Internet Standards/CD2.mdf/ccitt/1992/i/i113.asc

Text File | 1993-06-28 | 33KB | 1,470 lines

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INTERNATIONAL  TELECOMMUNICATION  UNION





CCITT    I.113

THE  INTERNATIONAL

TELEGRAPH  AND  TELEPHONE

CONSULTATIVE  COMMITTEE











INTEGRATED  SERVICES  DIGITAL

NETWORK  (ISDN)

GENERAL  STRUCTURE  AND  SERVICE

CAPABILITIES





VOCABULARY  OF  TERMS  FOR

BROADBAND  ASPECTS OF ISDN









Recommendation  I.113











Geneva, 1991











































































Printed in Switzerland















FOREWORD



    The CCITT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the Interna-
tional Telecommunication Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing
Recommendations on them with a view to standardizing telecommunications on a worldwide basis.

    The Plenary Assembly of CCITT which meets every four years, establishes the topics for study and approves
Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCITT
between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988).

    Recommendation I.113 was prepared by Study Group XVIII and was approved under the Resolution No.
2 procedure on the 5th of April 1991.





___________________









CCITT  NOTES



1)    In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunica-
tion Administration and a recognized private operating agency.

2)    A list of abbreviations used in this Recommendation can be found in Annex A.

















aITU1991

All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the ITU.







    Preamble to B-ISDN Recommendations

    In 1990, CCITT SG XVIII approved a first set of Recommendations on B-ISDN. These are:

I.113 û Vocabulary of terms for broadband aspects of ISDN

I.121 û Broadband aspects of ISDN

I.150 û B-ISDN asynchronous transfer mode functional characteristics

I.211 û B-ISDN service aspects

I.311 û B-ISDN general network aspects

I.321 û B-ISDN Protocol Reference Model and its application

I.327 û B-ISDN functional architecture

I.361 û B-ISDN ATM Layer specification

I.362 û B-ISDN ATM Adaptation Layer (AAL) functional description

I.363 û B-ISDN ATM Adaptation Layer (AAL) specification

I.413 û B-ISDN user-network interface

I.432 û B-ISDN user-network interface û Physical Layer specification

I.610 û Operation and maintenance principles of B-ISDN access

    These Recommendations address general B-ISDN aspects as well as specific service- and network-ori-
ented issues, the fundamental characteristics of the asynchronous transfer mode (ATM), a first set of relevant
ATM oriented parameters and their application at the user-network interface as well as impact on operation
and maintenance of the B-ISDN access. They are an integral part of the well established I-Series Recommen-
dations. The set of Recommendations are intended to serve as a consolidated basis for ongoing work relative to
B-ISDN both within CCITT and in other organizations. They may also be used as a first basis towards the devel-
opment of network elements.

    CCITT will continue to further develop and complete these Recommendations in areas where there are
unresolved issues and develop additional Recommendations on B-ISDN in the I-Series and other series in the
future.







PAGE BLANCHE









Recommendation I.113

Recommendation I.113



VOCABULARY  OF  TERMS  FOR  BROADBAND  ASPECTS  OF  ISDN





1    Introduction

    This Recommendation consists primarily of those terms and definitions that are considered essential to the
understanding and application of the principles of broadband aspects of the integrated services digital network
(BISDN). They are not exclusive to B-ISDN and are recommended also for application, in so far as they are rel-
evant, to other types of telecommunication networks.

    Included are terms that may already be defined in other CCITT/CCIR Recommendations. However, the
definitions given here embrace only the essential concepts and on that basis it is considered that they are not
inconsistent with the more specialized definitions that appear in those Recommendations.

    According to the conventions applied in this Recommendation, any term in common usage, but whose
use is deprecated, is shown in brackets as in the following example: "broadband [wideband]".

    Where a truncated term is widely used in an understood context the complete term is quoted following
the colloquial form, for example, "contribution, contribution application".

    Some definitions include terms in italics face to indicate that these terms are defined elsewhere in
this Recommendation.

    Annex A contains an alphabetical list of all the terms contained in this Recommendation.

    Annex B contains a list of abbreviations which are used in B-ISDN Recommendations.





2    Vocabulary of terms

    This section is divided into two sub-sections, 2.1 Services, and 2.2Interfaces, channels and transfer modes.
Within each sub-section the terms are listed and defined.



2.1    Services

101    broadband [wideband]

F: large bande

S: banda ancha

    A service or system requiring transmission channels capable of supporting rates greater than the pri-
mary rate.

102    broadcast

F: diffusion

S: difusi≤n

    A value of the service attribute "communication configuration", which denotes unidirectional distribu-
tion to all users.

    Note û This term should not be confused with the term "broadcasting service" as defined in the ITU
Radio Regulations.

103    connectionless service

F: service sans connexion

S: servicio sin conexi≤n

    A service which allows the transfer of information among service users without the need for end-to-
end call establishment procedures.

    Note û Connectionless services may be used to support both interactive and distribution services.

104    constant bit rate service

F: service α dΘbit constant

S: servicio de velocidad binaria constante

    A type of telecommunication service characterized by a service bit rate specified by a constant value.

105    contribution, contribution application

F: contribution

S: contribuci≤n; aplicaci≤n de contribuci≤n

    Use of a broadband service or channel for transferring audio or video information to a user for fur-
ther post-production processing and subsequent distribution.

106    conversational service

F: service conversationnel

S: servicio conversacional

    An interactive service which provides for bidirectional communication by means of real-time (no
store-and-forward) end-to-end information transfer from user to user.

107    distribution, distribution application

F: distribution; application de distribution

S: distribuci≤n; aplicaci≤n de distribuci≤n

    Use of a broadband service or channel for transferring audio, video or other information to a user or
a number of users who will not be expected to apply post-production processing to the information.

108    distribution service

F: service de distribution

S: servicio de distribuci≤n

    Service characterized by the unidirectional flow of information from a given point in the network to
other (multiple) locations. Distribution services are subdivided into two classes: distribution services without
user individual presentation control and distribution services with user individual presentation control.

109    distribution service with user individual presentation control

F: service distribuΘ avec contr⌠le de prΘsentation par l'usager

S: servicio de distribuci≤n con control de la presentaci≤n por el usuario

    A distribution service in which the information is provided as a sequence of information entities e.g.
frames with cyclical repetition, so that the user has the ability to select individual information entities and
can control the start and order of the information.

110    distribution service without user individual presentation control

F: service distribuΘ sans contr⌠le de prΘsentation par l'usager

S: servicio de distribuci≤n sin control de la presentaci≤n por el usuario

    A distribution service which users can access without having any control over the start and order of
the presentation of the distributed information.

111    enhanced-quality television

F: tΘlΘvision de qualitΘ amΘliorΘe

S: televisi≤n de calidad mejorada

    Television of quality superior to existing-quality television, but less than the quality of high-definition
television.

112    existing-quality television

F: tΘlΘvision de qualitΘ conventionnelle

S: televisi≤n de calidad convencional

    Television as defined in conventional 625-line and 525-line television standards, such as NTSC, PAL
and SECAM.

113    interactive service

F: service interactif

S: servicio interactivo

    A service which provides the means for bidirectional exchange of information between users or
between users and hosts. Interactive services are subdivided into three classes of services: conversational ser-
vices, messaging services and retrieval services.

114    messaging service

F: service de messagerie

S: servicio de mensajerφa

    An interactive service which offers user-to-user communication between individual users via storage
units with store-and-forward, mailbox and/or message handling, (e.g. information editing, processing and
conversion)  functions.

115    mixed document

F: document mixte

S: documento mixto

    A document that may contain text, graphics, data, image and moving picture information as well as
voice annotation

116    multimedia service

F: service multimΘdia

S: servicio multimedio

    A service in which the interchanged information consists of more than one type, such as text, graph-
ics, sound, image and video.

117    multipoint

F: multipoint

S: multipunto

    A value of the attribute "communication configuration" which denotes that the communication
involves more than two network terminations.

118    post-production processing

F: post-production (traitement aprΦs production)

S: tratamiento de posproducci≤n

    Further processing of contributed audio and video information, to change the form or presentation of
the information prior to its final utilization.

119    retrieval service

F: service de consultation

S: servicio de consulta

    An interactive service which provides the capability of accessing information stored in data base cen-
tres. This information will be sent to the user on demand only. The information can be retrieved on an indi-
vidual basis, i.e.the time at which an information sequence is to start is under the control of the user.

120    service bit rate

F: dΘbit de service

S: velocidad binaria de servicio

    The bit rate which is available to a user for the transfer of user information.

121    sound retrieval service

F: service de consultation de programmes sonores

S: servicio de consulta de programas sonoros

    On-demand (user initiated) retrieval of music and other audio information.

122    variable bit rate service

F: service α dΘbit variable

S: servicio de velocidad binaria variable

    A type of telecommunication service characterized by a service bit rate specified by statistically
expressed parameters which allow the bit rate to vary within defined limits.

123    videomessaging

F: messagerie vidΘo

S: videomensajerφa

    A messaging service for the transfer for moving pictures with or without other information.



2.2    Interfaces, channels and transfer modes

201    asynchronous time-division multiplexing

F: multiplexage temporel asynchrone

S: multiplexaci≤n asφncrona por divisi≤n en el tiempo; multiplexaci≤n temporal asφncrona

    A multiplexing technique in which a transmission capability is organized in undedicated slots filled
with cells with respect to each application's instantaneous real need. In this case, the terminal equipment (i.e.
the customer application) defines the actual transmitted bit rate, whatever this rate is, possibly variable dur-
ing the communication. This technique carries a labelled interface structure over a frame or a self-delineating
labelled interface.

202    asynchronous transfer mode (ATM)

F: mode de transfert asynchrone (ATM)

S: modo de transferencia asφncrono (MTA)

    A transfer mode in which the information is organized into cells; it is asynchronous in the sense that
the recurrence of cells containing information from an individual user is not necessarily periodic.

203    block

F: bloc

S: bloque

    A unit of information consisting of a header and an information field.

204    block payload

F: capacitΘ utile de bloc

S: cabida ·til del bloque; contenido ·til del bloque

    The bits in the information field within a block.

205    broadband access

F: accΦs large bande

S: acceso de banda ancha

    An ISDN access able to contain at least one channel capable of supporting a rate greater than the pri-
mary rate, or supporting an equivalent information transfer rate.

206    broadband communication channel

F: canal de communication large bande

S: canal de comunicaci≤n de banda ancha

    A specific portion of the information payload capacity, available to the user for ISDN services. A
broadband communication channel exists only during a call, as set-up by a signalling or administrative pro-
cedure.

207    cell

F: cellule

S: cΘlula

    A block of fixed length. It is identified by a label at the asynchronous transfer mode layer of the B-
ISDN protocol reference model.

208    cell delineation

F: cadrage cellule

S: delimitaci≤n de la cΘlula

    The identification of cell boundaries in a cell stream.

209    circuit transfer mode

F: mode de transfert par circuit

S: modo de transferencia circuito; modo de transferencia por circuitos

    A transfer mode in which transmission and switching functions are achieved by permanent allocation
of channels/bandwidth between the connections.

210    connection admission control

F: contr⌠le d'admission des connexions

S: control de admisi≤n de una conexi≤n

    The procedure within the control part of network nodes used to decide whether or not a request for a
(virtual) connection can be accepted based on the requested usage parameters and already established con-
nections.

211    deterministic; ATM deterministic

F: dΘterministe; ATM dΘterministe

S: determinφstico; MTA determinφstico

    A mode of the asynchronous transfer mode in which a constant information transfer capacity
expressed in terms of a predetermined limiting value for a given service is provided to the user throughout a
call.

212    frame

F: trame

S: trama

    A block of variable length identified by a label at layer 2 of the OSI reference model, e.g. an HDLC
block.

213    framed interface

F: interface tramΘe

S: interfaz entramado

    An interface where the serial bit stream is segmented into periodic physical frames. Each frame is
divided by a fixed partition into an overhead and an information payload portion.

214    general broadcast signalling virtual channel

F: canal virtuel de diffusion gΘnΘrale de la signalisation

S: canal virtual de se±alizaci≤n de difusi≤n general

    A virtual channel independent of service profiles and used for broadcast signalling.

215    header, cell header

F: en-tΩte; en-tΩte de cellule

S: encabezamiento; encabezamiento de cΘlula

    The bits within a cell allocated for functions required to transfer the cell payload within the network.

216    hybrid interface structure

F: structure d'interface hybride

S: estructura hφbrida de interfaz

    An interface structure which has a mixture of labelled channels and positioned channels.

217    information payload capacity

F: capacitΘ utile d'information

S: cabida ·til de informaci≤n

    The difference between the interface rate and the interface overhead rate, that is the bit rate of the
interface payload.

218    interface overhead

F: rΘsidu de l'interface

S: tara del interfaz

    The remaining portion of the bit stream after deducting the information payload. The interface over-
head may be essential (e.g. framing for an interface shared by users) or ancillary (e.g. performance monitor-
ing).

219    interface payload

F: capacitΘ utile de l'interface

S: cabida ·til del interfaz

    The portion of the bit stream of a framed interface which can be used for telecommunication services.
Any signalling is included in the interface payload.

220    interface rate; interface bit rate

F: dΘbit α l'interface; dΘbit binaire α l'interface

S: velocidad del interfaz; velocidad binaria del interfaz

    The gross bit rate at an interface, that is, the sum of the bit rates of the interface payload and the
interface overhead. Example: the bit rate at the boundary between the physical layer and the physical medium.

221    invalid cell

F: cellule invalide

S: cΘlula no vßlida

    A cell where the header is declared by the header error control process to contain errors.

222    labelled channel

F: canal ΘtiquetΘ

S: canal etiquetado

    A temporally-ordered collection of all block payloads having a common label value.

223    labelled deterministic channel

F: canal ΘtiquetΘ dΘterministe

S: canal etiquetado determinφstico

    A labelled channel with the property that the aggregated payload capacity of all blocks in each suc-
cessive interval of specified constant duration is a constant.

224    labelled interface structure

F: structure d'interface ΘtiquetΘe

S: estructura de interfaz etiquetado

    An interface structure in which all services and signalling are provided by labelled channels. A labelled
interface structure can be accommodated within a framed interface or a self-delineating labelled interface.

225    labelled multiplexing

F: multiplexage par Θtiquetage

S: multiplexaci≤n por etiquetado

    The multiplexing of labelled channels by concatenating the blocks of the different channels.

226    labelled statistical channel

F: canal ΘtiquetΘ statistique

S: canal etiquetado estadφstico

    A labelled channel in which the payload of the successive blocks of the channel is random and/or the
block durations are random.

227    logical signalling channel

F: canal logique de signalisation

S: canal l≤gico de se±alizaci≤n

    A logical channel for signalling information which is contained within an information channel or a
physical signalling channel.

228    meta-signalling

F: mΘta-signalisation

S: metase±alizaci≤n

    The procedure for establishing, checking and releasing signalling virtual channels.

229    network node interface (NNI)

F: interface de noeud de rΘseau (NNI)

S: interfaz de nodo de red (INR)

    The interface at a network node which is used to interconnect with another network node.

230    packet

F: paquet

S: paquete

    An information block identified by a label at layer 3 of the OSI reference model.

231    packet transfer mode

F: mode de transfert par paquets

S: modo de transferencia paquete; modo de transferencia por paquetes

    A transfer mode in which the transmission and switching functions are achieved by packet oriented
techniques, so as to dynamically share network transmission and switching resources between a multiplicity of
connections.

232    payload module

F: module de capacitΘ utile

S: m≤dulo de cabida ·til

    That portion of the information payload, of an interface, within which one or more channels entirely
exist.

233    periodic frame

F: trame pΘriodique

S: trama peri≤dica

    A transmission segment which is repeated at intervals of equal duration (e.g. 125 ╡sec), and may be
delineated by incorporating fixed periodic patterns into the bit stream.

234    physical frame

F: trame physique

S: trama fφsica

    A segment of a serial logical bit stream at an interface, partitioned into successive segments.

235    physical signalling channel

F: canal physique de signalisation

S: canal fφsico de se±alizaci≤n

    A dedicated physical channel (e.g. D-channel) used for signalling information. It may be used to carry
other information.

236    positioned channel

F: canal positionnΘ

S: canal ubicado; canal identificado por su posici≤n

    A channel that occupies bit positions which form a fixed periodic pattern (e.g. B-, H- and D-channels
in ISDN user network interfaces).

237    positioned interface structure

F: structure d'interface positionnΘe

S: estructura de interfaz de canales ubicados

    A structure in which all services and signalling are provided by positioned channels. Such a structure
can exist only within a framed interface.

238    selective broadcast signalling virtual channel

F: canal virtuel de diffusion sΘlective de la signalisation

S: canal virtual de se±alizaci≤n de difusi≤n selectiva

    A virtual channel allocated to a service profile and used for broadcast signalling.

239    self-delineating block

F: bloc α auto-cadrage

S: bloque autodelimitado

    A block with the property that its endpoints can be identified by examining the block itself. A defined
pattern or flag at the beginning of each block might serve to demarcate the block.

240    self-delineating labelled interface

F: interface ΘtiquetΘe α auto-cadrage

S: interfaz etiquetado autodelimitado

    An interface whose entire serial bit stream consists of a self-delineating labelled multiplexing.

241    signalling virtual channel

F: canal virtuel de signalisation

S: canal virtual de se±alizaci≤n

    A virtual channel for transporting signalling information.

242    statistical; ATM statistical

F: statistique; ATM statistique

S: estadφstico; MTA estadφstico

    A mode of the asynchronous transfer mode in which the information transfer capacity specified for a
given service provided to the user throughout a call is expressed in terms of values of parameters such as
mean, peak and standard deviation.

243    synchronous time division multiplexing

F: multiplexage temporel synchrone

S: multiplexaci≤n sφncrona por divisi≤n en el tiempo; multiplicaci≤n temporal sφncrona

    A multiplexing technique supporting the synchronous transfer mode(STM).

244    synchronous transfer mode (STM)

F: mode de transfert synchrone (STM)

S: modo de transferencia sφncrono (MTS)

    A transfer mode which offers periodically to each connection a fixed-length word.

245    throughput

F: charge utile

S: caudal de trßfico; caudal

    The number of data bits contained in a block (e.g. between the address field and the CRC field of the
LAPD-based frames) successfully transferred in one direction across a section per unit time.

246    transfer mode

F: mode de transfert

S: modo de transferencia

    Aspects covering transmission, multiplexing and switching in a telecommunications network.

247    transit delay

F: dΘlai de transit

S: retardo de trßnsito

    The time difference between the instant at which the first bit of the address field of a frame crosses
one designated boundary, and the instant at which the last bit of the closing flag of the frame crosses a sec-
ond designated boundary.

248    usage parameter control

F: contr⌠le des paramΦtres d'utilisation

S: control de los parßmetros de utilizaci≤n

    The taking of appropriate action if usage monitoring establishes that the negotiated values of the
information transfer parameters of a virtual channel or a virtual path are exceeded.

249    valid cell

F: cellule valide

S: cΘlula vßlida

    A cell where the header is declared by the header error control process to be free of errors.

250    virtual channel (VC)

F: canal virtuel (VC)

S: canal virtual (CV)

    A concept used to describe unidirectional transport of ATM cells associated by a common unique iden-
tifier value.

251    virtual channel connection

F: connexion de canal virtuel

S: conexi≤n de canal virtual

    A concatenation of virtual channel links that extends between two points where the adaptation layer is
accessed.

252    virtual channel link

F: liaison de canal virtuel

S: enlace de canal virtual

    A mean of unidirectional transport of ATM cells between a point where a virtual channel identifier
value is assigned and the point where that value is translated or removed.

253    virtual path (VP)

F: trajet virtuel (VP)

S: trayecto virtual (TYV)

    A concept used to describe unidirectional transport of ATM cells belonging to virtual channels that are
associated by a common identifier value.

254    virtual path connection

F: connexion de trajet virtuel

S: conexi≤n de trayecto virtual

    A concatenation of virtual path links that extends between the point where the virtual channel iden-
tifier values are assigned and the point where those values are translated or removed.

255    virtual path link

F: liaison de trajet virtuel

S: enlace de trayecto virtual

    The group of virtual channel links, identified by a common value of the virtual path identifier, between
the point where the VPI value is assigned and the point where the VPI value is translated or removed.







ANNEX A

(to Recommendation I.113)

Alphabetical list of terms contained in this Recommendation1)

201    asynchronous time-division multiplexing

202    asynchronous transfer mode

203    block

204    block payload

101    broadband [wideband]

205    broadband access

206    broadband communication channel

102    broadcast

207    cell

208    cell delineation

209    circuit transfer mode

210    connection admission control

103    connectionless service

104    constant bit rate service

105    contribution; contribution application

106    conversational service

211    deterministic; ATM deterministic

108    distribution service

109    distribution service with user individual presentation control

110    distribution service without user individual presentation control

107    distribution; distribution application

111    enhanced-quality television

112    existing-quality television

212    frame

213    frame interface

214    general broadcast signalling virtual channel

215    header; cell header

216    hybrid interface structure

217    information payload capacity

113    interactive service

218    interface overhead

219    interface payload

220    interface rate; interface bit rate

221    invalid cell

222    labelled channel

223    labelled deterministic channel

224    labelled interface structure

225    labelled multiplexing

226    labelled statistical channel

227    logical signalling channel

114    messaging service

228    meta-signalling

115    mixed document

116    multimedia service

117    multipoint

229    network node interface

230    packet

231    packet transfer mode

232    payload module

233    periodic frame

234    physical frame

235    physical signalling channel

236    positioned channel

237    positioned interface structure

118    post-production processing

119    retrieval service

238    selective broadcast signalling virtual channel

239    self-delineating block

240    self-delineating labelled interface

120    service bit rate

241    signalling virtual channel

121    sound retrieval service

242    statistical; ATM statistical

243    synchronous time division multiplexing

244    synchronous transfer mode

245    throughput

246    transfer mode

247    transit delay

248    usage parameter control

249    valid cell

122    variable bit rate service

123    videomessaging

250    virtual channel

251    virtual channel connection

252    virtual channel link

253    virtual path

254    virtual path connection

255    virtual path link







ANNEX B

(to Recommendation I.113)

List of abbreviations used in B-ISDN Recommendations

AAL            ATM Adaptation Layer

AAL-PCI        AAL protocol control information

AAL-SDU        AAL service data unit

ACE            Access connection element

AIS            Alarm indication signal

AL            Access Link

ATM            Asynchronous transfer mode

ATM-SDU        ATM service data unit

AU            Administrative unit

B-ISDN            Broadband aspects of integrated services digital network

B-ISDN PRM        Protocol reference model of the broadband aspects of ISDN

B-ISPBX            Private branch exchange for B-ISDN

B-NT            Network termination for B-ISDN

B-NT1            Network termination 1 for B-ISDN

B-NT2            Network termination 2 for B-ISDN

B-TA            Terminal adaptor for B-ISDN

B-TE            Terminal equipment for B-ISDN

BER            Bit error ratio

BIP            Bit interleaved parity

BOM            Beginning of message

C-n            Container-n

CAD-CAM        Computer aided design/computer aided manufacturing

CAMC            Customer access maintenance centre

CBR            Constant bit rate

CE            Connection element

CEQ            Customer equipment

CIME            Customer installation manintenance entities

CL            Connectionless

CLP            Cell loss priority

CLSF            Connectionless service function

CMI            Coded mark inversion

CN            Customer network

COH            Connection overhead

COM            Continuation of message

CON            Concentrator

CRC            Cyclic redundancy check

CRF            Connection related function

CRF(VC)        Virtual channel connection related function

CRF(VP)            Virtual path connection related function

CS            Convergence sublayer

CS-PDU            Convergence sublayer protocol data unit

DPL            Primary link for distribution services

DS            Digital section

EOM            End of message

ET            Exchange termination

FDDI            Fibre distributed data interface

FEBE            Far end blok error

FERF            Far end receive failure

GFC            Generic flow control

HDLC            High-level data link control

HDTV            High definition television

HEC            Header error control

HLF            Higher layer function

IPL            Primary link for interactive services

IRP            Internal reference point

IT            Information type

LAN            Local area network

LE            Local exchange

LFC            Local function capabilities

LI            Length indicator

LT            Line termination

MA            Medium adaptor

MAN            Metropolitan area network

MCD            Maintenance cell description

MID            Multiplexing identification

MSB            Most significant bit

MSP            Maintenance service provider

MUX            Multiplexor

NNI            Network-node interface

NP            Network performance

NT            Network termination

OAM            Operation and maintenance

OAMC            Operation, administration and maintenance centre

OSI            Open systems interconnection

PCI            Protocol control information

PDH            Plesiochronous digital hierarchy

PDU            Protocol data unit

PL            Physical layer

PL-OAM            Physical layer-operation and maintenance (cell)

PLK            Primary link

PM            Physical medium (sublayer)

POH            Path overhead

PON            Passive optical network

PRM            Protocol reference model

PT            Payload type

PTR            Pointer

QOS            Quality of service

RAI            Remote alarm indication

RES            Reserved

RG            Regenerator

RPOA            Recognized private operating agency

RS            Regenerator section

RU            Remote unit

SAP            Service access point

SAR            Segmentation and reassembly sublayer

SDH            Synchronous digital hierarchy

SDU            Service data unit

SFET            Synchronous frequency encoding technique

SN            Sequence number

SN            Sequence number protection

SOH            Section overhead

SP            Service provider

SPL            Service provider link

SPN            Subscriber premises network

SSM            Single segment message

ST            Segment type

STM            Synchronous transfer mode

STM-n            Synchronous transport module-n

SVC            Signalling virtual channel

TA            Terminal adaptor

TC            Transmission convergence sublayer

TCE            Transit connection element

TCRF            Transit connection related function

TE            Terminal equipment

TMN            Telecommunication management network

TPE            Transmission path endpoint

UNI            User-network interface

VBR            Variable bit rate

VC            Virtual channel

VC            Virtual container-n

VCC            Virtual channel connection

VCCE            Virtual channel connection endpoint

VCI            Virtual channel identifier

VP            Virtual path

VPC            Virtual path connection

VPCE            Virtual path connection endpoint

VPI            Virtual path identifier