1、. ITU-T RECMN+Q.2120 95 4862591 D599Y12 152 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU B-ISDN ATM ADAPTATION LAYER Q.2120 (02/95) B-ISDN META-SIGNALLING PROTOCOL ITU-T Recommendation Q.2120 (Previously “CCIlT Recommendation”) ITU-T RECMN*Q=2120 95 466
2、2571 0599433 O99 W FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The IT-T is responsible for studying technical, operating and tariff questions and issuing Recommen- dations on them with a view to standardizing
3、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 Recommendations on these topics. The approval of Recommendations by the Membe
4、rs of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). ITU-T Recommendation Q.2120 was prepared by ITU-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 Recommendatio
5、n, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1995 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including
6、 photocopying and microfilm, without permission in writing from the ITU. ITU-T RECMN*Q.2120 95 W 48b2591 0599414 T25 1 2 3 4 5 6 7 8 9 10 11 CONTENTS Scope and application 1.2 Application . Definitions . Abbreviations and Acronyms . General . Protocol model . 6.1 Modelling of Meta-signalling . 6.2 M
7、eta-signalling ATM LME service definition . 6.3 Services provided to the ATM LME by the ATM layer . Meta-signalling messages 7.1 ASSIGN REQUEST . 7.2 ASSIGNED 7.3 DENIED . 7.4 CHECK REQUEST 7.5 CHECK RESPONSE 7.6 REMOVED . Parameters 8.1 Protocol Discriminator (PD) . 8.3 Message Type (MT) . 1.1 Scop
8、e . 8.2 Protocol Version (PV) 8.4 Reference Identifier (RI) . 8.5 Signalling Configuration (SCON) 8.6 8.7 Signalling Virtual Channel Identifier B (SVCIB) 8.8 Point-to-point signalling virtual channel Cell Rate (PCR) . 8.9 Cause (CAU) 8.10 Service Profile Identifier (SPID) . Meta-signalling message f
9、ormatting and coding 9.1 Formatting principles 9.2 Formats and codes 9.3 Coding . . Prose description of Meta-signalling procedures . 10.1 Introduction . i 0.2 Focused messa revention 10.3 Signalling Virtual Channel Identifier A (SVCIA) 8.1 1 Cyclic Redundancy Check (CRC) General parameter examinati
10、on procedure 10.4 Assignment procedure 10.5 Check procedure . 10.6 Removal procedure . Timers . 1 1.1 Timer definitions Recommendation Q.2120 (02/95) Page 1 1 1 2 2 3 4 5 5 5 7 7 8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 9 9 10 10 10 10 10 16 16 17 17 18 20 22 24 24 1 ITU-T RECMN*Q*2120 95 M YB62591 0599435 961
11、 . Annex A . State overview diagrams . Annex C - Dynamic signalling configuration control . C.l Introduction C.2 Meta-signalling procedures . (user y side) . D . 1 General . Abbreviations and special symbols . Instructions for completing the PICS pro forma . D.5 Protocol Capabilities (PC) Messages -
12、Protocol data units (MS) . D.7 System Parameters (SP) Annex B - SDL description of Meta-signalling procedures . Annex D - Protocol Implementation Conformance Statement (PICS) pro formato Recommendation 4.2 120 D.2 D.3 D.4 D.6 Global statement of conformance . Page 24 26 49 49 49 53 53 53 53 54 54 55
13、 56 11 Recommendation Q.2120 (02/95) SUMMARY This Recommendation specifies the B-ISDN Meta-signalling protocol and procedures. The Meta-signalling protocol and procedures define the activity that assigns Signalling Virtual Channels on the B-ISDN User Network Interface (UNI). The Meta-signalling prot
14、ocol and procedures must be invoked by B-ISDN terminals on a multiple access UNI so that it is possible for its signalling channels to be allocated by the network. Once the signalling channels have been allocated, the signalling protocol stack can be created and signalling can proceed. Procedures ex
15、ist to detect and remove multiple signalling channel assignments. The Meta-signalling protocol operates over the Meta-signalling channel (Virtual Channel Identifier = 1) which must be available at all times on all UNIS. Keywords B-ISDN Meta-signalling svc Signalling Virtual Channel UNI User Network
16、Interface Broadband Integrated Services Digital Network Protocol for identification of Signalling Virtual Channels . Recommendation 4.2120 (02/95) 111 ITU-T RECMN*Q=ZL20 75 48b2591 0599YL7 734 Recommendation Q.2120 B-ISDN META-SIGNALLING PROTOCOL (Geneva, 1995) 1 Scope and application 1.1 Scope The
17、Meta-signalling protocol has procedures for the: - assignment of a point-to-point signalling virtual ch channel; nnel and asso iated broadcast signalling virtual - assignment of a point-to-point signalling virtual channel (see Annex C); - checking of the status of signalling virtual channels; - remo
18、val of signalling virtual channels. Using these procedures, Plane Management can: - resolve the possible contention for particular signalling virtual channels; - allocate cell rate to signalling virtual channels; - allocate a broadcast signalling virtual channel identity; - associate a signalling en
19、dpoint with a particular point-to-point signalling and broadcast signalling virtual channel pair. The broadcast signalling virtual channel which is associated with each signalling virtual channel is managed indirectly via its association with that channel. The procedures for assigning, checking and
20、removing the signalling virtual channels are independent of each other. Any relationship between them is under the control of Plane Management. 1.2 Application The Meta-signalling protocol is used to manage user-to-network signalling virtual channels and their associated broadcast signalling channel
21、s. However, the protocol may also be used over a virtual path connection between two users to manage user-to-user signalling virtual channels and associated broadcast signalling virtual channels. VCI = 1 shall be used for such a user-to-user Meta-signalling channel. In cases where there is a need to
22、 use the Meta-signalling channel for other applications, such applications must have a Protocol Discriminator format that is compatible with the Protocol Discriminator format described in this Recommendation. The other protocol discriminators should be set to a different value from meta-signalling t
23、o allow coincident operation of the other protocols with the meta-signalling protocol. The Meta-signalling protocol is not required for point-to-point configurations at the UNI. In such a point-to-point signalling configuration, VCI = 5 is the default value for the PSVCI, no BSVC is used and the def
24、ault value of the peak cell rate is 167 cells/sec. (see 3.7). Additional studies may necessitate a modification of this default value. As a network option, the Meta-signalling protocol also allows a user to request and be allocated a single PSVCI (VCI = 5) for signalling. (See Annex C.) NOTES 1 Reco
25、mmendation 1.361 2 reserves VCI values O through 15 for special purposes. These values cannot be used for Bandwidth is reserved, on a VP basis, for Meta-signalling only when Meta-signalling is supported on the VP. PSVCI or BSVCI except where indicated in 2. 2 Recommendation Q.2120 (0195) 1 ITU-T REC
26、MN*Q.2L20 95 4862593 0599438 670 2 References The following Recommendation 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 valid. All Recommendations and other referen
27、ces 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 Recommendations is regularly published. CCITT Recommen
28、dation 1.321 (1991), B-ISDN protocol reference model and its application. IT-T Recommendation 1.361 (1993), B-ISDN ATM layer specification LB-ISDN. ITU-T Recommendation 1.41 3 (1993), B-ISDN user-nemork inte$ace. ITU-T Recommendation 1.37 1 (1993), Truflc control and congestion control in B-ISDN. IT
29、U-T Recommendation 1.610 (1 993). B-ISDN operation and maintenance principles and functions. ITU-T Recommendation 1.363 (1993), B-ISDN ATM adaption layer (AAL) specification. IT-T Recommendation X.290 (1 999, OSI conformance testing methodology and framework for protocol Recommendations for ITU-T ap
30、plications - General concepts. Definitions For the purposes of this Recommendation, the following definitions apply: 3.1 Meta-Signalling Virtual Channel (MSVC): A virtual channel that is used to convey Meta-signalling messages across a UNI. This channel is identified by a standardised value of VCI =
31、 1 in every VP 2. The default value for the Virtual Path Identifier is O (i.e. VPI = O). User-to-user meta-signalling channels in a user-to-user virtual path shall also use VCI = 1. 3.2 Meta-Signalling Protocol Entity (MSPE): The ATM Layer Management protocol entity on either the network or user sid
32、e that establishes, checks or removes point-to-point and associated broadcast signalling virtual channels. 3.3 Meta-signalling virtual channel on the network side. Network Meta-Signalling Protocol Entity (NMSPE): This is the Meta-signalling protocol that terminates a 3.4 a Meta-signalling virtual ch
33、annel at the user side. User Meta-Signalling Protocol Entity (UMSPE): This is the Meta-signalling protocol entity that terminates 3.5 Broadcast Signalling Virtual Channel (BSVC): A broadcast signalling virtual channel is a uni-directional channel allocated by the network over which it will offer cal
34、ls to a user. This channel shall be the General Broadcast Signalling Virtual Channel (GBSVC) or a Selective Broadcast Signalling Virtual Channel (SBSVC). 3.6 Broadcast Signalling Virtual Channel. The BSVCI shall have the following values: Broadcast Signalling Virtual Channel Identifier (BSVCI): This
35、 identifier indicates the VCI value of a - 2, which is the value reserved in every VP 2 and is known as the General Broadcast SVC Identifier, - X, which is defined during the assignment phase and is known as a Selective Broadcast SVC Identifier. 2 Recommendation Q.2120 (02195) ITU-T RECMN*Q*2120 95
36、W 4862593 0577439 507 3.7 Point-to-point Signalling Virtual Channel (PSVC): A virtual channel that conveys ail point-to-point signalling for a given signalling endpoint. A signalling endpoint is assigned only one point-to-point signalling virtual channel and this channel is assigned, checked and rem
37、oved using the Meta-signalling protocol. In a point-to-point configuration, the PSVC is also used for call offering. 3.8 Point-to-point SVC Identifier (PSVCI): This identifier indicates the VCI value of a Point-to-point Signalling Virtual Channel (PSVC). The PSVCI may indicate the value 5 which is r
38、eserved per VP for the identification of a PSVC in a point-to-point signalling configuration. 3.9 ATM signalling endpoint: This is an association of a PSVCI and zero or one BSVCI. 3.10 Service Profde: The service profile is a collection of information maintained by a network to provide service to a
39、signalling entity. It allows, but does not require, different services to be provided to different signalling endpoints. It is network specific. The collection of information can contain: - - terminai subscription data; - directory number; - a non-standard protocol stack used by the user; supplement
40、ary service information, and other user or service data, as defined by a specific network. This collection of information is associated with a specific Service Profile Identifier (SPID) which can be communicated by Meta-signalling. 4 Abbreviations and Acronyms For the purposes of this Recommendation
41、 the following abbreviations are used: ATM BCD B-ISDN BSVC BSVCI CAU CDV CLP CRC GBSVC GBSVCI LME MSPE MSVC MSVCI MT NMSPE OAM PCR Asynchronous Transfer Mode Binary Coded Decimal Broadband Integrated Services Digital Network Broadcast Signalling Virtual Channel Broadcast Signalling Virtual Channel I
42、dentifier Cause Cell Delay Variation Cell Loss Priority Cyclic Redundancy Check General Broadcast Signalling Virtual Channel General Broadcast Signalling Virtual Channel Identifier Layer Management Entity Meta-signalling Protocol Entity Meta-signalling Virtual Channel Meta-signalling Virtual Channel
43、 Identifier Message Type Network Meta-signalling Protocol Entity Operations And Maintenance PSVC Cell Rate Recommendation 4.2120 (02/95) 3 PD PSVC PSVCI PV RI SAP SBSVCI SCON SPID svc SVCI SVCIA SVCIB UMSPE vc VCI VP VPI Protocol Discriminator Point-to-point Signalling Virtual Channel Point-to-point
44、 Signalling Virtual Channel Identifier Protocol Version Reference Identifier Service Access Point Selective Broadcast Signalling Virtual Channel Identifier Signailing Configuration Service Profile Identifier Signalling Virtual Channel Signalling Virtual Channel Identifier Signalling Virtual Channel
45、Identifier A Signalling Virtual Channel Identifier B User Meta-signalling Protocol Entity Virtual Channel Virtual Channel Identifier Virtual Path Virtual Path Identifier 5 General This Recommendation defines the B-ISDN Meta-signalling protocol (Version 1) that is used to establish and maintain the u
46、ser-network signalling connections which are applicable at the TB or Co-incident TB/SB reference points, see Recommendation 1.321 i. The procedures are asymmetric and are designed primarily for use over the user-network in terface (UNI) 1. The Meta-signalling protocol operates over the Meta-signalli
47、ng virtual channel. This channel has a pre-defined value of VCI = 1 in every Virtual Path (VP). The default peak cell rate of the meta-signalling virtual channel is 42 cells/sec. All Meta-signalling messages are equal to one ATM cell payload (Le. 48 octets) in length 2. The originating signalling en
48、tity shall set the CLP bit to O. The network may change the value of the CLP bit. The ATM-layer-user-to-ATM-user- layer-user indication shall always be set to the value “1” for meta-signalling cells. Bandwidth is reserved on a VP basis, for Meta-signalling, only when Meta-signalling is supported on
49、that VP. (For example, for a user-network VP, bandwidth is reserved for meta-signalling only when the VP is configured as a point-to- multipoint signalling configuration or when it is configured as a point-to-point signalling configuration and Annex C procedures apply.) The Broadcast Signalling Virtual Channel shall have the same cell rate and CDV (see 1.371 4) as the associated PSVC. As a consequence, when multiple PSVCs are associated with the BSVC, the BSVC must meet the most stringent constraint of the associated PSVCs. The protocol has procedures which enable th
