1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU B-ISDN APPLICATION PROTOCOLS FOR ACCESS SIGNALLING Q.2971 (1 0195) BROADBAND INTEGRATED SERVICES DIGITAL SUBSCRIBER SIGNALLING INTERFACE LAYER 3 SPECIFICATION CALUCONNECTION CONTROL DIGITAL NETWORK (B-ISDN) -
2、 SYSTEM NO. 2 (DSS 2) - USER-NETWORK FOR POINT-TO-MULTIPOINT ITU-T Recommendation Q.2971 (Previously “CCIlT Recornmendation”) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesFOREWORD The ITU-T (Telecommunication Standardization Sector)
3、is a permanent organ of the International Telecommunication Union (ITU). The 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 Standardiza
4、tion 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 Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (
5、Helsinki, March 1-12, 1993). ITU-T Recommendation 4.2971 was prepared by ITU-T Study Group 1 1 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 17th of October 1995. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a t
6、elecommunication administration and a recognized operating agency. O ITU 1996 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. COPYRI
7、GHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services1 2 3 4 5 6 7 8 9 10 11 12 13 14 CONTENTS Scope References Definitions Abbreviations . Description . Operational requirements . Primitive definitions and state definitions Coding requirements Si
8、gnalling procedures at the coincident SB and TB reference point . Procedures at the TB reference point for interworking with private B-ISDNs Interworking with other networks Interactions with supplementary services . Parameter values Dynamic description (SDLs) Annex A . Extensions for symmetric call
9、 operation Annex B . Transit network selection . Annex C - Amendments to Recommendation 4.2951 to support calls/connections using the procedures of Recommendation Q.297 1 . Annex D - Amendments to Recommendation Q.2957 to support calls/connections using the procedures of Recommendation Q.2971 . Anne
10、x E - Handling of the End-to-end transit delay information element Annex F - SDL Diagrams Page 1 1 2 2 3 3 4 5 16 29 35 35 35 36 36 37 37 46 51 53 Recommendation Q.2971 (10/95) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSUMMARY T
11、his Recommendation defines the operation of the Digital Subscriber Signalling System No. 2 (DSS 2) for the support of point-to-multipoint switched virtual channel connections, between a root and multiple leaves, at the TB or at the coincident SB and TB reference point of the User-to-Network Interfac
12、e of the Broadband Integrated Services Digital Network (B-ISDN). The procedures provide the capability to add or remove parties under the control of the root. In addition, a leaf party may initiate its withdrawal from the call. 11 Recommendation Q.2971 (10/95) COPYRIGHT International Telecommunicati
13、ons Union/ITU TelecommunicationsLicensed by Information Handling ServicesRecommendation Q.2971 BROADBAND INTEGRATED SERVICES DIGITAL NETWORK (B-ISDN) - DIGITAL SUBSCRIBER SIGNALLING SYSTEM NO. 2 SS 2) - USER-NETWORK INTERFACE LAYER 3 SPECIFICATION FOR POINT-TO-MULTIPOINT CALL/CONNECTION CONTROL (Gen
14、eva, 1995) 1 Scope This Recommendation specifies the signalling protocol for the establishing, maintaining and clearing of point-to- multipoint virtual channel callskonnections by means of the Digital Subscriber Signalling System No. 2 (DSS 2) at the TB reference point or coincident SB and TB refere
15、nce point (as defined in Recommendation 1.413) of the Broadband Integrated Services Digital Network (B-ISDN). In addition, this Recommendation specifies the protocol requirements at the TB reference point where the service is provided to the user via a private B-ISDN. This Recommendation specifies t
16、he signalling protocol to establish and clear point-to-multipoint callskonnections with unidirectional information transfer from the calling user (root) to all called users (leaves). The signalling protocol to establish and clear point-to-multipoint callskonnections with bidirectional information tr
17、ansport is outside the scope of this Recommendation. The capability described in this Recommendation is applicable to all connection oriented telecommunication services that are based on single point-to-multipoint virtual channel calls/connections with unidirectional information transport. This Reco
18、mmendation is applicable to equipment, supporting point-to-multipoint callskonnections, to be attached at either side of a TB reference point or coincident SB and TB reference point when used as an access to the public B-ISDN. 2 References The following Recommendations and other references contain p
19、rovisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying t
20、he most recent edition of the references listed below. A list of currently valid ITU-T Recommendations is regularly published. VI ITU-T Recommendation 4.293 1 (1993, Broadband Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling System No. 2 (DSS 2) - User-Network Interface (
21、UNI) layer 3 spec$cation for basic calVconnection control. VI ITLJ-T Recommendation 4.2130 (1994), B-ISDN signalling ATM adaptation layer - Service Specific Coordination Function for the support of signalling at the User-Network Interface (SSCF at UNI). 31 ITU-T Recommendation 1.327 (1993). B-ISDNfu
22、nctional architecture. 41 ITU-T Recommendation 1.413 (1993). B-ISDN user-network interface. PI ITU-T Recommendation 1.610 (1993), B-ISDN operation and maintenance principles andfunctions. C61 ITU-T Recommendation 4.2610 (1995). Broadband Integrated Services Digital Network (B-ISDN) usage of cause an
23、d location in B-ISDN User Part and DSS 2. Recommendation Q.2971 (10/95) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services3 ITU-T Recommendation Q.295 1 (1 993, Stage 3 description for number identification supplementary services using
24、B-ISDN Digital Subscriber Signalling System No. 2 (DSS 2) - Basic call. ITU-T Recommendation 4.2957 (1995), Stage 3 description for additional infonnution transfer supplementary services using B-ISDN Digital Subscriber Signalling System No. 2 (DSS 2) - Basic call. ITU-T Recommendation 4.2961 (1995).
25、 Broadband Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling System No. 2 (DSS 2) - Additional trafic parameters. Definitions For the purposes of this Recommendation, the following definitions apply: 3.1 party state: States for each party in the call (see 7.2.1) which are
26、known by the layer 3 entity. 3.2 link state: States on both sides of the interface which coincide with the call states defined in clause 2/Q.2931, i.e. the states of the Q.293 1 protocol handlers on both sides of the UNI and identified by their respective Call reference. 3.3 root: The source of the
27、point-to-multipoint connection. 3.4 leaf: One of the destinations of the point-to-multipoint connection. 3.5 add party queue: To facilitate the description of the point-to-multipoint protocol the concept of an add party queue is introduced. At an interface, this queue will hold add party requests pr
28、ior to the transmission of the add party request across the interface. This is a logical construct and should not constrain any implementation. 3.6 party state timer: Timers used in this Recommendation for the add party process. These timers are listed in clause 13. 3.7 endpoint reference: The ident
29、ifier for each party of a point-to-multipoint call which are known by the layer 3 entity. 4 Abbreviations For the purposes of this Recommendation, the following abbreviations are used: AAL ATM B-ISDN CRF DSS 2 OAM QOS SDL TE UNI ATM Adaptation Layer Asynchronous Transfer Mode Broadband Integrated Se
30、rvices Digital Network Connection Related Function (see Recommendation 1.327) Digital Subscriber Signalling System No. 2 Operation And Maintenance Quality Of Service Specification and Description Language Terminal Equipment (see Recommendation 1.327) User-Network Interface 2 Recommendation Q.2971 (1
31、0/95) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services ITU-T RECMN*Q-2973 95 4862591 0634082 T4T 5 Description 5.1 Application to interface structure The layer 3 procedures apply to the interface structures defined in Recommendation 1.4
32、134. 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 defined in Recommendation 4.2130. These primitives are used to illustrate the communication between the protocol layers and a
33、re not intended to specify or constrain implementations. 5.2 Capabilities supported by this Recommendation This Recommendation builds upon the capabilities in Recommendation Q.2931 for DSS 2 (see 1.5/Q.2931). The additional capability supported by the signalling protocol specified in this Recommenda
34、tion is the support of point-to- multipoint unidirectional switched channel connections. A point-to-multipoint virtual channel connection is a collection of associated ATM virtual channel links that connect two or more endpoints. This capability only supports unidirectional transport from the root t
35、o the leaves. Parties can be added and removed during the lifetime of the connection. 5.3 General overview This Recommendation presents the procedures, messages and information elements needed for supporting calls containing one point-to-multipoint connection. The point-to-multipoint connection is s
36、et up by first requesting the establishment of a connection between the root and one leaf, indicating point-to-multipoint in the Broadband bearer capability information element. After this setup has progressed to alerting or active state, additional leaves can be added to the connection by add party
37、 requests from the root. A leaf may be added or dropped from the call at any time while the call is in the active state. A new leaf can be added via the root issuing an add party request, as described above. A leaf can be dropped from the call by either the root or by the leaf. Multiple add party re
38、quests pending at the same time are allowed (e.g. the root node does not need to wait for a response related to one add party request before issuing the next one). Multiple drop party requests pending at the same time are allowed (.e. the root does not need to wait for a response related to one drop
39、 party request before issuing the next one). Each add party or drop party request is exclusively related to one party. If, as a result of a drop party procedure, there are no leaf parties remaining in the call, the entire call is released. 6 Operational requirements 6.1 Provision and withdrawal Some
40、 service providers may require prior service arrangement to be a root. No prior arrangement with the service provider is required to be a leaf. 6.2 Requirements on the originating network side See 6.1 above. 6.3 Requirements on the destination network side See 6.1 above. Recommendation Q.2971 (10/95
41、) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T RECMN*Q.297L 95 4862591 Ob14083 98b m 7 Primitive definitions and state definitions 7.1 Primitive definitions Clause 8/Q.293 1 shall apply. 7.2 State definitions This subclause d
42、efines an additional set of states called party states. These party states are used in addition to the basic call states (see clause 214.293 1) for a point-to-multipoint call. 7.2.1 B-ISDN party states The party states which may exist on the user or network side of the user-network interface are def
43、ined in this subclause, At an interface involved in a point-to-multipoint call there will be two types of states associated with this call: 1) States on both sides of the interface which coincide with the call states defined in clause 2/Q.2931, i.e. the states of the 4.2931 protocol handlers on both
44、 sides of the UNI and identified by their respective call reference. These states will henceforward be called the link states of the point-to-multipoint call at that interface. 2) States for each party in the call which are known by the layer 3 entity. These parties are identified by their endpoint
45、reference. These states will henceforward be called the parry states of the party associated with the call. NOTE - In each network there will be: For each signalling endpoint involved in the point-to-multipoint call, one link state. For each party associated with the point-to-multipoint call, one in
46、coming party state and one outgoing party state is maintained for each leaf reached through the network. Additionally, an endpoint reference value is associated with each reachable party, where this value (if not equal to O) may be remapped by the network such that a different value is used on the i
47、ncoming link from that used on the outgoing link heading towards the associated party. The party states which may exist on the user side or the network side of the user-network interface are: Null (PO) The party does not exist, no endpoint reference value has been allocated. Add Party Initiated (Pl)
48、 A SETUP or an ADD PARTY message has been sent to the other side of the interface for this party for the call. Add Party Received (P2) A SETUP or an ADD PARTY message has been received from the other side of the interface for this party for the call. Party Alerting Delivered (P3) An ALERTING or a PA
49、RTY ALERTING message has been sent to the other side of the interface for this party for the call. Party Alerting Received (P4) An ALERTING or a PARTY ALERTING message has been received from the other side of the interface for this party for the call. Drop Party Initiated (PS) A DROP PARTY message has been sent for this party of the call. Drop Party Received (P A DROP PARTY message has been received for this party of the call. 4 Recommendation 4.2971 (10/95) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesActive (W) O
