1、 STD-ITU-T RECMN 1.231-8-ENGL L77b D 48b2571 Ob21322 494 D INTERNATIONAL TELECOMMUNICATION UNION ITUmT TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.231.8 (07/96) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Service capabilities - Bearer services supported by an ISDN Circuit-mode bearer service
2、 categories: Circuit-mode 1920 kbitls unrestricted, 8 kHz structured bearer service ITU-T Recommendation 1.231.8 (Previously “CCIlT Recommendation”) STD-ITU-T RECMN 1.231-A-ENGL 177b 98b2571 b21323 380 ITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTLJRE Terminology
3、Description of ISDNs General modelling methods Telecommunication network and service attributes General description of asynchronous transfer mode SE Scope General aspects of services in ISDN Common aspects of services in the ISDN Teleservices supported by an ISDN Supplementary services in ISDN Netwo
4、rk functional principles Reference models Numbering, addressing and routing Connection types Performance objectives Protocol layer requirements General network requirements and functions Application of I-series Recommendations to ISDN user-network interfaces Layer 1 Recommendations Layer 2 Recommend
5、ations Layer 3 Recommendations Multiplexing, rate adaption and support of existing interfaces Aspects of ISDN affecting terminal requirements OVERALL NETWORK ASPECTS AND F“CTI0NS ISDN USER-NETWORK INTERFACES INTERNETWORK INTERFACES MAINTENANCE PRINCIPLES B-ISDN EQUIPMENT ASPECTS ATM equipment Manage
6、ment of ATM equipment .100-1.199 .l 10-1.119 .120-1.129 1.130-1.139 i. 140-1.149 . 150-1.199 1.210-1.219 L240-1.249 L250-1.299 r.300-1.399 1.310-1.319 1.320-1.329 1.330-1.339 r.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 1.440-1.449 1.450-1.459 1.460-1.469 1.470
7、-1.499 1.500-1.599 1.600-1.699 1.700-1.799 1.730-1.749 1.750-1.799 For further details, please refer to ITU-T List of Recommendations. STD-ITU-T RECMN 1.231.B-ENGL 179b = LiBb2571 Ob21324 217 FOREWORD The IT-T (Telecommunication Standardization Sector) is a permanent organ of the International Telec
8、ommunication Union (IT). The IT-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 ye
9、ars, establishes the topics for study by the -T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the IT-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). IT-T Recommendation 1.23
10、 1.8 was revised by IT-T Study Group 1 (1993-1996) and was approved under the WTSC Resolution No. I procedure on the 19th of July 1996. NOTE In this Recommendation, the expression ?Administration? is used for conciseness to indicate both a telecommunication administration and a recognized operating
11、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 IT. Recommendation 1.231.8 (07/96) 1 1 2 3 8 9 CONTENTS 11 Definition
12、. Description . 2.1 General description . 2.2 Specific terminology . Procedures 3.1 Provision/withdrawal 3.2 Normal procedures 3.4 Alternative procedures Network capabilities for charging 3.3 Exceptional procedures . Interworking requirements . Applicability of supplementary services Attributes and
13、values of attributes of the circuit-mode 1920 kbids unrestricted, 8 kHz structured bearer service category Provision of individual circuit-mode 1920 kbids unrestricted. 8 kHz structured bearer services Dynamic description Recommendation 1.231.8 (07196) Page 1 1 1 1 1 1 2 2 2 4 5 5 STD-ITU-T RECMN 1.
14、23L.B-ENGL L77b m 48b2571 ObZL32b 07T m Subscription option Recommendation 1.231.8 Value CIRCUIT-MODE BEARER SERVICE CATEGORIES: CIRCUIT-MODE 1920 kbitfs UNRESTRICTED, 8 IrHz STRUCTURED BEARER SERVICE Maximum number of information channels available at user B Maximum number of total calls present at
15、 user B (revised in 1996) - m, where m is not greater than the number of information channels on the interface - n, where n is not greater than the number of information channels on the interface 1 Definition This bearer service category provides the unrestricted transfer of 1920 kbit/s user informa
16、tion over an Hlychannel at the Sf reference point. Transfer of OAM (Operations, Administration and Maintenance) information for reserved and permanent services may be provided via a D-channel in another interface structure. NOTE -Time Slot Sequence Integrity (TSSI) should be guaranteed between SIT r
17、eference points. 2 Description 2.1 General description This circuit-mode bearer service category allows: - two users (e.g. terminals, PABXs) in a point-to-point configuration to communicate via the ISDN using 1920 kbit/s digital signals over the H12-channe1, in both directions continuously; three or
18、 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 network retains the call information of the original call upon encountering busy or
19、being released. It is a network provider option. The minimum value of this timer shall be 15 seconds. 3 Procedures 3.1 Provisiodwithdrawal Provision of this service will be by pre-arrangement with Administrations. This bearer service is offered with several subscription options which apply separatel
20、y 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. User B can be an ISDN number or group of ISDN numbers on the interface. Recommendation 1.231.8 (07/96) 1 STD-ITU
21、-T RECMN 1.231.8-ENGL L77b m LiBb2571 Ob21327 T2b m 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 required bearer service; the request includes a number identifyi
22、ng 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 the required infomati
23、on, or not en bloc. b) Indications during call set-up After initiating a call the calling user will receive an acknowledgment 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. The calling user shall als
24、o 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 connection is established, an indication of this is sent to the callin
25、g 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 Hrchannel is then available for the transmission of 1920 kbi/s digital signals in both directions continuously, wi
26、thout 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 one user terminates the call, an appropriate indication is sent to t
27、he 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 will be ceased. A user inputting a non-valid network number will b
28、e 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 network to be busy (either network-determined user busy or user-determin
29、ed 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 the call set-up will be ceased. iii) On a call to a user whose te
30、rminal 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 indication by the network and the call set-up will be ceased. ii) c) Fail
31、ure situations due to network conditions A 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. Failure situation due to called user state andor network conditions A user at
32、tempting 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. retention timer. d) 2 Recommendation 1.231.8 (07/96) - STD-ITU-T RECMN 1-23L.B-ENGL L77b W
33、 iBb2571 Ob21328 7b2 W 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 circuit but affording the users a deg
34、ree 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 between the network and the user. Connectio
35、n establishment and termination is as follows. 3.4.1.1.1 Normal reserved service procedures a) Connection establishment The user requests the service by service subscription as an administrative process. The subscription includes information identifying both users, the required bearer service, the t
36、ime (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 between the two interfaces is activated a
37、nd 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 (T3), as an administrative process be
38、tween the subscriber and the service provider. b) 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 components of the connection will be ac
39、cording to basic call procedures and the supplementary services subscribed to by the users. c) 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 connection may be terminated by eith
40、er or both of the users by indicating this to the network by signalling on the D-channel. d) 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 means of signalling on the D
41、-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-to-point configuration, t
42、he reserved service connection is not available while in the deactivated state. Temporary deactivation and reactivation may be achieved using the HOLD supplementary service. e) Programmed cyclical activation and deactivation Optionally, reserved communication services between pre-defined users may b
43、e 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 activatioddeactivation programme are beyo
44、nd the scope of this Recommendation. Recommendation 1.231.8 (07/96) 3 STDmITU-T RECMN 1-23L-B-ENGL L77b qBb259L Ob21327 BT7 W 3.4.1.1.2 Exceptional reserved service procedures a) Failure situations due to user error None identified. Failure situations due to user state Normal call procedures apply.
45、Failure situations due to network conditions i) b) 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 for a defined period of t
46、ime or until the cai1 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) Failure situations due to u
47、ser 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 - Availabiliy NOTE - Grade of service is not applicable to a reserved communication service. D
48、efinitions 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 (Recommendation G.821 is cross-ref
49、erenced in Recommendation 1.352). The procedure for assessment of the service availability performance may be found in Recom- mendation M.1016. The service availability performance of reserved services requires further study. 3.4.1.4 Dimensioning of network resources for reserved communication service Information regarding the dimensioning of network resources for reserved communication services may be found in Recommendation E.731, “Methods for dimensioning resources operating in circuit switched mode”. 3.4.1.5 Information transfer capability The
