1、:CH, REPORT ETR 003 October 1994 Second Edition Source: ETSI TC-NA Reference: RTR/NA-O42102 UDC: 621.395 Key words: Quality of service, network performance Network Aspects (NA); General aspects of Quality sf Service (QoS) and Network Performance (NP) ETSI European Telecommunications Standards Instit
2、ute ETSI Secretariat Postal address: 06921 Sophia Antipolis Cedex - FRANCE Office address: Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE Tel.: +33 92 94 42 O0 - Fax: +33 93 65 47 16 European Telecommunications Standards Institute 1 994. All rights reserved. No part may be reproduced exce
3、pt as authorised by written permission. The copyright and the foregoing restriction on reproduction extend to all media in which the information may be embodied. 340V583 0136650 7T3 - Page 2 ETR 003: October 1994 Whilst every care has been taken in the preparation and publication of this document, e
4、rrors in content, typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to “ETSI Editing and Standards Approval Dept.“ at the address shown on the title page. 3404583 0136651 b3T m Page 3 ETR 003: October 1994 Contents Foreword . 5 Introduction 5 1 Scope .
5、 7 2 References . 7 3 Definitions and abbreviations 7 3.1 Definitions . 7 3.2 Abbreviations 7 4 Quality of Service (00s) 8 4.1 Generic definition of QoS 8 4.2 Particular definitions of 00s 8 4.2.1 00s requirements of the userkustomer 8 4.2.2 00s offered by service provider 8 4.2.3 00s achieved by se
6、rvice provider 9 4.2.4 QoS perceived by the user/customer 9 4.3 General comments . 9 5 Network Performance (NP) . 10 6 Service performance 10 7 Relationship between 00s and NP . 11 8 Methodology for handling aspects of NP related to 00s . 11 8.1 8.2 Capture and defining of userskustomers QoS require
7、ments . 13 8.3 Arriving at 00s offered . 13 8.4 Mapping and specifying NP objectives . 14 8.5 8.6 Establishment of 00s achieved 15 8.7 The basics of the methodology 11 Measurement of NP (including feedback) . 14 Assessment of 00s perceived and subsequent follow-up . 15 Annex A: An example of generic
8、 framework for capture of users/customers 00s requirements . 16 A.l Introduction . 16 A.2 Glossary of terms . 16 A.3 Description of cells in the generic 00s matrix . 19 A.3.1 Cell reference 1 . 19 A.3.2 Cell reference 2 . 20 A.3.3 Cell reference 3 . 21 A.3.4 A.3.5 Cell reference 5 . 23 A.3.6 Cell re
9、ference 6 . 24 A.3.7 A.3.8 A.3.9 Cell reference 9 . 27 A.3.1 O Cell reference 1 O 28 Cell reference 4 . 22 Cell reference 7 . 25 Cell reference 8 . 26 m 3404583 0336652 576 m Page 4 ETR 003: October 1994 A.3.1 1 Cell reference 1 1 . . . . . . . . . . , . . . . . , , , , , . , . . . . , . , . . . . .
10、 , . . , , , , , -29 History . , , , , , . , , . ,. , , . . . . ,. ,. , , ,. , ,. . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . 30 Page 5 ETR 003: October 1994 Foreword This second edition ETSI Technical Report (ETRI was produced by the Netwo
11、rk Aspects (NA) Technical Committee of the European Telecommunications Standards Institute (ETSI). This ETR replaces ETR 003 (1990) (Edition 1): “General aspects of quality of service and network performance in digital networks, including ISDN“, which shall be withdrawn by ETSI. ETRs are informative
12、 documents resulting from ETSI studies which are not appropriate for European Telecommunication Standard (ETS) or Interim European Telecommunication Standard (LETS) status. . An ETR may be used to publish material which is either of an informative nature, relating to the use or the application of ET
13、Ss or I-ETSs, or which is immature and not yet suitable for formal adoption as an ETS or an LETS. Introduction The Quality of Service (aos) is defined in a generic sense and definitions of four viewpoints are added. These viewpoints are the customers (or users) 00s requirements, 00s offered by the s
14、ervice or Network Provider (NP), QoS achieved by the service or NP and QoS perceived by the user or customer. Addition of these four viewpoints helps to deal with the QoS in a clearer manner. The relationships between the four viewpoints are shown. A methodology shows how the associated activities o
15、f the four viewpoints fit together. The progression of activities associated with the four 00s viewpoints (starting with the users/customers QoS) is termed the QoS cycle. Capture of users/customers QoS requirements is the starting point. An example framework to facilitate this capture is described i
16、n the annex. This framework may be used to ascertain the users/customers QoS requirements for any telecommunications service. This exercise is to allow service providers to plan future service offerings more in accordance with users/customers requirements. A brief description is given on the handlin
17、g of the principal activities associated with the 00s cycle. The ultimate aim is to facilitate the provision of a level of service as agreed between the user/customer and the service provider. m 3404583 0336654 349 m Page 7 ETR 003: October 1994 I Scope This second edition ETSI Technical Report (ETR
18、I: a) states the general aspects pertinent to Quality of Service (00s) and Network Performance (NP); b) states the relationship between the QoS and NP; and c) identifies the salient aspects of the principal stages in the management of 00s related to NP. The content of this ETR reflects the need to p
19、rovide a level of quality to be agreed by the user/customer and the service provider. 2 References This ETR incorporates by dated and undated reference, provisions from other publications. These references are cited at the appropriate places in the text and the publications are listed hereafter. For
20、 dated references, subsequent amendments to or revisions of any of these publications apply to this ETR only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. 11 I CCITT Recommendation E.800 (1 988): “Quality of servic
21、e and dependability vocabulary“. 3 Definitions and abbreviations 3.1 Definitions For the purposes of this ETR, the following definitions apply: customer: The party that pays for the telecommunication services provided. network provider: An organisation that provides a network for the provision of te
22、lecommunications service. If the same organisation offer services it also becomes the service provider. service provider: An organisation that offers a telecommunications service to the customers and/or users. A service provider need not be a network provider. user: The party that make use of the te
23、lecommunication services provided. 3.2 Abbreviations For the purposes of this ETR, the following abbreviations apply: CPE NP QoS Telco Customer Premises Equipment Network Performance Quality of Service Telecommunications company Previous page is blank W 3404583 0336655 285 W Page 8 ETR 003: October
24、1994 4 Quality of Service (aos) 4.1 Generic definition of QoS QoS defined in CCITT Recommendation E.800 i11 may be considered as the generic definition. It is reproduced below: “The collective effect of service performance which determine the degree of satisfaction of a user of the service“. 4.2 Par
25、ticular definitions of QoS In addition to the generic definition it is useful to define the various viewpoints of QoS. The purpose of recommendations relating to 00s and NP can then be more easily be focused if the different 00s viewpoints are defined. 4.2.1 QoS requirements of the user/cuatomer QoS
26、 requirements by the user/customer is the statement of the level of quality of a particular service required or preferred by the user/customer. The level of quality may be expressed by the ucer/customer in technical or non-technical language. A typical user/customer is not concerned with how a parti
27、cular service is provided, or with any of the aspects of the networks internal design, but only with the resulting end-to-end service quality. From the users/customers point of view, 00s is expressed by parameters that: - focus on user/customer-perceivable effects, rather than their causes within th
28、e network; - do not depend in their definition on assumptions about the internal design of the network; - take into account all aspects of the service from the users/customers point of view; - may be assured to a user/customer by the service providersl; - are described in network independent terms a
29、nd create a common language understandable by both the user/customer and the service provider. EXAMPLE: A user may state that the acceptable number of occasions when moderate difficulty in call clarity could be tolerated is once in one hundred calls. The service provider translates this requirement
30、into NP parameters and assign target values in the performance of the network elements to achieve the target of not more than 1 call in 100 experiencing moderate difficulty. 4.2.2 00s offered by service provider 00s offered by the service provider is a statement of the level of quality expected to b
31、e offered to the user/customer by the service provider. The level of quality is expressed by values assigned to 00s parameters. These parameters are usually designed to be understandable to the user/customer. Each service would have its own set of 00s parameters. EXAMPLE: A service provider may stat
32、e that the availability of basic telephony service is 99,9 % in a year with not more than a 15 minute break on any one occasion. = 3404583 O136656 111 = v 4 QoS Requirements A, Page 9 ETR 003: October 1994 -; 1 e- Criteria ? Network : Performance Non-Network . Objectives Offered A Related Criteria A
33、 4.2.3 00s achieved by service provider QoS Perceived 00s achieved by the service provider is a statement of the level of quality achieved by the service provider. This is expressed by values assigned to parameters, which are, as far as possible, same as those for the QoS offered. These performance
34、figures are summarised for specified periods of time, e.g. for the previous 3 months. : Network i Performance : Measured QoS 4 7 Achieved EXAMPLE: The service provider may state that the achieved availability for a given duration (eng. one year) was 99,95 % or unavailable for 262,8 minutes . over a
35、365 day year. 4.2.4 QoS perceived by the userlcustomer QoS perceived by the user/customer is a statement expressing the level of quality experienced by them. The 00s perceived is expressed, usually in terms of degrees of satisfaction and not in technical terms. Technical terms may be expressed where
36、 the user/customer is able to understand and use these. QoS perceived is assessed by customer surveys and from users/customers own comments on levels of service. EXAMPLE: A user/customer may state that on unacceptable was difficulty in getting through the network to rating of 2 may be given on a 4 p
37、oint scale. 4.3 General comments number of occasions there make a call; a satisfaction Figure 1 shows how the various 00s viewpoints inter-relate with each other. Legend l_l.l .b Shows feedback -b Shows activity b) the incidence of intelligible crosstalk from another conversation will be less than 1
38、 in 1 O00 conversations; c) the service is available in “n“ countries from UK. Page 11 ETR 003: October 1994 7 The relationship between 00s and NP is illustrated in figure 2. Relationship between QoS and NP I QoS criteria I Non network related Network related QoS criteria Network performance Target
39、- range parameters I or limit Parameter 1 Parameter 2 Parameter N Figure 2: Relationship between 00s and NP In figure 2, QoS is the starting point for the development of NP parameters and targets. NP parameters specified are chosen for the most effective operation of the network. An example of mappi
40、ng of 00s into NP is shown below: - QoS requirement for telephony: not more than x % of connections made to experience difficulty on the clarity of conversation; - . the NP requirements upon mapping may be stated as; parameters identified as contributing to call clarity: transmission loss, noise (im
41、pulsive and non impulsive), echo, delay, crosstalk, voice clipping, (and possibly others); - end-to-end target values for each parameter may be specified. The sum effect should result in not more than x % of calls experiencing difficulty in call clarity. Empirical relationships between values for th
42、e above parameters and the percentage of users/customers experiencing call clarity difficulty should be made available. From these relationships meaningful allocation of target values for individual parameters can be made so that not more than a specified percentage of users/customers are likely to
43、experience difficulty for call clarity. The parameter target values are then broken down to element performance. 8 Methodology for handling aspects of NP related to QoS 8.1 The basics of the methodology A methodology illustrated in figure 3 shows the key elements in the derivation of network perform
44、ance parameters from the 00s requirements of the userlcustomer and the subsequent management of NP. The principal activities on the part of the user/customer, service provider and the NP are separated by a dotted line. The users 00s requirements is the starting point. This is mapped to 00s offered p
45、arameters by the service provider. These are mapped to network and non-network related performance parameters. The network related parameters are mapped into NP parameters and target values are assigned. Planning documentation are derived from these. A set of monitoring systems keeps track of the de
46、sired performance. The achieved end-to-end QoS performance is derived from the measurements and combined with the non network related QoS. This is compared with the users/customers 00s perceived obtained, usually customer surveys. Corrective action is taken where necessary. - W 3404583 013bb59 920 W
47、 Page 12 ETR 003: October 1994 The following subclauses deal with the principal stages of the methodology in more detail. 1 f f I Y -l I . Figure 3: Methodology for the management of NP related to 00s = 31104583 Ol13bbbO 642 W Page 13 ETR 003: October 1994 8.2 The method for capturing ucers/customer
48、s QoS requirements for any telecommunications service involves two steps. An example of a generic method is shown in annex A. In the first step a service-specific framework is derived by identifying the service specific criteria for the particular service under consideration. Capture and defining of
49、 userclcustomers 00s requirements In the second step the QoS requirements of the users/customers are ascertained. This is done by administering the service specific framework by an agency familiar with obtaining such information from the user/customer. The service specific framework is used as a template for the capture of the 00s requirements of the user/customer. It is important that the derivation of the service specific framework and the questionnaire is not too narrowly defined restricting users/customers expression
