ISO/IEC 8480:1995
(Main)Information technology — Telecommunications and information exchange between systems — DTE/DCE interface back-up control operation using ITU-T Recommendation V.24 interchange circuits
Information technology — Telecommunications and information exchange between systems — DTE/DCE interface back-up control operation using ITU-T Recommendation V.24 interchange circuits
Specifies the procedures for back-up operation applicable to data transmission on a leased line when implemented through a single interface, controlling both the leased and the back-up facilities, using ITU-T Recommendation V.24 interchange circuits in conjunction with either the 25-pole connector (ISO 2110) or the 26-pole connector (ISO/IEC 11569). Cancels and replaces the first edition, which has been technically revised.
Technologies de l'information — Télécommunications et échange d'information entre systèmes — Dispositif de secours à la jonction ETTD/ETCD réalisé à l'aide des circuits d'échange de la Recommandation UIT-T V.24
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Standards Content (Sample)
INTERNATIONAL
STANDARD 8480
Second edition
1995-09-I 5
Information technology -
Telecommunications and information
exchange between systems - DTE/DCE
interface back-up control operation using
ITU-T Recommendation V.24 interchange
circuits
Technologies de I’informa tion - T6lGcommunica tions et 6change
d’information entre systgmes - Dispositif de secours a la jonction
ETTD/ETCD r6alis6 ;i I’aide des circuits d’khange de la Recommandation
UT-T V.24
Reference number
ISO/I EC 8480: 1995(E)
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ISO/IEC 8480: 1995(E)
Foreword
lS0 (the International Organization for Standardization) and IEC (the Inter-
national Electrotechnical Commission) form the specialized system for
worldwide standardization. National bodies that are members of IS0 or
IEC participate in the development of International Standards through
technical committees established by the respective organization to deal
with particular fields of technical activity. IS0 and IEC technical commit-
tees collaborate in fields of mutual interest. Other international organiza-
tions, governmental and non-governmental, in liaison with IS0 and IEC,
also take part in the work.
In the field of information technology, IS0 and IEC have established a joint
technical committee, lSO/IEC JTC 1. Draft International Standards adopted
by the joint technical committee are circulated to national bodies for vot-
ing. Publication as an International Standard requires approval by at least
75 % of the national bodies casting a vote.
International Standard lSO/IEC 8480 was prepared by Joint Technical
Committee lSO/IEC JTC 1, Information technology, Subcommittee SC 6,
Telecommunications and information exchange between systems.
This second edition cancels and replaces the first edition
(IS0 8480:1987), which has been technically revised.
0 lSO/lEC 1995
All rights reserved. Unless otherwise specified, 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 publisher.
I SO/I EC Copyright Off ice l Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
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ISOllEC 8480 : 1995 (E)
Introduction
Where data transmission is provided on a leased line, there may be a
requirement to provide back-up operation, to be brought into use
whenever transmission via the leased line is, for any reason, not
possible.
There are several possible back-up facilities:
- back-up of a 2-wire leased line by one GSTN line;
- back-up of a 4-wire leased line by one GSTN line;
- back-up of a 4-wire leased line by two GSTN lines;
- back-up of a 2-wire/4=wire leased line by one/two lines of a private
switched network;
- back-up of a 2-wire leased ine by one
SDN line, using a terminal
adaptor’ ;
- back-up of a 4-wire leased ine by one SDN line, using a terminal
1 -
adaptor .
NOTES
I - This list may not be exhaustive.
2 - the terminal adaptor may be separate equipment or physically combined
with the DCE.
The variety of facilities should not be visible in the protocol used at the
DTElDCE interface to exchange the interface control and status
information necessary for back-up control. To achieve this, a
standardised approach to the required protocol is essential.
The
majority of applications are, however, restricted to the first two of the
listed possibilities.
In consequence, this international Standard
describes the protocol requirements where only one back-up facility is
provided as the alternative to data transmission on the leased line. For
other arrangements of facilities, although this International Standard is
not directly applicable, it nevertheless should be used as a guide to the
protocol requirements.
’ Terminal Adaptor functions are described in ITU-T Recommendation
(previously CCITT Recommendation) V. II 0, Support of data term!&
equipments wifh V-series type interfaces by an integrated services digital
network, and CCITT Recommendation V. 120, Supporf by an /SD/V of data
terminal equipment with V-series type interfaces with provision for statistical
muhpexing.
. . .
III
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MMEC 8480 : 1995 (E)
INTERNATIONAL STANDARD 0 ISCMEC
Telecommunications and information
Information technology -
- DTE/DCE interface back-up control
exchange between systems
operation using IT&T Recommendation V.24 interchange circuits
ISO/IEC 11569:1993, information technology -
1 scope
Telecommunications and information exchange
This international Standard specifies the procedures
between systems - 26-pole interface connector
for back-up operation applicable to data transmission
dimensions and confacf number
mateabilify
on a leased line when implemented through a single
assignments.
interface, controlling both the leased and the back-up
facilities, using KU-T Recommendation V.24 ITU-T Recommendation’ V.24: 1993, List of definifions
for interchange circuits between data terminal
interchange circuits in conjunction with either the 25-
equipment and data circuit-terminating equipment.
pole connector (IS0 2110) or the 26.pole connector
(ISOIIEC 11569).
The method used to switch the transmission of data
3 Definitions
automatically from the leased line to or from the
back-up facility is not specified in this International
For the purposes of this International Standard, the
Standard.
following definitions apply.
This International Standard is not applicable where
3.1 answering station: the station at which the
back-up (calling or answering) is achieved by manual
DCE switches to the back-up facility when a back-up
means.
request is received (e.g. an incoming call).
NOTES
3.2 authorized mode: the mode in which switching
1 The procedures specified in this International Standard
to the back-up facility is done at the DCE initiative
may be used at the answering end only, the calling end
when the DCE is authorized by the DTE to do so.
only, or both ends of a connection.
NOTE - In the event that the DTE cannot control this facility
2 An ordinary DCE (i.e. one not implementing back-up
over the interface, selection of this mode within the DCE
control) may be provided at either end of the back-up
during installation is permitted.
circuit and only for back-up purposes. For example, a
calling station could provide one or more separate auto-dial
3.3 calling station: the station at which the DCE
GSTN lines to provide back-up on demand to a greater
has to send to the called station a back-up request
number of leased lines.
(e.g. a call for the other end to switch to the back-up
facility).
3.4 direct mode: the mode in which switching to
2 Normative references
the back-up facility is done at the DTE initiative.
The following standards contain provisions which,
4 Switching to back-up operation
through reference in this text? constitute provisions of
this International Standard. At the time of publication,
The state diagrams applicable to back-up operation,
the editions indicated were valid. All standards are
encompassing the procedures at both the calling and
subject to revision, and parties to agreements based
the answering stations, are shown in figure 1 for direct
on this International Standard are encouraged to
mode, and in figure 2 for authorized mode.
investigate the possibility of applying the most recent
When interchange circuit 108 is implemented, it shall
editions of the standards indicated below. Members
be in the ON condition. When circuit 108 is not
of IEC and IS0 maintain registers of currently valid
implemented, the DCE shall operate as if circuit 108
International Standards.
were present and in the ON condition.
IS0 21 IO:1 989, lnformafion technology - Data
- 25-pole DTWDCE interface
communication
connector and confact number assignments.
1 Previously CCITT Recommendation
1
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ISO
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