1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU B-ISDN APPLICATION PROTOCOLS FOR ACCESS SIGNALLING Q.2931 (02/95) BROADBAND INTEGRATED SERVICES SUBSCRIBER SIGNALLING SYSTEM No. 2 LAYER 3 SPECIFICATION FOR BASIC CALUCONNECTION CONTROL DIGITAL NETWORK (B-ISD
2、N) - DIGITAL (DSS 2) - USER-NETWORK INTERFACE (UNI) ITU-T Recommendation Q.2931 (Previously “CCIlT Recommendation”) ITU-T RECflN+Q.293L 95 W 4862593 Ob04793 2T3 FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The
3、ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommen- dations 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
4、for study by the ITU-T Study Groups which, in their turn, produce Recommendations 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 (Helsinki, March 1-12, 1993). ITU-T Recommendation 4.2931 was prepared by ITU-
5、T Study Group 11 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 7th of February 1995. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1995
6、All 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. ITU-T RECMN*Q.293L 95 m 4862593 Ob04794 L3T m CONTENTS 1 Scope 1.1 Definitions, abbr
7、eviations and references . 1.2 Application to interface structure . 1.3 Capabilities supported by this Recommendation 2 Overview of call/connection control 2.1 B-ISDN calkonnection states 2.2 Additional B-ISDN calVconnection states relating to interworking requirements . 2.3 B-ISDN callkonnection st
8、ates for global call reference . 3 Message functional definitions and content . 3.1 Messages for B-ISDN call and connection control . 3.2 Additional or modified messages related for the support of 64 kbit/s based ISDN circuit-mode services . 3.3 Messages used with the global call reference . 4 Gener
9、al message format and information elements coding 4.1 Overview 4.2 Protocol discriminator 4.3 Call reference 4.4 Message type. and message length . 4.5 Variable length information elements for B-ISDN environment 4.6 Information elements for the support of 64 kbit/s based ISDN circuit-mode services .
10、 5 B-ISDN calVconnection control procedures 5.1 CalVconnection establishment at the originating interface . 5.2 CalVconnection establishment at the destination interface - Point-to-point access configuration call offering . 5.3 CalVconnection establishment at the destination - Point-to-multipoint ac
11、cess arrangement call offering . 5.4 CalVconnection clearing . 5.5 Restart procedure 5.6 Handling of error conditions . 5.7 Error procedures with explicit action indication . 5.8 Handling of messages with insufficient information 5.9 Notification procedures 6 Procedures for the support of 64 kbit/s
12、based circuit-mode ISDN services in B-ISDN and access signalling interworking between N-ISDN and B-ISDN . 6.1 Introduction 6.2 Information elements for N-ISDN services in B-ISDN 6.3 Interworking N-ISDN + B-ISDN 6.4 Interworking B-ISDN + N-ISDN 6.5 Overlap sending and receiving . 6.6 Notification of
13、interworking . 6.7 Additional features with regard to the provision of N-ISDN services 7 List of timers 7.1 Timers in the network side 7.2 Timers in the user side Recommendation Q.2931 (02/95) Page 1 1 1 1 5 5 6 6 7 8 16 25 27 27 28 28 32 34 79 81 82 86 90 90 91 94 99 100 101 101 101 102 104 105 106
14、 108 109 110 110 110 1 8 Primitives . 8.1 Introduction 8.2 Description of the primitives Annex A . Network side and user side SDL diagrams . A.l Network side SDL diagrams . A.2 User side SDL diagramas . Annex B . Compatibility checking . B.2 Calling side compatibility checking B.3 Called side compat
15、ibility and address checking . B.l Introduction Annex C . Broadband low layer information negotiation . C.l General C.2 Low layer compatibility notification to the called user C.3 B-LLI negotiation between users C.4 Alternate requested values Annex D . Transit network selection D.l Selection not sup
16、ported . D.2 Selection supported . Annex E . Mapping functions to support 64 kbit/s based circuit-mode ISDN services in B-ISDN and interworking between N-ISDN and B-ISDN (DSS 1DSS 2) E.l Introduction E.2 Mapping functions for the direction DSS 2 + DSS 1 E.3 Mapping functions for the direction DSS 1
17、+ DSS 2 E.4 Codepoint values of information elements to support 64 kbit/s based circuit-mode ISDN services in B-ISDN . Annex F . ATM adaptation layer parameters indication and negotiation . F . 1 General F.2 ATM adaptation layer parameter indication in the SETUP message . F.3 Maximum CPCS-SDU size n
18、egotiation F.4 MID range negotiation F.5 Use of forward and backward maximum CPCS-SDU size by the AAL entity in the user plane . Annex G Annex H . Extensions for symmetric call operation . Annex I . Handling of the OAM traffic descriptor . 1.1 Use of the OAM traffic descriptor information element .
19、1.2 Handling of the OAM traffic descriptor information element in the SETUP message 1.3 Procedure at the destination user-network interface . Annex J . Definitions. Abbreviations and References J.l Definitions 5.2 Abbreviations 5.3 References . Annex K -Handling of the End-to-end transit delay infor
20、mation element . K.l General K.2 Handling of the End-to-end transit delay information element in the SETUP message at the originating UNI . K.3 Handling of the End-to-end transit delay information element in the SETUP message at the destination UNI . Page 115 115 115 118 118 163 207 207 207 207 208
21、208 209 209 209 210 210 210 211 211 211 214 216 218 218 219 219 220 220 220 221 221 221 221 222 222 222 226 227 229 229 230 230 11 Recommendation Q.2931 (02/95) K.4 Handling of the End-to-end transit delay information element by the called user . K.5 Handling of the End-to-end transit delay informat
22、ion element in the CONNECT message at the destination UNI . K.6 Handling of the End-to-end transit delay information element in the CONNECT message at the originating UNI . Annex L - Examples for Message Structure and Information Element Format L.l Introduction L.2 Structure using of an information
23、subfield identifiers L.3 The ordering of information elements Appendix I - Guidelines for the use of Instruction indicators Appendix II - Information items for connection establishment in B-ISDN II.1 Scope . II.2 Information items specified by the calling terminal . Appendix III - Status monitoring
24、procedures for Semi-permanent Virtual Channel Connections . III.1 Messages used for SPC status . III.2 General information elements . 111.3 Other information elements III.4 Procedures across the UNI ILI.5 Error conditions III.6 System timers I11.7 System parameters Page 230 231 231 231 231 231 233 2
25、34 236 236 236 238 239 240 242 243 247 247 247 . Recommendation Q.2931 (OW95) 111 . SUMMARY This Recommendation specifies the procedures for the establishing, maintaining and clearing of network connections at the B-ISDN user network interface. The procedures are defined in terms of messages exchang
26、ed. This Recommendation is intended to specify the essential features, procedures and messages required for callkonnection control. However, there are some details of procedure which have not yet been specified, and which will be subject to further study. iv Recommendation Q.2931 (OW95) ITU-T RECMN*
27、Q-293L 95 Recommendation Q.2931 BROADBAND INTEGRATED SERVICES DIGITAL NETWORK (B-ISDN) - DIGITAL SUBSCRIBER SIGNALLING SYSTEM NO. 2 (DSS 2) - USER-NETWORK INTERFACE (UNI) LAYER 3 SPECIFICATION FOR BASIC CALL/CONNECTION CONTROL (Geneva, 1995) 1 Scope This Recommendation specifies the procedures for t
28、he establishing, maintaining, and clearing of network connections at the B-ISDN user-network interface. The procedures are defined in terms of messages exchanged. This Recommendation is intended to specify the essential features, procedures and messages required for calllconnection control. This Rec
29、ommendation specifies the layer 3 calVconnection states, messages, information elements, timers and procedures used for the control of B-ISDN point-to-point on-demand calls on virtual channels within the overall scope of Release 1 of B-ISDN as specified in Recommendation Q.2010. The procedures speci
30、fied by this Recommendation are applied at the interface between a B-ISDN terminal equipment and a B-ISDN public network (reference point SB and TB coincident) as well as at the interface between a B-ISDN customer network and a B-ISDN public network (i.e. at the TB reference point). Other Recommenda
31、tions may use additional messages, additional operations (using Facility information element), additional information elements and/or modification of existing information elements to support additional capabilities in DSS 2. 1.1 Definitions, abbreviations and references These are provided in Annex J
32、. 1.2 Application to interface structure The layer 3 procedures apply to the interface structures defined in Recommendation 1.413. They use the functions and services provided by layer 2. The layer 3 procedures request the services of layer 2 and receive information from layer 2 using the primitives
33、 defined in Recommendation 4.2130. These primitives are used to illustrate the communication between the protocol layers and are not intended to specify or constrain implementations. 1.3 Capabilities supported by this Recommendation The basic capabilities supported by the Release 1 Signalling specif
34、ied in this Recommendation are listed below: Demand (switched virtual) channel connections. Point-to-point switched channel connections. Connections with symmetric or asymmetric bandwidth requirements. Single-connection (point-to-point) calls. Basic signalling functions via protocol messages, inform
35、ation elements and procedures. Class X, Class A and Class C ATM transport services. Request and indication of signalling parameters. Recommendation Q.2931 (02/95) . - 1 8) VCI negotiation. 9) Out-of-band signalling for all signalling messages. 10) Error recovery. 11) Public UNI addressing formats fo
36、r unique identification of ATM endpoints. 12) End-to-end compatibility parameter identification. 13) Signalling interworking with N-ISDN and provision of N-ISDN services. 14) Forward compatibility. The following subclauses describe each capability in more detail. 1.3.1 Support of demand (switched) c
37、hannel connections The purpose of this specification is to support on-demand (switched) channel connections. These connections are established in real-time using signalling procedures. Demand connections can remain active for an arbitrary amount of time but would not automatically be re-established
38、after a network failure. In contrast, permanent connections are those that are set up and tom down via provisioning. Permanent connections generally remain established for long periods of time and should automatically be re-established in the event of network failure. 1.3.2 Support of point-to-point
39、 connections A point-to-point connection is a collection of associated ATM virtual channel (VC) or virtual path (W) links that connect two endpoints. The Release 1 Signalling specified in this Recommendation supports point-to-point virtual channel (VC) connections. 1.3.3 Support of connections with
40、symmetric or asymmetric bandwidth The Release 1 Signalling specified in this Recommendation supports point-to-point, bidirectional connections that have bandwidth specified independently in the forward and backward directions. The forward direction is from the calling party to the called party, whil
41、e the backward direction is from the called party to the calling party. 1.3.4 Support of a single connection per call The Release 1 Signalling specified in this Recommendation will support one and only one connection per call. 1.3.5 Protocol support for basic signalling functions The signalling prot
42、ocol supports the following basic functions at the UNI interface: CalVConnection Set-up This is the aspect of the protocol which supports the establishment of a callkonnection between different parties. It includes CalVConnection Request and CalVConnection Answer. CalVConnection Request This protoco
43、l function allows an originating party to request the establishment of a call/connection to a certain destination. In this request, the originating party may provide information related to the callkonnection. CalVConnection Answer This protocol function allows the destination party to respond to an
44、incoming call/connection request. The destination party may include information related to the calVconnection (rejecting the calVconnection request is considered part of the CalVConnection Clearing function). CalLXonnection Clearing This protocol function allows any party involved in a calVconnectio
45、n to initiate its removal from an already established callkonnection. This function also allows a destination party to reject its inclusion in a callkonnection. 2 Recommendation Q.2931 (02195) ITU-T RECMN*Q.2933 95 4862.593 Ob04800 263 Reason for Clearing This protocol function allows the clearing p
46、arty to indicate the cause for initiating its removal from a callkonnection. Out-ofBand Signalling This function specifies that callkonnection control information uses a channel different from the channels used for exchanging data information between the end-parties (i.e. a specific VPCWCI value wil
47、l be used for the calkonnection control signalling channel). 1.3.6 Support of Class A, Class C and Class X (see Recommendation 1.21 1) Class A service is a connection-oriented, constant bit rate ATM transport service. Class A service has end-to-end timing requirements. Class A service may require st
48、ringent cell loss, cell delay and cell delay variation performance. The user chooses the desired bandwidth and the appropriate QOS in the SETUP message to establish a Class A connection. Class C service is a connection-oriented variable bit rate (see Note) ATM transport service. Class C service has
49、no end-to-end timing requirements. The user chooses the desired bandwidth and QOS with appropriate information elements in a SETUP message to establish a Class C connection. NOTE - For Bearer Class C, the network may allocate resources, as if Bearer Class A was requested. Class X service is a connection-oriented ATM transport service where the AAL, traffic type (VBR or CBR) and timing requirements are user defined (i.e. transparent to the network). The user chooses only the desired bandwidth and QOS with appropriate information elements in a SETUP message to establish a Class X conne
