1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T E.860TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2002) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Quality of telecommunication services: concepts, models, objectives and dependability planning Use o
2、f quality of service objectives for planning of telecommunication networks Framework of a service level agreement ITU-T Recommendation E.860 ITU-T E-SERIES RECOMMENDATIONS OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS INTERNATIONAL OPERATION Definitions E.100E.103
3、 General provisions concerning Administrations E.104E.119 General provisions concerning users E.120E.139 Operation of international telephone services E.140E.159 Numbering plan of the international telephone service E.160E.169 International routing plan E.170E.179 Tones in national signalling system
4、s E.180E.189 Numbering plan of the international telephone service E.190E.199 Maritime mobile service and public land mobile service E.200E.229 OPERATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN THE INTERNATIONAL TELEPHONE SERVICE Charging in the international telephone service E.230E.249
5、 Measuring and recording call durations for accounting purposes E.260E.269 UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON-TELEPHONY APPLICATIONS General E.300E.319 Phototelegraphy E.320E.329 ISDN PROVISIONS CONCERNING USERS E.330E.349 INTERNATIONAL ROUTING PLAN E.350E.399 NETWORK MANAGEM
6、ENT International service statistics E.400E.409 International network management E.410E.419 Checking the quality of the international telephone service E.420E.489 TRAFFIC ENGINEERING Measurement and recording of traffic E.490E.505 Forecasting of traffic E.506E.509 Determination of the number of circ
7、uits in manual operation E.510E.519 Determination of the number of circuits in automatic and semi-automatic operation E.520E.539 Grade of service E.540E.599 Definitions E.600E.649 Traffic engineering for IP-networks E.650E.699 ISDN traffic engineering E.700E.749 Mobile network traffic engineering E.
8、750E.799 QUALITY OF TELECOMMUNICATION SERVICES: CONCEPTS, MODELS, OBJECTIVES AND DEPENDABILITY PLANNING Terms and definitions related to the quality of telecommunication services E.800E.809 Models for telecommunication services E.810E.844 Objectives for quality of service and related concepts of tel
9、ecommunication services E.845E.859 Use of quality of service objectives for planning of telecommunication networks E.860E.879 Field data collection and evaluation on the performance of equipment, networks and services E.880E.899 For further details, please refer to the list of ITU-T Recommendations.
10、 ITU-T Rec. E.860 (06/2002) i ITU-T Recommendation E.860 Framework of a service level agreement Summary The liberalization and deregulation process that started during the last decade in the telecommunications environment is still running and it is cause of meaningful changes. Increasing competition
11、, favoured also by customer performance requirements, produces big pressures upon service/network providers. The latter, after having faced especially cost reductions for several years, nowadays try to improve quality of service (QoS) in order to differentiate their products from those of their comp
12、etitors. In addition the situation is complicated by the increasing demand of global services which involve in their provisioning several service/network providers. Therefore, roles of all entities that take part to service provision and their relationships have to be described. The scope is to stat
13、e responsibilities of each provider and to assure quality of service required from customer. A useful tool in formalizing the mentioned inter-relationships between entities is Service Level Agreement (SLA), that is the result of a negotiation between two or more parties with the objective of reachin
14、g a common understanding about service delivered, its quality, responsibilities, priorities, etc. This Recommendation describes a generic structure of SLA adopting an approach independent from the type of service and the technology used. That approach is useful especially in a multi-provider environ
15、ment which today has become reality. Source ITU-T Recommendation E.860 was prepared by ITU-T Study Group 2 (2001-2004) and approved under the WTSA Resolution 1 procedure on 29 June 2002. ii ITU-T Rec. E.860 (06/2002) FOREWORD The International Telecommunication Union (ITU) is the United Nations spec
16、ialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on
17、a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid dow
18、n in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication
19、administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or ap
20、plicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had/had not received notice of intellectual property, protected by patents, which may be required t
21、o implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2003 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without t
22、he prior written permission of ITU. ITU-T Rec. E.860 (06/2002) iii CONTENTS Page 1 Introduction 1 2 Quality of Service definitions and terms 1 2.1 Entity 1 2.2 Interaction Points and Interfaces 2 2.3 Service, Service Element and Service Access Point 3 2.4 Quality of Service. 4 2.5 Service Level Agre
23、ement (SLA) 4 2.6 Relationships between Quality of Service and Network Performance 4 3 Abbreviations 5 4 Approach to multi-provider environment. 6 5 Service Level Agreement (SLA) 7 5.1 What is a SLA 7 5.2 Structure of a SLA 8 5.2.1 Introduction 8 5.2.2 Scope 8 5.2.3 Confidentiality 8 5.2.4 Review pr
24、ocess. 9 5.2.5 Compensations . 9 5.2.6 Signatories 9 5.3 QoS agreement . 9 5.3.1 Interface description . 9 5.3.2 Traffic patterns . 10 5.3.3 QoS parameters and objectives 10 5.3.4 Measurements. 14 5.3.5 Reaction patterns 15 6 Applying Service Level Agreement in a multi-provider environment. 16 6.1 E
25、nd-to-End QoS . 16 6.2 End-to-End SLA. 17 6.3 A general procedure . 18 Appendix I Examples of classification parameters. 20 ITU-T Rec. E.860 (06/2002) 1 ITU-T Recommendation E.860 Framework of a service level agreement 1 Introduction The liberalization and deregulation process that started during th
26、e last decade in the telecommunications environment is still running and it is cause of meaningful changes. Increasing competition, favoured also by customer performance requirements, produces big pressures upon service/network providers. The latter, after having faced especially cost reductions for
27、 several years, nowadays try to improve quality of service (QoS) in order to differentiate their products from those of their competitors. In addition the situation is complicated by the increasing demand of global services which involve in their provisioning several service/network providers. There
28、fore, roles of all entities that take part to service provision and their relationships have to be described. The scope is to state responsibilities of each provider and to assure quality of service required from customer. A useful tool in formalizing the mentioned inter-relationships between entiti
29、es is Service Level Agreement (SLA), that is the result of a negotiation between two or more parties with the objective of reaching a common understanding about the service delivered, its quality, responsibilities, priorities, etc. In the following a generic structure of SLA is described adopting an
30、 approach independent from the type of service and the technology used. That approach is useful especially in a multi-provider environment which today has become reality. Therefore we begin with recalling QoS terms and definitions (clause 2) and the one stop responsibility concept (clause 4). Afterw
31、ards the structure of a SLA is described in all its components (clause 5) and its application in a multi-provider environment is illustrated in clause 6. 2 Quality of Service definitions and terms A standardization of terms and definitions in QoS is important for two main reasons: to avoid the confu
32、sion introduced by contrasting terms and definitions; to maintain the consistency between different groups involved in developing telecommunication standards. In this clause terms and definitions for a QoS Framework are introduced, referring to E.800 for the other QoS terms. 2.1 Entity An Entity is
33、a generic unit involved in using/delivering a service. It is characterized by its states and its transitions from a state to another (Figure 2-1). During a transition an entity can execute functions and interact with other entities through its outputs. 2 ITU-T Rec. E.860 (06/2002) E.860_F2-1ENTITYST
34、ATE1STATEJSTATENTRANSITIONFigure 2-1/E.860 States and transitions of an entity An entity that delivers a service to another entity is called provider while the entity that receives the service is called user. The term user may indicate either an end user, a regulatory authority or a service provider
35、. The latter receives a service from another service provider. 2.2 Interaction Points and Interfaces An Interaction Point is a point where two entities can exchange information. A group of interaction points at the logical boundary between two entities constitutes an interface (Figure 2-2). E.860_F2
36、-2ENTITY ENTITYPROVIDERUSER(Re)negotiationPerformanceMeasurementsService requestService deliveryInteraction PointINTERFACEFigure 2-2/E.860 Provider, user, service, interface, interaction points Sometimes an interaction point between user and provider may not belong to their logical interface althoug
37、h this point remains under the control of the provider. Interaction points can be located either on horizontal interface (between domains of the same functional level) or on vertical interface (between domains of different functional level) (Figure 2-3). It is often useful to group more entities tog
38、ether in one; obviously the correspondent interfaces will be redefined in a convenient way. ITU-T Rec. E.860 (06/2002) 3 E.860_F2-3Functional level n Domain ADomain BDomain CDomain D“horizontal interfaces“vertical interfaces“Functional level n1 Figure 2-3/E.860 “Vertical“ and “horizontal“ interfaces
39、 2.3 Service, Service Element and Service Access Point A service is a group of functions provided by an organization to a user through an interface E.800. The interaction points located in the interface between the SPs domain and the users domain are called Service Access Point (SAP) and represent t
40、he points where service is delivered. SAPs definition is very important because all service components located between the SAPs in the SLA are under the SPs responsibility. In performance reporting, more SAPs may often be grouped in a SAP Group. The concept of layered architecture may be applied als
41、o in service definition and in performance estimation (e.g., Service Availability delivered from a provider to a user in correspondence of a SAP) (Figure 2-4). E.860_F2-4CUSTOMERSERVICE PROVIDER 1SERVICE PROVIDER 2SERVICESERVICESAPGroupSAPGroupSE SE SE SESE SE SE SESE Service ElementSAP Service Acce
42、ss PointFigure 2-4/E.860 Service composition The example in Figure 2-4 shows a customer who buys a service from SP1 stipulating an agreement which contains responsibilities and priorities related to quality of service; in respect of this agreement performance parameters have to be provided in corres
43、pondence of SAP group by the provider to the customer. 4 ITU-T Rec. E.860 (06/2002) To deliver the service, provider 1 combines more service elements (SE) which may be at its own disposal or bought from other providers. Obviously, to reach the QoS level contracted with the customer, SP1 has to deman
44、d a suitable QoS from SP2 which delivers the SE used. 2.4 Quality of Service The Quality of Service definition in E.800 refers to “the collective effect of service performance which determines the degree of satisfaction of a user of the service“. However, considering the latest developments, in orde
45、r to be compliant with E.800 and to have a useable definition in a contract, we will describe QoS as the “degree of conformance of the service delivered to a user by a provider in accordance with an agreement between them“, a definition that can be considered as a measurable subset of the E.800. The
46、 latter definition, in fact, is more market-oriented even if QoS is measured from the customers point of view in both definitions. This is, in fact, the factor that finally produces success or failure of the service. 2.5 Service Level Agreement (SLA) A Service Level Agreement is a formal agreement b
47、etween two or more entities that is reached after a negotiating activity with the scope to assess service characteristics, responsibilities and priorities of every part. A SLA may include statements about performance, tariffing and billing, service delivery and compensations. Every performance repor
48、ting may include only the QoS parameters agreed in the correspondent SLA. 2.6 Relationships between Quality of Service and Network Performance The overall quality of a telecommunication service, as perceived from customers point of view, is influenced by many factors which are correlated with networ
49、k performance parameters. ITU-T Rec. E.860 (06/2002) 5 Figure 2-5 shows such a relationship: E.860_F2-5ServiceabilityDependabilityQoS - Quality of ServiceNP - Network PerformanceServiceRetainabilityPerformanceServiceAccessibilityPerformanceServiceOperabilityPerformanceServiceSupportPerformanceQuality ofServiceServiceIntegrityPerformanceServiceSecurityPerformanceCharging PerformanceTrafficabilityPerformancePlanningPerformanceProvisioningPerformanceAdministrationPerformanceResourcesand FacilitiesReliabilityPerformanceAvaila
