support attached LANs and can perform
conversion from SDLC to Ethernet and Token Ring. See also
FRAD.
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Cisco Frame Relay access device |
See
Cisco FRAD.
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CiscoFusion |
Cisco internetworking architecture that "fuses" together the
scalability, stability, and security advantages of the latest
routing technologies with the performance benefits of ATM and LAN
switching, and the management benefits of VLANs. See also
Cisco IOS software.
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Cisco Information Online |
See
CIO.
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Cisco Internetwork Operating System software |
See
Cisco IOS software.
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Cisco IOS software |
Cisco Internetwork Operating System software. Cisco system
software that provides common functionality, scalability, and
security for all products under the CiscoFusion architecture. The
Cisco IOS software allows centralized, integrated, and automated
installation and management of internetworks, while ensuring support
for a wide variety of protocols, media, services, and platforms. See
also
CiscoFusion.
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Cisco LightStream 100 |
Cisco LightStream 100 ATM switch, a fully nonblocking ATM
switch operating at up to 2.4 Gbps and supporting multiple ATM lines
of 155-Mbps data speed as well as a variety of LAN and WAN
interfaces. The LightStream 100 switch can serve as part of an ATM
workgroup or small campus backbone connecting a number of ATM
routers, multilayer LAN switches, and high-performance servers and
clients.
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Cisco LightStream 2020 |
Cisco LightStream 2020 Enterprise ATM switch,
for campus and wide-area applications. The LightStream 2020 ATM
switch supports trunks operating at T1/E1 data rates and provides a
migration path through T3/E3 into a SONET/SDH OC-3 trunk. The
LightStream 2020 intelligent edge modules support a variety of
services including frame forwarding, Frame Relay, ATM UNI, and LAN
internetworking.
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CiscoView |
GUI-based device-management software application that provides
dynamic status, statistics, and comprehensive configuration
information for Cisco internetworking devices. In addition to
displaying a physical view of Cisco device chassis, CiscoView also
provides device monitoring functions and basic troubleshooting
capabilities, and can be integrated with several leading SNMP-based
network management platforms.
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Cisco Workgroup Adapter |
Series of Cisco workgroup adapters that allow workstations to
connect to CDDI or FDDI interfaces operating at 100 Mbps.
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Cisco Workgroup Concentrator |
Series of Cisco workgroup concentrators that combines the compact
form factor of workgroup concentrators with the versatility of
modular hubs. Supports from 4 to 32 combinations of CDDI or FDDI
ports.
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CiscoWorks |
Series of SNMP-based internetwork management software applications.
CiscoWorks includes applications for monitoring router and access
server status, managing configuration files, and troubleshooting
network problems. CiscoWorks applications are integrated on several
SNMP-based network management platforms, including SunNet Manager,
HP OpenView, and IBM NetView.
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Class A station |
See
DAS.
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Class B station |
See
SAS.
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classfull network |
Network that uses traditional IP network addresses of class A, class
B, and class C.
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classical 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.
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classless interdomain routing |
See
CIDR.
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classless network
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Network that does not use the traditional IP network addressing
(class A, class b, and class c), but defines the network boundary
using a prefix value that indicates the number of bits used for the
network portion.
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class of service |
See
COS.
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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.
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CLC |
Cell line card. Card on the LightStream 2020 ATM switch
that, in conjunction with an access card, supports up to two OC-3c
edge ports or one OC-3c trunk port. A CLC can be configured as an
edge card or a trunk card.
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Clear To Send |
See
CTS.
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CLI |
Command line interface. The command-line interface on the
LightStream 2020 that runs on NPs and Sun SPARCstations and is used
to monitor and control an ATM network.
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client |
Node or software program (front-end device) that requests services
from a server. See also
back end,
front end, and
server.
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client-server computing |
Term used to describe distributed computing (processing) network
systems in which transaction responsibilities are divided into two
parts: client (front end) and server (back end). Both terms (client
and server) can be applied to software programs or actual computing
devices. Also called distributed computing (processing).
Compare with
peer-to-peer computing.
See also
RPC.
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client-server model |
Common way to describe network services and the model user processes
(programs) of those services. Examples include the nameserver/nameresolver
paradigm of the DNS and fileserver/file-client relationships such as
NFS and diskless hosts.
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CLNP |
Connectionless Network Protocol (CLNP) is a protocol stack developed
originally as a replacement for TCP/IP with the anticipation that
this OSI suite would take over being based upon the standard OSI
7-layer model. This has not happened, however one protocol within
CLNP called IS-IS has become very popular within the Internet
community due to its scalability as the Internet grows. See also
CLNS.
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CLNS |
Connectionless Network Service (CLNS) is the OSI network layer
service similar to bare IP service. A CLNS entity communicates over
Connectionless Network Protocol (CLNP) with its peer CLNS entity.
CLNP is the OSI equivalent of IP. CLNP provides the interface
between CLNS and upper layers. CLNS does not perform connection
setup or termination because paths are determined independently for
each packet that is transmitted through a network. In addition, CLNS
provides best-effort delivery, which means that no guarantee exists
that data will not be lost, corrupted, miss-ordered, or duplicated.
CLNS relies on transport layer protocols to perform error detection
and correction. See also
CLNP.
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CLP |
Cell loss priority. Field in the ATM cell header that
determines the probability of a cell being dropped if the network
becomes congested. Cells 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.
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cluster controller |
1. Generally, an intelligent device that provides the connections
for a cluster of terminals to a data link.
2. In SNA, a programmable device that controls the
input/output operations of attached devices. Typically, an IBM 3174
or 3274 device.
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CMI |
Coded mark inversion. ITU-T line coding technique specified
for STS-3c transmissions. Also used in DS-1 systems. See also
DS-1 and
STS-3c.
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CMIP |
Common Management Information Protocol. OSI network
management protocol created and standardized by ISO for the
monitoring and control of heterogeneous networks. See also
CMIS.
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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.
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CMNS |
Connection-Mode Network Service. Extends local X.25
switching to a variety of media (Ethernet, FDDI, Token Ring). See
also
CONP. |
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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.
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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.
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coaxial cable |
Cable consisting of a hollow outer cylindrical conductor that
surrounds a single inner wire conductor. Two types of coaxial cable
are currently used in LANs: 50-ohm cable, which is used for digital
signaling, and 75-ohm cable, which is used for analog signal and
high-speed digital signaling.
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code bits |
Control functions (such as setup and termination of a session).
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CODEC |
Coder-decoder. Device that typically uses PCM to transform
analog signals into a digital bit stream, and digital signals back
into analog.
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coded mark inversion |
See
CMI.
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coder-decoder |
See
CODEC.
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coding |
Electrical techniques used to convey binary signals.
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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.
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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.
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collision detection |
See
CSMA/CD.
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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.
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command line interface |
See
CLI.
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Committed Burst |
See
Bc. |
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committed information rate |
See
CIR.
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common carrier |
Licensed, private utility company that supplies communication
services to the public at regulated prices.
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common channel signaling |
See
CCS.
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Common Link Access for Workstations |
See
CLAW.
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Common Management Information Protocol |
See
CMIP.
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Common Management Information Services |
See
CMIS.
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common mode |
Term used to describe problems involving either the hot or neutral
wires and the safety ground wire on a power line. See
normal mode.
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common part convergence sublayer |
See
CPCS.
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Common Programming Interface for Communications |
See
CPI-C.
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common transport semantic |
See
CTS.
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communication |
Transmission of information.
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communication controller |
In SNA, a subarea node (such as an IBM 3745 device) that contains an
NCP.
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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.
|
|
communications line |
The physical link (such as wire or a telephone circuit) that
connects one or more devices to one or more other devices.
|
|
community |
In SNMP, a logical group of managed devices and NMSs in the same
administrative domain.
|
|
Community Antenna Television |
Now known as CATV. See
CATV.
|
|
community string |
Text string that acts as a password and is used to authenticate
messages sent between a management station and a router containing
an SNMP agent. The community string is sent in every packet between
the manager and the agent.
|
|
Compact Gateway Server |
See
CGS.
|
|
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.
|
|
complete sequence number PDU |
See
CSNP.
|
Compressed Serial Link Internet Protocol
|
See
CSLIP.
|
|
compression |
The running of a data set through an algorithm that reduces the
space required to store or the bandwidth required to transmit the
data set. Compare with
companding and
expansion.
|
|
Computer Science Network |
See
CSNET.
|
|
concentrator |
See
hub.
|
|
conductor |
Any material with a low resistance to electrical current. Any
material capable of carrying an electrical current. See
insulator.
|
|
Conférence Européenne des Postes et des Télécommunications |
See
CEPT. |
|
config-register 0x10f |
Command used to enter configuration register values. |
|
Configuration Builder |
Cisco software application that lets you create configuration files
for multiple routers without knowing the router command-line syntax.
Configuration Builder is a Microsoft Windows-based application that
enables you to configure multiple routers simultaneously;
automatically detect the model, software version, image type, and
the number and type of installed interfaces on the router you are
configuring; and quickly import predefined priority queuing lists,
access lists, and filters into multiple configuration files.
|
configuration database
|
File of attribute settings created using the Cisco LightStream
configurator. A global database holds configuration information for
the entire LightStream-based ATM backbone and is stored on the NMS.
A local database, stored in each LightStream 2020 ATM switch,
contains just the configuration information for that switch.
Configuration data includes definitions of chassis, cards, ports,
VCs, and the attributes that describe them. See also
configurator.
|
|
configuration management |
One of five categories of network management defined by ISO for
management of OSI networks. Configuration management subsystems are
responsible for detecting and determining the state of a network.
See also
accounting management,
fault management,
performance management,
and
security management.
|
|
configuration register |
In Cisco routers, a 16-bit, user-configurable value that determines
how the router functions during initialization. The configuration
register can be stored in hardware or software. In hardware, the bit
position is set using a jumper. In software, the bit position is set
by specifying a hexadecimal value using configuration commands.
|
|
configurator |
Management tool used with the LightStream 2020 ATM switch that is
used to create configuration database files for the nodes in an ATM
network. The configurator is an HP OpenView-based application that
runs on an NMS. See also
configuration database.
|
|
configure memory |
Command used to load configuration information from NVRAM.
|
|
configure terminal |
Command used to configure manually from the console terminal.
|
|
congestion |
Traffic in excess of network capacity.
|
|
congestion avoidance |
The mechanism by which a LightStream-based ATM network controls
traffic entering the network to minimize delays. In order to use
resources most efficiently, lower-priority traffic is discarded at
the edge of the network if conditions indicate that it cannot be
delivered. Sometimes abbreviated CA.
|
|
connectionless |
Term used to describe data transfer without the existence of a
virtual circuit. Compare with
connection-oriented. See
also
virtual circuit.
|
|
Connectionless Broadband Data Service |
See
CBDS.
|
|
Connectionless Network Protocol |
See
CLNP.
|
|
Connectionless Network Service |
See
CLNS.
|
connection management
|
See
CMT.
|
|
Connection-Mode Network Service |
See
CMNS.
|
|
connection-oriented |
Term used to describe data transfer that requires the establishment
of a virtual circuit. See also
connectionless. See also
virtual circuit.
|
|
Connection-Oriented Network Protocol |
See
CONP.
|
|
CONP |
Connection-Oriented Network Protocol. OSI protocol
providing connection-oriented operation to upper-layer protocols.
See also
CMNS.
|
|
console |
DTE through which commands are entered into a host.
|
|
constant bit rate |
See
CBR.
|
|
Consultative Committee for International Telegraph and
Telephone |
See
CCITT.
|
|
content-addressable memory |
See
associative memory.
|
|
contention |
Access method in which network devices compete for permission to
access the physical medium. Contrast with
circuit switching and
token passing.
|
|
control point |
See
CP.
|
|
ControlStream traffic management |
Traffic management scheme used by the LightStream 2020 ATM switch.
Includes congestion avoidance, traffic shaping, and traffic
policing, and allows links to operate at high levels of utilization
by scaling back lower-priority, delay-tolerant traffic at the edge
of the network when congestion begins to occur.
|
|
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.
|
|
convergence sublayer |
See
CS.
|
|
conversation |
In SNA, an LU 6.2 session between two transaction programs.
|
|
Cooperation for Open Systems Interconnection Networking in
Europe |
See
COSINE. |
|
Copper Distributed Data Interface |
See
CDDI.
|
|
copy flash tftp |
Command used to copy the system image to a TFTP server.
|
|
copy running-config startup-config |
Command used to store the current configuration in RAM into NVRAM.
|
|
copy running-config tftp |
Command used to store the current configuration in RAM on a network
TFTP server.
|
|
copy tftp flash |
Command used to download the new image from the TFTP server.
|
|
copy tftp running-config |
Command used to load configuration information from a network TFTP
server.
|
|
core gateway |
The primary routers in the Internet.
|
|
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.
|
|
Corporation for Open Systems |
See
COS.
|
|
Corporation for Research and Educational Networking |
See
CREN.
|
|
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 a 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.
|
|
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.
|
|
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.
|
|
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. |
|
CP |
Control point. In SNA networks, element that identifies the
APPN networking components of a PU 2.1 node, manages device
resources, 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.
|
|
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.
|
|
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.
|
|
CPI-C |
Common Programming Interface for Communications.
Platform-independent API developed by IBM and used to provide
portability in APPC applications. See also
APPC.
|
|
cps |
Cells per second.
|
|
CPU |
Central processing unit. The part of a computer that
controls all the other parts. It fetches instructions from memory
and decodes them. This may cause it to transfer data to or from
memory or to activate peripherals to perform input or output. |
|
CRC |
Cyclic redundancy check. Error-checking technique in which
the frame recipient calculates a remainder by dividing frame
contents by a prime binary divisor and compares the calculated
remainder to a value stored in the frame by the sending node.
|
|
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. |
cross talk
|
Interfering energy transferred from one circuit to another.
|
|
CS |
Convergence sublayer. One of the two sublayers of the AAL
CPCS, responsible for padding and error checking. PDUs passed from
the SSCS are appended with an 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.
|
|
CSA |
Canadian Standards Association. Agency within Canada that
certifies products that conform to Canadian national safety
standards.
|
|
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.
|
|
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.
|
|
CSNET |
Computer Science Network. Large internetwork consisting
primarily of universities, research institutions, and commercial
concerns. CSNET merged with BITNET to form CREN. See also
BITNET and
CREN.
|
|
CSNP |
Complete sequence number PDU (CSNP) contain a list of all LSPs from
the current database. CSNPs are used to inform other routers of LSPs
that may be outdated or missing from their own database. This
ensures that all routers have the same information and are
synchronized. The packets are similar to an OSPF database
description packet.
|
|
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.
|
|
csumon |
Tool available on the LightStream 2020 ATM switch, accessible from
the bash shell. Csumon allows connection to an external CSU/DSU on a
low-speed line for monitoring and control purposes, and can display
statistics on the internal CSU/DSU of a medium-speed line.
|
|
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. |
|
Customer Information Control System |
See
CICS. |
|
customer premises equipment |
See
CPE.
|
|
custom queuing
|
A method of queuing that is used to guarantee bandwidth for traffic
by assigning queue space to each protocol.
|
|
cut sheet |
A rough diagram indicating where cable runs are located and the
numbers of rooms they lead to.
|
|
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.
|
|
CxBus |
Cisco Extended Bus. Data bus for interface processors on
Cisco 7000 series routers that operates at 533 Mbps. See also
Switch Processor.
|
|
CyBus |
1.067-Gbps data bus for interface processors. Used in the Cisco 7500
series routers. See also
Cisco 7500.
|
|
cycles per second |
See
hertz.
|
|
cyclic redundancy check |
See
CRC.
|
