SIST ETS 300 133-7 E1:2003
(Main)Paging Systems (PS); Enhanced Radio MEssage System (ERMES); Part 7: Operations and maintenance aspects
Paging Systems (PS); Enhanced Radio MEssage System (ERMES); Part 7: Operations and maintenance aspects
Network Management Functions Functional Specification Interfaces for O and M (Protocols and Messages)
Sistemi osebnega klica (PS) ¬– Evropski sistem za radijsko sporočanje (ERMES) – 7. del: Vidiki obratovanja in vzdrževanja
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2003
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Paging Systems (PS); Enhanced Radio MEssage System (ERMES); Part 7: Operations
and maintenance aspects
Ta slovenski standard je istoveten z: ETS 300 133-7 Edition 1
ICS:
33.070.20 Sistem za osebni klic Paging systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN ETS 300 133-7
TELECOMMUNICATION July 1992
STANDARD
Source: ETSI TC-PS Reference: DE/PS-2001-7
ICS: 33.080
ERMES, network management, operations and maintenance
Key words:
Paging systems (PS);
European Radio Message System (ERMES)
Part 7 : Operation and maintenance aspects
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - secretariat@etsi.fr
X.400: Internet:
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1992. All rights reserved.
New presentation - see History box
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ETS 300 133-7: July 1992
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.
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ETS 300 133-7: July 1992
Contents
Foreword.7
1 Scope .9
2 Normative references .9
3 Definitions. 10
4 Abbreviations.11
5 ERMES telecommunication management network architecture.12
6 Network management functions.13
6.1 General.13
6.2 Operations .13
6.2.1 Subscriber data management.13
6.2.2 System configuration management .14
6.2.3 Status control.14
6.2.4 Traffic records for charging and accounting .15
6.3 Maintenance.15
6.3.1 Alarm management .15
6.3.1.1 Alarm generation .15
6.3.1.2 Alarm processing and logging.16
6.3.2 Corrective maintenance .16
6.3.2.1 Failed unit isolation .16
6.3.2.2 Fault localisation.17
6.3.2.3 Repair and replacement phases.17
6.3.2.4 Test functions. 17
6.3.2.5 Restoration to service . 17
6.3.3 Preventive maintenance .17
6.4 Performance and QOS management.17
6.4.1 Traffic data.18
6.4.1.1 Average rate of input requests. 18
6.4.1.2 Average rate of call not accepted or conditionally
accepted ACK.18
6.4.1.3 Average rate of input messages .19
6.4.1.4 Average rate of outgoing page messages.19
6.4.1.5 Average message length.19
6.4.1.6 Number of requests for subscriber feature and
supplementary services.19
6.4.1.7 Roaming data. 20
6.4.2 QOS and network performance parameters.20
6.4.2.1 Average call accepted acknowledgement delay .20
6.4.2.2 Average page accepted acknowledgement delay.21
6.4.2.3 Average waiting time for transmission in PNC .21
6.4.2.4 Average waiting time for transmission in PAC .21
6.4.2.5 Average message delivery time .21
6.4.2.6 PNC throughput .22
6.4.3 Traffic management actions .22
6.4.3.1 Flow control .22
6.4.3.2 Active channels re-arrangement.23
6.4.3.3 Modification of control parameters in PAC .23
7 Interfaces. 23
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ETS 300 133-7: July 1992
7.1 General .23
7.2 Functional interfaces (internal to the network operation) .23
7.2.1 OMC to PNC-OS functional interface .24
7.2.1.1 OMC to PNC-OS messages.24
7.2.1.2 PNC-OS to OMC messages.25
7.2.2 OMC to PAC-OS interface.25
7.2.2.1 OMC to PAC-OS messages.25
7.2.2.2 PAC-OS to OMC messages.25
7.2.3 OMC to BS interface .26
7.2.3.1 OMC to BS messages .26
7.2.3.2 OMC to MD messages .26
7.2.3.3 MD to OMC messages .26
7.2.3.4 MD to BS messages.26
7.3 IOMC (OMC to OMC) interface .26
7.3.1 OMC operations.27
7.3.2 Use of ACSE.27
7.3.3 Use of ROSE.28
7.3.4 OMC addressing.29
8 Operations and Maintenance Centre (OMC).29
8.1 Functions.30
8.1.1 Operations.30
8.1.2 Maintenance .31
8.1.3 Performance and QOS management .32
8.1.4 Calculation of call acceptance.32
8.1.4.1 Availability evaluation for GAs.32
8.1.4.2 Delay evaluation for geographical areas .33
8.2 OMC database .33
9.2 Interworking with the telecommunication network.36
9.2.1 Data from PNC to PNC-OS .36
9.2.2 Actions and data from PNC-OS to PNC.37
9.3 PNC-OS database .37
10 PAC-OS and mediation device functions.38
10.1 PAC-OS .38
10.1.1 Functions.38
10.1.1.1 Operations .38
10.1.1.2 Maintenance.39
10.1.1.3 Performance and QOS management.39
10.1.2 Interworking with the telecommunication network .39
10.1.2.1 Data from PAC to PAC-OS .40
10.1.2.2 Actions and data from PAC-OS to PAC.40
10.1.3 PAC-OS database.40
10.2 Mediation device .41
11 The operations and maintenance part of the base station .41
11.1 Functions.41
11.1.1 Operations.41
11.1.2 Maintenance .42
11.2 BS database.42
Annex A (normative): Formal description of the IOMC .43
A.1 IOMC ROSE operations .43
A.2 IOMC ROSE ASN-1 transcription .52
Annex B (informative): General aspects of telecommunication management.66
B.1 Network management concepts.66
B.1.1 Operations.66
B.1.2 Maintenance .66
B.1.3 Performance and QOS management .68
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ETS 300 133-7: July 1992
B.2 Network management functions.70
B.2.1 General . 70
B.2.2 Functional distribution .70
Annex C (informative): Conformance with the I3 and I2 interfaces .72
C.1 I3 Interface.72
C.2 I2 interface .74
History.76
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ETS 300 133-7: July 1992
Foreword
This European Telecommunication Standard (ETS) has been produced by the Paging Systems (PS)
Technical Committee of the European Telecommunications Standards Institute (ETSI).
This ETS comprises seven parts with the generic title "Paging systems; European Radio Message System
(ERMES)". The title of each part is listed below:
- ETS 300 133-1: "Part 1 - General aspects"
- ETS 300 133-2: "Part 2 - Service aspects"
- ETS 300 133-3: "Part 3 - Network aspects"
- ETS 300 133-4: "Part 4 - Air interface specification"
- ETS 300 133-5: "Part 5 - Receiver conformance specification"
- ETS 300 133-6: "Part 6 - Base station specification"
- ETS 300 133-7: "Part 7 - Operation and maintenance aspects"
This part, ETS 300 133-7, specifies the network management of the European Radio Message System
(ERMES) system, specifically the Operations and Maintenance (O&M) aspects, including performance and
Quality of Service (QOS) management.
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ETS 300 133-7: July 1992
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ETS 300 133-7: July 1992
1 Scope
This part of the seven part European Telecommunication Standard (ETS) 300 133 describes the
operations and maintenance aspects of the European Radio Message System (ERMES). It defines and
describes the architecture of the telecommunication management network and also the network
management functions. Telecommunication management network entities and the functional interfaces
between these entities and the network elements are defined and described.
2 Normative references
This ETS incorporates by dated or undated reference, provisions from other publications. These normative
references are cited at the appropriate places in the text and the publications are listed hereafter. For
dated references, subsequent amendments to, or revisions of any of these publications apply to this ETS
only when incorporated in it by amendment or revision. For undated references the latest edition of the
publication referred to applies.
[1] ETS 300 133-3 (1992): "Paging systems; European Radio Message System
(ERMES) Part 3: Network aspects".
[2] ETS 300 133-2 (1992): "Paging systems; European Radio Message System
(ERMES) Part 2: Service aspects".
[3] CCITT Recommendation M.60 "Maintenance terminology and definitions".
[4] CCITT Recommendation G.106: "Terms and definitions related to quality of
service availability and reliability".
[5] CCITT Recommendation M.21: "Principles for a maintenance philosophy and
considerations for maintenance strategy for telecommunication services".
[6] CCITT Recommendation M.20: "Maintenance philosophy for telecommunication
networks".
[7] CCITT Recommendation M.30 (1990): "Principles for a telecommunication
management network".
[8] CCITT Recommendation M.36: "Principles for the maintenance of ISDNs".
[9] CCITT Recommendation Q.795: "Operations, Maintenance and Administration
Part (OMAP)".
[10] CCITT Recommendation X.219: "Remote operations: model, notation and
service definitions".
[11] CCITT Recommendation X.217: "Association control service definition for open
systems interconnection".
[12] CCITT Recommendation X.213: "Network service definition for open systems
interconnection".
[13] CCITT Recommendation X.208: "Specification of abstract syntax notation one
(ASN.1)".
[14] CCITT Recommendation X.209: "Specification of basic encoding rules for
abstract syntax notation one (ASN.1)".
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ETS 300 133-7: July 1992
3 Definitions
For the purposes of this part of ETS 300 133, the following definitions shall apply.
Basic OSF: the operations system function which controls a network element.
Data communication function: the means for telecommunication management data exchange between
function blocks.
ERMES Telecommunication Management Network (TMN): the operations and maintenance part of the
overall ERMES paging network.
Interface OMC - BS: the functional interface between the operations and maintenance centre and a base
station.
Interface OMC - PAC-OS: the functional interface between the operations and maintenance centre and the
operations system of a paging area controller.
Interface OMC - PNC-OS: the functional interface between the operations and maintenance centre and the
operations system of a paging network controller.
IOMC (OMC - OMC): the interface between different network operators' OMCs.
Maintenance: the technical, administrative and supervisory actions intended to keep an item in, or restore it
to, a state in which it can perform its defined function.
Maintenance entity (ME): an equipment of the telecommunication network which is defined between two or
more interfaces as an object of the network management strategy. The main MEs are the PNC, the PAC
and the BS.
Mediation device: a stand alone device which performs mediation functions.
Mediation functions: functions which act on information passing between network element functions and
operator system functions. Major mediation functions include communication control, protocol conversion
and data handling, communication of primitive functions, processes involving decision making and data
storage.
Network element: an element of the operator network.
Network operations system: performs the network basis telecommunication management network
application functions by communicating with the basic operations system functions.
Operations: the combination of technical and administrative actions that enables an item to perform a given
function.
Operations and maintenance centre: the control and data collection entity associated with a
telecommunication management network.
Operations system: the stand alone system which performs operations system functions.
Operations systems functions: functions performed by the operations system. The OSFs process
information related to telecommunication management to support and/or control the realisation of various
telecommunication management functions.
Paging area controller - operations system: the basic operations system dealing with the paging area
controller.
Paging network controller - operations system: the basic operations system dealing with the paging
network controller.
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ETS 300 133-7: July 1992
PNC throughput: the number of elementary operations performed by a PNC in a time unit. The term
"elementary operation" indicates the processing of an AdC or an information request message or a
complete message. The throughput offers an idea of load distribution within the network. It can be used for
singling out network bottle-necks, hence giving information for management and design purposes.
Quality Of Service (QOS): a combination of traffic performance, availability, service integrity, service
support and service operability.
Telecommunication management network: the operations and maintenance part of an operator network. It
provides management functions to the telecommunication network and offers communications between
itself and the telecommunication network.
Work station function: the function providing communications between function blocks and the user.
4 Abbreviations
ACK/NACK Positive/Negative acknowledgement
ACSE Association Control Service Element
AdC Address Code
ASN Abstract Syntax Notation
BS Base Station
DCF Data Communication Functions
DCN Data Communication Network
EOM End of Message
FSI Frequency Subset Indicator
FSN Frequency Subset Number
GA Geographical Area
HW Hardware
I2 Interface PAC-BS
I3 Interface PNC-PAC
IOMC Interface OMC-OMC
LCN Local Communication Network
MD Mediation Device
ME Maintenance Entity
MEF Maintenance Entity Function
MHS Message Handling System
MF Mediation Function
MMI Man Machine Interface
NE Network Element
NEF Network Element Function
NM Network Management
NMF Network Management Function
OMC Operations and Maintenance Centre
O&M Operations and Maintenance
OS Operations System
OSF Operations System Functions
OSI Open System Interconnect
PA Paging Area
PAC Paging Area Controller
PAC-OS Paging Area Controller - Operations System
PDU Protocol Data Unit
PNC Paging Network Controller
PNC-H Paging Network Controller - Home
PNC-I Paging Network Controller - Input
PNC-OS Paging Network Controller - Operations System
PNC-T Paging Network Controller - Transmit
PSPDN Packet Switched Public Data Network
PSTN Public Switched Telephone Network
QAF Q-Adapter Function
QOS Quality of Service
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ETS 300 133-7: July 1992
ROSE Remote Operations Service Element
RF Radio Frequency
RP Reference Point
SDU Service Data Unit
SEF Support Entity Function
SW Software
TLC Telecommunication
TMN Telecommunication Management Network
TO Tone Only
TX Transmitter
WSF Work-Station Function
5 ERMES telecommunication management network architecture
The ERMES system functional architecture is shown in figure 1. The telecommunication (TLC) and
Telecommunication Management Network (TMN) environments are clearly separated.
The network management actions and functions required to support this network can be grouped in three
categories:
- operations;
- maintenance;
- performance and Quality of Service (QOS) management.
A further category covering network administration is the responsibility of individual network operators and
does not come within the scope of this specification.
Within each operator network the following network elements are the object of operations and
maintenance actions:
- the Paging Network Controller (PNC);
- the Paging Area Controller (PAC);
- the Base Station (BS);
- the interconnection links.
Three classes of Operations System Functions (OSFs) can be identified in the network. The basic OSFs
are associated with a particular network element. The network OSFs are responsible for management
actions involving the entire network. The service OSFs are responsible for transactions between operator
networks and interaction with service providers.
The entities which deal with the TMN part of the operator network are Operations and Maintenance Centre
(OMC), PNC-OS, PAC-OS and Mediation Device (MD). In particular:
- the OMC deals with the network Operation System (OS) and service OS functions. The OMC
controls all the Operations and Maintenance (O&M) functions in the operator network and
exchanges data with other OMCs;
- the PNC-OS and PAC-OS deal with the basic OSFs related to the associated telecommunication
entity;
- the MD handles the mediation functions for the connected BSs. It implements concentration,
distribution and protocol conversion.
OSs and MDs can be functionally separated from the related network elements and they may be
implemented together.
Each OS can have its own database where information about the entity status is stored. If lower level
entities exist, some O&M information about them should also be stored in the database. This database
may also contain information required by the telecommunication network.
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ETS 300 133-7: July 1992
Every network element should contain maintenance entity functions and support entity functions involved in
the transfer of maintenance information, the failure handling process and basic traffic measurements.
General aspects and the philosophy of operations, maintenance and performance management are
described in Annex B along with Network Management Functions (NMFs) contained in the network
elements and the OSFs.
|
| TMN2
|
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‡ OMC ˆ˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜¿ | ‡ OMC ‡
‡ ˆ˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜¿ ‡ | ‡ ‡
‡ ˆ˜˜˜˜˜˜˜˜˜˜¿ ‡ ‡ | ‡ ‡
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‡ ‡ ‡ ‡ |
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‡ ‡ ‡ ‡ ‡ +--------------------
‡ ‡ ‡ ‡ ‡
‡PNC-OS ‡ ‡ ‡ ‡
‡ ‡ ‡ ‡ ‡
‡ ‡ ‡ ‡ ‡
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‡ �˜˜˜˜`˜˜¿ �˜˜˜˜`˜˜¿ ‡
‡ ‡ ‡ ‡ ‡ ‡
‡ ‡ ‡ ‡ ‡ �˜˜`˜˜¿
‡ ‡PAC-OS ‡ ‡PAC-OS ‡ ‡ MD ˆ˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜¿
‡ ‡ ‡ ‡ ‡ ‡ ˆ˜˜˜˜˜˜˜˜˜˜˜˜˜¿ ‡
‡ ‡ ‡ ‡ ‡ �˜˜˜˜˜� ‡ ‡
‡ �˜˜˜´˜˜˜� �˜˜˜´˜˜˜� ‡ ‡
TMN1 ‡ ‡ ‡ ‡ ‡
-----------------‡-------------‡------------‡----------------------------‡---------‡---------------
TLC1 ‡ ‡ ‡ ‡ ‡
‡ �˜˜˜`˜˜˜¿ ‡ ‡ ‡
‡ ‡ ‡ ‡ ‡ ‡
‡ ‡ ‡ ‡ ‡ ‡
‡ ‡ PAC ‡ ‡ ‡ ‡
�˜˜˜`˜˜˜¿ ‡ ‡ ‡ ‡ ‡
‡ ˆ˜˜˜˜˜· ‡ ‡ ‡ ‡
‡ ‡ �˜˜˜˜˜˜˜� ‡ ‡ ‡
‡ PNC ‡ ‡ ‡ ‡
‡ ‡ �˜˜˜`˜˜˜¿ ‡ ‡
‡ ˆ˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜· ‡ �˜˜`˜˜¿ ‡
�˜˜˜˜˜˜˜� ‡ ‡ ‡ BS ‡ ‡
‡ PAC ˆ˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜· ‡ ‡
‡ ‡ �˜˜˜˜˜� �˜˜`˜˜¿
‡ ˆ˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜˜· BS ‡
�˜˜˜˜˜˜˜� ‡ ‡
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Figure 1: ERMES system functional architecture
6 Network management functions
6.1 General
The network management functions identified in Clause 5 are defined in this clause and other information
which aids understanding of their characteristics and objectives, are described.
6.2 Operations
The term operations is intended to include configuration management as well as some of the more
classical concepts such as status handling and recording functions.
6.2.1 Subscriber data management
Subscriber data management, as an administrative function, is mainly a network operator matter.
The subscription status database for both mobile and fixed subscribers is associated with the PNC as
described in ETS 300 133-3 [1], subclauses 13.2.1 to 13.2.5.
The OMC can add or delete subscribers to the PNC database and modify the subscription status
according to operator needs or user requests.
The operator may collect administrative and traffic demand data not directly related to the
telecommunication process.
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ETS 300 133-7: July 1992
6.2.2 System configuration management
This operations function performs modifications, updating and integration of the hardware/software
resources. System configuration changes can impact either on the devices (or parts of them) which are the
object of the modification, or act at network level, if the change also implies a data re-arrangement in
contiguous network elements.
Three functions can be identified:
- control of the network elements;
- upgrades of the network elements;
- network or network element reconfiguration.
For both upgrades and reconfigurations, the following operations sequence should be followed:
- the network element is isolated from service;
- the new software is loaded or a new part of the element is installed;
- the network elements directly interworking with the modified element, are informed of the
modification;
- system testing is performed in order to ensure correct working mode of the modified element;
- the network element is restored to service and the appropriate network elements informed.
In particular cases some of the above actions can be avoided or the order changed.
Upgrades and reconfigurations refer to both hardware and software entities and, in general, they are
performed through:
- local actions (status updating, software loading, hardware installation);
- OMC (centralised) actions, such as software downloading, status and configuration updating, testing
of the upgraded facilities.
The OMC shall keep a record of the current version of the network configuration, specifying the installed
elements and the interconnection resources. All upgrades and network element reconfigurations shall be
registered by the OMC (even if they are performed locally). Hence the OMC is continuously updated about
the software and hardware versions installed in the network. For back up purposes, a copy of the running
programs should be available.
The system configuration management requires some capabilities to be implemented in the TMN. This
impacts on the specification of the OMC and Network Elements (NEs), namely:
- request/report of the configuration status (OMC --> NE / NE --> OMC);
- modification command and notification (OMC <--> NE) assignment or cancellation of internal entities;
- request/report of the internal assignments (OMC <--> NE);
- setting of service parameters and thresholds (OMC --> NE);
- time co-ordination and network synchronisation control (OMC <--> NE).
6.2.3 Status control
This operations function is strictly tied to the maintenance environment. As a result of maintenance action,
any change of the network element functionality is registered as a service state change.
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ETS 300 133-7: July 1992
The same procedure applies if an item is removed from service for diagnostic tests.
Accordingly every hardware/software entity can be characterised by its:
- operations state (in service, out of service, busy for maintenance);
- working state (working, busy, unloaded);
- access state (the entity can/cannot be reached for use in the network).
Control of the device state should act both locally and through the OMC by means of the following
functions:
- status request (OMC --> NE);
- status report (NE --> OMC);
- scheduling of the status report (OMC --> NE);
- allow/inhibit automatic restoration, if present (OMC --> NE);
- set the operations state of a network element, i.e. in service, out of service, busy for maintenance
(OMC --> NE).
6.2.4 Traffic records for charging and accounting
The information required for charging can be retrieved from the OMC database. Basic accounting data,
e.g. that related to international traffic can be exchanged between operators. It is up to the operators to
choose the communication means and the information to be exchanged.
6.3 Maintenance
Maintenance aspects of the ERMES network are considered in three categories, namely alarm
management, corrective maintenance and preventive maintenance.
Alarm management includes all system characteristics involved in the process of detecting, displaying and
communicating the occurrence of a failure and storing the relevant information.
Corrective maintenance refers to the set of actions which should be taken by the network operator as soon
as information about a failure occurrence is available.
Preventive maintenance deals with all functions required to check the system functionality in the absence of
a specific fault indication, with the objective of decreasing the overall system failure rate. Routine tests are
an example of such functions.
6.3.1 Alarm management
The PNC, PAC and BS should each contain autonomous supervision functions which are managed in
parallel with the normal telecommunication functions.
Generally they are too dependent on hardware and software design to be standardised.
6.3.1.1 Alarm generation
The alarms can be classified as:
- urgent alarms;
- deferred alarms;
- anomaly indications.
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ETS 300 133-7: July 1992
The allocation of an appropriate alarm depends on the controlled hardware and software configuration as
well as on the operator policy.
The PNC, PAC and BS can contain the following capabilities:
- autonomous alarm generation according to the previous categories;
- alarm report to the OMC. The report rules are influenced by the alarm importance;
urgent alarms should be immediately sent to the OMC while deferred alarms or anomalies may be
detected, stored, grouped and then sent to the OMC according to a less severe report requirement;
- generation of a response message to an Alarm Status Information Request, explicitly produced by
the OMC;
- modification of internal alarm criteria, such as thresholds and alarm state definition. This feature is
activated by an explicit request from either the OMC or a local human intervention. In the latter case,
the OMC should be notified of the new alarm configuration;
- modification of alarm report rules, e.g. the report frequency for deferred alarms or anomaly
indications.
The complementary alarm management capabilities of the OMC are described in Clause 8.
All alarm messages and alarm reports shall contain:
- originating maintenance entity;
- alarm identification;
- detection time;
- additional information for fault localisation (if available).
6.3.1.2 Alarm processing and logging
The OMC should contain alarm correlation capabilities in order to isolate the induced malfunctionings from
the original faults. Such filtering and synthesis functions are normally performed through human intervention
and the use of correlation and analysis programs located in the OMC.
The alarms autonomously generated by the maintenance entity as well as those explicitly requested by the
OMC shall be registered and possibly stored in the OMC for deferred utilisation. Storage rules should
allow efficient subsequent retrieval by the operator according to a classification based on the alarm
message attributes.
6.3.2 Corrective maintenance
When an urgent or deferred alarm is generated, a corrective maintenance action should follow with an
intervention policy which depends on the alarm gravity and on the possible consequences on the service
quality. Corrective maintenance is a serial process generally carried out in the following order.
6.3.2.1 Failed unit isolation
After failure detection the faulty unit(s) shall be isolated (if appropriate) to prevent the system from failure
propagation or simply to allow for switching to redundancy, when provided by the system design. The
impact on the system behaviour of this action concerns operations, since the configuration associated with
the faulty maintenance entity should be first of all recorded in the OMC, so that the network functionality
state is always available at a centralised point.
Other actions can follow if the system is capable of reacting with some kind of dynamic management. One
example is redundancy intervention which can be automatic or commanded manually, either locally or from
the OMC.
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6.3.2.2 Fault localisation
Efficient repair action depends on the availability of procedures for localising the fault to a small set of
repairable units (e.g. boards or functions) where the failure has occurred. Fault localisation programs are
heavily dependent on system design and on the hardware and software design of the maintenance entity.
In general such programs can either be located in the individual equipment or centralised in the OMC. In
any case, the operator should be given the possibility of:
- activating/deactivating the procedure;
- defining a diagnostics plan, together with the report of the results obtained by running the
localisation programs.
6.3.2.3 Repair and replacement phases
Definition and the consequent duration of these phases depends on the operator organisation and the
maintenance policy (repair crews and logistic structure, spare parts allocation and provisioning). Basic
system design also affects the repair time since modularity, provisioning of diagnostic tools, etc. can help
human intervention and limit the degradation period. Even if the repair and replacement phases heavily
impact on system availability they are not a standardisation object.
6.3.2.4 Test functions
When the repair has been completed specific tests aimed at verifying functional correctness of the
maintained element should be carried out. One of the possible outcomes is that the spare unit itself is
faulty. The activation of test procedures should be possible on site or remotely from the OMC. The first
alternative is most common in the case of direct human intervention while the second seems applicable
when switching to a redundant unit has been commanded from the OMC.
The following test functions should be provided within network elements following either a local or a remote
command:
- test activation;
- test reporting;
- definition or modification of the test parameters.
6.3.2.5 Restoration to service
After successful completion of the repair phase, the repaired unit should be restored to service (or to a
redundancy role). Any change of network configuration should be logged. If some dynamic management
actions have been decided after fault isolation, the changed parameters should be restored to the initial
value.
6.3.3 Preventive maintenance
Every maintenance entity should be equipped with appropriate procedures capable of performing routine
tests on all repairable units so that (at least) a subset of deviations from the operational behaviour can be
detected before a real malfunction occurs. The procedures for performing routine tests are logically
connected to the system design, even if it is an operator concern to define the most appropriate policy for
running such tests (frequency, etc.). Test paging messages can be sent to check the correct operation of
the network.
6.4 Performance and QOS management
In this subclause traffic data collection, QOS and network performance parameters, and traffic
management actions are addressed. These follow the performance management concepts described in
Annex B.
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The measurements needed for estimating the traffic and performance parameters are classified by:
a) the measurement planning; in this sense a measurement can be:
- permanent, when performed continuously by the operator;
- periodic, when performed according to a regular time plan;
- on request;
b) the measurement rules; in this sense there can be:
- sampled measurements, defined with a specified sampling rate;
- continuous measurements, normally used to measure time intervals spent in given system
states;
- discrete measurements, performed by incrementing a counter when a given event occurs.
6.4.1 Traffic data
Traffic data can be collected to provide the operator with some tools for network planning and for verifying
the correct working environment of the devices. Normally specific statistical tools are needed to process
the collected data.
Each traffic parameter is characterised by its definition, the applied measurement plan, and the adopted
measurement rules. In general, traffic parameters are associated with the network entities, the access
network or the type of service.
6.4.1.1 Average rate of input requests
This traffic data is based on a permanent - discrete measurement, consisting of incrementing a counter
whenever an "AdC for message transmission" is received.
The average is taken by dividing the counter content by the relevant collection time (typically ranging from
15 minutes to 1 hour).
It is categorised:
- per access network (Public Switched Telephone Network (PSTN), Telex, Message Handling System
(MHS), etc.) and in this case it applies to the Input PNC (PNC-I);
- per originating operator network (from another PNC). In this case it applies to Home PNC (PNC-H).
6.4.1.2 Average rate of call not accepted or conditionally accepted ACK
This traffic data is based on a permanent - discrete measurement. A counter is incremented whenever a
"call not accepted ACK" is sent towards the calling party.
Averaging time ranges from 15 minutes to 1 hour.
It is categorised:
- per access network. In this case it applies to PNC-I;
- per originating operator network (from another PNC). In this case it applies to PNC-H;
- according to the reason of refusal, i.e.:
* mobile user subscription state (after the check with PNC-H);
* time-out expired before response from PNC-H;
* wrong or interrupted user-network dialogue;
* network status for call acceptance (availability and delay) and in this case it applies to PNC-I.
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6.4.1.3 Average rate of input messages
Permanent - discrete measurement. The counter is incremented whenever an End of Message (EOM)
pattern is received, closing a message input by the calling party.
Averaging time ranges from 15 minutes to 1 hour.
It is categorised:
- per access network, in PNC-I;
- per originating operator network. In this case it applies to Transmit PNC (PNC-T);
- per kind of service (numeric, alphanumeric or transparent data);
- according to the correctness of the message (in order to distinguish between valid and invalid
messages).
6.4.1.4 Average rate of outgoing page messages
Permanent - discrete measurement. A co
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