ITU-T Q 2726 2-1996 B-ISDN User Part - Call Priority - Series Q Switching and Signalling Broadband ISDN - B-ISDN Application Protocols for the Network Signalling《B-ISDN用户部分 呼叫优先》.pdf

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1、STD-ITU-T RECMN Q*272b-Z-*ENL 177b W Lidb257L Oh31307 03Ca INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Q.2726.2 (07/96) SERIES Q: SWITCHING AND SIGNALLING Broadband ISDN - B-ISDN application protocols for the network Sig na Il i ng B-ISDN user part - C

2、all priority ITU-T Recommendation Q.2726.2 (Previously CCIlT Recommendation) STD-ITU-T RECMN d*272b-Z-ENGL 177b IIP lib257L Ob31308 T72 iS ITU-T Q-SERIES RECOMMENDATIONS SWITCHING AND SIGNALLING CLAUSES APPLICABLE TO ITU-T STANDARD SYSTEMS SPECIFICATION OF SIGNALLING SYSTEMS No. 4 AND No. 5 SPECIFIC

3、ATIONS OF SIGNALLING SYSTEM No. 6 SPECIFICATIONS OF SIGNALLING SYSTEM R1 SPECIFICATIONS OF SIGNALLING SYSTEM R2 DIGITAL EXCHANGES INTERWORKING OF SIGNALLING SYSTEMS SPECIFICATIONS OF SIGNALLING SYSTEM No. 7 DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 PUBLIC LAND MOBILE NETWORK INTERWORKING WITH SATEL

4、LITE MOBILE SYSTEMS INTELLIGENT NETWORK BROADBAND ISDN General aspects ATM adaptation layer Signalling network protocols Common aspects of B-ISDN application protocols for acces network signalling and interworking SIGNALLING IN THE INTERNATIONAL MANUAL SERVICE INTERNATIONAL AUTOMATIC AND SEMI-AUTOMA

5、TIC WORK1 NG FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN Q.l-Q.3 Q.4-Q.59 Q.60-Q.99 Q.lO0-Q.119 Q.120-Q.249 Q.250-Q.309 Q.310-Q.399 Q.400-Q.499 Q.500-Q.599 Q.60O-Q.699 Q. 700-Q. 849 Q.850-Q.999 Q. 1000-Q. 1 O99 Q.llOO-Q. 11 99 Q.1200-Q.1999 Q.2000-Q.2999 Q.2000-Q.2099 Q.210O-Q.2199 Q.22

6、00-Q.2599 d 8.2600-Q.2699 signallin B-ISDN application protocols for access signalling Q.2900-Q.2999 For further details, please refer to ITU-T List of Recommendations. STD-ITU-T RECMN 4.Z72b-Z-ENGL 319b R 48b259L Ob33309 909 W ITU-T RECOMMENDATION Q.2726.2 B-ISDN USER PART - CALL PRIORITY Summary T

7、his Recommendation specifies the extensions to the Broadband ISDN User Part for the support of the Broadband call priority service. Source ITU-T Recommendation Q.2726.2 was prepared by ITU-T Study Group 11 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 9th of July 1996

8、. FOREWORD IT (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions

9、 and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendat

10、ions on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 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.

11、NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTAL PROPERTY RIGHTS The IT draws attention to the possibility that the practice or implementation of this Recommendation

12、 may involve the use of a claimed Intellectual Property Right. The 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

13、 of this Recommendation, the ITU hadhad 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 T

14、SB patent database. O ITU 1997 Ail rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. 11 Recommendation 4.2726.2 (07/96) 2 2.1 2.2 2.3 2.4

15、2.5 STD-ITU-T RECMN l.272L-Z-ENGL L97b m Y8b254L b3L31L 5b7 CONTENTS Page Call priority Overview 2.1.1 Scope . 2.1.2 References . 2.1.3 Abbreviations B-ISDN user part messages and parameters . 2.2.1 Parameters and parameter subfields 2.2.2 Messages . Application process procedures 2.3.1 Priority han

16、dling procedures . Application service elements and pnmtives Primitives between SACF and application process . 2.4.3 ASE descriptions . Intenvorking . 2.5.1 Intenvorking with CS-1 nodes 2.5.2 Intenvorking With ISUP 2.5.3 Intenvorking with DSS 2 . . 2.4.1 2.4.2 Primitives between BCC ASE and SACF . 1

17、 2 2 3 3 3 Appendix I . Coding of instruction indicators 6 Recommendation 4.2726.2 (07/96) . 111 Recommendation 4.2726.2 B-ISDN USER PART - CALL PRIORITY (Geneva, 1996) 2 Call priority 2.1 Overview 2.1.1 Scope This Recommendation specifies optional extensions to the Broadband ISDN User Part to suppo

18、rt call priority handling. These specifications allow for preferential treatments for high priority calls during network congestion based on the priority level of the call. It defines: - - new message and parameter coding needed; additional primitives and primitive parameters needed to model the new

19、 capabilities according to the specification model for the B-ISDN User Part defined in Recommendation 4.2764; enhancements to the Application Process procedures; and enhancements to the description of the Application Service Element. - - This Recommendation is applicable to simultaneous establishmen

20、ts of a single call/connection in a point-to-point configuration. 2.1.2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were

21、valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommen

22、dations is regularly published. ITU-T Recommendation Q.2764 (1995), Signalling System No. 7 B-ISDN User Part (B-ISUP) - Basic call procedures. ITU-T Recommendation 4.2650 (1 995), Interworking between Signalling System No. 7 Broadband ISDN User Part (B-ISUP) and Digital Subscriber Signalling System

23、No. 2 (DSS 2). CCITT Recommendation 1.255.4 (1 990), Community of interest supplementary services: Prioris service. CCITT Recommendation 1.255.3 (1 990), ISDN general structure and service capabilities: Multi-Level Precedence and Preemption. ITU Recommendation 4.735.3 (1993), Stage 3 description for

24、 community of interest supplementary service using SS No. 7: Multi-Leve I Precedence and Preemption. CCITT Recommendation Q.955.1 (1992), Stage 3 description for community of interest supplementary service using DSS I: Closed User Group. Recommendation 4.2726.2 (07/96) 1 STDeITU-T RECMN Q=272b*Z-ENG

25、L 177: II 48b2591 Ob31313 33“ 1 ext. 7 ITU Recommendation Q.955.3 (1993), Stage 3 description for community of interest supplementary service using DSS I: Multi-Level Precedence and Preemption. Spare Priority 2.1.3 Abbreviations This Recommendation uses the following abbreviations. BCC Bearer Connec

26、tion Control B-ISDN B-ISUP Broadband ISDN User Part cc Call Control cs-1 Capability Set 1 CUG Close User Group DSS 2 IAM Initial Address Message IE Information Element ISDN Integrated Services Digital Network ISUP ISDN User Part MLPP Multi-Level Precedence and Preemption SACF Single Association Cont

27、rol Function TCC Telephony Country Code Broadband Integrated Services Digital Network Digital Subscriber Signalling System No. 2 1 II digit 3rd II digit 2.2 B-ISDN user part messages and parameters 2“d II digit 4h II digit 2.2.1 Parameters and parameter subfields The following new parameter and para

28、meter subfields are required in B-ISDN. 2.2.1.1 Priority The format of the Priority parameter field as used by the procedures of this Recommendation is shown in Figure 2-1. The parameter name code allocated to the Priority parameter is O1 10 O1 1 1. 8 7 6 5 4 3 2 1 Least significant bit Octet 1 2 3

29、4 5 6 Figure 2-UQ.2726.2 - Priority parameter 2 Recommendation Q.2726.2 (07/96) STD-ITU-T RECMN Q=27Zb=Z-ENGL L77b W 4BbZ571 Ob31314 27b M - Prioriiy (octet 1) Four binary coded bits indicating priority coded as follows: O O O O level 1 (highest) O00 1 level2 O0 1 O level3 O0 1 1 level4 O 1 O O leve

30、l 5 (lowest) other values are reserved. - Domain (octets 2-6) The domain consists of four International identification digits, followed by a pure binary coded national domain. I International Identification (II) (octets 2-3) Each II digit is coded in a binary coded decimal representation fi-om O to

31、9. The first digit is coded O. The Telephony Country Code (TCC) follows in the Td to the 4 II digits (the most significant TCC digit is in the 2nd II digit). If octet 3 is not required, it is coded all zeros. National domain (octets 4-6) National domain contains a code expressing in pure binary the

32、number allocated to a national- specific domain to uniquely identifj a customer domain across multiple ISDN networks. Bit 8 of octet 4 is the most significant bit and bit 1 of octet 6 is the least significant bit. 2.2.2 Messages The following tables show the impact of the new parameters on message c

33、oding. 2.2.2.1 IAM The following new parameters can be carried in the IAM: See Table 2-1. Table 2-UQ.2726.2 - Additional parameter to be included in the IAM I IAM I I Priority parameter I 2.3 Application process procedures 2.3.1 Priority handling procedures Under the normal condition, when the netwo

34、rk is not congested and the exchange has the necessary resources to complete it, the call is processed without special treatments. 1 The code for National Domain is to be assigned and administered by different national Administrations. Recommendation Q.2726.2 (07/96) 3 STD-ITU-T RECMN Q-272b-Z-ENGL

35、L99b iBb259L Ob31315 102 In times of network congestion, when the exchange does not have sufficient resources to complete all of the incoming connection setup requests, as one option, the exchange may give preferential treatments based on the priority level. The preferential treatment should include

36、 access to reserved network resources, e.g.: 1) the highest priority calls are given access to available network resources including the resources reserved for highest priority calls; 2) the second highest priority calls are given access to available network resources including the resources reserve

37、d for the second highest priority calls, except for the resources reserved for the highest priority calls, and so on; n) Allocation of reserved network resources to specific priority levels is implementation specific, and is not a subject for standardization. If the exchange cannot complete a high p

38、riority call even after application of the preferential treatment, it clears the call. No existing calls shall be preempted in support of the high priority call. calls of the lowest priority level have no access to reserved network resources. 2.3.1.1 Originating exchange The originating exchange rec

39、eives a SETUP message with Priority IE. It validates the indicated priority level to ensure that it does not exceed the highest priority level assigned to the user. If Priority IE does not exist, the exchange processes it as a normal call. The exchange includes the priority information in the outgoi

40、ng IAM message as Priority parameter and passes on to the intermediate exchange. 2.3.1.2 Intermediate exchange When an intermediate exchange receives an IAM with the Priority parameter, the Priority parameter shall be passed on unchanged. 2.3.1.3 Destination exchange The destination exchange maps th

41、e priority level in the received Priority parameter to the Priority Information Element in the SETUP message. 2.3.1.4 A network that does not support the Call Priority Handling is required, if bilaterally agreed, to convey the Priority parameter intact. If the parameter is received from another netw

42、ork, the network should pass them on with no action taken, if bilaterally agreed, with no effect on the network that does not support the Call Priority Handling. Networks that do not support Call Priority Handling 2.4 The following subclause identifies impacts on the B-ISUP Application Service Eleme

43、nts and the primitives exchanged between ASES as shown in Recommendation 4.2764. Application service elements and primitives 2.4.1 Primitives between SACF and application process 2.4.1.1 Setup Requesthdication primitive Table 2-2 shows new parameter that must be added to the Setup Requesthdication p

44、rimitive. 4 Recommendation 4.2726.2 (07/96) Table 2-2/Q.2726.2 - Parameter for Setup Requestfindication primitive Priority I Setup Requestnndication I B-ISDN I O Priority IE Table 2-3/Q.2726.2 - Parameter for Link Setup Requesthdication primitive Priority Priority IE I Link Setup Requesflndication I

45、 Priority 2.4.3 ASE descriptions No changes are required to the ASE descriptions for BCC or CC ASES. 2.5 Interworking 2.5.1 Interworking with CS-1 nodes CS-1 nodes do not support the Priority parameter defined in this Recommendation and accordingly will treat this as unrecognized signalling informat

46、ion. The Instruction Indicators for the Priority parameter shall be set to transfer the parameter transparently so as to cause the call to be processed by a CS-1 node using only the parameters defined in CS-1. The Priority parameter will be passed transparentIy at a transit exchange. The coding of t

47、he instruction indicators for the Priority parameter shall be set as shown in Appendix I in order to support the correct behaviour. 2.5.2 Interworking with ISUP The Priority Parameter will be discarded at the B-ISUPASUP interworking point. The coding of the instruction indicators for the Priority pa

48、rameter shall be set as shown in Appendix I in order to support the correct behaviour. 2.5.3 Interworking with DSS 2 The following mapping of DSS 2 Information Elements to B-ISUP parameters is followed, in addition to those mappings already shown in Recommendation Q.2650. I SETUP I IAM I SETUP I Rec

49、ommendation Q.2726.2 (07/96) 5 STD*ITU-T RECMN Q.272b-Z-ENGL L77b = 48b2571 Ob31317 TA5 M APPENDIX I Coding of instruction indicators The instruction indicators for the Priority Parameter will be coded as follows: Transit at intermediate Exchange Transit interpretation Release call indicator Do not release call Send notification indicator Do not send notification Discard message indicator Do not discard message Discard parameter indicator Do not discard parameter Pass on not possible indicator Discard parameter Broadbandnarrow-band interworking indicator Discard par