rfc1208.txt

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Network Working Group                                        O. Jacobsen
Request for Comments: 1208                                      D. Lynch
                                                           Interop, Inc.
                                                              March 1991


                     A Glossary of Networking Terms

Status of this Memo

   This RFC is a glossary adapted from "The INTEROP Pocket Glossary of
   Networking Terms" distributed at Interop '90.  This memo provides
   information for the Internet community.  It does not specify an
   Internet standard.  Distribution of this memo is unlimited.

Introduction

   This glossary is adapted from "The INTEROP Pocket Glossary of
   Networking Terms" produced to help you understand the many terms--and
   in particular the myriad of acronyms--that can be encountered at the
   INTEROP Tutorials, Conference, and Exhibition.

   To keep this document reasonably small we have deliberately omitted
   common computer and communications terms such as disk, modem, byte,
   and VLSI.  In addition, the definitions have been kept brief.  We
   recommend that you consult the glossaries found in the major computer
   networking textbooks for more comprehensive definitions.

   We also realize that producing this glossary is akin to shooting at a
   moving target.  The computer and communications industries are moving
   very rapidly, and terms and acronyms are born every day.  You are
   invited to submit words which you think should be included in future
   editions.

Glossary

   abstract syntax: A description of a data structure that is
   independent of machine-oriented structures and encodings.

   ACSE: Association 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.

   address mask: A bit mask used to select bits from an Internet address
   for subnet addressing.  The mask is 32 bits long and selects the
   network portion of the Internet address and one or more bits of the
   local portion.  Sometimes called subnet mask.



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   address resolution: A means for mapping Network Layer addresses onto
   media-specific addresses.  See ARP.

   ADMD: Administration 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 PRMD.

   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, DUA, MTA.

   ANSI: American National Standards Institute.  The U.S.
   standardization body. ANSI is a member of the International
   Organization for Standardization (ISO)

   AOW: Asia and Oceania Workshop.  One of the three regional OSI
   Implementors Workshops, equivalent to OIW and EWOS.

   API: Application Program Interface.  A set of calling conventions
   defining how a service is invoked through a software package.

   Application Layer: The top-most layer in the OSI Reference Model
   providing such communication services as electronic mail and file
   transfer.

   ARP: Address Resolution Protocol.  The Internet protocol used to
   dynamically map Internet addresses to physical (hardware) addresses
   on local area networks. Limited to networks that support hardware
   broadcast.

   ARPA: Advanced Research Projects Agency.  Now called DARPA, the U.S.
   government agency that funded the ARPANET.

   ARPANET: A packet switched network developed in the early 1970s.  The
   "grandfather" of today's Internet.  ARPANET was decommissioned in
   June 1990.

   ASN.1: Abstract Syntax Notation One.  The OSI language for describing
   abstract syntax.  See BER.

   attribute: The 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.




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   Autonomous 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
   subnetwork.

   backbone: The primary connectivity mechanism of a hierarchical
   distributed system.  All systems which have connectivity to an
   intermediate system on the backbone are assured of connectivity to
   each other.  This does not prevent systems from setting up private
   arrangements with each other to bypass the backbone for reasons of
   cost, performance, or security.

   Bart Simpson (R): Internet and OSI cult hero.

   baseband: Characteristic of any network technology that uses a single
   carrier frequency and requires all stations attached to the network
   to participate in every transmission.  See broadband.

   BER: Basic Encoding Rules.  Standard rules for encoding data units
   described in ASN.1.  Sometimes incorrectly lumped under the term
   ASN.1, which properly refers only to the abstract syntax description
   language, not the encoding technique.

   big-endian: A format for storage or transmission of binary data in
   which the most significant bit (or byte) comes first.  The reverse
   convention is called little-endian.

   BITNET: Because It's Time NETwork.  An academic computer network
   based originally on IBM mainframe systems interconnected via leased
   9600 bps lines.  BITNET has recently merged with CSNET, The
   Computer+Science Network (another academic computer network) to form
   CREN: The Corporation for Research and Educational Networking.  See
   CSNET.

   BOC: Bell Operating Company.  More commonly referred to as RBOC for
   Regional Bell Operating Company.  The local telephone company in each
   of the seven U.S. regions.

   bridge: A device that connects two or more physical networks and
   forwards packets between them.  Bridges can usually be made to filter
   packets, that is, to forward only certain traffic.  Related devices
   are: repeaters which simply forward electrical signals from one cable
   to another, and full-fledged routers which make routing decisions
   based on several criteria.  In OSI terminology, a bridge is a Data
   Link Layer intermediate system.  See repeater and router.

   broadband: Characteristic of any network that multiplexes multiple,
   independent network carriers onto a single cable.  This is usually



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   done using frequency division multiplexing.  Broadband technology
   allows several networks to coexist on one single cable; traffic from
   one network does not interfere with traffic from another since the
   "conversations" happen on different frequencies in the "ether,"
   rather like the commercial radio system.

   broadcast: A packet delivery system where a copy of a given packet is
   given to all hosts attached to the network.  Example: Ethernet.

   BSD: Berkeley Software Distribution.  Term used when describing
   different versions of the Berkeley UNIX software, as in "4.3BSD
   UNIX."

   catenet: A network in which hosts are connected to networks with
   varying characteristics, and the networks are interconnected by
   gateways (routers).  The Internet is an example of a catenet.  See
   IONL.

   CCITT: International Consultative Committee for Telegraphy and
   Telephony.  A unit of the International Telecommunications Union
   (ITU) of the United Nations.  An organization with representatives
   from the PTTs of the world.  CCITT produces technical standards,
   known as "Recommendations," for all internationally controlled
   aspects of analog and digital communications.  See X Recommendations.

   CCR: Commitment, Concurrency, and Recovery.  An OSI application
   service element used to create atomic operations across distributed
   systems.  Used primarily to implement two-phase commit for
   transactions and nonstop operations.

   client-server model: A common way to describenetwork services and the
   model user processes (programs) of those services.  Examples include
   the name-server/name-resolver paradigm of the DNS and file-
   server/file-client relationships such as NFS and diskless hosts.

   CLNP: Connectionless Network Protocol.  The OSI protocol for
   providing the OSI Connectionless Network Service (datagram service).
   CLNP is the OSI equivalent to Internet IP, and is sometimes called
   ISO IP.

   CLTP: Connectionless Transport Protocol.  Provides for end-to-end
   Transport data addressing (via Transport selector) and error control
   (via checksum), but cannot guarantee delivery or provide flow
   control.  The OSI equivalent of UDP.

   CMIP: Common Management Information Protocol.  The OSI network
   management protocol.




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   CMOT: CMIP Over TCP.  An effort to use the OSI network management
   protocol to manage TCP/IP networks.

   connectionless: The model of interconnection in which communication
   takes place without first establishing a connection.  Sometimes
   (imprecisely) called datagram.  Examples: LANs, Internet IP and OSI
   CLNP, UDP, ordinary postcards.

   connection-oriented: The model of interconnection in which
   communication proceeds through three well-defined phases: connection
   establishment, data transfer, connection release.  Examples: X.25,
   Internet TCP and OSI TP4, ordinary telephone calls.

   core gateway: Historically, one of a set of gateways (routers)
   operated by the Internet Network Operations Center at BBN.  The core
   gateway system forms a central part of Internet routing in that all
   groups must advertise paths to their networks from a core gateway,
   using the Exterior Gateway Protocol (EGP).  See EGP, backbone.

   COS: Corporation for Open Systems.  A vendor and user group for
   conformance testing, certification, and promotion of OSI products.

   COSINE: Cooperation for Open Systems Interconnection Networking in
   Europe.  A program sponsored by the European Commission, aimed at
   using OSI to tie together European research networks.

   CREN: See BITNET and CSNET.

   CSMA/CD: Carrier Sense Multiple Access with Collision Detection.  The
   access method used by local area networking technologies such as
   Ethernet.

   CSNET: Computer+Science Network.  A large computer network, mostly in
   the U.S. but with international connections.  CSNET sites include
   universities, research labs, and some commercial companies.  Now
   merged with BITNET to form CREN.  See BITNET.

   DARPA: Defense Advanced Research Projects Agency.  The U.S.
   government agency that funded the ARPANET.

   Data Link Layer: The OSI layer that is responsible for data transfer
   across a single physical connection, or series of bridged
   connections, between two Network entities.

   DCA: Defense Communications Agency.  The government agency
   responsible for the Defense Data Network (DDN).





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   DCE: Distributed Computing Environment.  An architecture of standard
   programming interfaces, conventions, and server functionalities
   (e.g., naming, distributed file system, remote procedure call) for
   distributing applications transparently across networks of
   heterogeneous computers.  Promoted and controlled by the Open
   Software Foundation (OSF), a consortium led by HP, DEC, and IBM.  See
   ONC.

   DDN: Defense Data Network.  Comprises the MILNET and several other
   DoD networks.

   DECnet: Digital Equipment Corporation's proprietary network
   architecture.

   DNS: Domain Name System.  The distributed name/address mechanism used
   in the Internet.

   domain: In the Internet, a part of a naming hierarchy.
   Syntactically, an Internet domain name consists of a sequence of
   names (labels) separated by periods (dots), e.g., "tundra.mpk.ca.us."
   In OSI, "domain" is generally used as an administrative partition of
   a complex distributed system, as in MHS Private Management Domain
   (PRMD), and Directory Management Domain (DMD).

   dotted decimal notation: The syntactic representation for a 32-bit
   integer that consists of four 8-bit numbers written in base 10 with
   periods (dots) separating them.  Used to represent IP addresses in
   the Internet as in: 192.67.67.20.

   DSA: Directory System Agent.  The software that provides the X.500
   Directory Service for a portion of the directory information base.
   Generally, each DSA is responsible for the directory information for
   a single organization or organizational unit.

   DUA: Directory User Agent.  The software that accesses the X.500
   Directory Service on behalf of the directory user.  The directory
   user may be a person or another software element.

   EARN: European Academic Research Network.  A network using BITNET
   technology connecting universities and research labs in Europe.

   EGP: Exterior Gateway Protocol.  A reachability routing protocol used
   by gateways in a two-level internet.  EGP is used in the Internet
   core system.  See core gateway.

   encapsulation: The technique used by layered protocols in which a
   layer adds header information to the protocol data unit (PDU) from
   the layer above.  As an example, in Internet terminology, a packet