ETSI EG 202 009-3 V1.3.1 (2015-07)

User Group; Quality of ICT services; Part 3: Template for Service Level Agreements (SLA)

REG/USER-00044-3

General Information

• Status: Published
• Publication Date: 05-Jul-2015
• Technical Committee: USER - User Group
• Current Stage: 12 - Completion
• Due Date: 07-Jul-2015
• Completion Date: 06-Jul-2015

Standards Content (Sample)

ETSI EG 202 009-3 V1.3.1 (2015-07)






ETSI GUIDE
User Group;
Quality of ICT services;
Part 3: Template for Service Level Agreements (SLA)

---------------------- Page: 1 ----------------------
2 ETSI EG 202 009-3 V1.3.1 (2015-07)



Reference
REG/USER-00044-3
Keywords
ICT, QoS, quality, service, SLA, user
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: [phone]  Fax: [phone]

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the only prevailing document is the
print of the Portable Document Format (PDF) version kept on a specific network drive within ETSI Secretariat.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
http://portal.etsi.org/tb/status/status.asp
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying
and microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© European Telecommunications Standards Institute 2015.
All rights reserved.

TM TM TM
DECT , PLUGTESTS , UMTS and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members.
TM
3GPP and LTE™ are Trade Marks of ETSI registered for the benefit of its Members and
of the 3GPP Organizational Partners.
GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association.
ETSI

---------------------- Page: 2 ----------------------
3 ETSI EG 202 009-3 V1.3.1 (2015-07)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 9
4 SLA Principles . 9
5 SLA Contract . 10
5.0 SLA contract principles . 10
5.1 SLA Generic Model . 11
5.2 Actors and roles . 12
5.3 High level constraints . 12
6 User part: Demand. 13
6.0 User part composition . 13
6.1 The demand: SLO (Service Level Objective) . 13
6.2 Geographical features, coverage . 14
6.3 Use conditions . 14
7 Provider part: Offer . 14
7.0 Offer content . 14
7.1 Description of the services: Technical features . 14
8 Conditions of contract . 15
8.0 Main aspects of the contract customization . 15
8.1 Duration of the contract (agreement) . 15
8.2 Guarantees . 15
8.3 SLA management actions . 15
8.4 SLA Violations . 16
8.5 Penalties . 17
8.5.0 Penalties policies . 17
8.5.1 Penalties on delivery delay . 17
8.5.2 Penalties on Guaranteed Time To Repair (GTTR) . 17
8.5.3 Penalties on Guaranteed Service Availability Ratio (GSAR) . 17
8.5.4 Other penalties . 18
8.5.5 Payment of penalties . 18
8.6 SLA Cost: Type of SLA contract . 18
8.7 Cessation . 18
9 Building a Service Level Agreement (SLA) . 18
9.0 The four stages of building a SLA. 18
9.1 Start Up . 19
9.2 Negotiation . 19
9.2.0 Negotiation main principle . 19
9.2.1 Offer definition: Service composition . 19
9.2.2 QoS Monitoring . 19
9.2.3 Confirm issues . 20
9.2.4 Determine costs and payment . 20
9.3 Implementation . 20
9.4 Review . 20
ETSI

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4 ETSI EG 202 009-3 V1.3.1 (2015-07)
10 Revision procedures of SLA contract. 20
11 Conclusion . 21
Annex A (informative): Bibliography . 22
History . 23

ETSI

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5 ETSI EG 202 009-3 V1.3.1 (2015-07)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This ETSI Guide (EG) has been produced by ETSI User Group (USER).
This is a revision of the earlier edition which included, among other contributions, parts of the University of
Wollongong (AU) SLA template and guidelines have been incorporated, in particular in annex A. The current revision
takes into account the changes to parts 1 and 2.
The present document is part 3 of a multi-part deliverable covering the quality of telecom services, as identified below:
Part 1: "Methodology for identification of indicators relevant to the Users";
Part 2: "User related indicators on a service specific basis";
Part 3: "Template for Service Level Agreements (SLA)".
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
Quality of Service can be evaluated from different perspectives and therefore using different measurement methods:
a) The first is related to the reliability of the equipment and can be measured accurately via technical means,
although these measures might be expensive because of both the dispersion of the test results and the size of
the sample to be tested.
b) The second is related to the service provision and is closely linked to the use of the service. Therefore
appropriate metric have to be defined according to this use.
c) The last is intended to measure the subjective satisfaction of the customer and there is often no other means
than a survey to get it.
In the two first categories, technical means can be used to perform the measurements and in such cases, standards are
often useful to achieve a common approach; therefore standards are given as references where appropriate. They
include a precise definition of what is meant as a failure: total failure, poor performance, etc.
Assessing these different aspects is of paramount importance to the provider who endeavours to improve the offered
QoS. From a user viewpoint, the end-to-end QoS is the most relevant. Hence objective and subjective measurements
may be usefully combined for a better assessment of the QoS.
ETSI

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6 ETSI EG 202 009-3 V1.3.1 (2015-07)
Measurements of every interesting metric all the time might be very expensive and could jeopardize service
performances. It is often cheaper and sufficient to get them via a poll. In addition, it may be convenient to rely on a
third party to carry out these measurements to avoid any criticism from one of the involved parties.
In the current state of the service provisioning it is worth noting that:
a) QoS is not a quantity that can be measured using some deterministic meter. The evaluation of QoS can only be
performed statistically. Statistical rules apply and to obtain a precision of 1 %, the size of the sample analysed
should be as large as 1 000 units and the sample should be taken out of a population 100 or 1 000 times larger.
This implies practically that the QoS assessment needs a very large number of measurements.
b) If an operator commits himself to a 99 % or 99,9 % QoS level, this means that less than 1 item out of 100 or
1 000 is out of the specified range. Adding the traditional sampling ratios and precision of measurement ratios
6 7
leads to populations as large as 10 or 10 units.
c) An SLA that concerns units, dozens or hundreds of anything (leased lines, Frame relay circuits, etc.) with
99 % committed QoS is meaningful if and only if these units are taken out of a very big population.
d) It is hopeless to expect that screening the "very best" units out of a poor quality population would allow
guarantying high QoS level for the selected items. A poor quality product might certainly contain some high
quality "nuggets" but the indicators enabling their sorting out are hazardous.
e) The only means to obtain high level QoS products from an operator is to make sure that:
- the purchased service is widely provided and the provider is mastering all manufacturing, installation and
support processes;
- the average QoS score of his production is close to the commitment he is intending to negotiate with you;
- a quality assurance plan exists, has been labelled, is annually monitored and is auditable in accordance
with ISO 9000 standard family.
QoS and Reliability in the ICT area, concerns more and more aspects supplementary to the product or service as
described in clause 6 in addition to the performance indicators.
The existence of a Quality assurance plan labelled, monitored and auditable is key to the QoS. Moreover, in some
aspects like security or charging/billing there are no other means to ensure that the QoS expected is actually provided.
In this context, the achievement of a satisfying SLA requires an in depth analysis of the user needs for which guidance
is given in ETSI EG 202 009-1 [i.1] and ETSI EG 202 009-2 [i.2].
ETSI

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7 ETSI EG 202 009-3 V1.3.1 (2015-07)
1 Scope
In the current competitive world, Quality of Service (QoS) is becoming, jointly with cost, a key parameter in selling and
buying telecommunications services. At the same time, technology and liberalization trends are raising new types of
concerns unknown with the Plain Old Telephony Services (POTS) using switched connections provided by a single
monopoly supplier. As explained in other parts of ETSI EG 202 009 [i.1] and [i.2], the monitoring of a QoS
commitment should refer to contractual values set either by governmental rules or in a mutual agreement between the
provider and its customer. This is why achieving a SLA is more often perceived as the best means to meet specific QoS
requirements while ensuring the optimal cost/quality ratio to the customer and the provider in a win-win perspective.
Nowadays, there are several standards describing QoS measurements but the questions of which indicators are to be
monitored and which values they should meet are still open. This part of the document defines a framework for a
Service Level Agreement between a customer and a supplier of ICT (Information and Communication Technology)
Services. Such framework uses the service specific QoS metrics proposed in ETSI EG 202 009-2 [i.2] to evaluate the
Quality of Service, while ETSI EG 202 009-1 [i.1] gives a methodology to identify the indicators relevant to the users.
The present document was written to make available to the providers and users of any kind of ICT services a common
basis for mutual understanding about SLA. It aims to establish adequacy between the user's requirements in terms of
Service Level Objectives (SLO) and the providers' offer with the associated QoS.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EG 202 009-1: "User Group; Quality of telecom services; Part 1: Methodology for
identification of indicators relevant to the Users".
[i.2] ETSI EG 202 009-2: "User Group; Quality of telecom services; Part 2: User related indicators on a
service specific basis".
[i.3] Directive 2002/21/EC of the European Parliament and of the Council of 7 March 2002 on a
common regulatory framework for electronic communications networks and services (Framework
Directive) - (article 17).
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8 ETSI EG 202 009-3 V1.3.1 (2015-07)
[i.4] Regulation (EC) No 717/2007 of the European Parliament and of the Council of 27 June 2007 on
roaming on public mobile telephone networks within the Community and amending Directive
2002/21/EC.
[i.5] Regulation (EC) No 544/2009 of the European Parliament and of the Council of 18 June 2009
amending Regulation (EC) No 717/2007 on roaming on public mobile telephone networks within
the Community and Directive 2002/21/EC on a common regulatory framework for electronic
communications networks and services.
[i.6] Directive 2009/140/EC of the European Parliament and of the Council of 25 November 2009
amending Directives 2002/21/EC on a common regulatory framework for electronic
communications networks and services, 2002/19/EC on access to, and interconnection of,
electronic communications networks and associated facilities, and 2002/20/EC on the authorisation
of electronic communications networks and services.
[i.7] Corrigendum to Directive 2009/140/EC of the European Parliament and of the Council of 25
November 2009 amending Directives 2002/21/EC on a common regulatory framework for
electronic communications networks and services, 2002/19/EC on access to, and interconnection
of, electronic communications networks and associated facilities, and 2002/20/EC on the
authorisation of electronic communications networks and services.
[i.8] Directive 2002/22/EC of the European Parliament and of the Council of 7 March 2002 on
universal service and users' rights relating to electronic communications networks and services
(Universal Service Directive) - (article 11, 22 and annex III).
[i.9] Directive 2009/136/EC of the European Parliament and of the Council of 25 November 2009
amending Directive 2002/22/EC on universal service and users" rights relating to electronic
communications networks and services, Directive 2002/58/EC concerning the processing of
personal data and the protection of privacy in the electronic communications sector and Regulation
(EC) No 2006/2004 on cooperation between national authorities responsible for the enforcement
of consumer protection laws (Text with EEA relevance).
[i.10] Corrigendum to Directive 2009/136/EC of the European Parliament and of the Council of 25
November 2009 amending Directive 2002/22/EC on universal service and users" rights relating to
electronic communications networks and services, Directive 2002/58/EC concerning the
processing of personal data and the protection of privacy in the electronic communications sector
and Regulation (EC) No 2006/2004 on cooperation between national authorities responsible for
the enforcement of consumer protection laws.
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in ETSI EG 202 009-1 [i.1] and the following
apply:
access session: all the processes to establish the terms and conditions of the user access (e.g. authentication, selection of
service profile) during the connection of a user to a system
NOTE: See figure 3.
connectivity session: all the processes providing technology-independent interfaces to establish and maintain the access
to service composition through different networks
NOTE: See figure 3.
network session: all the processes and events allowing the user to connect to start a service session
NOTE: The network session is composed of the access session and connectivity session. The processes are on
different planes, and this is why this composition is called vertical (see figure 3).
service session: all the processes and events in the time interval between initialization and termination of an application
implementing a service composition
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9 ETSI EG 202 009-3 V1.3.1 (2015-07)
NOTE: These services are of the same nature and located on the service plane, this is why this composition is
called horizontal (see figure 3).
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AU Australia
E2E End-to-End
EC European Council
FCAPS Fault, Configuration, Accounting, Performance, Security
GSAR Guaranteed Service Availability Ratio
GTTD Guaranteed Time To Delivery
GTTR Guaranteed Time To Repair
ICT Information & Communication Technology
ID IDentifier
ITU-T International Telecommunication Union - Telecommunication sector
MOS Mean Opinion Score
MTBF Mean Time Between Failures
MTTR Mean Time To Repair
OR Opinion Rating
PaaS Platform as a Service
POTS Plain Old Telephony Service
QoS Quality of Service
SLA Service Level Agreement
SLO Service Level Objective
SME Small and Medium Enterprise
4 SLA Principles
A Service Level Agreement (SLA) is an agreement formally negotiated between client and service provider.
The SLA serves as a means of formally documenting the service(s), performance expectations, responsibilities and
limits between service providers and their users. It deals with managing service quality through the customer experience
life cycle. This means managing service quality beyond the in-use phase of the life cycle in order to include sales,
provisioning, in-use phase and service termination aspects.
Another key aspect of SLAs is the need to incorporate an element of flexibility of contract, in order to accommodate
environmental change that is common within organizations. One way of building flexibility is to separate the areas of
agreement that are unlikely to change, from the details that can be altered according to negotiation.
A review process should be put in place and each party to the agreement should discuss and monitor the agreement
throughout its life and state who will be responsible for reviewing performance.
It is important to define how the agreement will be monitored and the mechanisms that will be used to resolve issues
that may arise during the course of the agreement. If the service levels and standards have been defined clearly, and
indicators to measure performance have been established, then, the monitoring will be relatively easy. The agreement
should build a process for feedback between both parties, via reporting or another agreed communication method
between the representatives of both parties.
A service level is an agreed process which may include one or more of the following elements to describe the service
behaviour:
• Service features and service composition.
• Quantitative aspects.
• Quality aspects.
• Conditions of use.
• Cost/tariff.
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10 ETSI EG 202 009-3 V1.3.1 (2015-07)
When both parties have established agreed service levels, the next step is to agree on methods of measurement of
service level performance. It is essential to implement a system that will provide credible results; otherwise all parties
within the process may lose confidence.
The SLA should be described in two parts:
• The users request their requirements, corresponding to the Demand.
• The offer by provider with the guarantees provided (services offers associated QoS, penalties) corresponding
to the offer.
In the first part, in ETSI EG 202 009-1 [i.1], the expression of the request as SLO has been described.
In the second part, in ETSI EG 202 009-2 [i.2], in accordance with the method, indicators which reflect the expected
behaviour of the service have been identified. But indicators imply measures whose conditions need to be precisely
defined between the provider and his customer.
Therefore it is important that in the SLA the following points are made:
• Who will evaluate it?
• What are the acceptable measuring procedures (test specification i.e. ITU-T recommendation, or ETSI
standard and the frequency of measurement, sample size, confidence limits, etc.)?
• In the event of a dispute or disagreement, what are the resolution procedures?
• What are the penalty clauses?
• Who will be the arbitrating body in the event of a disagreement?
• The final stage consists in selecting, among the QoS parameters, the most relevant ones, the level of which
will be monitored with respect to the agreed commitments as described in the SLA.
Here should be taken into account the relevant aspects of the current regulation, e.g. the European Directives (Directive
2002/21/EC [i.3] as amended by [i.4], [i.5], [i.6] and [i.7], Directive 2002/22/EC [i.8]) as amended by [i.9] and [i.10] as
well as the corresponding national regulation.
5 SLA Contract
5.0 SLA contract principles
A Service Level Agreement (SLA) is a contract that defines an agreement between two parties: user a
...

Final draft ETSI EG 202 009-3 V1.3.0 (2015-04)






ETSI GUIDE
User Group;
Quality of ICT services;
Part 3: Template for Service Level Agreements (SLA)

---------------------- Page: 1 ----------------------
2 Final draft ETSI EG 202 009-3 V1.3.0 (2015-04)



Reference
REG/USER-00044-3
Keywords
ICT, QoS, quality, service, SLA, user
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: [phone]  Fax: [phone]

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the only prevailing document is the
print of the Portable Document Format (PDF) version kept on a specific network drive within ETSI Secretariat.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
http://portal.etsi.org/tb/status/status.asp
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying
and microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© European Telecommunications Standards Institute 2015.
All rights reserved.

TM TM TM
DECT , PLUGTESTS , UMTS and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members.
TM TM
3GPP and LTE are Trade Marks of ETSI registered for the benefit of its Members and
of the 3GPP Organizational Partners.
GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association.
ETSI

---------------------- Page: 2 ----------------------
3 Final draft ETSI EG 202 009-3 V1.3.0 (2015-04)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 8
4 SLA Principles . 8
5 SLA Contract . 10
5.0 SLA contract principles . 10
5.1 SLA Generic Model . 10
5.2 Actors and roles . 11
5.3 High level constraints . 12
6 User part: Demand. 12
6.0 User part composition . 12
6.1 The demand: SLO (Service Level Objective) . 12
6.2 Geographical features, coverage . 13
6.3 Use conditions . 14
7 Provider part: Offer . 14
7.0 Offer content . 14
7.1 Description of the services: Technical features . 14
8 Conditions of contract . 15
8.0 Main aspects of the contract customization . 15
8.1 Duration of the contract (agreement) . 15
8.2 Guarantees . 15
8.3 SLA management actions . 15
8.4 SLA Violations . 16
8.5 Penalties . 17
8.5.0 Penalties policies . 17
8.5.1 Penalties on delivery delay . 17
8.5.2 Penalties on Guaranteed Time To Repair (GTTR) . 17
8.5.3 Penalties on Guaranteed Service Availability Ratio (GSAR) . 17
8.5.4 Other penalties . 18
8.5.5 Payment of penalties . 18
8.6 SLA Cost : Type of SLA contract . 18
8.7 Cessation . 18
9 Building a Service Level Agreement (SLA) . 18
9.0 The four stages of building a SLA. 18
9.1 Start Up . 19
9.2 Negotiation . 19
9.2.0 Negotiation main principle . 19
9.2.1 Offer definition: Service composition . 19
9.2.2 QoS Monitoring . 19
9.2.3 Confirm issues . 20
9.2.4 Determine costs and payment . 20
9.3 Implementation . 20
9.4 Review . 20
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4 Final draft ETSI EG 202 009-3 V1.3.0 (2015-04)
10 Revision procedures of SLA contract. 20
11 Conclusion . 21
Annex A (informative): Bibliography . 22
History . 23

ETSI

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5 Final draft ETSI EG 202 009-3 V1.3.0 (2015-04)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This final draft ETSI Guide (EG) has been produced by ETSI User Group (USER), and is now submitted for the ETSI
standards Membership Approval Procedure.
This is a revision of the earlier edition which included, among other contributions, parts of the University of
Wollongong (AU) SLA template and guidelines have been incorporated, in particular in annex A. The current revision
takes into account the changes to parts 1 and 2.
The present document is part 3 of a multi-part deliverable covering the quality of telecom services, as identified below:
Part 1: "Methodology for identification of indicators relevant to the Users";
Part 2: "User related indicators on a service specific basis";
Part 3: "Template for Service Level Agreements (SLA)".
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
Quality of Service can be evaluated from different perspectives and therefore using different measurement methods:
a) The first is related to the reliability of the equipment and can be measured accurately via technical means,
although these measures might be expensive because of both the dispersion of the test results and the size of
the sample to be tested.
b) The second is related to the service provision and is closely linked to the use of the service. Therefore
appropriate metric have to be defined according to this use.
c) The last is intended to measure the subjective satisfaction of the customer and there is often no other means
than a survey to get it.
In the two first categories, technical means can be used to perform the measurements and in such cases, standards are
often useful to achieve a common approach; therefore standards are given as references where appropriate. They
include a precise definition of what is meant as a failure: total failure, poor performance, etc.
Assessing these different aspects is of paramount importance to the provider who endeavours to improve the offered
QoS. From a user viewpoint, the end-to-end QoS is the most relevant. Hence objective and subjective measurements
may be usefully combined for a better assessment of the QoS.
ETSI

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6 Final draft ETSI EG 202 009-3 V1.3.0 (2015-04)
Measurements of every interesting metric all the time might be very expensive and could jeopardize service
performances. It is often cheaper and sufficient to get them via a poll. In addition, it may be convenient to rely on a
third party to carry out these measurements to avoid any criticism from one of the involved parties.
In the current state of the service provisioning it is worth noting that:
a) QoS is not a quantity that can be measured using some deterministic meter. The evaluation of QoS can only be
performed statistically. Statistical rules apply and to obtain a precision of 1 %, the size of the sample analysed
should be as large as 1 000 units and the sample should be taken out of a population 100 or 1 000 times larger.
This implies practically that the QoS assessment needs a very large number of measurements.
b) If an operator commits himself to a 99 % or 99,9 % QoS level, this means that less than 1 item out of 100 or
1 000 is out of the specified range. Adding the traditional sampling ratios and precision of measurement ratios
6 7
leads to populations as large as 10 or 10 units.
c) An SLA that concerns units, dozens or hundreds of anything (leased lines, Frame relay circuits, etc.) with
99 % committed QoS is meaningful if and only if these units are taken out of a very big population.
d) It is hopeless to expect that screening the "very best" units out of a poor quality population would allow
guarantying high QoS level for the selected items. A poor quality product might certainly contain some high
quality "nuggets" but the indicators enabling their sorting out are hazardous.
e) The only means to obtain high level QoS products from an operator is to make sure that:
- the purchased service is widely provided and the provider is mastering all manufacturing, installation and
support processes;
- the average QoS score of his production is close to the commitment he is intending to negotiate with you;
- a quality insurance plan exists, has been labelled, is annually monitored and is auditable in accordance
with ISO 9000 standard family.
QoS and Reliability in the ICT area, concerns more and more aspects supplementary to the product or service as
described in clause 6 in addition to the performance indicators.
The existence of a Quality assurance plan labelled, monitored and auditable is key to the QoS. Moreover, in some
aspects like security or charging/billing there are no other means to ensure that the QoS expected is actually provided.
In this context, the achievement of a satisfying SLA requires an in depth analysis of the user needs for which guidance
is given in ETSI EG 202 009-1 [i.1] and ETSI EG 202 009-2 [i.2].
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1 Scope
In the current competitive world, Quality of Service (QoS) is becoming, jointly with cost, a key parameter in selling and
buying telecommunications services. At the same time, technology and liberalization trends are raising new types of
concerns unknown with the Plain Old Telephony Services (POTS) using switched connections provided by a single
monopoly supplier. As explained in other parts of ETSI EG 202 009 [i.1] and [i.2], the monitoring of a QoS
commitment should refer to contractual values set either by governmental rules or in a mutual agreement between the
provider and its customer. This is why achieving a SLA is more often perceived as the best means to meet specific QoS
requirements while ensuring the optimal cost/quality ratio to the customer and the provider in a win-win perspective.
Nowadays, there are several standards describing QoS measurements but the questions of which indicators are to be
monitored and which values they should meet are still open. This part of the document defines a framework for a
Service Level Agreement between a customer and a supplier of ICT (Information and Communication Technology)
Services. Such framework uses the service specific QoS metrics proposed in ETSI EG 202 009-2 [i.2] to evaluate the
Quality of Service, while ETSI EG 202 009-1 [i.1] gives a methodology to identify the indicators relevant to the users.
The present document was written to make available to the providers and users of any kind of ICT services a common
basis for mutual understanding about SLA. It aims to establish adequacy between the user's requirements in terms of
Service Level Objectives (SLO) and the providers' offer with the associated QoS.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EG 202 009-1: "User Group; Quality of telecom services; Part 1: Methodology for
identification of indicators relevant to the Users".
[i.2] ETSI EG 202 009-2: "User Group; Quality of telecom services; Part 2: User related indicators on a
service specific basis".
[i.3] Directive 2002/21/EC of the European Parliament and of the Council of 7 March 2002 on a
common regulatory framework for electronic communications networks and services (Framework
Directive) - (article 17).
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8 Final draft ETSI EG 202 009-3 V1.3.0 (2015-04)
[i.4] Directive 2002/22/EC of the European Parliament and of the Council of 7 March 2002 on
universal service and users' rights relating to electronic communications networks and services
(Universal Service Directive) - (article 11, 22 and annex III).
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in ETSI EG 202 009-1 [i.1] and the following
apply:
access session: all the processes to establish the terms and conditions of the user access (e.g. authentication, selection of
service profile) during the connection of a user to a system
NOTE: See figure 3.
connectivity session: all the processes providing technology-independent interfaces to establish and maintain the access
to service composition through different networks
NOTE: See figure 3.
network session: all the processes and events allowing the user to connect to start a service session
NOTE: The network session is composed of the access session and connectivity session. The processes are on
different planes, and this is why this composition is called vertical (see figure 3).
service session: all the processes and events in the time interval between initialization and termination of an application
implementing a service composition
NOTE: These services are of the same nature and located on the service plane, this is why this composition is
called horizontal (see figure 3).
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AU Australia
E2E End-to-End
EC European Council
FCAPS Fault, Configuration, Accounting, Performance, Security
GSAR Guaranteed Service Availability Ratio
GTTD Guaranteed Time To Delivery
GTTR Guaranteed Time To Repair
ICT Information & Communication Technology
ID IDentifier
ITU-T International Telecommunication Union - Telecommunication sector
MOS Mean Opinion Score
MTBF Mean Time Between Failures
MTTR Mean Time To Repair
OR Opinion Rating
PaaS Platform as a Service
POTS Plain Old Telephony Service
QoS Quality of Service
SLA Service Level Agreement
SLO Service Level Objective
SME Small and Medium Enterprise
4 SLA Principles
A Service Level Agreement (SLA) is an agreement formally negotiated between client and service provider.
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The SLA serves as a means of formally documenting the service(s), performance expectations, responsibilities and
limits between service providers and their users. It deals with managing service quality through the customer experience
life cycle. This means managing service quality beyond the in-use phase of the life cycle in order to include sales,
provisioning, in-use phase and service termination aspects.
Another key aspect of SLAs is the need to incorporate an element of flexibility of contract, in order to accommodate
environmental change that is common within organizations. One way of building flexibility is to separate the areas of
agreement that are unlikely to change, from the details that can be altered according to negotiation.
A review process should be put in place and each party to the agreement should discuss and monitor the agreement
throughout its life and state who will be responsible for reviewing performance.
It is important to define how the agreement will be monitored and the mechanisms that will be used to resolve issues
that may arise during the course of the agreement. If the service levels and standards have been defined clearly, and
indicators to measure performance have been established, then, the monitoring will be relatively easy. The agreement
should build a process for feedback between both parties, via reporting or another agreed communication method
between the representatives of both parties.
A service level is an agreed process which may include one or more of the following elements to describe the service
behaviour:
• Service features and service composition.
• Quantitative aspects.
• Quality aspects.
• Conditions of use.
• Cost/tariff.
When both parties have established agreed service levels, the next step is to agree on methods of measurement of
service level performance. It is essential to implement a system that will provide credible results; otherwise all parties
within the process may lose confidence.
The SLA should be described in two parts:
• The users request their requirements, corresponding to the Demand.
• The offer by provider with the guarantees provided (services offers associated QoS, penalties) corresponding
to the offer.
In the first part, in ETSI EG 202 009-1 [i.1], the expression of the request as SLO has been described.
In the second part, in ETSI EG 202 009-2 [i.2], in accordance with the method, indicators which reflect the expected
behaviour of the service have been identified. But who says indicator, says measure and who will measure …
Therefore it is important that in the SLA the following points are made:
• Who will evaluate it?
• What are the acceptable measuring procedures (test specification i.e. ITU-T recommendation, or ETSI
standard and the frequency of measurement, sample size, confidence limits, etc.)?
• In the event of a dispute or disagreement, what are the resolution procedures?
• What are the penalty clauses?
• Who will be the arbitrating body in the event of a disagreement?
• The final stage consists in selecting, among the QoS parameters, the most relevant ones, the level of which
will be monitored with respect to the agreed commitments as described in the SLA.
Here should be taken into account the relevant aspects of the current regulation, e.g. the European Directives (Directive
2002/21/EC [i.3], Directive 2002/22/EC [i.4]) as well as the corresponding national regulation.
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5 SLA Contract
5.0 SLA contract principles
A Service Level Agreement (SLA) is a contract that defines an agreement between two parties: user and service
provider (see figure 1). It describes the terms and conditions of service provisioning. On the user side, it identifies the
user requirements. On the provider side, it indicates the commitments (capabilities) of the provider to the client.
The SLA serves as a means of formally documenting the service(s), performance expectations, responsibilities and
limits between service providers and their users.

Figure 1: SLA Contract
An effective SLA acknowledges that clients and service providers have responsibilities and obligations to each other. It
is important to address these points in the SLA development phase, and acknowledge them in writing. An agreement
that clearly defines the roles and responsibilities of both parties will be of particular benefit if problems arise. The SLA
should be used in any case as a means to improve the process and the mutual understanding and not to relieve
responsibility of one party on the other party.
Parties should consist of 1 or 2 representatives from each party who may have an interest in the outcomes of the service.
An important step in the process is to identify needs and expectations for the specified services. This enables both
parties to understand what service attributes are most valued by each group. A service attribute is the aspect of service
quality that is most important to the client/customer.
The service provider needs to discuss its capacity and potential constraints on providing the service to the
customer/client. This will assist both parties to gain an understanding of each other's requirements and reduce
unrealistic expectations. If there are concerns or issues regarding service levels they should be discussed at the
negotiations stage, not when a SLA is close to implementation.
The critical areas of service should be identified and both client and service provider need to agree on a minimum level
of service to ensure client satisfaction.
It is necessary at this stage, for clients to distinguish their specific needs from broader expectations regarding the
service, and to appropriately prioritize service requirements. It may also be appropriate for the provider to detail the
range of services they can provide. This way both parties can fully identify their needs and expectations and agree on
which services w
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