A&B bit signaling AAL
AARP AARP probe packets ABI
ABM ABR Abstract Syntax
ACAP access-group access list
access method Access Network Access Nodes
access permission accounting management
ACE ACF ACF/NCP
ACIA ACK ACL
ACOnet ACMS ACPM
ACS ACSE Active Devices
active hub active monitor ActiveX
adaptive routing ADCCP
Address addressed call mode Address Mask
Address Resolution adjacency adjacent nodes
administrative distance ADMD Administrivia
ADPCM ADSL ADSU
advertising AEC AEP
AFAIK AFI AFP
AFS Agent AGS
AGS+ AI AIF
AKA alarm a-law
Alias alignement error ALOHA
AM AMI amplitude
Analog Analog Loopback Analog Transmission
Anchor Annotation Anonymous FTP
ANSI AOCE AOW
APaRT API APL
Apollo Domain APPC APPI
APPI Forum AppleTalk Application
Application Layer applique APPN
APSE ARA area
Archie Archive Server Archive Site
ARCnet argument Ariadnet
ARM (Adv. RISC Machine) ARM (Asynch. Response Mode) ARNES
ARP ARPA ARPANET
ARQ AS ASBR
ASC ASCII ASIC
ASM-CS ASN.1 ASPI
Assigned Numbers ASTRA Asynchronous
ATDM ATG ATM (Asynchronous Transfer Mode)
ATM (Adobe Type Manag.) ATN ATP
attenuation Attribute AU
Authentication authority zone automatic call reconnect
autonomous confeder. autonomous switching Autonomous System
Auto-Magic AVI AVR
A&B bit signaling Procedure
used in most T1 transmission facilities
where one bit from every sixth frame of each of 24T1 subchannels is used
for carrying supervisory signaling information.
Adaption Layer). Fully independent of the physical layer,
this ATM layer converts higher-layer information, such as data packets,
into ATM cells for transmission across the ATM
network. At the receiving end, the AAL converts the cells back into the
higher-layer information. For more info search on the ATM
Address Resolution Protocol). In the AppleTalk protocol
stack that maps a data-link address to a network address.
AARP probe packets Packets
asking if a randomly selected node ID is being used by another node in
a nonextended Apple Talk network.
If not, the sending node uses the node ID. If so, it chooses a different
ID and sends more AARP probe packets.
Binary Interface). Application interfaces that enable binary
applications to function compatibly on operating system environments with
minor differences, such as varying implentations of UNIX System V for Intel-based
Also: (American Bell Inc.).
Balanced Mode). An HDLC
(and derivative protocol) communication mode supporting peer-oriented point-to-point
communications between two stations, where either station can initiate
Bit Rate). QOS
class defined by the ATM Forum for ATM networks. ABR is used for connections
that do not require timing relationships between source and destination.
ABR provides no guarantees in terms of cell loss or delay, providing only
best-effort service. Traffic sources adjust their transmission rate in
response to information they receive describing the status of the network
and its capability to successfully deliver data. For more info search on
A description of a data structure that is independent of machine-oriented
structures and encodings.[Source: RFC1208]
Configuration Access Protocol). "ACAP enhances IMAP
by letting you set up address books, user options, and other data for universal
access. At this writing, no internet proprietary products have implemented
ACAP because the Internet Engineering Task Force (IETF),
the group responsible for developing Internet standards, has not yet approved
the final specification. A final spec should be out early this year, and
implementations will likely follow soon after."
(Area Border Router). Router located on the border
of one or more OSPF areas that connects
those areas to the backbone network. ABRs are considered members of both
the OSPF backbone and the attached areas. They therefore maintain routing
tables describing both the backbone topology and the topology of the other
From the article, "Your
E-Mail Is Obsolete" in the February 1997 issue of BYTE.
interface subcommand that applies an access list to an interface.
access list A
list kept by CISCO routers to control access to or from the router for
a number of services (for example, to restrict packets with a certain IP
address from leaving a particular interface on the network server).
access method Software
within an SNA processor that controls
the flow of information through a network. Generally, the way that network
devices access the network medium.
Access Network That
portion of a public switched network that connects access nodes to individual
subscribers. The Access Network today is predominantly passive twisted
pair copper wiring. [Source: ADSL Forum]
Access Nodes Points
on the edge of the Access Network that concentrate individual access lines
into a smaller number of feeder lines. Access Nodes may also perform various
forms of protocol conversion. Typical Access Nodes are Digital Loop Carrier
systems concentrating individual voice lines to T1
lines, cellular antenna sites, PBXs,
and Optical Network Units.[Source:
access permission In
UNIX a set of permissions associated with every file and directory that
determine who can read it, write to it, or execute it. Only the owner of
the file (or the super-user) can change these permissions.
accounting management One
of five categories of network management defined by ISO
for management of OSI networks.
Accounting management subsystems are responsible for collecting network
data relating to resource usage. See also configuration management, fault
management, performance management, and security management.
Computing Environnment) OR ( Automatic Calling
Communications Function). A group of SNA
products that provide distributed processing and resource sharing.
Communication Function/Network Control Program). The primary SNA
network control program. ACF/NCP rides in the communications controller
and interfaces with the SNA access method in the host processor to control
Communications Interface Adapter). Chips that provide data formatting and
control to RS-232 serial interfaces.
A type of message sent to indicate that a block of data arrived at it destination
without error. See also: NAK [Source:
Also: (Amsterdam Compiler Kit).
ACL (Access Control
List). Most network security systems operate by allowing selective use
of services. An Access Control List is the usual means by which access
to, and denial of, services is controlled. It is simply a list of the services
available, each with a list of the hosts permitted to use the service.
Austrian Academic Computer Network. The national R&D network
which provides services to all universities, some research centers, as
well as to educational, cultural and governmental sites in Austria.
Control & Management System). DEC
Control & Protocol Machine). ACSE
Control Store). CCA/VTS
OR (Advanced Communication Service). Bell System.
Control Service Element). The method used in OSI
for establishing a call between two applications. Checks the identities
and contexts of the application entities, and could apply an authentication
security check. [Source:RFC1208]
Active Devices In
Token Ring, a device that requires
AC power for operation. In current loop applications, a device capable
of supplying the current for the loop.
active hub A
multiported device that amplifies LAN
active monitor A
device responsible for managing a Token
Ring . It makes sure, for example that tokens are not lost or that
frames do not circulate indefinitely. A network node is selected to be
the active monitor if it has the highest MAC address on the ring. See also
ring monitor and standby
answer to Java. ActiveX is a stripped
down implementation of OLE designed
to run over slow Internet links. More aboutActiveX
Domain). A collection of hosts and routers, and the interconnecting network(s),
managed by a single administrative authority.[Source: RFC1983].
adapter A PC
board, usually installed inside a computer system, that provides network
communication capabilities to and from that computer system. The term adapter
often is used interchangeably with NIC.
adaptive routing See
Data Communications Control Protocol). An ANSI standard bit-oriented data-link-control
are four types of addresses in common use within the Internet. They are
email address; IP, internet or Internet address; hardware or MAC address;
and URL. See also: Email Address,
IP Address, Internet
Address, MAC address, Uniform
Resource Locator. [Source: RFC1983].
addressed call mode A
mode that permits control signals and commands to establish and terminate
calls in V.25bis.
Address Mask A
bit mask used to identify which bits in an IP address correspond to the
network and subnet portions of the address. This mask is often referred
to as the subnet mask because the network portion of the address (i.e.,
the network mask) can be determined by the encoding inherent in an IP address.
See also: Classless Inter-domain Routing.
Conversion of a network-layer address (e.g. IP address) into
the corresponding physical address (e.g., MAC address). See also: IP
Address, MAC address
relationship formed between selected neighboring routers and end nodes
for the purpose of exchanging routing information. Adiacency is based upon
the use of a common media segment.
adjacent nodes In
SNA, nodes that are connected to a given
node with no intervening nodes. In DECnet
and OSI, adjacent nodes are nodes that
share a common segment (Ethernet,
A rating of the trustworthiness of a routing information source.
In Cisco routers, administrative distance is expressed as a numerical value
between 0 and 255 (the higher the value, the lower the trustworthiness
Management Domain). An X.400
Message Handling System public service carrier. Examples: MCImail and ATTmail
in the U.S., British Telecom Gold400mail in the U.K. The ADMDs in all countries
worldwide together provide the X.400 backbone. See also: PRMD.
tasks, most often related to the maintenance of mailing lists, digests,
news gateways, etc.[Source: ZEN]
Differential Pulse Code Modulation). A CCITT
standardized technique for encoding analog voice signals into a digital
form at 32 kpbs (half the standard PCM
rate) Four bits describe the difference between adjacent samples at a rate
of 8000 times per second.
Digital Subscriber Line). A new modem technology, converts existing twisted-pair
telephone lines into access paths for multimedia and high speed data communications.
ADSL transmits more than 6 Mbps to a subscriber, and as much as 640 kbps
more in both directions. Such rates expand existing access capacity by
a factor of 50 or more without new cabling. ADSL can literally transform
the existing public information network from one limited to voice, text
and low resolution graphics to a powerful, ubiquitous system capable of
bringing multimedia, including full motion video, to everyone's home this
Follow the ADSL Forum link
to find out more information about vendors
and tutorial related
ADSU (ATM Data
Service Unit) (DSU). A DSU used to access
an ATM network via High-speed Serial
Interface (HSSI). For more info
search on the ATM
method through which routers maintain lists of usable routes by sending
routing or service updates within specified rates of time.
AEP (AppleTalk Echo
Protocol). Used to test connectivity between two AppleTalk nodes. One node
sends a packet to another node and receives a duplicate, or echo, of that
AFAIK "As Far
As I Know"
Frame Identifier). Specifies the format of the initial domain
identifier (IDI) in the initial
domain part (IDP) of an OSI
File System). An alternative networked file system developed
at Carnegie Mellon University as part of Mach and later incorporated into
the OSF/1 operating system. See NFS.
Agent In the client-server
model, the part of the system that performs information preparation and
exchange on behalf of a client or server application. See NMS,
Gateway Server). Cisco nine-slot bridge/router.
Gateway Server PLUS). Cisco nine-slot bridge/router
with a ciscoBus switching complex. Five of the slots connect to the ciscoBus.
IFF). A format developed by Apple Computer Inc. for storing high-quality
sampled audio and musical instrument information. It is also used by SGI
and several professional audio packages.
Indication Signal). In T1,
an all-ones signal transmitted in lieu of the normal signal to maintain
transmission continuity and to indicate to the receiving terminal that
there is a transmission fault that is located either at, or upstream from,
the transmitting terminal.
Also: (Action b>Item System) OR (Automatic Intercept
AKA "Also Known
alarm A message
notifying an operator or administrator of a network problem.
a-law The CCITT
companding standard used in the conversion between analog and digital signals
in PCM systems. A-law is employed primarily
in European telephone networks and is similar to the North American mu-law
alert In NetView,
a problem record sent to a network operator that warrants action at the
rule or process for arriving at a solution to a problem.
Alias A name,
usually short and easy to remember, that is translated into another name,
usually long and difficult to remember. [Source: RFC1983].
alignement error In
IEEE 802.3 networks, an error that
occurs when a received frame's total number of bits is not divisible by
eight. Alignment errors usually are caused by frame damage due to collision.
ALOHA An access
control technique for transmission media systems that permits multiple
stations to transmit simultaneously. in the ALOHA system, stations transmit
whenever they have data to send and unacknouwledged transmissions are repeated.
Modulation). A modulation technique whereby information is conveyed
thruogh the amplitude of the carrier signal.
Mark Inversion). A bipolar coding scheme in wich successive
ones (marks) must alternate in polarity (alternate between positive and
maximum value of an analog or digital waveform.
Analog Not digital.
A continuous wave or signal (such as the human voice).
A testing technique wich isolates faults in transmission equipment
by performing a loopback on the data at the analog (line) side of the modem.
The transmission of a continuously variable signal, as opposed
to a discrete (digital) one.
of NCSA Mosaic that lets you
add personal notes to World Wide Web
Anonymous FTP Anonymous
FTP allows a user to retrieve documents, files, programs, and other archived
data from anywhere in the Internet without having to establish a userid
and password. By using the special userid of "anonymous" the network user
will bypass local security checks and will have access to publicly accessible
files on the remote system. See also: Archive
Site, File Transfer Protocoll,
World Wide Web. [Source: RFC1983].
National Standards Institute). This organization is
responsible for approving U.S. standards in many areas, including computers
and communications. Standards approved by this organization are often called
ANSI standards (e.g., ANSI C is the version of the C language approved
by ANSI). ANSI is a member of ISO. See also: International
Organization for Standardization. [Source: NNSC]
Open Collaborative Environment).
and Oceania Workshop). One of the three regional OSI
Implementors Workshops, equivalent to OIW
and EWOS .[Source: RFC1208]
Packet Recognition/Translation). Technology that allows
a server to be attached to CDDI or FDDI without requiring the reconfiguration
of applications or network protocols. APaRT recognizes specific data link
layer encapsulation packet types and, when these packet types are transferred
from one medium to another, translates them into the native format of the
Program Interface).A set of calling conventions defining
how a service is invoked through a software package. [Source: RFC1208]
APL (A Programming
Language).A high-level, interpreted language that supports subprogram
and is effective for mathematical and scientific applications.
Apollo Domain Proprietary
network protocol suite developed by Apollo Computer for communication on
proprietary Apollo networks.
Peer-to-Peer Communications). An IBM SNA peer-to-peer
communications scheme that lets SNA applications communicate directly with
peer SNA applications.
Peer-to-Peer Internetworking). An open-standard IP-architecture
for SNA peer-to-peer networking.
APPI Forum An
open forum for vendors, users, and analysts formed to define and develop
open systems solutions for SNA peer-to-peer networking.
networking protocol developed by Apple Computer for communication between
Apple Computer products and other computers. This protocol is independent
of the network layer on which it is run. Current implementations exist
for Localtalk, a 235Kb/s local area network; and Ethertalk, a 10Mb/s local
area network. [Source: NNSC]
program that performs a function directly for a user. FTP,
mail and Telnet clients are examples
of network applications. [Source: RFC1983].
The top-most layer in the OSI
Reference Model providing such communication services as electronic mail
and file transfer.
mounting plate containing connector hardware for attachment to the network.
Appliques translate communication signals from a network interface into
signals expected by the communication standard of choice (such as RS-232
Peer-to-Peer Networking). An IBM SNA facility that
provides distributed processing based on Type 2.1 network nodes and LU
Programming Support Environment).
Remote Access). Protocol that provides Macintosh users direct
access to information and resources at a remote AppleTalk site
area A logical
set of ISO CLNS-based,
DECnet-based, or OSPF-based
segments connected by routers.
Archie A system
to automatically gather, index and serve information on the Internet. The
initial implementation of archie provided an indexed directory of filenames
from all anonymous FTP archives on the Internet. Later versions provide
other collections of information. See also: Archive
Site, Gopher, Prospero,
Wide Area Information Servers.
For more information about Archie see also Archie
Archive Server An
email-based file transfer facility offered by some systems. [Source: ZEN]
Archive Site A
machine that provides access to a collection of files across the Internet.
For example, an anonymous FTP archive site provides access to arcived material
via the FTP protocol. WWW servers can also serve as archive sites. See
also: Anonymous FTP, Archie,
Wide Area Information Servers,
World Wide Web. [Source: RFC1983].
(Attached Resource Computer Network). A 2.5-Mbps token
bus LAN developed in the late 1970s
and early 1980s by Datapoint Corporation. ARCnet's primary characteristics
are simplify, ease of use, and relative lack of expense.
UNIX a mathematical term that refers to a number, character or word which
changes the action of the command it is applied to.
The Greek National Internet service.
Response Mode). An HDLC
communication mode involving one primary and at least one secondary, where
either the primary or one of the secondaries can initiative transmissions.
The Academic and Research Network of Slovenia.
Resolution Protocol). Used to dynamically discover the low
level physical network hardware address that corresponds to the high level
IP address for a given host. ARP is limited to physical network systems
that support broadcast packets t hat can be heard by all hosts on the network.
See also: Proxy ARP, Reverse
Address Resolution Protocol. [Source: RFC1983].
The protocol is defined in RFC826
For further information about ARP parameters you can see the document in
html format or you can download
the original document in text format at ftp.isi.edu/in-notes/iana/assignments/arp-parameters.
Research Projects Agency). Now called DARPA, the U.S.
government agency that funded the ARPANET.[Source: RFC1208]
ARPANET A packet
switched network developed in the early 1970s. The "grandfather" of today's
Internet. ARPANET was decommissioned in June 1990.[Source: RFC1208]
Retransmission reQuest). A communications feature where the
receiver asks the transmitter to resend a block or frame because errors
were detected by the receiver.
System). Internet (TCP/IP) terminology for a collection of gateways
(routers) that fall under one administrative entity and cooperate using
a common Interior Gateway Protocol (IGP).
See also: Subnet. [Source: RFC1208]
System Boundary Router). ABR located between an OSPF
autonomous system and a non-OSPF network. ASBRs run both OSPF and another
routing protocol, such as RIP. ASBRs must reside in a nonstub OSPF area.
See also ABR, non-stub area, and OSPF.
ASC (Apple Sound
Standard Code for Information Interchange).
A standard character-to-number encoding widely used in the computer industry.
See also: EBCDIC. [Source: RFC1983].
A character - to - 7bit number encoding, which is the US national version
of the standard ISO 646 code. See also ISO 646. A table of the ASCII character
set can be found in the file /usr/pub/ascii on every UNIX system.
A chassis-based communication server with up to 16 MB of memory and up
to 112 asynchronous ports. This communication server can have Ethernet,
Token Ring, or synchronous serial
Syntax Notation One). The language used by the OSI
protocols for describing abstract syntax. This language is also used to
encode SNMP packets. ASN.1 is defined in ISO
documents 8824.2 and 8825.2. See also: Basic
Encoding Rules. [Source: RFC1983].
SCSI Programming Interface).
which documents the currently assigned values from several series of numbers
used in network protocol implementations. This RFC is updated periodically
and, in any case, current information can be obtained from the Internet
Assigned Numbers Authority (IANA). If you are developing a protocol or
application that will require the use of a link, socket, port, protocol,
etc., please contact the IANA to receive a number assignment. See also:
ASTRA Is the EARN
service that allows users to retrieve documents from databases known by
ASTRA throughout the network. Users can send their queries to the ASTRA
server wich in turn forwards the query to the related database servers.
This provides an easy-to-use uniform access method to a large number of
databases. Anyone who can send electronic mail to EARN/Bitnet can access
ASTRA. Interactive user interfaces (clients) to ASTRA are available for
VM and VMS systems on the EARN/Bitnet network. [Source: EARN Association]
by individual bytes, not related to specific timing on the transmitting
end. [Source: ZEN]
Time Division Multiplexing). A method of sending information
in which normal time division multiplexing (TDM)
is used, excepted that time slots are allocated as needed rather than preassigned
to specific transmitters.
Translation Gateway). A Cisco DECnet
routing software function that allows a router to route multiple, independent
DECnet networks and to establish a user-specified address translation for
selected nodes between networks.
difference between transmitted and received power due to loss trough equipment,
lines or other transmission devices. Measured in decibels.
ATM (Adobe Type
ATM (Asynchronous Transfer
Mode) A standard which defines high-load, high-speed (1.544Mbps
through 1.2Gbps), fixed-size packet (cell) switching with dynamic bandwidth
allocation. ATM is also known as "fast packet". [Source: RFC1983].
For more info search on the ATM
Transition Network) OR (Automated Test Network).
Transaction Protocol) OR (All Tests P).
form of information items provided by the X.500
Directory Service. The directory information base consists of entries,
each containing one or more attributes. Each attribute consists of a type
identifier together with one or more values. Each directory Read operation
can retrieve some or all attributes from a designated entry. [Source: RFC1392]
AU A sound format.
Unit Interface). An IEEE 802.3
cable connecting the MAU (Media
Access Unit) to the networked device. The term AUI also can be used to
refer to the host back-panel connector to which an AUI cable might attach.
Also called transceiver cable.
Use Policy). Many transit networks have policies which restrict the use
to which the network may be put. For example, some networks may only be
used for non-commercial purposes. Some AUPs limit the type of material
which can be made available to the public (e.g., pornographic material).
Enforcement of AUPs varies with the network. See also: netiquette.
A/UX Apple's version
verification of the identity of a person or process.[Source: MALAMUD]
authority zone Associated
with DNS, an authority zone is a section
of the domain-name tree for which one name server is the authority.
automatic call reconnect
Feature permitting automatic call rerouting away from a failing
A group of autonomous system () that trust their own network
reachability/routing information more than they trust that received from
other or confederations.
autonomous switching Feature
on Cisco routers that provides faster packet processing by allowing the
ciscoBus to switch packets independently without interrupting the system
wich happens pseudo-automatically, and is usually too complex to go into
any further than to say it happens "automagically".[Source: ZEN]
AVI (Audio Video
Interface). A Microsoft technology.
AWG (American Wire
Gauge) The System wich specifies wire size.