1、STD-ITU-T RECMN 1-23L.b-ENGL L77b 48b2571 Ob21278 3T5 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.231.6 (07/9 6) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Service capabilities - Bearer services supported by an ISDN Circuit-mode bearer service cat
2、egories: Circuit-mode 384 kbitls unrestricted, 8 kHz structured bearer service ITU-T Recommendation 1.231.6 (Previously “CCIlT Recommendation”) STD-ITU-T RECMN 1*23L*b-ENGL L77b 48b2571 Ob21277 231 ITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE I. 100-1.199 Term
3、inology I. 110-1.1 19 Description of ISDNs I. 120-1.129 General modelling methods I. 130-1.139 Telecommunication network and service attributes I. 140-1.149 General description of asynchronous transfer mode I. 150-1.199 General aspects of services in ISDN I/ Scope 1.200-1.209 1.210-1.219 II Common a
4、spects of services in the ISDN 1.220-1.229 11 Teleservices supported by an ISDN 1.240-1.249 Supplementary services in ISDN Network functional principles Reference models Numbering, addressing and routing Connection types Performance objectives Protocol layer requirements General network requirements
5、 and functions Application of I-series Recommendations to ISDN user-network interfaces Layer 1 Recommendations Layer 2 Recommendations Layer 3 Recommendations Multiplexing, rate adaption and support of existing interfaces Aspects of ISDN affecting terminal requirements OVERALL NETWORK ASPECTS AND FU
6、NCTIONS ISDN USER-NETWORK INTERFACES “ETWORK INTERFACES MAINTENANCE PRINCIPLES B-ISDN EQUIPMENT ASPECTS ATM equipment Management of ATM equipment 1.250-1.299 1.300-1.399 1.3 10-1.319 1.320-1.329 1.330-1.339 1.340-1.349 1.350-1.359 1.360-1.369 1.370-1.399 1.400-1.499 1.420-1.429 1.430-1.439 1.440-1.4
7、49 1.450-1.459 1.460-1.469 1.470-1.499 1.500-1.599 1.600-1.699 1.700-1.799 I. 730-1.749 1.750-1.799 For further details, please refer to ITU-T List of Recommendations STD-ITU-T RECMN 1-23L.b-ENGL 179b 4862591 Ob21300 883 FOREWORD The IT-T (Telecommunication Standardization Sector) is a permanent org
8、an 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 Standardization Conference (W
9、TSC), 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 (Helsinki, March 1-
10、12, 1993). ITU-T Recommendation 1.231.6 was revised by ITU-T Study Group 1 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 19th of July 1996. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication admini
11、stration 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. Recommendation 1.231.6 (07/96
12、) i 1 2 3 8 9 11 STD-ITU-T RECMN 1.23L.b-ENGL L99b LIBb259L Ob2L30L 7LT CONTENTS Definition . Description . 2.1 General description . 2.2 Specific terminology . Procedures 3.1 Provision/withdrawal 3.2 Normal procedures 3.3 Exceptional procedures . 3.4 Alternative procedures Network capabilities for
13、charging Applicability of supplementary services Interworking requirements . Attributes and values of attributes of the circuit-mode 384 kbit/s unrestricted, 8 kHz structured bearer service category Provision of individual circuit-mode 384 kbiils unrestricted, 8 kHz structured bearer services Dynami
14、c description Recommendation 1.231.6 (07/96) Page 1 STD* ITU-T Subscription option RECMN 1-23L.b-ENGL Value Recommendation 1.231.6 CIRCUIT-MODE BEARER SERVICE CATEGORIES: CIRCUIT-MODE 384 kbit/s UNRESTRICTED, 8 kHz STRUCTURED BEARER SERVICE (revised in 1996) 1 Definition This bearer service category
15、 provides the unrestricted transfer of 384 kbius user information over an three or more users in a multipoint configuration (refer to Recommendation 1.254 for the supplementary service description). - 2.2 Specific terminology 2.2.1 retention timer: This timer specifies the amount of time that the ne
16、twork retains the call information of the original call upon encountering busy or being released. It is a network provider option. The minimum value of this timer shall be 15 seconds. 3 Procedures 3.1 Provisiodwithdr awal Provision of this service will be by pre-arrangement with Administrations. Thi
17、s bearer service is offered with several subscription options which apply separately to each ISDN number or group of ISDN numbers on the interface. For each subscription option, only one value can be selected. Subscription options for the interface are summarized below. Maximum number of information
18、 channels available at - m, where m is not greater than the number of information I user B I channels on the interface - n, where n is not greater than the number of information channels I on the interface Maximum number of total calls present at user B I User B can be an ISDN number or group of ISD
19、N numbers on the interface. Recommendation 1.231.6 (07/96) 1 STD-ITU-T RECMN 1*23L-b-ENGL L77b Li8b2591 Ob21303 572 3.2 Normal procedures All user-network signalling is done on the D-channel. a) Originating the service (call Set-up) The call is originated by the user requesting from the network the
20、required bearer service; the request includes a number 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
21、the network either en bloc, containing all 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 a
22、n incoming call of this bearer service. The calling user shall also be given 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 call reaches the called user and the conn
23、ection is established, an indication of this 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). Once established, the %-channel is then available for the transmission
24、 of 384 kbit/s digital signals in both directions continuously, without alteration by the network. No restriction is placed by the network on the content of the digital signals. c) Terminating the call The call may be terminated by either or both of the users by indicating this to the network. If on
25、e user terminates the call, an appropriate indication is sent to the other user. 3.3 Exceptional procedures a) Failure situations due to user error i) A user inputting a network-identifiable, improper service request will be given an appropriate failure indication by the network and the call Set-up
26、will be ceased. A user inputting a non-valid network number will be given an appropriate failure indication by the network and the call Set-up will be ceased. ii) b) Failure situations due to called user state i) A calling user attempting to establish a call to a user who is identified by the networ
27、k to be busy (either network-determined user busy or user-determined user busy) will be given an appropriate failure indication by the network. A user attempting to establish a call to a user whose terminal equipment fails to respond will be given an appropriate failure indication by the network and
28、 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 attempting to establish the call will be given an appropriate failure indicat
29、ion by the network and the call Set-up will be ceased. ii) c) Failure situations due to network conditions A calling user attempting to establish a call but meeting call failure situations due to network conditions (e.g. congestion) will be given an appropriate failure indication by the network. Fai
30、lure situation due to called user state andor network conditions A calling user attempting to establish a call but meeting call failure situations due to network conditions (e.g. congestion) or called user state (e.g. busy) can have service data retained for a specified period of time, i.e. retentio
31、n timer. d) 2 Recommendation 1.231.6 (07196) STD-ITU-T RECMN 3.4 Alternative procedures 3.4.1 Reserved service procedures A reserved communication service provides a long duration connection, typically (but not exclusively) in excess of one month, between users, that is analogous to a private leased
32、 circuit but affording the users a degree of control over connection establishment and termination not available on private leased circuits. 3.4.1.1 Connection establishment and termination Connection establishment and termination is by a combination of administrative procedures and signalling betwe
33、en the network and the user. Connection establishment and termination is as follows. 3.4.1.1.1 Normal reserved service procedures Connection establishment The user requests the service by service subscription as an administrative process. The subscription includes information identifying both users,
34、 the required bearer service, the time (Tl) that the connection is to be established and, optionally, the time (T2) that the connection is to be terminated, or the duration for which the connection is to remain established (T3). At time (Tl), the network-to-network component of the connection betwee
35、n the two interfaces is activated and a notification is sent to each user. Either user can now activate the user-to-network components of the connection by signalling on the D-channel. Optionally, the subscriber may modify the time for which the reserved communication service connection is active (T
36、3), as an administrative process between the subscriber and the service provider. indications during connection establishment Both users receive indications of the establishment of the network-to-network component of the connection. Indications during the establishment of the user-to-network compone
37、nts of the connection will be according to basic call procedures and the supplementary services subscribed to by the users. Connection termination At time T2 the network will initiate termination of the connection by signalling to each user on the D-channel. Optionally, prior to time T2, the connect
38、ion may be terminated by either or both of the users by indicating this to the network by signalling on the D-channel. Temporary deactivation and reactivation Prior to time T2, one user may temporarily deactivate the user-to-network component of the connection by indicating this to the network by me
39、ans of signalling on the D-channel. A connection deactivated by these means may subsequently, but prior to time T2, be reactivated by a request to the network by means of signalling on the D-channel. Network-to-network components of the connection remain established during this procedure. In a point
40、-to-point configuration, the reserved service connection is not available while in the deactivated state. Temporary deactivation and reactivation may be achieved using the HOLD supplementary service. Programmed cyclical activation and deactivation Optionally, reserved communication services between
41、pre-defined users may be activated and deactivated on a cyclical basis, at pre-defined times, and on pre-defined days. The number of programmed reserved communication connection activatioddeactivation to be provided per user per day, and degree of flexibility to be provided in the activationdeactiva
42、tion programme are beyond the scope of this Recommendation. Recommendation 1.231.6 (07196) 3 - STD-ITU-T RECMN 1.23L*b-ENGL L97b 48b259L Ob21305 3b5 3.4.1.1.2 Exceptional reserved service procedures a) Failure situations due to user error None identified. b) Failure situations due to user state Norm
43、al call procedures apply. Failure situations due to network conditions i) c) The network, when attempting to establish a call but meeting a call failure situation due to network conditions (e.g. congestion), will periodically (for example at five minute intervals) re-attempt to establish the call fo
44、r a defined period of time or until the call is established. Should an established call be prematurely released as a result of a network failure, which is detectable by the network, the network will attempt to re-establish the call to both users terminals and continue as per c) i) above. ii) d) Fail
45、ure situations due to user state andor network conditions None identified. 3.4.1.2 Operation and maintenance support Operation and maintenance support is covered in the 1.600-Series of Recommendations. 3.4.1.3 Quality of service - Availability NOTE - Grade of service is not applicable to a reserved
46、communication service. Definitions concerning availability may be found in Recommendations in the E.800-Series. Definitions concerning the duration of unavailable time for international digital connections forming part of an integrated services digital network may be found in Annex NG.821 (Recommend
47、ation G.821 is cross-referenced in Recommendation 1.352). The procedure for assessment of the service availability performance may be found in Recommen- dation M.1016. The service availability performance of reserved services requires further study. 3.4.1.4 Dimensioning of network resources for rese
48、rved communication service Information regarding the dimensioning of network resources for reserved communication services may be found in Recommendation E.73 1, “Methods for dimensioning resources operating in circuit switched mode”. 3.4.1.5 Information transfer capabuity The format and content of
49、information conveyed across a reserve communication service is entirely at the discretion of the user(s) subject to any constraints imposed by the requested bearer service or national regulations. 3.4.2 Permanent service procedures Permanent service procedures operate in the same manner as reserved service procedures except that the duration (T3) is considerably greater. This is for further study. 4 Network capabilities for charging This Recommendation does not cover charging principles. Future Recommendations in the D-Series are expected to contain that information. It
