1、ITU-T RECMN*I-232- 3 93 4862591 0583795 525 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.232.3 INTEGRATED SERVICES DIGITAL NETWORK (ISDN) SERVICE CAPABILITIES BEARER SERVICES SUPPORTED BY AN ISDN (03/93) USER SIGNALLING BEARER SERVICE CATEGORY (USBS)
2、ITU-T Recommendation 1.232.3 (Previously “CCITT Recommendation”) ITU-T RECMN*I.232- 3 73 H 4862571 0583796 461 W FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, ope
3、rating and tariff questions 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, established the topics for study by the ITU-T Study Groups which, in thei
4、r turn, produce Recommendations on these topics. ITU-T Recommendation 1.232.3 was revised by the ITU-T Study Group I (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the Intemational Telecommunication Union (ITU), the CCITT ce
5、ased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of .this Recomm
6、endation, no change has been made in the text to references containing the acronyms “CCITT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommun
7、ication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1994 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical
8、, including photocopying and microfilm, without permission in writing from the ITU. ITU-T RECMN+Im232. 3 93 4862591 0583797 3T8 W CONTENTS 1 Definition . 2 Description . 2.1 General description . 2.2 Specific terminology . 3 Procedures 3.1 Provision/withdraw al 3.2 Normal procedures 3.3 Exceptional
9、procedures . 3.4 Alternative procedures 4 5 Interworking requirements . 6 7 Attributes 8 Provision of user signalling bearer service 9 Dynamic description Network capabilities for charging Interaction with supplementary services Annex A - Network flow control mechanism for user signalling bearer ser
10、vices Page 1 3 3 3 4 4 5 13 Recommendation 1.2323 (03/93) 1 ITU-T RECMN*I*232- 3 93 ICIB 4862593 0583798 234 Recommendation 1.232.3 USER SIGNALLING BEARER SERVICE CATEGORY (USBS) (Melbourne, 1988; revised at Helsinki, 1993) 1 Definition This bearer service category is intended to support transfer of
11、 service data units (SDUs) via the D-channel. It is to be used in applications where limited amounts of information are to be exchanged between customer installations, or where information must be exchanged between customer installations and high layer functions) (HLFs) in the ISDN. Examples of such
12、 applications include support of user management protocols, and transfer of control information between any kind of user equipments including ISPBXs across a public ISDN. 2 Description 2.1 General description The user signalling bearer service (USBS) allows the user to send and receive information o
13、n a D-channel. This information is passed transparently (i.e. without modification of contents) through the network. SDUs are expected to be delivered, in sequence, with a high probability: and probability of misdelivery, mutilation and duplication is expected to be very low. Normally the network wi
14、ll not interpret or act upon this information. Service data units are transmitted after establishing the user signalling bearer service connection. (To send SDUs during the call setup or release phase may be a supplementary service such as user-to-user signalling service 1 and 2.) Service data units
15、 transmitted by this service are limited to 252 octets. As a network provider option, limitations may also be placed on the amount of data a user is permitted to transfer in a given time period (e.g. the throughput can be limited through use of explicit mechanisms, see Annex A). This service may be
16、provided either on demand or as a permanent service. This service is different from, and should not be confused with, the user-to-user signalling supplementary service (see Recommendation 1.257). The user-to-user supplementary service is used in conjunction with either a bearer service or a teleserv
17、ice. 2.2 Specific terminology For further study. 3 Procedures 3.1 Provisiodwithdrawai The service is normally provided on a subscription basis. However some networks may not require specific subscription to the USBS since it may be offered as a default for general ISDN subscription. 3.2 Normal proce
18、dures All user-network signalling is done on the D-channel. As a network option there may be a maximum allowable number of USBS calls present per D-channel. If so, this limit will define the network determined user busy condition for USBS. High layer functions are defined in Recommendation 1.210. Re
19、commendation 1.232.3 (03/93) 1 ITU-T RECMN*I=232- 3 93 m 4862593 0583799 170 I 3.2.1 Activatioddeactivatiodregistration For further study. 3.2.2 Demand service procedures a) Originating the service (call Set-up) The USBS call is originated by the user requesting from the network the required bearer
20、service and identifying the called user. Other information, as required, for the bearer service and for use by the network in supplementary services provided to the called user (e.g. calling line identity) may also be included. This request may be given to the network either en bloc, containing all
21、the required information, or not en bloc. b) Indications during call set-up After initiating a call, the calling user will receive an acknowledgement that the network is able to process the call. The called user will receive an indication of the arrival of an incoming call of this bearer service. Th
22、e calling user shall also receive an indication that the incoming call is being offered to the called user, when an indication is received by the network that the called user is being informed of this call. When the called user answers the call and the connection is established, an indication of thi
23、s is sent to the calling user. The called user may also provide other information for use by the network in supplementary services provided to other users (e.g. connected line identity). The relationship of a connected user with the called user requires further study. c) Information transfer phase O
24、nce the connection is established, charging may begin (if charging has a time component) and service data units may be transferred in both directions simultaneously, without alteration by the network. No restriction is placed on the content of service data units, as long as their length does not exc
25、eed a maximum of 252 octets. The network will attempt to deliver service data units in the sequence received without duplication, mutilation or misdelivery. d) Terminating the call The call may be terminated by either or both of the users by indicating this to the network. If one user terminates the
26、 call, an appropriate indication is sent to the other user. 3.3 Exceptional procedures 3.3.1 Activatioddeactivatiodregistration For further study. 3.3.2 Invocation and operation a) Failure situations due to user error: i) ii) Failure situations due to called user state: i) an improper service reques
27、t from the user will result in an appropriate failure indication by the network, and the call Set-up will be ceased; an invalid called party number from the user will result in an appropriate failure indication by the network, and the call Set-up will be ceased. b) a calling user attempting to estab
28、lish a connection to a busy called user (either network determined busy or user determined busy) will receive an appropriate failure indication from the network and the caii Set-up will be ceased; ii) if the called user fails to respond, the calling user will receive an appropriate failure indicatio
29、n from the network and the call Set-up will be ceased; iii) on a call to a user whose terminal equipment has responded that the called user is being informed of the call but has failed to answer within a defined period of time, the calling user will receive an appropriate failure indication from the
30、 network and the call Set-up will be ceased; iv) if the called user elects not to accept the connection, the calling user will receive an appropriate failure indication from the network and the call Set-up will be ceased. 2 Recommendation 1.232.3 (03/93) ITU-T RECMN*I*232- 3 33 4862593 0583800 712 e
31、 c) Failure situations due to network conditions: i) if USBS on demand is not available from the network, an appropriate failure indication will be sent to the user, and the call set-up will be ceased; ii) if the network is temporarily unable to provide the USBS on demand, an appropriate failure ind
32、ication will be sent to the user, and the call set-up will be ceased. In extreme circumstances of network congestion or failure, service data units may be discarded. Users wishing to ensure reliable transport must employ end-to-end protocols e.g. the class 4 transport protocol (see Recommendation X.
33、224). 3.4 Alternative procedures 3.4.1 Reserved service procedures For further study. 3.4.2 Permanent service procedures In the case of permanent service, no procedures are needed to establish the connection. Service data units may be transferred in both directions simultaneously, without alteration
34、 by the network. No restriction is placed on the content of service data units, as long as their length does not exceed a maximum of 252 octets. The network will attempt to deliver service data units in the sequence received, without duplication, mutilation or misdelivery. In case of failure situati
35、ons due to user error, user state or network conditions, appropriate failure indications will be signaled from the network. In extreme circumstances of network congestion or failure, service data units may be discarded. Users wishing to ensure reliable transport must employ end-to-end protocols e.g.
36、 the class 4 transport protocol (see Recommendation X.224). 4 Network capabilities for charging This Recommendation does not cover charging principles. Future Recommendations in the D-Series are expected to contain that information. 5 Interworking requirements Interworking between the USBS service a
37、nd the following services requires further study: a) b) c) PSPDN services. virtual call and permanent virtual circuit bearer service category (see Recommendation 1.232.1); additional packet mode bearer services; 6 Interaction with supplementary services For further study. Recommendation 1.232.3 (03/
38、93) 3 7 Attributes Attributes/values Attributes Information transfer attributes and values 1. Information transfer mode 2. Information transfer rate 3. Information transfer capability 4. Structure 5. Establishment of communication 6. Symmetry 7. Communication configuration Access attributes and valu
39、es 8. Access channel and rate 9. Access protocol 9.1 Signalling access protocol layer 1 9.2 Signalling access protocol layer 2 9.3 Signalling access protocol layer 3 9.4 Information access protocol layer 9.5 Information access protocol layer 2 9.6 Information access protocol layer 3 General attribut
40、es and values 10. Supplementary services provided 1 1. Quality of Service 12. Interworking possibilities 13. Operational and commercial 8 Provision of user signalling bearer service a) Overall provision: A b) Variations of secondary attributes Possible values of attributes Packet Throughput is for f
41、urther study Unrestricted digital SDU integrity Demandpermanent Bidirectional symmetric Point-to-point I.430D.43 1 I.44Ofi.441 1.450/1.451 L430n.431 1.44on.441 1.450n.45 1 Under study Under study Under study Under study I I I of configuration l Provision Communication Symmetry Establishment of commu
42、nication I A I Permanent I Symmetric I Pt-Pt I A I Pt-Pt Bidirectional Demand 4 Recommendation 1.232.3 (03/93) ITU-T RECMN*I-232. 3 93 4862571 0583602 595 IIP 1.441 1.431 c) Access 1.441 1.43 1 Access channel control Signalling and OAM (Note 1) Channel and rate Protocols 1.45 1 1.430 I D(64) I 1.45
43、1 User information Provision I 1 I Channel andrate I Protocols I I 1.45 1 1.441 1.430 A D(W I 1.45 1 I A l 9 Dynamic description The dynamic description for this service on demand basis is given in Figures 1 to 6. Recommendation 1.232.3 (03193) 5 ITU-T RECMNtI.232- 3 93 = Y862591 0583803 421 6 Recom
44、mendation 1.232.3 (03/93) ITU-T RECMN*I.232. 3 93 4862593 0583804 368 out call confirmation Outgoing call Incoming call confirmation 1 Incoming call 0 rejection i rejection TOI 03250-93/d02 FIGURE 2A.232.3 USBS basic call process - Macro definition - Establish connection Validate request I to destin
45、ation Disconnecting II (J rejection confir- T010326%93/d03 FIGURE 3l.232.3 USBS basic call process - Macro definition - Outgoing call Recommendation 1.232.3 (03193) 7 ITU-T RECMN*I-232- 3 93 4862593 0583805 2T4 I (7) Incoming Disconnecting I (J rejection number of total calls Disconnect indication I
46、 I rejection I W i Setup indication Set (now and response timer, timer 1) Wait for user response FIGURE 4D.232.3 (sheet 1 of 3) USBS basic call process - Macro-definition - Incoming call 8 Recommendation 1.232.3 (03/93) ITU-T RECMN*I-232. 3 93 L)8625L 0583806 130 lM ._ c 5 i o 0-J i5 II II -l Recomm
47、endation 1.232.3 (03/93) 9 ITU-T RECMN*I.232. 3 93 4862591 0583807 077 Record identity of respwiding user B Only from terminals which did not User responded reportalerting I I I I - Reset (timer 2) Connect /*No answer signalling resources Disconnect PA user*/ setup confirmation i*Answer*/ Connected
48、indication mm (alerting) I Set cause value 1 Release indication User responded Disconnecting iii; rejection cmfir- FIGURE 4A.232.3 (end) USBS basic call process - Macro definition - Incoming call TO1 03270-9WdO6 10 Recommendation 1.232.3 (03/93) ITU-T RECMN*I.232. 3 93 48b259L 0583808 TO3 Disconnect
49、 PA-usePl Release indication 0 Release request 0 resources I cmf ir- mation Release indcation D t Disconnected Release request Release resources confir- TO1 03280-9Wd07 FIGURE 5K232.3 USBS basic call process - Macro definitions - Disconnec/*A-user*/ and disconnec/*B-user*/ Recommendation 1.232.3 (03/93) 11 ITU-T RECMN*I.232. 3 93 4862571 0583809 9YT I Disconnecting 0 Disconnect indication cl Disconnecting a Release resources rejection TO1 03290-93d08 FIGURE 6A.232.3 USBS basic call process - Macro definition - Disconnecting 12 Recommendation 1.232.3 (03/93) ITU-T RECMN*I
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