1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.231.7 (07/96) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Service capabilities - Bearer services supported by an ISDN Circuit-mode bearer service categories: Circuit-mode 1536 kbitls unrestricted, 8 kHz s
2、tructured bearer service ITU-T Recommendation 1.231.7 (Previously “CCITT Recommendation”) STD-ITU-T RECMN 1-231.7-ENGL 199b LiBb2571 Ob21311 bb9 ITU-T I-SERDES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE Terminology Description of ISDNs Generai modelling methods Telecommuni
3、cation network and service attributes I. 100-1.199 I. 110-1.1 19 1.120-1.129 1.130-1.139 I. 140-1.149 II Generai description of asynchronous transfer mode I. 150-1.199 General aspects of services in ISDN H 1.200-1.209 1.2 10-1.219 Common aspects of services in the ISDN 1.220-1.229 Teleservices suppo
4、rted by an ISDN Supplementary services in ISDN Network functional principies 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
5、interfaces Layer 1 Recommendations OVERALL NETWORK ASPECTS AND FUNCTIONS ISDN USER-NETWORK INTERFACES 1.240-1.249 1.250-1.299 1.300-1.399 1.310-1.319 1.320-1.329 1.330-1.339 1.340-1.349 1.350-1.359 1.3 60-1.369 1.370-1.399 1.400-1.499 1.420-1.429 1.430-1.439 II Layer 2 Recommendations 1.440-1.449 La
6、yer 3 Recommendations Multiplexing, rate adaption and support of existing interfaces Aspects of ISDN affecting terminal requirements INTERNETWORK INTERFACES MAINTENANCE PRINCIPLES B-ISDN EQUIPMENT ASPECTS ATM equipment Management of ATM equipment 1.450-1.459 1.460-1.469 1.470-1.499 1,500-1.599 1.600
7、-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 1-231-7-ENGL 177b 9 48b2571 Ob21312 5T5 FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (IT).
8、 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 years, establishes the top
9、ics for study by the IT-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 1-12, 1993). IT-T Recommendation 1.231.7 was revised by IT
10、U-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 administration and a recognized operating agency. O ITU 1996 Al
11、l 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 1.231.7 (07/96) 1 1 2 3 8 9 STD-ITU-T RECMN 1.231.7-ENGL 199b 48b2571 O
12、b21313 Li31 W CONTENTS Definition . Description . 2.1 General description . 2.2 Specific terminology . Procedures 3.1 Provisiodwithdrawal 3.2 Normal procedures 3.3 Exceptional procedures . 3.4 Alternative procedures Network capabilities for charging Interworking requirements . Applicability of suppl
13、ementary services Attributes and values of attributes of the circuit-mode 1536 kbit/s unrestricted. 8 kHz structured bearer service category Provision of individual circuit-mode 1536 kbit/s unrestricted, 8 ki-b structured bearer services Dynamic description Page 1 1 1 1 5 5 11 Recommendation 1.231.7
14、 (07/96) Recommendation 1.231.7 Subscription option Maximum number of information channels available at user B CIRCUIT-MODE BEARER SERVICE CATEGORIES: CIRCUIT-MODE 1536 kbit/s UNRESTRICTED, 8 kHz STRUCTURED BEARER SERVICE Value m, where m is not greater than the number of information channels on the
15、 interface - (revised in 1996) Maximum number of total calls present at user B 1 Definition - n, where n is not greater than the number of information channels on the interface This bearer service category provides the unrestricted transfer of 1536 kbiVs user information over an Hl1-channel at the S
16、/T 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 reference points. 2 Description
17、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 1536 kbii/s digital signals over the Hl 1-channel, in both directions continuously; three or more users in a multipoint co
18、nfiguration (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 being released. It is a networ
19、k provider option. The minimum value of this timer shall be 15 seconds. 3 Procedures 3.1 Provision/withdraw al Provision of this service will be by pre-arrangement with Administrations. This bearer service is offered with several subscription options which apply separately to each ISDN number or gro
20、up 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 1.231.7 (07/96) 1 1b 3.2 Normal procedures All user-n
21、etwork 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 identifying the called user. Other information. as required, for the bearer service and for u
22、se 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 ali the required information, or not en bloc. b) Indications during call set-up After initiating a call the c
23、alling 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. The calling user shall also be given an indication that the incoming call is being offered to the called use
24、r, 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 calling user. The called user may also provide other information for use by the network
25、in supplementary services provided to other users (e.g. connected line identity). Once established, the Hl1-channel is then available for the transmission of 1536 kbit/s digital signals in both directions continuously, without alteration by the network. No restriction is placed by the network on the
26、 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 the other user. 3.3 Exceptional procedures a) Failure situations due to user err
27、or 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 be given an appropriate failure indication by the network and the call Set-up wi
28、ll 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-determined user busy) will be given an appropriate failure indication by the network. A
29、 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 terminal equipment has responded that the called user is being informed of the ca
30、ll 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) Failure situations due to network conditions A user attempting to establish a call
31、but meeting call failure situations due to network conditions (e.g. congestion) will be given an appropriate failure indication by the network. Failure situations due to called user state andor network conditions A user attempting to establish a call but meeting call failure situations due to networ
32、k 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 1.231.7 (07/96) 3.4 Alternative procedures 3.4.1 Reserved service procedures A reserved communication service provides a long durat
33、ion 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 degree of control over connection establishment and termination not available on private leased circuits. 3.4.1.1 Connection establishment an
34、d termination Connection establishment and termination is by a combination of administrative procedures and signalling between the network and the user. Connection establishment and termination is as follows. 3.4.1.1.1 Normal reserved service procedures a) Connection establishment The user requests
35、the service by service subscription as an administrative process. The subscription includes information identifying both users, the required bearer service, the time (TI) that the connection is to be established and, optionally, the time (T2) that the connection is to be terminated, or the duration
36、for which the connection is to remain established (T3). At time (Ti), the network-to-network component of the connection between 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
37、 D-channel. Optionally, the subscriber may modify the time for which the reserved communication service connection is active (T3), as an administrative process between the subscriber and the service provider. b) Indications during connection establishment Both users receive indications of the establ
38、ishment of the network-to-network component of the connection. Indications during the establishment of the user-to-network components of the connection will be according to basic call procedures and the supplementary services subscribed to by the users. c) Connection termination At time T2 the netwo
39、rk 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 either or both of the users by indicating this to the network by signalling on the D-channel. d) Temporary deactivation and reactivation Prior
40、 to time T2, one user may temporady deactivate the user-to-network component of the connection by indicating this to the network by means 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 mean
41、s of signalling on the D-channel. Network-to-network components of the connection remain established during this procedure. In a point-to-point configuration, the reserved service connection is not available while in the deactivated state. Temporary deactivation and reactivation may be achieved usin
42、g the HOLD supplementary service. Programmed cyclical activation and deactivation e) Optionally, reserved communication services between 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 communicat
43、ion connection activatioddeactivation to be provided per user per day, and degree of flexibility to be provided in the activatioddeactivation programme are beyond the scope of this Recommendation. Recommendation 1.231.7 (07/96) 3 3.4.1.1.2 Exceptional reserved service procedures a) Failure situation
44、s due to user error None identified. b) Failure situations due to user state Normal 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 period
45、ically (for example at five minute intervals) re-attempt to establish the call for 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-establ
46、ish the call to both users terminals and continue as per c) i) above. ii) d) Failure situations due to user state ador network conditions None identified. 3.4.1.2 Operation and maintenance support Operation and maintenance support is covered in the 1.60-Series of Recommendations. 3.4.1.3 Quality of
47、service - Availability NOTE - Grade of service is not applicable to a reserved communication service. Definitions concerning availability may be found in Recommendations in the E.80-Series. Definitions concerning the duration of unavailable time for international digital connections forming part of
48、an integrated services digital network may be found in Annex NG.821 (Recommendation G.821 is cross-referenced 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 servi
49、ces 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.73 1, “Methods for dimensioning resources operating in circuit switched mode”. 3.4.1.5 Information transfer capability The format and content of 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 Perman
