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- .rs
- .\" Troff code generated by TPS Convert from ITU Original Files
- .\" Not Copyright ( c) 1991
- .\"
- .\" Assumes tbl, eqn, MS macros, and lots of luck.
- .TA 1c 2c 3c 4c 5c 6c 7c 8c
- .ds CH
- .ds CF
- .EQ
- delim @@
- .EN
- .nr LL 40.5P
- .nr ll 40.5P
- .nr HM 3P
- .nr FM 6P
- .nr PO 4P
- .nr PD 9p
- .po 4P
-
- .rs
- \v | 5i'
- .sp 1P
- .ce 1000
- \v'3P'
- SECTION\ 1
- .ce 0
- .sp 1P
- .ce 1000
- \fBGENERAL\ PRINCIPLES\ OF\ MAINTENANCE\fR
- .ce 0
- .sp 1P
- .ce 1000
- \fBAND\ MAINTENANCE\ ORGANIZATION\fR
- .ce 0
- .sp 1P
- .sp 2P
- .LP
- \fBRecommendation\ M.70\fR
- .RT
- .sp 2P
- .ce 1000
- \fBGUIDING\ PRINCIPLES\ ON\ THE\ \fR \fBGENERAL\ MAINTENANCE\fR
- .EF '% Fascicle\ IV.1\ \(em\ Rec.\ M.70''
- .OF '''Fascicle\ IV.1\ \(em\ Rec.\ M.70 %'
- .ce 0
- .sp 1P
- .ce 1000
- \fBORGANIZATION\ FOR\ TELEPHONE\(hyTYPE\ INTERNATIONAL\ CIRCUITS\fR
- .ce 0
- .sp 1P
- .LP
- \fB1\fR \fBGeneral\fR
- .sp 1P
- .RT
- .PP
- In order to furnish guiding principles to Administrations, the
- CCITT recommends the following principles for the general maintenance
- organization for international circuits.
- .RT
- .PP
- 1.1
- Definitions relating to the various maintenance elements, each representing
- a set of functions, are given in Recommendations\ M.710
- to\ M.725 for automatic circuits, and in Recommendations\ M.1012\ [1],
- M.1013\ [2], M.1014\ [3] for leased and special circuits.
- .sp 9p
- .RT
- .PP
- 1.2
- The size and complexity of the maintenance organization will
- depend on the particular case and the particular country concerned. In some
- instances it may be possible to carry out all sets of functions from a
- single location; in others only some of the functions might be combined
- and carried
- out from one location. The precise arrangement will depend on the
- Administration concerned, and the CCITT limits itself to defining the functions
- of the separate elements, leaving the manner in which the elements are
- grouped to be determined by the Administration.
- .LP
- .PP
- 1.3
- If a country so desires and/or if it judges that the complexity of its
- international telecommunications so requires, the international maintenance
- organization can be responsible for all types of circuit for which
- Study\ Group\ IV makes recommendations.
- .sp 2P
- .LP
- \fB2\fR \fBTypes of circuits\fR \fBto be catered for\fR
- .sp 1P
- .RT
- .PP
- The types of circuits to be catered for are as follows:
- .PP
- public circuits:
- .RT
- .LP
- \(em
- telephone circuits,
- .LP
- \(em
- voice\(hyfrequency telegraph circuits,
- .LP
- \(em
- phototelegraph circuits,
- .LP
- \(em
- sound\(hyprogramme circuits, etc.;
- .LP
- leased circuits:
- .LP
- \(em
- telephone circuits: point\(hyto\(hypoint and multiterminal,
- .LP
- \(em
- voice\(hyfrequency telegraph circuits,
- .LP
- \(em
- data circuits: point\(hyto\(hypoint and multiterminal,
- .LP
- \(em
- multi\(hyfacility circuits, that is, phototelegraph plus
- voice\(hyfrequency telegraph; speech plus voice\(hyfrequency telegraph;
- simultaneous or alternative transmission,
- .LP
- \(em
- phototelegraph circuits,
- .LP
- \(em
- sound\(hyprogramme circuits, etc.
- .bp
- .sp 2P
- .LP
- \fB3\fR \fBMaintenance organization\fR
- .sp 1P
- .RT
- .PP
- The maintenance of international public telephone circuits relies upon
- the ability of each Administration to fulfil the various functions and
- responsibilities noted in the Series\ M\ Recommendations. Where such circuits
- are manual, as opposed to automatic, it is assumed that the Administration
- will
- select and provide the relevant elements such as the \fIfault report point\fR
- \fI(circuit)\fR and the \fItesting point (transmission)\fR together with
- \fIcircuit\fR
- \fIcontrol\fR and \fIsub\(hycontrol station\fR assignments as appropriate.
- .PP
- For automatic circuits all the elements noted in Recommendation\ M.710 apply.
- .PP
- Leased and special international circuits require the services of a
- Transmission Maintenance Point (International Line) (TMP\(hyIL) which is
- described in Recommendation\ M.1014\ [3]. The circuit control and sub\(hycontrol
- functions and responsibilities on leased and special international circuits
- are noted in
- Recommendations\ M.1012\ [1] and\ M.1013\ [2] and include a close cooperation
- with the TMP\(hyIL.
- .PP
- For operations at other levels (group, supergroup, etc.), specific
- responsibilities are allotted to particular repeater stations. At each
- level, maintenance is based on the appointment of a \fIcontrol station\fR
- and one or more \fIsub\(hycontrol stations\fR Additional information concerning
- control and
- sub\(hycontrol stations follows in Recommendations\ M.80 and\ M.90 and is
- supplemented by that contained in Recommendations\ M.1012\ [1] and M.1013\ [2],
- M.723, M.724, N.5\ [4] and N.55\ [5].
- .PP
- The attention of Administrations is drawn to the need for exchanging contact
- forms (similar to those for maintenance units for automatic circuits as
- described in Recommendation\ M.93) which give telephone numbers, staffing
- hours, etc. for units involved in the maintenance of leased circuits and the
- higher order transmission systems.
- .RT
- .sp 2P
- .LP
- \fBReferences\fR
- .sp 1P
- .RT
- .LP
- [1]
- CCITT Recommendation \fICircuit control station for leased and special\fR
- \fIcircuits\fR , Vol.\ IV, Rec.\ M.1012.
- .LP
- [2]
- CCITT Recommendation \fISub\(hycontrol station for leased and special\fR
- \fIcircuits,\fR Vol.\ IV, Rec.\ M.1013.
- .LP
- [3]
- CCITT Recommendation \fITransmission maintenance point (international\fR
- \fIline) (TMP\(hyIL)\fR , Vol.\ IV, Rec.\ M.1014.
- .LP
- [4]
- CCITT Recommendation \fISound programme control, sub\(hycontrol and send\fR
- \fIreference stations\fR , Vol.\ IV, Rec.\ N.5.
- .LP
- [5]
- CCITT Recommendation \fIOrganization, responsibilities and functions
- of\fR \fIcontrol and sub\(hycontrol stations for international television
- connections,\fR \fIlinks, circuits and circuit sections\fR , Vol.\ IV,
- Rec.\ N.55.
- \v'1P'
- .LP
- .sp 2P
- .LP
- \fBRecommendation\ M.75\fR
- .RT
- .sp 2P
- .sp 1P
- .ce 1000
- \fBTECHNICAL\ SERVICE\fR
- .EF '% Fascicle\ IV.1\ \(em\ Rec.\ M.75''
- .OF '''Fascicle\ IV.1\ \(em\ Rec.\ M.75 %'
- .ce 0
- .sp 1P
- .LP
- \fB1\fR \fBGeneral\fR
- .sp 1P
- .RT
- .PP
- 1.1
- The term \*Qtechnical service\*U (sometimes \*Qtechnical
- services\*U) is used throughout the Series M Recommendations. The term
- is used to indicate the appropriate authorities within an Administration
- which have
- responsi
- bility for: making international agreements on technical and
- engineering aspects of provision and maintenance, allocating responsibilities
- to maintenance units within the same Administration, specifying provision
- and maintenance facilities, and determining provision and maintenance policy
- and
- overseeing its implementation. Thus it can be seen that the responsibilities
- of the technical service are at a higher administrative level than those
- of the
- staff concerned with day\(hyto\(hyday operation of international services.
- .sp 9p
- .RT
- .LP
- .PP
- 1.2
- The staff of the technical service is generally part of the
- central headquarters of the Administration. However, Administrations sometimes
- delegate some or all of their technical service responsibilities to regional
- centres or even operational maintenance units. In such cases the technical
- service remains responsible for ensuring that the delegated responsibilities
- are satisfactorily carried out.
- .bp
- .sp 9p
- .RT
- .sp 2P
- .LP
- \fB2\fR \fBOutline of responsibilities\fR
- .sp 1P
- .RT
- .PP
- As far as international cooperation and coordination are concerned, the
- responsibilities of the technical service
- are specified in various Series M\ Recommendations. The following list,
- which is not exhaustive, serves to illustrate the type of functions normally
- performed by the technical service of an Administration:
- .RT
- .LP
- \(em
- making international agreements on the appointment of control
- and sub\(hycontrol stations, and ensuring that the stations so
- appointed are advised accordingly;
- .LP
- \(em
- reaching international agreements on all matters relating to
- the engineering provision of new and rearranged telephone
- circuits, leased circuits,\ etc.; digital blocks, paths,\ etc.;
- groups, supergroups,\ etc.; and so on;
- .LP
- \(em
- exchanging contact point and other maintenance information
- between Administrations;
- .LP
- \(em
- the escalation procedure in Recommendation M.711 acting as a
- centralized escalation point for those faults and problems which
- cannot be cleared by staff at maintenance units, even after
- discussions between the managers of such units. For example,
- escalation may be required where special test equipment or
- specialized expertise is needed;
- .LP
- \(em
- ensuring the satisfactory preparation and execution of
- routine maintenance schedules;
- .LP
- \(em
- developing and keeping up to date plans for the restoration
- of service in the event of the failure of international
- transmission systems;
- .LP
- \(em
- ensuring that other Administrations are advised of planned
- interruptions to transmission systems in its own country, and
- ensuring that steps are taken to minimize their effect on
- international services.
- .PP
- The functions mentioned above are based on responsibilities
- imposed on the technical service by Series M Recommendations.
- .sp 2P
- .LP
- \fB3\fR \fBContact point information\fR
- .sp 1P
- .RT
- .PP
- Contact point information for the technical service should be
- exchanged between Administrations in accordance with Recommendation\ M.93. If
- the responsibilities of the technical service have been split on a
- functional basis, contact point information for each separate function
- should be exchanged. If technical service responsibilities have been delegated
- (as
- envisaged in \(sc\ 1.2 above), contact point information for the responsible
- central headquarters staff should be exchanged.
- \v'1P'
- .RT
- .LP
- .sp 2P
- .LP
- \fBRecommendation\ M.80\fR
- .RT
- .sp 2P
- .sp 1P
- .ce 1000
- \fBCONTROL\ STATIONS\fR
- .EF '% Fascicle\ IV.1\ \(em\ Rec.\ M.80''
- .OF '''Fascicle\ IV.1\ \(em\ Rec.\ M.80 %'
- .ce 0
- .sp 1P
- .LP
- \fB1\fR \fBDefinition of control station\fR
- .sp 1P
- .RT
- .PP
- A control station is that point within the general maintenance
- organization which fulfils the control responsibilities for the circuit,
- group, supergroup, digital section, etc., assigned to it.
- .RT
- .LP
- .sp 2P
- .LP
- \fB2\fR \fBAppointment of control stations\fR
- .sp 1P
- .RT
- .PP
- The following principles for control stations apply to:
- .RT
- .LP
- \(em
- every international circuit (circuit control station),
- .LP
- \(em
- every international group, supergroup, digital block, digital
- path, etc. (group control station, supergroup control station,
- digital block control station, digital path control station,
- etc.),
- .LP
- \(em
- every line link, every regulated line section and every
- digital section (line link control station, regulated line
- section control station, digital section control station) using
- a symmetric pair line, a coaxial line, an optical fibre or a
- radio\(hyrelay link.
- .bp
- .sp 1P
- .LP
- 2.1
- \fICircuit control station\fR
- .sp 9p
- .RT
- .PP
- A circuit control station is nominated for each international
- circuit used for public telephony or for leased or special purposes in
- accordance with Recommendations\ M.723 and\ M.1012\ [1] as appropriate. In the
- case of sound\(hyprogramme or television circuits, the terminal ISPC
- .PP
- (International Sound\(hyProgramme Centre) or ITC (International Television
- Centre) at the receiving end should be nominated as the control station.
- (See Recommendations\ N.1\ [2], N.5\ [3] and\ N.55\ [4].)
- .RT
- .sp 1P
- .LP
- 2.2
- \fIGroup, supergroup, digital block, etc. control stations\fR
- .sp 9p
- .RT
- .PP
- For each international group, supergroup, digital block, etc., the terminal
- repeater station is a control station for its incoming direction of
- transmission. There are thus two control stations, one for each direction
- of transmission.
- .RT
- .sp 1P
- .LP
- 2.3
- \fIRegulated line section control station\fR
- .sp 9p
- .RT
- .PP
- The procedure is the same as for groups, supergroups, digital
- blocks, etc., that is to say, each of the terminal repeater stations is a
- control station for the incoming direction of transmission.
- .RT
- .sp 1P
- .LP
- 2.4
- \fIDigital path control station\fR
- .sp 9p
- .RT
- .PP
- For each digital path, each terminal station is a control station for its
- incoming direction of transmission. There are thus two control
- stations, one for each direction of transmission.
- .RT
- .LP
- .sp 2P
- .LP
- \fB3\fR \fBResponsibilities of circuit control stations\fR
- .sp 1P
- .RT
- .PP
- See Recommendations\ M.723 and\ M.1012\ [1] concerning public
- automatic telephone circuits, leased circuits and special circuits,
- respectively. See Recommendations\ N.5\ [3] and N.55\ [4] in connection with
- sound\(hyprogramme and television circuits.
- .RT
- .sp 2P
- .LP
- \fB4\fR \fBResponsibilities of control stations for groups,
- supergroups, digital paths, etc.\fR
- .sp 1P
- .RT
- .PP
- 4.1
- Group, supergroup, digital block, digital path, regulated line section,
- line link, etc. control stations are responsible for the incoming
- direction of transmission only.
- .sp 9p
- .RT
- .PP
- 4.2
- Each control station is responsible for ensuring that the
- group,
- supergroup, digital block, digital path, link, line, etc. with which it is
- concerned is set up and maintained to the required standards. In particular,
- it is responsible for:
- .sp 9p
- .RT
- .LP
- a)
- controlling lining\(hyup measurements to within the
- recommended limits and keeping records of reference measurements
- (initial measurements) for \fIanalogue transmission systems\fR ;
- .LP
- b)
- ensuring that the performance of digital transmission
- systems is kept within recommended limits and keeping records of
- initial measurements;
- .LP
- c)
- ensuring that routine maintenance measurements are carried
- out on the due dates, using the specified methods and in such a
- way that interruptions to service are limited to the shortest
- possible duration;
- .LP
- d)
- ensuring that the stations concerned take action when a
- fault occurs, and controlling the various tests or
- investigations necessary in clearing the fault. It must be
- possible to report faults discovered at any time of the day or
- night;
- .LP
- e)
- informing the circuit control station of any condition
- which might affect the operation of the circuits under its
- control;
- .LP
- f
- )
- seeking the authority of the circuit control station
- for any action which will take a circuit, or circuits, out of
- service;
- .LP
- g)
- knowing what are the possibilities of rerouting any faulty groups, supergroups,\
- etc.;
- .LP
- h)
- recording, on forms provided for the purpose, all incidents
- which arise, giving the time of occurrence of the incident, the
- exact location if known, the action taken if any, and the time of restoration
- to service.
- .bp
- .PP
- 4.3
- Thus, for technical purposes (maintenance, lining\(hyup) the control function
- for digital paths, groups, supergroups, mastergroups,
- supermastergroups and regulated line sections are divided between the two
- directions of transmission, the station at the incoming end being the control
- station in each case. However, it is considered desirable to have a single
- routing form for each, giving information about both directions of
- transmission, and in order that this and similar documentation may be prepared
- and distributed on a methodical basis, these documentary functions shall
- be
- added to the responsibilities of one of the control stations, this
- \fIcontrol station for documentary purposes\fR being chosen by agreement
- between the Administrations concerned.
- .LP
- .sp 2P
- .LP
- \fBReferences\fR
- .sp 1P
- .RT
- .LP
- [1]
- CCITT Recommendation \fICircuit control station for leased and special\fR
- \fIcircuits\fR , Vol.\ IV, Rec.\ M.1012.
- .LP
- [2]
- CCITT Recommendation \fIDefinitions for application to international\fR
- \fIsound\(hyprogramme transmissions\fR , Vol.\ IV, Rec.\ N.1.
- .LP
- [3]
- CCITT Recommendation \fIControl and subcontrol stations for\fR
- \fIsound\(hyprogramme circuits, connections, etc.\fR , Vol.\ IV, Rec.\ N.5.
- .LP
- [4]
- CCITT Recommendation \fIOrganization, responsibilities and functions\fR
- \fIof control and sub\(hycontrol ITCs and control and sub\(hycontrol stations\fR
- \fIfor international television connections, links, circuits and\fR
- \fIcircuit sections\fR , Vol.\ IV, Rec.\ N.55.
- \v'1P'
- .LP
- .sp 2P
- .LP
- \fBRecommendation\ M.90\fR
- .RT
- .sp 2P
- .sp 1P
- .ce 1000
- \fBSUB\(hyCONTROL\ STATIONS\fR
- .EF '% Fascicle\ IV.1\ \(em\ Rec.\ M.90''
- .OF '''Fascicle\ IV.1\ \(em\ Rec.\ M.90 %'
- .ce 0
- .sp 1P
- .LP
- \fB1\fR \fBDefinition of sub\(hycontrol station\fR
- .sp 1P
- .RT
- .PP
- A sub\(hycontrol station is a point within the general maintenance
- organization which fulfils the sub\(hycontrol responsibilities of the circuit,
- group, supergroup, etc. digital section, assigned to it.
- .RT
- .sp 2P
- .LP
- \fB2\fR \fBAppointment of sub\(hycontrol stations\fR
- .sp 1P
- .RT
- .PP
- The following principles apply to:
- .RT
- .LP
- \(em
- every international circuit (circuit sub\(hycontrol station),
- for whatever purpose (telephony, telegraphy, sound\(hyprogramme,
- data transmission, etc.). (See in particular
- .LP
- Recommendations\ N.5\ [1] in connection with sound\(hyprogramme
- circuits and\ N.55\ [2] in connection with television circuits);
- .LP
- \(em
- every international digital block, digital path, group,
- supergroup, mastergroup or supermastergroup (digital block
- sub\(hycontrol station, digital path sub\(hycontrol station, group
- sub\(hycontrol station, supergroup sub\(hycontrol station, etc.);
- .LP
- \(em
- every line link, every regulated line section and every
- digital line section (line link sub\(hycontrol station, regulated
- line section sub\(hycontrol station, digital line section
- sub\(hycontrol station) using a symmetric pair line, a coaxial
- line, an optical fibre or a radio\(hyrelay link.
- .PP
- The technical service of the Administration concerned designates the station
- that is to act as a sub\(hycontrol station in its country and informs the
- technical service of the country responsible for the control station
- accordingly.
- .LP
- .sp 2P
- .LP
- 2.1
- \fITerminal sub\(hycontrol stations\fR
- .sp 1P
- .RT
- .sp 1P
- .LP
- 2.1.1
- \fITerminal sub\(hycontrol stations for circuits\fR
- .sp 9p
- .RT
- .PP
- For each circuit a terminal circuit sub\(hycontrol station is
- appointed in accordance with Recommendations\ M.724 and M.1013\ [3] as
- appropriate.
- .PP
- For unidirectional constituted circuits the terminal station at the
- sending end should be the terminal circuit sub\(hycontrol station. In particular,
- in the case of sound\(hyprogramme or television circuits, the terminal
- ISPC
- or ITC at the sending end should be the terminal sub\(hycontrol station.
- (See\ Recommendations\ N.5\ [1] and\ N.55\ [2].)
- .bp
- .RT
- .sp 1P
- .LP
- 2.1.2
- \fITerminal sub\(hycontrol stations for digital blocks, digital paths,\fR
- \fIgroups, supergroups, etc.\fR
- .sp 9p
- .RT
- .PP
- At the two ends of a digital block, digital path, group,
- supergroup, etc., the terminal stations are designated as terminal digital
- block, digital path, group, supergroup, etc., sub\(hycontrol stations for the
- direction of transmission for which they are not the digital block, digital
- path, group, supergroup, etc., control station.
- .RT
- .LP
- .sp 1P
- .LP
- 2.1.3
- \fITerminal sub\(hycontrol station for a digital section, line link or\fR
- \fIa regulated line section\fR
- .sp 9p
- .RT
- .PP
- At the two ends of a digital section, line link or a regulated
- line section, the terminal stations are designated as terminal digital
- section, line link or regulated line section sub\(hycontrol station for the
- direction of transmission for which they are not the digital section, line
- link or regulated line section control station.
- .RT
- .sp 2P
- .LP
- 2.2
- \fIIntermediate sub\(hycontrol stations\fR
- .sp 1P
- .RT
- .sp 1P
- .LP
- 2.2.1
- \fIIntermediate sub\(hycontrol stations for circuits\fR
- .sp 9p
- .RT
- .PP
- In transit countries in which a circuit is brought to audio
- frequencies or 64\ kbit/s, etc., an intermediate circuit sub\(hycontrol
- station is appointed at a suitable point for each direction of transmission.
- It is left to the country concerned to choose:
- .RT
- .LP
- \(em
- where this point shall be;
- .LP
- \(em
- whether the sub\(hycontrol functions for the two directions of
- transmission are vested in one station or two stations
- (see Figure\ 1/M.90);
- .LP
- \(em
- whether, as may be desirable in the case of a large country,
- each direction of transmission has more than one circuit
- sub\(hycontrol station per transit country.
- .LP
- .rs
- .sp 10P
- .ad r
- \fBFIGURE\ 1/M.90, p.\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .sp 1P
- .LP
- 2.2.2
- \fIIntermediate sub\(hycontrol stations for paths and links\fR
- .sp 9p
- .RT
- .PP
- In general, for digital paths and analogue links, in transit
- countries in which the path or link concerned appears in its characteristic
- bit rate or in its basic frequency range, an intermediate sub\(hycontrol
- station is appointed for each direction of transmission. The countries
- concerned have the same prerogatives as those indicated above for circuits
- (see \(sc\ 2.2.1 and
- Figure\ 1/M.90).
- .RT
- .sp 1P
- .LP
- 2.2.3
- \fIIntermediate sub\(hycontrol stations for regulated line sections\fR
- .sp 9p
- .RT
- .PP
- In transit countries, a regulated line section intermediate
- sub\(hycontrol station is appointed for each direction of transmission,
- the same discretion as for circuits being given to the country concerned
- (see \(sc\ 2.2.1
- above and Figure\ 1/M.90).
- .RT
- .LP
- .sp 1P
- .LP
- 2.3
- \fICombination of functions\fR
- .sp 9p
- .RT
- .PP
- Any, or all, of the above functions may be vested in one station, depending
- on the arrangements in the country concerned.
- .bp
- .RT
- .sp 2P
- .LP
- \fB3\fR \fBResponsibilities of sub\(hycontrol stations for circuits\fR
- .sp 1P
- .RT
- .PP
- See Recommendations\ M.724 and M.1013\ [3] concerning automatic
- public telephone circuits, leased circuits and special circuits, respectively.
- See also Recommendations\ N.5\ [1] and\ N.55\ [2] in connection with
- sound\(hyprogramme and television circuits.
- .RT
- .sp 2P
- .LP
- \fB4\fR \fBResponsibilities of sub\(hycontrol stations for groups,
- supergroups, digital blocks, digital paths, etc.\fR
- .sp 1P
- .RT
- .PP
- The responsibilities of sub\(hycontrol stations are, for the sections which
- they control, similar to those given in Recommendation\ M.80 for control
- stations, but in addition they include:
- .RT
- .LP
- \(em
- cooperating with the control stations and other sub\(hycontrol
- stations in locating and clearing faults;
- .LP
- \(em
- setting up and maintaining that part of the digital path,
- group link, supergroup link, mastergroup link, or regulated line link
- between the through\(hyconnection stations nearest to the two
- frontiers;
- .LP
- \(em
- seeing that the transmission on the national section with
- which they are concerned is within the prescribed limits;
- .LP
- \(em
- reporting to the control station all relevant details
- concerning the location and subsequent clearance of faults;
- .LP
- \(em
- keeping the necessary records on lining\(hyup (analogue
- transmission) or initial measurements (digital transmission),
- fault location and fault clearing for the section for which they
- are responsible.
- .PP
- In addition to the above responsibilities, an intermediate
- sub\(hycontrol station (in a transit country) is responsible for initiating
- fault localization tests on the sections it controls in response to reports
- from
- other control or sub\(hycontrol stations.
- .LP
- .sp 2P
- .LP
- \fBReferences\fR
- .sp 1P
- .RT
- .LP
- [1]
- CCITT Recommendation \fIControl and sub\(hycontrol stations for\fR
- \fIsound\(hyprogramme circuits, connections, etc.,\fR Vol.\ IV, Rec.\ N.5.
- .LP
- [2]
- CCITT Recommendation \fIOrganization, responsibilities and functions\fR
- \fIof control and sub\(hycontrol ITCs and control and sub\(hycontrol stations\fR
- \fIfor international television connections, links, circuits and\fR
- \fIcircuit sections\fR , Vol.\ IV, Rec.\ N.55.
- .LP
- [3]
- CCITT Recommendation \fICircuit sub\(hycontrol station for leased and\fR
- \fIspecial circuits\fR , Vol.\ IV, Rec.\ M.1013.
- \v'6p'
- .sp 2P
- .LP
- \fBRecommendation\ M.93\fR
- .RT
- .sp 2P
- .ce 1000
- \fBEXCHANGE\ OF\ CONTACT\ POINT\ INFORMATION\fR
- .EF '% Fascicle\ IV.1\ \(em\ Rec.\ M.93''
- .OF '''Fascicle\ IV.1\ \(em\ Rec.\ M.93 %'
- .ce 0
- .ce 1000
- \fBFOR\ THE\ MAINTENANCE\ OF\ INTERNATIONAL\ SERVICES\fR
- .ce 0
- .sp 1P
- .ce 1000
- \fBAND\ THE\ INTERNATIONAL\ NETWORK\fR
- .ce 0
- .sp 1P
- .LP
- \fB1\fR \fBGeneral\fR
- .sp 1P
- .RT
- .PP
- The attention of Administrations is drawn to the need for
- exchanging information about telephone numbers, telex numbers, staffing
- hours,\ etc., for units involved in the maintenance of international
- telecommunication services. The exchange of such information is of great
- assistance to international cooperation and has an important bearing on
- maintenance efficiency.
- .PP
- This Recommendation lists services for which information should be
- exchanged. The list is not exhaustive and Administrations are asked to
- consider, when intending to introduce a new service, what contact point
- information will be required.
- .bp
- .RT
- .sp 2P
- .LP
- \fB2\fR \fBAspects to be covered by the exchange of information\fR
- .sp 1P
- .RT
- .sp 1P
- .LP
- 2.1
- \fITechnical service\fR
- .sp 9p
- .RT
- .PP
- The general functions and responsibilities of the \*Qtechnical
- service\*U are given in Recommendation M.75.
- .PP
- Where technical service responsibility within an Administration has
- been divided on a functional basis, contact point information relating
- to each function (for example, maintenance of telephone circuits, provision
- of leased circuits, exchange of information for changes in national numbering
- plans and circuit order of selection) should be supplied.
- .RT
- .sp 1P
- .LP
- 2.2
- \fIAutomatic and semi\(hyautomatic telephone service\fR
- .sp 9p
- .RT
- .PP
- For each international centre, contact point information for each of the
- maintenance elements in Recommendations\ M.715 to M.725 should be
- exchanged.
- .RT
- .sp 1P
- .LP
- 2.3
- \fIManual telephone circuits\fR
- .sp 9p
- .RT
- .PP
- For each international centre which has responsibility for manually operated
- international telephone circuits, appropriate maintenance contact
- point information should be exchanged.
- .RT
- .sp 1P
- .LP
- 2.4
- \fIOther international services\fR
- .sp 9p
- .RT
- .PP
- Contact point information, which should at least include
- information for fault reporting purposes, should be exchanged for the following
- international services:
- .RT
- .LP
- \(em
- circuit\(hyswitched public data communication service;
- .LP
- \(em
- packet\(hyswitched public data communication service;
- .LP
- \(em
- public telegram service;
- .LP
- \(em
- teletex service;
- .LP
- \(em
- telex service;
- .LP
- \(em
- public facsimile service (bureau and telefax);
- .LP
- \(em
- store and forward facsimile switching service;
- .LP
- \(em
- phototelegraph service.
- .sp 1P
- .LP
- 2.5
- \fICommon channel signalling systems\fR
- .sp 9p
- .RT
- .PP
- For each international centre where common channel signalling is
- employed, contact point information should be exchanged for the maintenance
- units which have responsibility for the following:
- .RT
- .LP
- \(em
- signalling system No. 6 transfer link (Recommendation
- M.760);
- .LP
- \(em
- signalling system administrative control
- (Recommendations\ M.762 and\ M.782).
- .PP
- Where an Administration has subdivided the maintenance functions of the
- SS No.\ 6 transfer link (for example, into fault reporting, control
- station,\ etc.), appropriate contact point information should be supplied.
- .sp 1P
- .LP
- 2.6
- \fILeased and special circuits\fR
- .sp 9p
- .RT
- .PP
- For each international centre which has responsibility for leased and special
- circuits, contact point information should be exchanged for the
- following:
- .RT
- .LP
- \(em
- fault report point;
- .LP
- \(em
- testing point;
- .LP
- \(em
- transmission maintenance point (international line)
- (Recommendation M.1014\ [1]);
- .LP
- \(em
- circuit control/sub\(hycontrol station
- (Recommendations\ M.1012\ [2] and M.1013\ [3]);
- .LP
- \(em
- restoration point for individual circuits.
- .bp
- .sp 1P
- .LP
- 2.7
- \fISound programme and television\fR
- .sp 9p
- .RT
- .PP
- Contact point information for the following centres concerned with sound
- and television should be exchanged:
- .RT
- .LP
- \(em
- international sound\(hyprogramme centre (ISPC)
- (Recommendation\ N.1\ [4]);
- .LP
- \(em
- international television centre (ITC)
- (Recommendation\ N.51\ [5]);
- .LP
- \(em
- programme booking centre (PBC)
- (Recommendation\ D.180\ [6]).
- .sp 1P
- .LP
- 2.8
- \fIGroups, supergroups, etc., digital paths and blocks and\fR
- \fItransmission systems\fR
- .sp 9p
- .RT
- .LP
- .PP
- For each international centre, contact point information should be exchanged
- for the following:
- .RT
- .LP
- \(em
- fault report point (Recommendation\ M.130);
- .LP
- \(em
- testing point (for routines, functional tests and fault
- localization);
- .LP
- \(em
- control/sub\(hycontrol station (Recommendations M.80 and M.90);
- .LP
- \(em
- restoration control point (Recommendation M.725);
- .LP
- \(em
- restoration implementation point.
- .sp 1P
- .LP
- 2.9
- \fISetting\(hyup and lining\(hyup activities\fR
- .sp 9p
- .RT
- .PP
- Where staff separate from those concerned with day\(hyto\(hyday
- maintenance are used for setting\(hyup and lining\(hyup new or rearranged
- telephone circuits, leased circuits, groups, supergroups, etc., relevant
- contact point
- information should be exchanged.
- .RT
- .sp 2P
- .LP
- \fB3\fR \fBExchange and distribution of contact point information\fR
- .sp 1P
- .RT
- .PP
- Annexes A, B, C, D and E to this Recommendation contain \*Qforms\*U to
- be used for the purpose of exchanging contact point information.
- .PP
- For convenience, the form in Annex B covers contact points for the
- automatic, semi\(hyautomatic and manual telephone service, and SS No.\ 6.
- .PP
- Each form provides for specific telephone numbers, telex numbers and
- answerback codes, together with the hours of staffing for each contact point
- and the name
- .FS
- The name to be used is that by which the maintenance unit is known within
- the Administration and should ideally be the name used by
- maintenance staff when answering the telephone.
- .FE
- of the maintenance unit
- involved. The \fIremarks\fR columns on the forms should be used to supply other
- useful information, such as languages spoken, telephone number of the
- supervising officer of the maintenance unit.
- .PP
- Each contact point is afforded two horizontal lines. If the
- maintenance unit normally responsible for a particular contact point is
- staffed during restricted hours only, alternative contact point information
- should be supplied in the lower line for use outside those hours.
- .PP
- In some situations a single telephone number, telex number, etc., will
- cover all contact points for, say, leased and special circuits at an
- international centre. In other situations, each contact point may have
- its own number. The actual arrangements will depend upon the particular
- organization
- existing within the Administration concerned.
- .PP
- Each Administration should distribute completed forms (Annexes\ A to\ E)
- to all Administrations likely to have use of the contact point information
- involved. Furthermore, revised issues of the forms should be distributed as
- required, for example, to reflect organizational changes, because a new
- international centre has been put into service.
- .PP
- Copies of contact point information distributed to, and received from,
- other Administrations should be made readily available to all staff at
- maintenance centres involved in international services or the international
- network. In this way, such staff are made aware of both their own functions
- and responsibilities and those of the maintenance organizations of other
- Administrations.
- .bp
- .RT
- .LP
- .ce 1000
- ANNEX\ A
- .ce 0
- .ce 1000
- (to Recommendation M.93)
- .sp 9p
- .RT
- .ce 0
- .LP
- .rs
- .sp 20P
- .ad r
- \fBFigure A\(hy1/M.93 [T1.93], p.\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .rs
- .sp 20P
- .ad r
- Blanc
- .ad b
- .RT
- .LP
- .bp
- .ce 1000
- ANNEX\ B
- .ce 0
- .ce 1000
- (to Recommendation M.93)
- .sp 9p
- .RT
- .ce 0
- .LP
- .rs
- .sp 47P
- .ad r
- \fBFigure B\(hy1/M.93 [T2.93], p. 3\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .ce 1000
- ANNEX\ C
- .ce 0
- .ce 1000
- (to Recommendation M.93)
- .sp 9p
- .RT
- .ce 0
- .LP
- .rs
- .sp 47P
- .ad r
- \fBFigure C\(hy1/M.93 [T3.93], p. 4 \ \ \ \ A L'ITALIENNE\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .ce 1000
- ANNEX\ D
- .ce 0
- .ce 1000
- (to Recommendation M.93)
- .sp 9p
- .RT
- .ce 0
- .LP
- .rs
- .sp 47P
- .ad r
- \fBFigure D\(hy1/M.93 [T4.93], p. 5 \ \ \ A L'ITALIENNE\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .ce 1000
- ANNEX\ E
- .ce 0
- .ce 1000
- (to Recommendation M.93)
- .sp 9p
- .RT
- .ce 0
- .LP
- .rs
- .sp 47P
- .ad r
- \fBFigure E\(hy1/M.93 [T5.93], p. 6 \ \ \ \ A L'ITALIENNE\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .sp 2P
- .LP
- \fBReferences\fR
- .sp 1P
- .RT
- .LP
- [1]
- CCITT Recommendation \fITransmission maintenance point international\fR
- \fIline (TMP\(hyIL)\fR , Vol.\ IV, Rec.\ M.1014.
- .LP
- [2]
- CCITT Recommendation \fICircuit control station for leased and special\fR
- \fIcircuits\fR , Vol.\ IV, Rec.\ M.1012.
- .LP
- [3]
- CCITT Recommendation \fISub\(hycontrol station for leased and special\fR
- \fIcircuits\fR , Vol.\ IV, Rec.\ M.1013.
- .LP
- [4]
- CCITT Recommendation \fIDefinitions for application to international\fR
- \fIsound\(hyprogramme transmissions\fR , Vol.\ IV, Rec.\ N.1.
- .LP
- [5]
- CCITT Recommendation \fIDefinitions for application to international\fR
- \fItelevision transmissions\fR , Vol.\ IV, Rec.\ N.51.
- .LP
- [6]
- CCITT Recommendation \fIInternational sound\(hy and television\(hyprogramme\fR
- \fItransmissions\fR , Vol.\ II, Rec.\ D.180.
- \v'1P'
- .LP
- .sp 2P
- .LP
- \fBRecommendation\ M.100\fR
- .RT
- .sp 2P
- .sp 1P
- .ce 1000
- \fBSERVICE\ CIRCUITS\fR
- .EF '% Fascicle\ IV.1\ \(em\ Rec.\ M.100''
- .OF '''Fascicle\ IV.1\ \(em\ Rec.\ M.100 %'
- .ce 0
- .sp 1P
- .PP
- To facilitate the general maintenance of the international
- telephone network, \fIservice circuits\fR should be set up as may be necessary
- between relevant maintenance units taking part in the international service.
- .sp 1P
- .RT
- .PP
- For the purposes of this Recommendation, a distinction is made
- between the following types of service circuit:
- .LP
- \(em
- \fBDirect service circuit\fR : a telephone or teleprinter
- (teletypewriter) service circuit serving only two stations and
- linking them directly.
- .LP
- \fINote\fR \ \(em\ It will also be necessary to consider the
- communications required by technical staff for setting up and
- maintaining very long circuits routed over a number of major
- systems in tandem, e.g.\ London\(emSingapore circuits. These may
- require service circuits to be interconnected.
- .LP
- \(em
- \fBOmnibus service circuit\fR (see Figure\ 1/M.100\ below): a
- telephone or teleprinter (teletypewriter) service circuit
- serving more than two stations connected in series, any or all
- of which may make connection to the service circuit
- simultaneously.
- .LP
- \(em
- \fBMultiterminal service circuit\fR (see Figure\ 2/M.100\ below):
- a telephone or teleprinter (teletypewriter) service circuit
- serving more than two stations and having at least one branching
- point. On each \fIbranch\fR of this circuit a certain number of
- stations can be connected in series. Every station served can
- enter the circuit individually.
- .LP
- \fINote\fR \ \(em\ Attention is drawn to the possible use of selective
- signalling on omnibus and multiterminal service circuits and to
- the problems that may arise in achieving the necessary stability
- on such circuits.
- .PP
- It is recommended that for the maintenance of international
- circuits:
- .LP
- 1)
- all attended stations should be connected direct to the
- public telephone network;
- .LP
- 2)
- the terminal stations of an international system should be
- provided with a direct telephone service circuit;
- .LP
- 3)
- terminal and intermediate stations on an international
- system should be provided with an omnibus telephone service
- circuit;
- .LP
- 4)
- where the provision of direct teleprinter (teletypewriter)
- service circuits is impracticable or uneconomical, important
- repeater stations on international routes should be provided with
- international telex facilities;
- .LP
- The equipment of the telegraph local end used on service
- telegraph circuits must be capable of transmitting and receiving
- signals conforming to International Telegraph Alphabet\ No.\ 2 and
- must be in accordance with the provisions of
- CCITT\ Recommendations;
- .LP
- 5)
- maintenance staff responsible for international circuits
- should have authority to make priority calls in the
- international telephone service\ [1];
- .bp
- .LP
- .rs
- .sp 47P
- .ad r
- \fBFigure 1/M.100 p.10\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .LP
- .rs
- .sp 37P
- .ad r
- \fBFigure 2/M.100, p.11\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- 6)
- all service circuits should in general conform to the
- Recommendations of the CCITT in respect of their quality and
- maintenance. However, service circuits may have a restricted
- quality which must nevertheless be such as to provide efficient
- communication when maintenance personnel have to use languages
- other than their mother tongue;
- .LP
- 7)
- in the event of a major interruption involving service
- circuits, these should be accorded priority in restoration;
- .LP
- 8)
- the terminal stations of a long international submarine
- cable system should be provided with a direct teleprinter
- (teletypewriter) service circuit;
- .LP
- 9)
- terminal and intermediate stations on a long international
- submarine cable system should be provided with an omnibus
- teleprinter (teletypewriter) service circuit.
- .PP
- The CCIR has issued Recommendation\ 400\(hy2 concerning
- service circuits for radio\(hyrelay links. (For the convenience of readers,
- this Recommendation is reproduced below. CCIR Report\ 444\ [2] also
- applies.)
- .bp
- .LP
- .sp 1P
- .ce 1000
- CCIR\ RECOMMENDATION\ 400\(hy2
- .FS
- This
- Recommendation applies to radio\(hyrelay systems which will transmit at least
- 60\ telephone channels or a television signal and comprise two staffed
- terminal stations, in which the signals are demodulated to baseand, and any
- number of unstaffed intermediate stations. This Recommendation applies,
- where appropriate, to trans\(hyhorizon radio\(hyrelay systems.
- .FE
- .ce 0
- .sp 1P
- .ce 1000
- \fBSERVICE\ CHANNELS\ TO\ BE\ PROVIDED\ FOR\ THE\ OPERATION\fR
- .ce 0
- .sp 1P
- .ce 1000
- \fBAND\ MAINTENANCE\ OF\ RADIO\(hyRELAY\ SYSTEMS\fR
- .ce 0
- .sp 1P
- .ce 1000
- (Question 4/9, Geneva, 1982)
- .sp 9p
- .RT
- .ce 0
- .sp 1P
- .ad r
- (1956 | | 959 | | 963 | | 966 | | 970)
- .ad b
- .RT
- .LP
- The\ CCIR,
- .sp 1P
- .RT
- .LP
- CONSIDERING
- .PP
- \fIa)\fR
- that service channels are required for the maintenance,
- supervision and control of radio\(hyrelay systems;
- .sp 9p
- .RT
- .PP
- \fIb)\fR that if, for any reason, the radio\(hyrelay system itself fails to
- function, communication between various stations along the route, and from
- those stations to other points is likely to assume special importance;
- .PP
- \fIc)\fR that agreement is desirable on the number and function of the
- service channels to facilitate the planning of radio\(hyrelay systems;
- .PP
- \fId)\fR that service channels will be used to provide:
- .LP
- \(em
- omnibus voice circuits,
- .LP
- \(em
- express voice circuits,
- .LP
- \(em
- supervisory circuits,
- .LP
- \(em
- control and operational circuits;
- .PP
- \fIe)\fR that service channels will not be connected to the public
- telephone network,
- .LP
- UNANIMOUSLY\ RECOMMENDS
- .PP
- that, on international radio\(hyrelay systems:
- .sp 9p
- .RT
- .PP
- \fB1.\fR
- all staffed stations should be connected directly to the public
- telephone network;
- .PP
- \fB2.\fR
- when a radio\(hyrelay link is extended by means of short cable
- sections, and these cable sections and the radio\(hyrelay link taken together
- constitute a regulated line section, the terminal stations of the radio\(hyrelay
- link itself should have speaker circuits to the stations at the ends of
- the
- regulated line section;
- .LP
- .PP
- \fB3.\fR
- a telephone service channel (omnibus voice circuit) should be set up to
- connect together all the stations on the system, whether staffed or not;
- .PP
- \fB4.\fR
- a second telephone service channel (express voice circuit) should be provided
- for direct telephonic communication between the staffed stations
- receiving supervisory signals;
- .PP
- \fB5.\fR
- provisions for the transmission of supervisory and control signals should
- be subject to agreement between the Administrations concerned;
- .PP
- \fB6.\fR
- the telephone service channels should possess, whenever possible, the characteristics
- (excluding noise power) recommended by the CCITT for
- international telephone circuits and, in particular, should be able to
- transmit the frequency band 300 to 3400\ Hz;
- .PP
- \fB7.\fR all telephone service channels (including those used for
- supervisory and control circuits) up to a length of 280\ km should, whenever
- possible, not exceed a mean noise power in any hour of 20 | 00\ pW0p
- psophometrically weighted, at a point of zero relative level.
- .LP
- \fINote\fR \ \(em\ Service channels may be provided over an auxiliary radio\(hyrelay
- system, over the main radio\(hyrelay system, or by other unrelated means,
- either on a primary or stand\(hyby basis. In the case of express voice
- circuits, the use of regular multiplex channels within the telephony baseband
- is acceptable,
- where this is possible.
- .bp
- .sp 2P
- .LP
- \fBReferences\fR
- .sp 1P
- .RT
- .LP
- [1]
- CCITT, \fIInstructions for the International Telephone Service,\fR
- Articles\ 46 to\ 49, ITU, Geneva, 1985.
- .LP
- [2]
- CCIR Report \fIService channels for analogue radio\(hyrelay systems\fR ,
- Vol.\ IX, Report\ 444, ITU, Geneva, 1986.
- \v'1P'
- .sp 2P
- .LP
- \fBRecommendation\ M.110\fR
- .RT
- .sp 2P
- .sp 1P
- .ce 1000
- \fBCIRCUIT\ TESTING\fR
- .EF '% Fascicle\ IV.1\ \(em\ Rec.\ M.110''
- .OF '''Fascicle\ IV.1\ \(em\ Rec.\ M.110 %'
- .ce 0
- .sp 1P
- .LP
- \fB1\fR \fBAccess points for testing purposes\fR
- .sp 1P
- .RT
- .PP
- Access points are required to enable lining\(hyup and subsequent
- maintenance operations to be performed on international circuits. The
- required access points are as follows:
- .RT
- .PP
- 1.1
- Recommendation M.565 describes and defines the access
- points needed for international public telephone circuits, these points
- being referred to as \*Q
- circuit access points
- \*U and \*Q
- line access
- points
- \*U.
- .sp 9p
- .RT
- .PP
- Line access points and circuit access points (or appropriate means for
- reaching the circuit access points) should be provided for testing all
- circuits which are used for the provision of international telecommunication
- services.
- .PP
- Where a circuit uses channel associated signalling, it should be
- possible to identify and measure at the circuit access points, the
- signal\(hytransmission parameters, e.g.,\ type of signal, sequence, timing,
- duration, level and frequency.
- .RT
- .PP
- 1.2
- Test access points
- should also be provided for circuits
- connected through a repeater station in transit from one country to another.
- Such access points are known as \*Q
- intermediate access points
- \*U.
- .PP
- 1.3
- On a leased circuit, the circuit access points are regarded as
- being located in the renter's premises, at the demarcation point where
- connections are made to the terminal equipment used on the circuit
- .FS
- The
- access points required for digital leased circuits have yet to be specified.
- This matter is for further study by Study Group\ IV, in association with
- Study Group\ XV.
- .FE
- .
- .PP
- 1.4
- Test access points should also be available at the terminal
- international centre for circuits terminating within the country at a place
- remote from the international centre, for example, in the premises of the
- users of leased circuits or in a voice\(hyfrequency telegraph terminal
- station, etc.
- Such access points, known as line access points, should be available directly
- or indirectly to the transmission maintenance point (international line)
- as
- defined in Recommendation\ M.1014\ [1] for such circuits.
- .PP
- 1.5
- In addition to those mentioned in \(sc\(sc\ 1.1 to 1.4 above, access
- points should be provided on the audio input and output of FDM channel
- multiplex and primary PCM multiplex equipments.
- .PP
- 1.6
- Access points for testing purposes should be provided on all
- primary order digital paths. Such access points, known as
- digital path
- access points
- , should be located as near to the ends of the digital path as possible.
- .PP
- With suitable digital test equipment, such digital path access
- points enable in\(hyservice circuit monitoring to be carried out when, for
- example, digital paths are directly interfaced with digital exchanges or
- transmultiplexers.
- .PP
- When the digital path is out of service, this same point can be used to
- transmit and receive signals for both digital path and circuit testing.
- .RT
- .PP
- 1.7
- Figure 1/M.110 shows an example of the basic access points
- for international telephone circuits terminated on an analogue exchange, and
- for a variety of other telephone\(hytype circuits. Figure\ 2/M.110 shows the
- basic access points for telephone circuits terminated on a digital exchange.
- Figures\ 1/M.110 and 2/M.110 both show that remote access has been
- provided to the \*Qcircuit access points\*U of automatic telephone circuits.
- .PP
- 1.8
- Series M Recommendations relating to the various types of
- international circuits specify how the above\(hymentioned access points should
- be used for line\(hyup and maintenance purposes.
- .bp
- .LP
- .rs
- .sp 47P
- .ad r
- \fBFigure 1/M.110, p. 9\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .LP
- .rs
- .sp 35P
- .ad r
- \fBFigure 2/M.110, p. 10\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .sp 2P
- .LP
- \fB2\fR \fBMeasuring and testing equipment\fR
- .sp 1P
- .RT
- .PP
- 2.1
- The basic types of measuring equipment needed in an analogue
- environment are:
- .sp 9p
- .RT
- .LP
- \(em
- signal generators (fixed and variable frequency oscillators
- and calibrated sending units),
- .LP
- \(em
- level\(hymeasuring sets,
- .LP
- \(em
- calibration units,
- .LP
- \(em
- psophometers,
- .LP
- \(em
- standard frequency source (or access to such a source),
- .LP
- \(em
- equipment for signalling tests.
- .PP
- In addition, delay distortion measuring equipment, frequency
- counters, interruption recorders, programme meters, impulsive noise counters,
- phase jitter meters, automatic transmission measuring equipment, and equipment
- for non\(hylinear and total distortion measurement may be required.
- .bp
- .PP
- 2.2
- The basic types of test and measuring equipment needed in a
- digital environment are as mentioned in \(sc\ 2.1 above. This need can
- be met by
- equivalent digital test/measuring equipment, or by analogue equipment and
- the use of a \*Qtest coder/decoder\*U to convert digital access points
- to analogue
- access points. In some situations, testers for the following will prove
- useful:
- .sp 9p
- .RT
- .LP
- \(em
- bit error ratio;
- .LP
- \(em
- error\(hyfree or errored seconds;
- .LP
- \(em
- code violations;
- .LP
- \(em
- timing jitter;
- .LP
- \(em
- frame alignment.
- .LP
- .PP
- 2.3
- The actual requirements for a particular testing centre will
- depend upon the types of circuit existing at that centre, and the range of
- tests and measurements that are specified for those circuits in the
- relevant Series\ M Recommendations. Reference should also be made to the
- \*Qfacility\*U requirements specified for the testing points defined in
- Recommendations\ M.717, M.718 and M.719.
- .PP
- 2.4
- The implementation of the worldwide transmission and switching
- plans makes it necessary for international circuits to be lined up and\fR
- maintained to a very high degree of accuracy.
- .PP
- It is essential, therefore, to use measuring equipment of high
- accuracy and stability in order that the maintenance requirements given
- in the relevant Series M\ Recommendations for circuits are met, and to
- ensure
- uniformity of measurement results.
- .PP
- To this end it is desirable that measuring equipment provided for
- lining\(hyup and maintaining all classes of circuits should, wherever possible,
- conform to the measuring instrument specifications given in the Series\ O
- Recommendations. Where no CCITT specification is available, the best order
- of accuracy and stability should be provided, consistent with cost and
- type of
- measurement to be made.
- .RT
- .sp 2P
- .LP
- \fBReference\fR
- .sp 1P
- .RT
- .LP
- [1]
- CCITT Recommendation \fITransmission maintenance point international
- line\fR \fI(TMP\(hyIL)\fR , Vol.\ IV, Rec.\ M.1014.
- \v'1P'
- .sp 2P
- .LP
- \fBRecommendation\ M.120\fR
- .RT
- .sp 2P
- .sp 1P
- .ce 1000
- \fBACCESS\ POINTS\ FOR\ MAINTENANCE\fR
- .EF '% Fascicle\ IV.1\ \(em\ Rec.\ M.120''
- .OF '''Fascicle\ IV.1\ \(em\ Rec.\ M.120 %'
- .ce 0
- .sp 1P
- .PP
- For lining\(hyup and fault localization it is proposed to define access
- points at boundaries such as between switching and transmission. A
- division of maintenance responsibilities can be achieved with the aid of
- line access points, digital path access points and analogue link access
- points. The following concepts are compatible with the division shown in
- Recommendations\ Q.45 (Figure\ 1/Q.45)\ [1] and Q.502 (Figure\ 1/Q.502)\ [2].
- .sp 1P
- .RT
- .LP
- a)
- A line access point separates an analogue exchange from
- analogue or digital transmission [see\ a) and\ b) of
- Figure\ 1/M.120].
- .LP
- Location and interfaces of line access points are defined in
- Recommendation\ M.565.
- .LP
- b)
- A digital path access point separates a digital exchange
- from analogue or digital transmission [see\ c) and\ d) of
- Figure\ 1/M.120].
- .LP
- Digital path access points are located at the input and
- output ports of digital paths. Interfaces are defined in
- Recommendation\ G.703\ [3].
- .LP
- c)
- A line access point separates the digital exchange from the
- analogue transmission [see\ e) of Figure\ 1/M.120].
- .LP
- d)
- An analogue link access point separates a digital exchange
- from an analogue transmission if line access or digital path
- access is not provided. f
- ) of Figure\ 1/M.120 shows as an
- example the collocation of a transmultiplexer with a digital
- exchange.
- .LP
- Analogue link access points are located at the input and
- output ports of analogue links. Interfaces are defined in
- Recommendation\ G.233\ [4].
- .PP
- Normally line access points, digital path access points and
- analogue link access points are provided as equipment interface,
- e.g.\ accessible at distribution frames.
- .bp
- .LP
- .rs
- .sp 43P
- .ad r
- \fBFigure 1/M.120, p.\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .sp 2P
- .LP
- \fBReferences\fR
- .sp 1P
- .RT
- .LP
- [1]
- CCITT Recommendation \fITransmission Characteristics of an International\fR
- \fIExchange\fR , Vol.\ VI, Rec.\ Q.45.
- .LP
- [2]
- CCITT Recommendation \fIInterfaces\fR , Red Book, Vol.VI, Rec. Q.502, ITU,
- Geneva, 1985.
- .LP
- [3]
- CCITT Recommendation \fIPhysical/Electrical Characteristics of\fR
- \fIHierarchical Digital Interfaces\fR , Vol.\ III, Rec.\ G.703.
- .LP
- [4]
- CCITT Recommendation \fIRecommendations Concerning Translating Equipment\fR
- , Vol\ III, Rec.\ G.233.
- .bp
- .sp 2P
- .LP
- \fBRecommendation\ M.125\fR
- .RT
- .sp 2P
- .sp 1P
- .ce 1000
- \fBDIGITAL\ LOOPBACK\ MECHANISMS\fR
- .EF '% Fascicle\ IV.1\ \(em\ Rec.\ M.125''
- .OF '''Fascicle\ IV.1\ \(em\ Rec.\ M.125 %'
- .ce 0
- .sp 1P
- .LP
- \fB1\fR \fBGeneral\fR
- .sp 1P
- .RT
- .PP
- Loopback can be one of the mechanisms which may be applied to fault localization
- and failure detection. This Recommendation provides digital
- loopback definitions and describes loopback applications related to the
- maintenance phases of Recommendation\ M.20.
- .RT
- .sp 2P
- .LP
- \fB2\fR \fBDigital loopback definitions\fR
- .sp 1P
- .RT
- .PP
- A \fBdigital loopback\fR is a mechanism incorporated into a piece of equipment
- whereby a bidirectional communication path may be connected back upon itself
- so that some or all of the information contained in the bit stream sent
- on the transmit path is returned on the receive path.
- .PP
- The \fBloopback point\fR is the location of the loopback.
- .PP
- The \fBloopback control mechanism\fR is the means by which the loopback
- is operated and released from the loopback control point.
- .PP
- The \fBloopback control point\fR is the point which has the ability to
- directly control loopbacks.
- .PP
- The loopback control point may receive requests for loopback operation
- from several loopback requesting points.
- .PP
- The \fBloopback requesting point\fR is the point which requests the
- loopback control point to operate loopbacks.
- .PP
- \fINote\ 1\fR \ \(em\ Loopback requests should be subject to identification
- and authorization.
- .PP
- \fINote\ 2\fR \ \(em\ Possible locations of loopback requesting points
- are: the network, or a telecommunications management network (TMN), or
- a maintenance
- service provider (MSP).
- .PP
- The \fBloopback test pattern\fR is the test information transmitted
- during the operation of the loopback in the channel or channels which are
- to be redirected by the loopback.
- .PP
- \fINote\ 1\fR \ \(em\ The generation of the test pattern used over the
- loopback may or may not take place at the control point.
- .PP
- The \fBloopback application\fR is the maintenance phase for which the loopback
- operation is used, as defined in Recommendation\ M.20.
- .RT
- .sp 1P
- .LP
- 2.1
- \fILoopback types\fR
- .sp 9p
- .RT
- .PP
- The following three types of loopback mechanisms are
- defined:
- .RT
- .LP
- a)
- \fBcomplete loopback\fR \ \(em\ A complete loopback is a physical layer
- [1] mechanism which operates on the full bit stream. At the loopback
- point, the received bit stream shall be transmitted back towards the
- transmitting station without modification.
- .LP
- \fINote\fR \ \(em\ The use of the term \*Qcomplete loopback\*U is not
- related to implementation since such a loopback may be provided by means of
- active logic elements or controlled unbalance of hybrid transformer,\ etc. At
- the control point only the information channels may be available.
- .LP
- b)
- \fBpartial loopback\fR \ \(em\ A partial loopback is a physical
- layer [1] mechanism which operates on one or more specified channels
- multiplexed within the full bit stream. At the loopback point, the received
- bit stream associated with the specified channel(s) shall be transmitted
- back
- towards the transmitting station without modification.
- .LP
- c)
- \fBlogical loopback\fR \ \(em\ A logical loopback acts selectively on
- certain information within a specified channel or channels and may result
- in some specified modification of the looped information. Logical loopbacks
- may be defined to apply at any layer\ [1], depending on the detailed maintenance
- procedures specified.
- .bp
- .PP
- For each of the above three types of loopback mechanisms, the
- loopback may be further categorized as either transparent or
- non\(hytransparent:
- .LP
- i)
- A \fBtransparent loopback\fR is one in which the signal
- transmitted beyond the loopback point (the forward signal) when the loopback
- is activated, is the same as the received signal at the loopback point.
- See
- Figure\ 1 | )/M.125.
- .LP
- ii)
- A \fBnon\(hytransparent loopback\fR is one in which the signal transmitted
- beyond the loopback point (the forward signal) when the loopback is activated
- is not the same as the received signal at the loopback point. The
- forward signal may be defined signal or unspecified. See
- Figure\ 1 | )/M.125.
- .PP
- \fINote\fR \ \(em\ Whether or not a transparent loopback is used, the
- loopback should not be affected by facilities connected beyond the point at
- which the loop is provided, e.g.,\ by the presence of short circuits, open
- circuits or foreign voltages.
- .PP
- Annex A to this Recommendation shows some examples of loopbacks.
- .RT
- .LP
- .rs
- .sp 40P
- .ad r
- \fBFigure 1/M.125, p.\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .sp 2P
- .LP
- \fB3\fR \fBLoopback applications\fR
- .sp 1P
- .RT
- .sp 1P
- .LP
- 3.1
- \fIFailure detection\fR
- .sp 9p
- .RT
- .PP
- In order to detect failures related to networks maintained by
- different maintenance organizations, loopbacks should be applied at the
- borderline separating the maintenance responsibilities. Loopbacks should be
- located in the maintenance entities (ME) adjacent to the borderline and as
- close as possible to the borderline. Part of the bit stream can be involved
- in failure detection. Figure\ 2/M.125 shows an example with failure detection
- originated in locations\ A and\ B.
- .RT
- .LP
- .rs
- .sp 9P
- .ad r
- \fBFigure 2/M.125, p.\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .sp 1P
- .LP
- 3.2
- \fIFault localization\fR
- .sp 9p
- .RT
- .PP
- The localization of faults in networks consisting of \fIn\fR
- maintenance entities requires at least \fIn\fR \ +\ 1 loopback mechanisms. The
- loopback point should be as close as possible to the in\(hy and output ports of
- the ME in order to include as much as possible of the ME in the loopback
- mechanism. (See example in Figure\ 3/M.125.) Part of the bit stream or the
- complete bit stream can be involved in fault localization, originated in
- locations\ A or\ B.
- .RT
- .LP
- .rs
- .sp 11P
- .ad r
- \fBFigure 3/M.125, p.\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .sp 1P
- .LP
- 3.3
- \fIVerification\fR
- .sp 9p
- .RT
- .PP
- Verification can require performance tests and measurements of the complete
- bit stream.
- .PP
- The same loopback location can be used as for fault localization.
- .RT
- .sp 2P
- .LP
- \fB4\fR \fBLoopback operation and release\fR
- .sp 1P
- .RT
- .PP
- Loopbacks can be operated/released locally or remotely. Remote
- operation/release can be based on in\(hyservice addressing (e.g.,\ layer\ 1
- protocols) or it can require separate loopbacks addressing systems.
- .RT
- .sp 2P
- .LP
- \fB5\fR \fBLoopback examples\fR (under study \(em see Annex A)
- .bp
- .sp 1P
- .RT
- .ce 1000
- ANNEX\ A
- .ce 0
- .ce 1000
- (to Recommendation M.125)
- .sp 9p
- .RT
- .ce 0
- .LP
- .rs
- .sp 48P
- .ad r
- \fBFigure A\(hy1/M.125, p.\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .sp 2P
- .LP
- \fBReference\fR
- .sp 1P
- .RT
- .LP
- [1]
- CCITT Recommendation \fIReference model of open system\fR \fIinterconnection
- for CCITT applications\fR , Vol.\ VIII,
- Recommendation\ X.200.
- \v'1P'
- .sp 2P
- .LP
- \fBRecommendation\ M.130\fR
- .RT
- .sp 2P
- .ce 1000
- \fBOPERATIONAL\ PROCEDURES\ IN\ LOCATING\ AND\ CLEARING\fR
- .EF '% Fascicle\ IV.1\ \(em\ Rec.\ M.130''
- .OF '''Fascicle\ IV.1\ \(em\ Rec.\ M.130 %'
- .ce 0
- .sp 1P
- .ce 1000
- \fBTRANSMISSION\ FAULTS\fR
- .ce 0
- .sp 1P
- .PP
- \fB1\fR
- The reporting of faults on automatic circuits is dealt
- with in Recommendations\ M.715 and\ M.716; for leased and special circuits in
- Recommendations\ M.1012\ [1], M.1013\ [2] and M.1014\ [3] and for Signalling
- System\ No.\ 6 in Recommendation\ M.762. These principles should likewise be
- applied to the reporting of faults on groups, supergroups, etc.,\ to the
- \fIfault report point\fR in a repeater station.
- .sp 1P
- .RT
- .sp 2P
- .LP
- \fB2\fR \fBBasic principles for locating a fault on a circuit\fR
- .sp 1P
- .RT
- .PP
- 2.1
- The following principles apply to all types of circuit, however constituted:
- .sp 9p
- .RT
- .LP
- i)
- The
- fault report
- is received by the relevant fault
- report point and passed on to the circuit control station.
- .LP
- ii)
- The circuit control station should immediately arrange for
- the circuit to be withdrawn from service.
- .LP
- iii)
- Appropriate overall measurements and tests should be made
- to verify the existence of the fault.
- .LP
- iv)
- Measurements should be made on the sections of the circuit
- between the \fIend\fR of the circuit (circuit access point,
- voice\(hyfrequency telegraph terminal or renter's termination,
- etc.) and the international line access point at the terminal
- international centre to find whether the fault is on these
- sections in either of the terminal countries concerned.
- .LP
- v)
- If the fault is proved in these sections, national practices
- should be applied to locate and clear the fault.
- .LP
- vi)
- If the fault is proved to be on the international line,
- maintenance personnel at the terminal international centres
- involved should make tests and measurements appropriate to the
- type of fault in cooperation with any intermediate sub\(hycontrol
- station until the fault has been located between two adjacent
- sub\(hycontrol stations, that is, to a circuit section. These two
- stations should then control the detailed location of the fault
- and its subsequent clearance within their section.
- .LP
- \fINote\fR \ \(em\ Some types of circuit may be routed via a circuit
- multiplication system (CMS). The terminal Administrations must
- bilaterally agree on a detailed fault localization procedure for
- circuits routed via the particular circuit multiplication system
- in use between them. Annex\ A to this Recommendation contains an
- outline of a fault location procedure upon which detailed
- arrangements could be based.
- .LP
- vii)
- As soon as possible, the use of any permitted rerouting
- possibilities that there may be for the line or sections thereof
- should be made, in order to restore service on the circuit.
- .LP
- viii)
- If the circuit section is routed on the channel of an
- FDM group or a primary digital block, the group \fIor\fR digital
- block control should be informed of the fault in order to take
- the necessary action.
- .LP
- ix)
- When the fault has been cleared the sub\(hycontrol station in
- whose country the fault was located should immediately notify
- the control station either directly or via the appropriate
- maintenance unit of the nature of the fault and the time and
- details of its clearance.
- .LP
- x)
- The controlling end should cooperate with the noncontrolling
- end and should make overall measurements, requesting further
- adjustments if necessary.
- .LP
- xi)
- When the circuit meets the specified requirements, the
- control station arranges to restore the circuit to
- service.
- .bp
- .PP
- 2.2
- Figure\ 1/M.130 shows a sequence of operations that may be
- followed applying the principles given in\ \(sc\ 2.1 above.
- .sp 9p
- .RT
- .PP
- 2.3
- A typical sequence of operations covering transmission faults on transfer
- links of Signalling System\ No.\ 6 is shown in Figure\ 2/M.760.
- .sp 9p
- .RT
- .PP
- 2.4
- When a fault in a circuit section is proved to be due to an
- analogue group or a digital block fault, the basic fault procedures for the
- group or block are the same as those given for faults on an international
- line (see \(sc\ 2.1, vi and vii above).
- .sp 9p
- .RT
- .PP
- The sequence of operations followed by the group control station and the
- group sub\(hycontrol station in locating faults on a group is shown in
- Figure\ 2/M.130. Associated operations by other control and sub\(hycontrol
- functions are shown in Figures\ 3/M.130 and\ 4/M.130.
- .PP
- 2.5
- The operations mentioned above can sometimes be modified
- according
- to special circumstances. For example, if there is a cable fault in a terminal
- country and if this fault affects a large number of circuits, it will not
- generally be necessary to carry out all the operations given in \(sc\ 2.1
- above and Figure\ 1/M.130 in the order shown. (See also Supplement\ No.\
- 3.6\ [4])
- .sp 9p
- .RT
- .sp 2P
- .LP
- \fB3\fR \fBFaults observed at repeater stations as a result of local or
- extended alarms\fR
- .sp 1P
- .RT
- .PP
- All fault conditions affecting transmission that are observed at
- repeater stations as a result of local or extended alarms should be reported
- to the relevant fault report points of the country concerned, so that
- arrangements can be made to apply the fault clearing procedure.
- .RT
- .sp 2P
- .LP
- \fB4\fR \fBSpecial faults\fR
- .sp 1P
- .RT
- .PP
- In the case of unusual faults, or faults which are difficult to
- locate with the testing equipment that is available, or faults of a similar
- kind occurring very frequently on a particular section, the appropriate
- control station should inform its technical service without delay. This
- service, in
- cooperation with other technical services involved, will take the necessary
- action to locate such faults or, where appropriate, prevent such faults
- in the future by rearrangement of the circuit layout or equipment involved.
- The
- circuit control station should be kept informed of the progress of the
- action taken or proposed, the prospects of clearance and other pertinent
- details.
- .RT
- .sp 2P
- .LP
- \fB5\fR \fBEscalation procedure\fR
- .sp 1P
- .RT
- .PP
- Normally cooperation between maintenance elements in different
- Administrations will result in the satisfactory identification and correction
- of faults. There may be circumstances, however, where the fault escalation
- procedure defined in Recommendation\ M.711 may be required.
- .RT
- .LP
- .rs
- .sp 13P
- .ad r
- Blanc
- .ad b
- .RT
- .LP
- .bp
- .LP
- .rs
- .sp 47P
- .ad r
- \fBFigure\ 1/M.130 p. 16\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .LP
- .rs
- .sp 47P
- .ad r
- \fBFigure\ 2/M.130 p. 17\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .LP
- .rs
- .sp 47P
- .ad r
- \fBFigure\ 3/M.130 p. 18\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .LP
- .rs
- .sp 47P
- .ad r
- \fBFigure\ 4/M.130 p. 19\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .LP
- .bp
- .ce 1000
- ANNEX\ A
- .ce 0
- .ce 1000
- (to Recommendation M.130)
- .sp 9p
- .RT
- .ce 0
- .ce 1000
- \fBOutline procedure for
- \fBlocating faults on circuits routed\fR
- .sp 1P
- .RT
- .ce 0
- .ce 1000
- \fBvia a circuit multiplication system\fR
- .ce 0
- .PP
- \fIIntroductory Notes\fR \ \(em\ In this Annex, the term, \*Qcircuit
- multiplication system (CMS)\*U is used for convenience. It is intended
- to cover all systems which increase the number of circuits available from
- a transmission link by taking advantage of the fact that only one direction
- of transmission is used at any one time in a telephone conversation (one
- talker; one listener),
- and that normal speech patterns involve pauses, hesitations and silent
- intervals. Examples of such systems are TASI\(hyE and CELTIC.
- .sp 1P
- .RT
- .PP
- Reduced bit rate coding systems, e.g.\ transcoders, are not
- presently included in the description of CMSs found in this Recommendation.
- .sp 1P
- .LP
- A.1
- \fIGeneral\fR
- .sp 9p
- .RT
- .PP
- A circuit multiplication system consists of a transmit and receive equipment
- for each direction of transmission, interconnected by a number of
- \*Qchannels\*U (sometimes known as connect\(hy or connection\(hychannels).
- .PP
- Inputs and outputs of the CMS take the form of \*Qtrunks\*U, the
- number of which typically exceeds the number of channels by a factor of two.
- That is, a typical CMS provides an advantage of two trunks (and
- therefore, two circuits) per CMS channel.
- .PP
- Figure\ A\(hy1/M.130 depicts a generalized CMS, in this case interfaced
- at basic circuit level. Other circuit multiplication systems are interfaced
- by
- primary order digital paths (operated at\ 1544 or 2048\ kbit/s) on both
- trunk and channel sides of the CMS terminal equipment. Other interface
- arrangements are also possible.
- .PP
- When the CMS is taken out of service, due to a fault or on a planned basis,
- CMS trunks are switched through to CMS channels on a predetermined
- basis, one trunk per channel. The circuits routed on such trunks are called
- \*QCMS\(hyand\(hythrough\*U circuits
- . The circuits routed on the additional
- trunks derived by the CMS are called
- \*QCMS\(hyonly\*U circuits
- .
- .RT
- .sp 2P
- .LP
- A.2
- \fIFault localization procedure for circuits routed via CMS\fR
- .sp 1P
- .RT
- .sp 1P
- .LP
- A.2.1
- \fIImpact of CMS operation\fR
- .sp 9p
- .RT
- .PP
- At the time a fault is detected on a circuit routed via a CMS, a
- particular CMS trunk\(hyto\(hyCMS channel association existed. The fault
- localization procedures must recognize that the probability of reproducing
- this
- trunk\(hychannel association under testing conditions is very remote, particularly
- in modern circuit multiplication systems. In older systems (for example,
- those interfaced at basic circuit level), there is the possibility of reproducing
- the original trunk\(hychannel association, especially if both fault detection
- and
- testing occur during light traffic periods. This possibility should not be
- overlooked in the fault localization procedures for circuits routed via such
- systems.
- .RT
- .PP
- An important feature of many modern circuit multiplication systems is that
- they include self\(hydiagnostic procedures which continuously switch
- trunk/channel connections even when the traffic load does not necessitate
- interpolation. Such self diagnostic procedures include the monitoring of the
- .PP
- transmission performance of CMS channels
- .FS
- In some systems, minor loss
- variations are also automatically compensated for.
- .FE
- . When pre\(hyset
- thresholds (for example, of loss and noise) are exceeded, the CMS
- establishes a permanent trunk/channel connection (a so\(hycalled \fR
- \*Qtrunk/channel lock
- \*U), and alerts maintenance staff in a suitable
- manner.
- .PP
- To take account of these operating characteristics, the localization of
- faults on circuits assigned to a CMS follows a technique that is
- different from that used for normal (non\(hyCMS) circuits. Furthermore,
- the test procedures to be used differ slightly depending on whether the
- circuit under
- test is a CMS\(hyand\(hythrough circuit or a CMS\(hyonly circuit.
- .bp
- .RT
- .LP
- .rs
- .sp 27P
- .ad r
- \fBFigure\ A\(hy1/M.130, p. 8\fR
- .sp 1P
- .RT
- .ad b
- .RT
- .sp 1P
- .LP
- A.2.2
- \fICMS\(hyand\(hythrough circuits\fR
- .sp 9p
- .RT
- .PP
- If it is known that the CMS was out of service at the time
- the circuit fault was identified, and remains out of service during fault
- localization, the procedures employed for normal (non\(hyCMS) circuits can be
- used.
- .PP
- Tests made when the CMS is in service are carried out without
- regard to the CMS channel used. The existence of a fault is first verified
- .PP
- (or otherwise) by an initial test. If no fault is detected on the initial
- test, it is safe to assume that the fault may have been due to the CMS
- equipment or the interconnecting channel at the time the fault was observed.
- The circuit
- should be returned to service. A record of the fault should be given to the
- maintenance unit responsible for the CMS for their information and use
- when CMS and CMS channel tests are carried out. The fault report point
- (circuit) should keep a record of the fault and the action taken for future
- reference purposes.
- .PP
- If the fault is confirmed by the initial test and repeat tests, fault localization
- procedures depend upon the particular CMS involved. In
- modern systems a check should be made for the existence of a trunk/channel
- lock. If such a lock exists, normal fault localization procedures used
- for non\(hyCMS circuits may be used. On older systems, or if no trunk/channel
- lock exists on a modern system, it can be assumed the fault is external
- to the CMS and its interconnecting channels. Further tests should be made
- to
- identify the exact location of the fault, which should then be referred
- to the appropriate maintenance unit for attention.
- .PP
- When localizing faults on circuits routed via older CMSs,
- especially during periods of light traffic, there is a chance that the CMS
- channel is faulty if identical fault conditions are observed on initial and
- repeat tests \(em the CMS may not have switched channels. In this event,
- further localization tests must include the CMS channel associated with the
- circuit under test and the CMS terminal equipment.
- .bp
- .RT
- .sp 1P
- .LP
- A.2.3
- \fICMS\(hyonly circuits\fR
- .sp 9p
- .RT
- .PP
- Again, tests are made on the circuit without regard to the CMS
- channel being used.
- .PP
- The procedures for dealing with verified and unverified faults
- specified in \(sc\ A.2.2 above can be used for CMS\(hyonly circuits. However,
- trunk/channel locks are not generally possible on CMS\(hyonly circuits,
- and thus verified faults can be assumed to be external to the CMS and its
- interconnecting channels. Similar precautions to those in \(sc\ A.2.2 should be
- taken when localizing faults on circuits routed via older CMSs.
- .PP
- When CMSs are out of service, this type of circuit is removed
- from service and is not therefore available for testing purposes. Fault
- localization tests must await the return to service of the CMS.
- .RT
- .sp 1P
- .LP
- A.3
- \fICMS signalling channel faults\fR
- .sp 9p
- .RT
- .PP
- Faults and service problems observed on circuits routed via a CMS may be
- due to problems on the CMS signalling channel causing, for example,
- incorrect trunk\(hychannel switching. Many CMSs monitor the performance of the
- signalling channel(s) continuously. The information made available by such
- monitoring should be used by maintenance staff to help eliminate signalling
- channel problems as a source of circuit faults.
- .RT
- .sp 2P
- .LP
- \fBReferences\fR
- .sp 1P
- .RT
- .LP
- [1]
- CCITT Recommendation \fICircuit control station for leased and special\fR
- \fIcircuits\fR , Vol.\ IV, Rec.\ M.1012.
- .LP
- [2]
- CCITT Recommendation \fISub\(hycontrol station for leased and special\fR
- \fIcircuits\fR , Vol.\ IV, Rec.\ 1013.
- .LP
- [3]
- CCITT Recommendation \fITransmission maintenance point international\fR
- \fIline (TMP\(hyIL)\fR , Vol.\ IV, Rec.\ M.1014.
- .LP
- [4]
- CCITT Supplement No. 3.6 to Volume IV \fICrosstalk test device for\fR
- \fIcarrier\(hytransmission systems on coaxial systems\fR .
- .LP
- .rs
- .sp 24P
- .sp 2P
- .LP
- \fBMONTAGE: RECOMMANDATION M.140 SUR LE RESTE DE CETTE PAGE\fR
- .sp 1P
- .RT
- .LP
- .bp
-