Telecommunications & Networking Glossary
1Base-5 - Twisted pair cable with maximum
segment lengths of 500 meters and transmission speeds of up to 1
Mbit/sec.
10Base-2 - a transmission medium
specified by IEEE 802.3 that carries information at rates up to
10Mbps in baseband form using low-cost coaxial cable over
distances up to 185 meters (607 ft). Also called "thin
Ethernet" or "thinnet" or "thin coax" or
"cheapernet".
10Base-5 - a transmission medium
specified by IEEE 802.3 that carries information at rates up to
10Mbps in baseband form using 50 ohm coaxial cable over distances
up to 500 meters (1,640 ft). Also called "thick
Ethernet" or "thicknet" or "thick coax",
the cable is commonly referred to as yellow cable. Thick Ethernet
cable is typically used as a trunk or backbone path of the
network.
10Base-FL - IEEE 802.3 Fiber Optic
Ethernet. A fiber optic standard that allows up to 2,000 meters
(6,560 ft.) of multimode duplex fiber optic cable in a
point-to-point link.
10Base-T - a transmission medium
specified by IEEE 802.3 that carries information at rates up to
10Mbps in baseband form using twisted pair conductors. Also
called unshielded twisted pair (UTP) wire. Using low cost Level 3
or better UTP wiring, 100 meters (328 ft.) of point-to-point link
segments are possible. Uses RJ45 connectors and sometimes 50-pin
AMP connectors to a patch panel.
100Base-X - 100 Mbits/sec throughput
over hierarchical twisted-pair wiring configurations using the
existing CSMA/CD access method.
100Base-T4 - A particular alternative
within the 100Base-TX CSMA/CD proposals before the IEEE 802.3 for
a 100 Mb/s Ethernet that specifies four pair of UTP3, UTP4, or
UTP5. *
100Base-TX - A particular alternative
within the 100Base-TX CSMA/CD proposals before the IEEE 802.3 for
a 100 Mb/s Ethernet that specifies two pair of UTP5. *
100Base-T - A generic name for 100 Mb/s
twisted pair CSMA/CD proposals before the IEEE 802.3. Specific
proposals include 100Base-Tx and 100Base-T4. *
Access method - the way in which a
node is permitted to send data over the media. With Ethernet, the
node listens to the line to determine if it is available before
transmitting.
Adapter card - circuit board or
other hardware that provides the physical interface from a PC,
workstation or other equipment to the communications network.
Address - a number uniquely identifying
each node in a network.
ANSI (American National Standards
Institute) - a voluntary, U.S. based standards-setting
organization for the information processing industry. A member of
the ISO.
ASCII (American Standard Code for
Information Interchange) - a widely used 7-bit code-set
established by ANSI to achieve compatibility between products
manufactured by different companies.
Application layer - the seventh layer in
the OSI model which is ultimately responsible for managing
communication between application processes.
ARP (Address Resolution Protocol) - an
Internet Protocol that dynamically maps Internet addresses to
physical (hardware) addresses on a LAN.
AT-ADAPT-2 - a harmonic-style adapter
that allows direct conversion from a 50-pin Telco connector to
RJ45 receptacles.
ATM (Asynchronous Transfer Mode) - a new
type of cell switching technology which uses fixed-length packets
to transmit data from source to destination. ATM uses
fixed-length 53-byte cell-switching to transmit data, voice and
video over both LANs and WANs. Also referred to as BISDN and Cell
Relay.
AUI (Attachment Unit Interface) - the branch
cable interface located between a MAU (transceiver) and a DTE
(typically a workstation). Includes a 15-pin D-sub connector and
sometimes a 15-conductor twisted pair cable. Maximum length is 50
meters (164 ft.).
AWG (American Wire Gauge) - a system that
specifies wire size. The gauge varies inversely with the wire
diameter size.
Backbone - any network considered to
provide interconnection among subnetworks.
Backup Module - a repeater that
behaves as the management module when the Master fails in a
department concentrator.
Bandwidth - the difference between the
two limiting frequencies of a band, expressed in Hz (hertz).
Baseband - a transmission technique
that allows only one signal at time to travel on a cable.
Binding - a process during which a
protocol driver and a MAC driver exchange information, via the
NDIS interface library, about identities, capabilities, function
addresses, and binding context.
Bit - a contraction of Binary Digit. The
smallest unit of digital information.
Bit Rate (BR) - The rate of data throughput
on the medium in bits per second. Ethernet specifies 10 million
bits per second.
Bit Time - The duration of one bit
symbol (1/BR). Ethernet specifies a bit time of 100 ns.
Bps (bits per second) - a unit of measure
for the transmission of signals that represent characters of
data.
BNC connector - a specific type of
connector used for coaxial RG58 cable connection.
BOOTP (Boot Protocol) - a TCP/IP network
protocol that lets network nodes request configuration
information from a BOOTP "server" node.
Branch Cable - the AUI cable
interconnecting the DTE and MAU system components also known as a
Drop cable.
Bridge - a LAN interconnection device
used to link two or more local or remote LANs. Bridges are used
extensively in LAN systems to extend their physical dimensions or
modify their performance.
Bridge MIB - a specification that
defines an experimental portion of the Management Information
Base for use with network managing protocols in TCP/IP based
internets. In particular, it defines objects for managing bridges
based on the IEEE 802.1d draft standard between LAN segments.
Broadband - a method of transmission
in which data flows from source to destination in a different
form that existed at the source.
Brouter - a network device that can
perform the functions of both a bridge and a router.
Buffer - a block of storage used to hold
a portion of an information packet.
Buffer descriptor - a data structure
containing information about a buffer, such as a pointer to the
buffer's physical location, number of bytes, and size. It does
not include the actual data in the buffer.
Bus topology - the structure used in LANs
whereby connection between devices is accomplished by connecting
all devices to a single transmission medium such as fiber or
wire.
Byte - a sequence of eight adjacent bits
representing one character or digit.
CATNIP (Common Architechture for Next
Generation Internet Protocol) - One of the three IPng
candidates.
CHAP (Challenge Handshake Authentification
Protocol) - Authentification scheme for PPP where the password
not only is required to begin connection but is also required
during the connection - failure to provide a correct password
during either the login or challenge mode will result in
disconnect.
Client - in the ISO/OSI specifications,
the client is referred to as the service requester.
CLR (Cell Loss Ratio) - ATM performance
parameter which specifies the ratio of lost (non-delivered) cells
to the total cells transmitted over a given virtual circuit.
CLNP (Connectionless Network Protocol) -
the OSI equivalent to Internet IP, sometimes called ISO IP. The
OSI protocol for providing the OSI Connectionless Network Service
(datagram service).
CLTP (Connectionless Transport Protocol) -
the OSI equivalent to UDP. Provides for end-to-end Transport data
addressing and error control, but cannot guarantee delivery or
provide flow control.
CMIP (Common Management Information
Protocol) - the network management protocol defined by OSI
specifications. Used to convey CMIS defined operations over an
OSI network.
CMIS (Common Management Information
Services) - the portion of the OSI network management
specification which defines the management services available to
a network management system (works with CMIP).
CMOT (CMIP Over TCP) - an historical effort
to use the OSI network management protocol to manage TCP/IP
networks.
Coaxial cable - a form of cable
that has an inner conductor and an outer grounded shield
positioned around a common axis. There are two types, 10BASE2 (thinnet) and 10BASE5
(thicknet).
Collision - an unwanted condition in
which two packets are being transmitted over a medium at the same
time, resulting in destruction of the data.
Concentrator - any communications
device that allows a shared transmission medium to accommodate
more data sources than there are channels currently available
within the transmission medium. See Department
Concentrator.
Configuration management - the process
of obtaining information from network devices and using it to
manage their setups.
CSMA (Carrier Sense Multiple Access) - a
medium access control technique for multiple-access transmission
media. A station wishing to transmit first senses the medium and
transmits only if the medium is idle.
CSMA/CD (Carrier Sense Multiple Access
with Collision Detection) - a refinement of CSMA in which a
station ceases transmission if it detects a collision.
DCE (Data Communication Equipment) - In the
RS232 specification a module, such as a modem, which is used to
connect a DTE to other equipment. A repeater, hub, or switch
connected to a terminal or workstation is wired as a DCE.
DTE (Data Terminal Equipment) - In the RS232
specification a module which is typically at the end of the
segment. The DTE could be an Ethernet workstation or router that
is attached to a network.
Defense Data Network (DDN) - the MILENET and
several other Department of Defense networks.
Department Concentrator - a hub which
provides a large number of workstation connections. The term,
department concentrator, refers to multiple repeaters housed in
an AT-36C8 chassis. See Hub/Repeater,
Repeater.
Directory Access Protocol (DAP) - the
protocol used between a Directory User Agent (DUA) and a
Directory System Agent (DSA) in an X.500 directoru system.
Distributed Computing Environment - a
framework for distributed computing by the Open Software
Foundation.
Distributed Management Environment - a
framework for distributed management proposed by the Open
Software Foundation.
Driver - a set of software routines used
to control input and output from an operating system.
Ethernet - the LAN technology that uses
CSMA/CD physical access method and 10 Mbps digital transmission.
The forerunner of the IEEE 802.3 CSMA/CD standard.
Fiber optics- light transmission
through optical fibers for communication and signaling.
Finger - an Internet utility that
provides information about the users who are logged in to a
server, in an attempt to provide directory services.
FOIRL (Fiber Optic Inter Repeater Link) -
A fiber optic signaling method based on the IEEE
802.3 standard governing fiber optics. Allows up to 1,000 meters
(3,280 ft.) of multimode duplex fiber optic cable in a
point-to-point link.
50-Pin Telco (RJ21) - This connector
is very common in 10BASE-T wiring. As opposed to the RJ45 connector, the 50-pin Telco connector
concentrates up to 12 UTP connections onto one
connection. This concentration of UTP ports is then broken out
for connection to a punch-down block inside a building's wiring
closet. 50-pin Telco connections provide a very clean,
uncluttered interface to the building's wiring.
FTP (File Transfer Protocol) - a TCP/IP protocol for file transfer.
Harmonic Adapter - a simple way to
convert the 50-pin Telco connection to RJ45 connections.
Hot Swapping - the process of replacing
a hub module without bringing down the network. This process
occurs by sliding an active module into a fully powered up
concentrator, replacing a failed module.
Hub/Repeater - the central signal
distributor, used in a wiring topology consisting of several
point-to-point segments originating from a central point. The
term hub is often used interchangeably with the term repeater.
Multiport 10BASE-T, 10BASE2, and fiber optic (10BASE-FL, FOIRL)
repeaters are considered hubs. See Repeater.
Hub MIB - a specification that defines an
experimental portion of the Management Information Base for use
with network managing protocols in TCP/IP based internets. In
particular, it defines objects for managing IEEE 802.3 10
Mbpsecond baseband repeaters (also referred to as
"hubs").
IEEE (Institute of Electrical and
Electronics Engineers) - a U.S. professional organization active
in the creation, promotion, and support of communications
specifications and standards.
IEEE 802.3 - a physical layer standard
that uses the CSMA/ CD access method on a bus topology LAN.
IEEE 802.5 (Token Ring) - the IEEE
committee and its specification that defined a LAN protocol
suite. Originated by IBM, now an IEEE standard for a
token-passing, ring network that can be configured in a star
topology. Token Ring cards are available in 4 Mb/s and 16 Mb/s
versions. Subsequent upgrades for fiber are specified in ANSI
X3T9. *
IESG (Internet Engineering Steering Group)
- the executive committee of the IETF.
Impedance - an electrical
characteristic of a circuit dealing with the combination of the
AC and DC resistance and the appearance of that resistance to
attached circuits.
Interface layer - the layer in
the Internet suite of protocols responsible for transmission on a
single physical network.
Internet - a collection of networks
that are interconnected by linking devices such as bridges,
routers, and gateways to operate as a single large network.
Internet suite of protocols - a
collection of computer-communication protocols. Synonymous with
TCP/IP.
Internetworking - communication
among devices across multiple networks.
Interoperability - the process
whereby computers can operate interactively with each other
across a network without data conversion or human intervention.
IP (Internet Protocol) - a connectionless
protocol which provides best-effort delivery of datagrams across
an internet (the network layer protocol of the TCP/IP protocol
suite).
IPng (IP Next Generation) - Name for the
efforts of the Internet Engineering Task Force to define a new
version of the Internet Protocol (IP) to handle larger IP
addresses. There were three candidates - CATNIP, TUBA, and SIPP.
IPX (Internetwork Packet Exchange) - a
network layer protocol developed by Novell, Inc. and used in
NetWare implementations.
ISO (International Standards Organization) -
an organization that promotes the development of standards for
computers. Developers of the OSI model.
Jabber Lock-Up - the MAU's ability to
automatically inhibit the transmit data from reaching the medium
if the transmit data time exceeds a specified duration. This
duration is in the range of 20 ms to 150 ms. Jabber lock-up
protects the medium from being overrun with data packets from a
possibly defective device.
Jam - this term describes the collision
reinforcement signal output by the repeater to all ports. The jam
signal consists of 96 bits of alternating 1s and 0s. The purpose
is to extend a collision sufficiently so that all devices cease
transmitting.
JANET (Joint Academic Network) - A
university network in the U.K. With the increase in network speed
in recent years, it has been renamed to "Super-JANET."
Jitter - the fluctuation of the data
packet in respect to a standard clock cycle. Jitter is
undesirable and must be minimized.
JUNET - Japan UNIX Network.
Kernel- the software that interfaces
directly with the hardware (when referring to operating system
software).
LAN (Local Area Network) - a network system
that provides a relatively small area with high-speed data
transmission at a low error rate. May include PCs, printers,
minicomputers, and mainframes linked by a transmission medium
such as a coaxial cable or twisted pair wiring.
Layer - a conceptual level of network
processing functions defined by OSI model. Processing takes place
in layers starting from the physical transmission of data up
through to the commands of an end-user.
Learning bridge - a bridge which
automatically "learns" the topology of the LAN
addresses of each node as it receives packets. Requires little or
no setup at time of installation.
LED (Light Emitting Diode) - a solid state
device that radiates light at a single frequency through plastic
or glass.
MAC (medium access control) - the control
circuitry in a LAN that converts the protocols of the DTE to
those required by the LAN.
MAN (Metropolitan Area Network) - a network
whose facilities are restricted to individual populated areas.
Distances of up to 50 miles are possible.
Managed Module - an intelligent repeater
in a department concentrator chassis that makes management data
available to the Master.
Management Agent - software that is used
to view hub activity and set hub variables.
Master - a repeater in the top-most
position in a department concentrator chassis that contains and
downloads the management agent software to Backup and Slaves. The
Master contains the only active image of the management agent and
controls the management functions of the Backup and Slaves.
Master Station - a station or network
node that maintains direct control over other stations or nodes.
MAU (medium attachment unit) - a device used
to attach a processing node to a network at the physical level.
An example is the transceiver used to attach devices to an
Ethernet cable.
Medium - a physical conduit for data
transmission, e.g., coaxial cable or radio waves.
MDI (Medium Dependent Interface) - the
mechanical and electrical interface between the trunk cable
medium and the MAU. MDI-X is another version of the interface
that enables like devices to connect, using different pin-outs,
avoiding conflicts that occur when receiving and transmitting
packets use the same pin-out.
MIB (Management Information Base) - a
collection of objects that can be accessed via a network
management protocol.
Module - a single repeater when it is
mounted with other repeaters in an AT-36Cx or AT-36Ex
department concentrator chassis.
MOP (Maintenance Operations Protocol) - a
DEC protocol used for remote communications between hosts and
servers.
Multicast address - a 48-bit
identifier (as transmitted over an Ethernet network) naming the
group of stations that should receive a packet on the network. A
multicast address contains a unique group number by which
receiving stations can request to receive packets, rather than
being a bit mask (as for a functional address).
Multiport repeater - a
repeater that collects signals from one transmission channel and,
after performing the standard repeater functions, retransmits the
signals to more than one new transmission channel.
Multiport transceiver - a
transceiver that allows a number of devices to be attached to one
LAN transceiver attachment on the backbone network.
NREN (National Research and Education
Network) - a network that was expected to become the
state-of-the-art high-speed network for US research and
education. Now synonymous with the Information Superhighway.
NetWare - a network operating system
implementation and control approach developed by Novell, Inc.
that defines the network architecture and the software modules
needed for network operation. Also the name of the network
software.
Network - a communications system made
up of various stations.
Network Driver Interface Specification
(NDIS) interface library - an interface modeled as a set of
abstract functions that either cause a request to be submitted to
the operating system or cause a local action to be performed that
does not require full communications with other software
functions. The main purpose of the interface library is to allow
protocol drivers to send and receive packets on a network.
Network layer - the layer in the
OSI model that is responsible for ensuring that data passed to it
from the transport layer is routed and delivered through the
network.
Network management - a set of
procedures, software and operations designed to keep a network
operating near maximum efficiency.
Network redundancy - the
state of having more connecting links than the minimum required
to provide a connecting path between all nodes.
Network topology - the physical
and logical relationship of nodes in a network typically of
either a star, ring, tree, or bus topology, or some hybrid
combination thereof.
Node - a point where one or more functional
units interconnect transmission lines.
OSI (Open System Interconnection) - a seven
layer model developed by ISO for standardizing data transmission
functions so equipment made by different manufacturers can be
interconnected.
Packet - the basic unit of data transfer
in LANs. A chain of one or more buffers that compose a network
message.
Ping (Packet Internet Groper) - A program
used to test reachability of destinations by sending them an ICMP
echo request and waiting for a reply.
Packet switching - a method of
transmitting messages through a communications network in which
long messages are subdivided into short packets.
PSN (Packet Switch Node) - The modern term
used for nodes in the ARPNET and MILNET, formerly called
Interface Message Processors (IMPs).
Physical layer - the lowest level
in the OSI model, responsible for the transmission of bits across
the medium.
Physical Medium Attachment (PMA) - the
portion of the MAU that contains the functional circuitry.
Physical Signaling (PLS) - the portion of
the physical layer contained within the DTE that provides the
logical and functional coupling between MAU and data link layers.
Port - an interface of a computer or other
transmission device that acts as an input or output point, or
both.
Presentation layer - the level in the OSI
model responsible for adding structure to the units of data that
are exchanged.
Proprietary - a protocol or
communications system developed by a company, as opposed to those
emanating from a standards organization.
Protocol - the rules or conventions
used to govern the exchange of information between networked
nodes.
Repeater - a hardware device that
regenerates LAN signals to extend the length, topology or
interconnectivity of the network, or converts signals between
media at the same time.
RFC (Request for Comment) - the procedure
used by the Internet community to exchange ideas and establish
standards and specifications.
RMON (Remote network MONitoring probe) - a
device that was designed to help perform network management on a
network segment.
RJ-11 (Registered Jack 11) - A modular
4-wire jack and/or connector typically used with copper cable
having two twisted pairs,
usually unshielded twisted pair category 3 or category 5. Used
for telephony, 10Base-T and 100Base-Tx Ethernet LANs, and Token Ring LANs. *
RJ-45 - this connector is a 10BASE-T
standard for connecting UTP cabling. They are inexpensive and
easy to install onto UTP cable.
Router - a hardware/software product
which receives network layer datagrams and forwards them to their
destination based on the network layer address in the packet.
Session layer - the layer of the OSI
model responsible for establishing and maintaining communications
between two applications or software modules in different nodes.
SIPP (Simple Internet Protocol Plus) - One
of the three IPng candidates.
Slave station - a device that can
transmit only to a specific controlling node upon that
node’s request.
SNMP (Simple Network Management Protocol) -
a set of rules for performing network management functions.
Approved for use with TCP/IP in UNIX environments. Created within
the Internet community using the RFC process.
Subnetwork - a network that has been
connected to a larger and more powerful network system by a
bridge or router.
T-connectors - connectors used to
join thin Ethernet cable section. The connectors also have a
connector that is attached directly to a station.
Tap - a device in the feeder cable that
connects a device to a network.
TCP (Transmission Control Protocol) - the
transport protocol offering a connection-oriented transport
service in the Internet suite of protocols.
TCP/IP - the internetworking protocols
developed by the U.S. government’s Advanced Research Project
Agency (ARPA). Widely adopted and supported by computer and
software manufacturers as a standard computer networking
protocol.
Telnet - the standard interactive login
protocol in the Internet suite of protocols which operates over
the TCP/IP protocol. Allows a user to login to a remote computer
over the network.
TFTP (Trivial File Transfer Protocol) -
used on computers running TCP/IP, TFTP
quickly sends files across the network with fewer security
features than FTP.
Thicknet - see 10BASE5
Thinnet - see 10BASE2
Token Ring (IEEE 802.5) - the IEEE
committee and its specification that defined a LAN protocol
suite. Originated by IBM, now an IEEE standard for a
token-passing, ring network that can be configured in a star
topology. Token Ring cards are available in 4 Mb/s and 16 Mb/s
versions. Subsequent upgrades for fiber are specified in ANSI
X3T9. *
Topology - the physical arrangement of
devices in a network, regardless of their logical relationships.
Types include star, ring, and bus.
Transceiver - the attachment
hardware connecting the controller interface to the transmission
cable in IEEE 802.3 networks.
Transport layer - layer four of
the OSI model that provides reliable message delivery services to
higher level protocols.
TUBA (TCP and UDP with Bigger Addresses) -
one of the three IPng candidates.
Twisted pair wiring - two
insulated wires twisted together and used for transmission (the
twisting creates a low level of noise elimination).
Unshielded twisted pair (UTP) - see 10BASE-T
WAN (wide area network) - a network that
includes nodes distributed over a larger geographic area than can
be served by a LAN.
Wiring closet - a room containing
the individual network connections for all devices in a specific
area.
Workstation - a terminal station,
perhaps connected to a LAN, providing some
local processing capability and storage as well as access
to other workstations and shared resources.
* Some definitions
used in this document are from the hypertext product, LexiCAT,
and are the copyrighted property of TRA, with all rights reserved.
For additional information on LexiCAT or to obtain additional copies,
please contact TRA at 505 W. Bertrand Ave., St. Marys, KS, USA 66536.
Telephone 1-913-437-2000. LexiCAT is a registered trademark of TRA.
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