1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TEL ECO M M U NI CAT I ON STANDARDIZATION SECTOR OF ITU E.425 (0312 002) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Network management - Checking the quality of the in tern at i on a I te I e p h o n e servi
2、 ce Internal automatic observations ITU-T Recommendation E.425 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TEL ECO M M U N I CAT I ON STANDARDIZATION SECTOR OF ITU E.425 (O 3/2 O 02) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Network management - Chec
3、king the quality of the international telephone service Internal automatic observations ITU-T Recommendation E.425 ITU-T E-SERIES RECOMMENDATIONS OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS INTERNATIONAL OPERATION Definitions General provisions concerning Admini
4、strations General provisions concerning users Operation of international telephone services Numbering plan of the intemational telephone service International routing plan Tones in national signalling systems Numbering plan of the international telephone service Maritime mobile service and public la
5、nd mobile service OPERATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN THE DJTERNATIONAL TELEPHONE SERVICE Charging in the international telephone service Measuring and recording call durations for accounting purposes UTILIZATION OF THE RVTERNATIONAL TELEPHONE NETWORK FOR NON- TELEPHONY APP
6、LICATIONS General Phototelegraphy ISDN PROVISIONS CONCERNING USERS INTERNATIONAL ROUTING PLAN NETWORK MANAGEMENT International service statistics International network management Checking the quality of the international telephone service Measurement and recording of traffic Forecasting of traffic D
7、etermination of the number of circuits in manual operation Determination of the number of circuits in automatic and semi-automatic operation Grade of service Definitions Traffic engineering for IF-networks ISDN traffic engineering Mobile network traffic engineering TRAFFIC ENGINEERING QUALITY OF TEL
8、ECOMMUNICATION SERVICES: CONCEPTS, MODELS, OBJECTIVES AND DEPENDABILITY PLANNING Terms and definitions related to the quality of telecommunication c services Models for telecommunication services Objectives for quality of service and related concepts of telecommunication services Use of quality of s
9、ervice objectives for planning of telecommunication networks Field data collection and evaluation on the performance of equipment, networks and services E. 100-E.103 E.104-E.119 E. 120-E. 139 E.140-E.159 E.160-E.169 E. 1 70-E. 179 E.180-E.189 E.190-E.199 E.200-E.229 E.230-E.249 E.260-E.269 E.300-E.3
10、19 E.320-E.329 E.330-E.349 E.350-E.399 E.400-E.409 E.410-E.419 E.420-EA89 E.490-ES05 E.506-ES09 E.510-ES19 E.520-E. 5 39 E.540-ES99 E.600-E.649 E.650-E.699 E.700-E.749 E.750-E.799 E.800-E.809 E.810-E.844 E.860-E.879 E.88CE.899 E.845-E.859 For further details, please refer to the list of ITU-T Recomm
11、endations. ITU-T Recommendation E.425 Internal automatic observations Summary This Recommendation describes internal monitoring of network performance using specific performance parameters such as Answer Seizure Ratio (ASR), Answer Bid Ratio (ABR) and Network Effectiveness Ratio (NER). The advantage
12、s of internal monitoring is that a large volume of records can be collected which allows day-to-day evaluation of network performance. Source ITU-T Recommendation E.425 was revised by ITU-T Study Group 2 (2001-2004) and approved under the WTSA Resolution 1 procedure on 16 March 2002. ITU-T Rec. E.42
13、5 (03/2002) i FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized 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
14、questions and issuing Recommendations on them with a view to standardizing telecommunications on 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 Recommenda
15、tions on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down 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 IS0 and IEC. NOTE In this Recommendati
16、on, the expression “Administration“ is used for conciseness to indicate both a telecommunication 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
17、claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability 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 h
18、ad not received notice of intellectual property, protected by patents, which may be required to 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. O ITU 2002 All ri
19、ghts reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. 11 ITU-T Rec. E.425 (03/2002) CONTENTS Page 1 Definitions . essential information (of internal automatic observations) supplementary information (of internal automatic
20、observations) . Answer Seizure Ratio (ASR) Answer Bid Ratio (ABR) . Network Effectiveness Ratio (NER) 1.1 1.2 1.3 1.4 1.5 2 Merits of internal automatic observations 3 Time of observations 4 Exchange of the results of observations . 5 Classes of calls 6 Destination analysis from service observation
21、data 7 Details about supplementary information for Signalling System No . 5 7.1 Signalling faults 7.2 Ineffective calls associated with the calling subscriber 7.3 Ineffective calls associated with the called subscriber 7.4 Network 5 5 5 5 6 8 Equipment impact . 6 Annex A . Cause value categorization
22、 8 . ITU-T Rec . E.425 (03/2002) 111 ITU-T Recommendation E.425 Internal automatic observations1 1 Definitions 1.1 The Answer Seizure Ratio (ASR) (see 1.3) or Answer Bid Ratio (ABR) (see 1.4), whichever is appropriate in terms of attempts, completed attempts and percentage completed. The Network Eff
23、ectiveness Ratio (NER) (see 1.5) provides a good indication of the ability of a network to deliver calls. essential information (of internal automatic observations) 1.2 Information on signalling faults, subscriber behaviour and the network. supplementary information (of internal automatic observatio
24、ns) 1.3 Answer Seizure Ratio (ASR) ASR gives the relationship between the number of seizures that result in an answer signal and the total number of seizures. This is usually expressed as a percentage as follows: x100 Seizures resulting in answer signal Total seizures ASR = Measurement of ASR may be
25、 made on a route or on a destination code basis. The destination ASR is calculated on the total amount of traffic to the destination whichever the outgoing route used. A destination can be a mobile network, a country, a city, a service, etc. In the following example, the destination is a country. (S
26、ee Figure 1 .) The most accurate view of the performance of the distant network is achieved by measuring direct ASR as indicated below. Considering the traffic to a country B (i.e. the destination), the ASR to this destination is: Country B ASR = Direct + Indirect Seizures for country B resulting in
27、 Answers Direct + Indirect Total Seizures for country B Direct Seizures for country B resulting in Answers Direct Total Seizures for country B Direct Country B ASR = Indirect Seizures for country B resulting in Answers Indirect Total Seizures for country B Indirect Country B ASR = This Recommendatio
28、n also applies in case external monitoring equipment is used when a route is monitored constantly for all or a large (statistical significance) number of calls. Refer to 2.4/E.421. ITU-T Rec. E.425 (03/2002) 1 Figure UE.425 - Example of destination ASR The route ASR is calculated on the total amount
29、 of traffic on an outgoing route whichever the destination of this traffic. (See Figure 2.) Considering the traffic on a route c, the ASR on this route is: Seizures on the route c resulting in Answers Total seizures on the route c Route c ASR = 2 ITU-T Rec. E.425 (03/2002) . Switch T0209400-02 Figur
30、e 2/E.425 - Example of route ASR 1.4 Answer Bid Ratio (ABR) Gives the relationship between the number of bids that result in an answer signal and the total number of bids. Bids resulting in answer signal Total bids ABR = x100 ABR is expressed as a percentage and is a direct measure of the effectiven
31、ess of traffic from the point of measurement. It is similar to ASR except that it includes bids that do not result in a seizure. NOTE - There is not always a direct relationship between ASR and ABR since: - some reattempts can be generated by the switch which can lead to a lower ASR than ABR; - some
32、 bids can be lost by the switch which can lead to a lower ABR than ASR. 1.5 Network Effectiveness Ratio (NER) NER is designed to express the ability of networks to deliver calls to the far-end terminal. NER expresses the relationship between the number of seizures and the sum of the number of seizur
33、es resulting in either an answer message, or a user busy, or a ring no answer, or in the case of ISDN a terminal rejectiodunavailability. Unlike ASR, NER excludes the effects of customer behaviour and terminal behaviour. Like ASR, measurement of NER may be made on a route or on a destination code ba
34、sis (see 1.3). ITU-T Rec. E.425 (03/2002) 3 T0209410-02 Seizures resulting in Answer message or User Failure Total Seizures NER = See Annex A for Cause Value classification in User or Network failure category. Remarks: 4 Accurate measurement of NER is more complex than that of ASR. Accurate measurem
35、ent of NER requires more complete signalling than does ASR. Cause values provided by ITU-T Signalling System No. 7 TUP and ISUP can be used as a basis for the measurement of NER. This type of data is usually available from systems that capture signalling information. It may also be available on Call
36、 Detail Records. Even if ITU-T Signalling System No. 7 is used on the international link, the use of other signalling systems in the domestic network or in transit network, and their interworking with the Signalling System No. 7 may impact the accuracy of the measure. If multiple exchanges are invol
37、ved in the connection, accurate translation of the Cause values and Location across exchanges is necessary. NER should be regarded as a lower bound of the ability of a network to deliver calls. This is because it is not always possible to determine why calls were not delivered to the terminal. For e
38、xample, a network vacant code could be caused by either customer dialling errors or network routing errors. Customer dialling errors that are not detected by network screening mechanisms will reduce the NER for that network. Call attempts that do not complete due to network screening should not cont
39、ribute to NER. For example, a call attempt to a network vacant code caused by customer dialling error that is detected by screening shall not result in a seizure being counted for NER, and will not produce an answer, user busy, ring no answer or terminal reject disposition. Improved network screenin
40、g can serve to increase the NER of a network. NER is calculated as a percentage of seizures, specifically, seizures of international circuits. A seizure will be said to have taken place, if the originating international switch has reserved a trunk for a specific call and has begun the signalling pro
41、cedure to establish a call over that trunk. If an answer is received for a seizure, this seizure should be categorized as a network established call whatever the Cause Value received. ITU-T Rec. E.425 (03/2002) 10) If the location field contains the value LPN (private network serving the local user)
42、 or U (user) or RF” (private network serving the remote user), the seizure should be categorized as a network established call whatever the Cause Value received. 2 The advantage of internal monitoring is that a large volume of records can be collected. The large volume of data obtained from an inter
43、nal observation system allows day-to-day evaluation of network performance. Daily analysis of this information has proven invaluable in trouble detection, and, coupled with a good maintenance response, is instrumental in providing the best possible Quality of Service2. The disadvantage is that this
44、method does not have the capability of detecting tones or speech and therefore cannot present a complete representation of all call dispositions. To overcome this disadvantage, Administrations are advised to use ITU-T Rec. E.422 as well to supplement the data obtained from internal automatic observa
45、tions. Merits of internal automatic observations 3 Time of observations The results of the ASR, ABR daily profile should be recorded. This data can be hourly, in groups of hours, or a total day. 4 Exchange of the results of observations 4.1 The essential information3 should be exchanged monthly (pre
46、ferably by facsimile or telex) to all network analyses points of those Administrations who are interested (the analyses points can then make comparisons between different streams going to the same destination). If information on ASR or ABR can be supplied separately for direct routes and indirect ro
47、utes via transit countries, this should also be exchanged as being essential information, including the name of the transit country involved. 4.2 With respect to supplementary data such as: signalling faults, failures due to calling subscriber, failures due to called subscriber and failures due to t
48、he network, a quarterly exchange of information is appropriate. Because different formats will be required, mail seems the most likely means to be used for exchanging supplementary data. 4.3 Besides the monthly and quarterly exchange of information, a direct contact on all aspects should be made (by
49、 telephone) as soon as action is required to prevent a persistent drop in the Quality of Service. 5 Classes of calls The distinction between classes of calls (such as operator-operator, subscriber-subscriber and operator-subscriber) is considered useful in identifying problems relating to the Quality of Service. This can only be done if the language digit4 and some of the subsequent digits are analysed. * Using these techniques, one can improve the quality of service even when no distinction can be made between ring no answer, subscriber busy (or congestion indicated by congestion tone) an
