1、ITU-T RECMN*I*37b 95 1 48b25L Ob00238 137.1 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.376 (03/95) INTEGRATED SERVICES DIGITAL NETWORK (ISDN) OVERALL NETWORK ASPECTS AND FUNCTIONS ISDN NETWORK CAPABILITIES FOR THE SUPPORT OF THE TELEACTION SERVICE .
2、- ITU-T Recommendation 1.376 (Previously “CCITT Recommendation”) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T RECMN-%I*37b 95 9862591 Ob00239 073 FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent orga
3、n 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 (WT
4、SC), 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 IT-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12
5、. 1993). IT-T Recommendation 1.376 was prepared by ITU-T Study Group 13 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 19th of March 1995. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administ
6、ration and a recognized operating agency, O ITU 1995 Ali 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, COPYRIGHT International Telecom
7、munications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCONTENTS Scope Introduction Abbreviations . Objectives of Teleaction . Functional requirements . Functional architecture . 5.1 Teleaction reference configuration . 5.2 Service and management communication 5.3 Teleaction
8、 service attributes . Service aspects . 6.1 Bearer services and supplementary services . 6.2 Quality of service Network capabilities . 7.1 Connection related functions 7.2 End-to-end supervision and monitoring . 7.3 Description of various polling techniques Interworking issues 8.1 8.2 Interworking w
9、ith privatdpublic networks . 8.3 Interworking with mobile systems 6.3 Security levels . Interworking with dedicated teleaction networks . Appendix I . Teleaction service attributes table . Appendix II . Specific applications Page 1 1 1 1 2 3 3 4 5 5 5 7 8 8 8 9 9 10 10 10 10 10 12 . Recommendation 1
10、.376 (03/95) i COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services ITU-T RECMN*I.376 95 4862593 Ob00243 723 SUMMARY Teleaction in ISDN is a future alternative to dedicated alarm network and modem based solutions of today. The solutions for
11、 teleaction applications today are mostly proprietary. The harmonization of service parameters and classes of security has not been specified by IT-T (former CCIIT), but by the International Electrotechnical Committee (IEC). The dedicated teleaction network were made to offer a service with better s
12、ecurity than the one offered by solutions based on PSTN technology. The advantages of implementing such applications in ISDN are: - the customer access is expected to be less expensive in the caie where the ISDN access is used for several services; operation, administration and maintenance can be in
13、tegrated more easily with other services; the user-network interface will be standardized; teleaction applications can be combined with other ISDN services into new applications (e.g. Teleaction and Videophony). - - - The purpose of this Recommendation is to describe the ISDN network capabilities re
14、quired for the provision of teleaction teleservice in an ISDN environment. ii Recommendation 1.376 (03/95) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T RECNN*I-376 95 4862591 Ob00242 668 = Recommendation 1.376 ISDN NETWORK CAPA
15、BILITIES FOR THE SUPPORT OF THE TELEACTION SERVICE (Geneva, 1994) O Scope The purpose of this Recommendation is to describe the ISDN network capabilities required for the provision of teleaction teleservice in an ISDN environment. 1 Introduction Teleaction in ISDN is a future alternative to dedicate
16、d alarm networks and modem based solutions of today. The solutions for teleaction applications today are mostly proprietary. The harmonization of service parameters and classes of security has not been specified by ITU-T (former CCIT), but by the International Elctrotechnical Committee (IEC). The de
17、dicated teleaction networks were made to offer a service with better security than the one offered by solutions based on PSTN technology. The advantages of implementing such applications in ISDN are: - the customer access is expected to be less expensive in the case where the ISDN access is used for
18、 several services; operation, administration and maintenance can be integrated more easily with other services; the user-network interface will be standardized; teleaction applications can be combined with other ISDN services into new applications (e.g. Teleaction and Videophony). - - - 2 Abbreviati
19、ons For the purposes of this Recommendation, the following abbreviations apply: CRF Connection Related Functions DSS 1 EUT End User Terminal FMBS Frame Mode Bearer Service HLF High Layer Functions ISDN Integrated Services Digital Network SPT Services Provider Terminal TMF Teleaction Management Funct
20、ion USBS User Signalling Bearer Service Digital Subscriber Signalling System No. 1 - 3 Objectives of Teleaction The Teleaction teleservice consists of a class of applications characterized by a number of basic properties: - they are interactive applications; - they have normally a low throughput as
21、compared to the traditional information transfer rate of ISDN-channels; they involve very short messages between terminals and usually a single host; they involve a large number of low cost terminals; - - Recommendation 1.376 (03/95) 1 COPYRIGHT International Telecommunications Union/ITU Telecommuni
22、cationsLicensed by Information Handling ServicesITU-T RECINUI-376 95 m 48b259L Ob00243 5T4 m - - - they require protection against unauthorized access and modification of messages; they require a supervised mode of information transfer providing at least some error protection; they have stringent re
23、quirements on the response time to individual transactions, and the availability/ reliability of the service. The applications of the Teleaction teleservice in ISDN may be divided into two broad categories, each with its own network implications and specific security functions. These two categories
24、are: applications without other specific requirements regarding service reliability and security functions than those offered by the bearer service, called hereafter non-sensitive applications; and applications with additional security and reliability requirements, called hereafter sensitive applica
25、tions. 1) 2) Applications of the Teleaction teleservice are for example: - telemetry; - remote process control; - meter reading; - alarm surveillance: and - funds transactions. Several levels of security will have to be regarded in providing Teleaction teleservice in ISDN, ensuring reliable communic
26、ation paths between end-users and between end-users and service providers, preventing from unauthorized access to protected data. This may require the introduction of a Teleaction Management Function (TMF) within the basic ISDN-network. Clause 4 describes network-based basic functions and higher lay
27、er messaging transport protocols for this purpose. 4 Functional requirements For some Teleaction applications, a separate unit called the Teleaction Management Function (TMF) within the public ISDN network, fulfils two major security requirements. The TMF ensures that the relevant applicatiodtermina
28、l is functioning, and that any disruption of service is immediately reported to the Service Provider Terminal or to the associated end-user terminal. The TMF also authenticates both the user terminals and the service provider terminal. ISDN does not offer today any dedicated mechanism guaranteeing t
29、hat the terminal (EUT or SPT) has not been replaced by a fake. In addition, network status information may be offered by the TMF to the SPT. If the service provider operates through the Packet Switched Data Network or a dedicated network, the TMF is considered to be the interworking unit, and is req
30、uired to perform adequate protocol translation. This clause outlines the functional requirements considered to be important to Teleaction applications, independently of where these functions are allocated. The following basic functions have been identified: application-independent secure telGaction
31、message delivery service from a terminal to a service provider and vice versa; protection against active attacks such as terminal replacement, terminal emulation, message modification or deletion, or spurious connection intitiation; message broadcasting from a service provider to a predefined number
32、 of destinations, e.g. for energy consumption monitoring and control; notification to the service provider of any loss, modification or deletion of messages; secure and permanent terminal monitoring, for example the detection of any deliberate disconnection by an intruder of the line between termina
33、l and the TMF, with immediate notification to the service provider of a terminal being considered inactive; fast message delivery according to predefined priority levels, ensuring for example the overriding of any alarm message over funds transactions or low priority alarm messages; protection again
34、st disclosure of message content to a third party according to a predefined message sensitivity level; 2 Recommendation 1.376 (03195) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITIJ-T 95 4862593 Ob00244 430 8) alternative routing i
35、n case of failure of network equipment of any kind (CRF, TMF, transmission, etc.); 9) notification of an alternative service provider in case of failure to communicate with the primary service provider; 10) traffic logging for audit and statistical purposes. NOTE - Some of the distinctions between t
36、eleaction messaging and conventional X.400 messaging are the very short time-to-delivery which is normally required to be 10-30 seconds, the limited set of delivery services that shortens the length of the message header, the secure permanent monitoring of the terminals by the SPT or by the network
37、that may impose a high level of traffic not carrying information and the stringent requirements in case of a single point of failure. 5 Functional architecture This clause describes the functional architecture, the reference configuration, the interfaces and the service attributes of the Teleaction
38、service, in accordance with the 1.200 and 1.300-Series Recommendations. The reference configuration complies with the requirements of the basic architectural model of 2D.324. The interfaces and service attributes comply with the requirements of Recommendation 1.210. 5.1 Teleaction reference configur
39、ation Figure 1 describes a generic reference configuration for the support of the Teleaction service by an ISDN. It describes the general functional arrangements involved, without going into the details of the many variations of the attributes of Recommendation 1.340 that may lead to a large number
40、of potential connection types. Basic network, including CRF and ) t“ tKx Dedicated teleaction T1302920-94/d01 NOTES 1 2 This figure does not preclude the SPT being connected to a dedicated teleaction network. A dedicated teleaction network can be a physical or a virtual net based upon, e.g. PSTN or
41、PSPDN. FIGURE 1D.376 Reference Configuration for the support of the Teleaction service by an ISDN Recommendation 1.376 (03/95) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services ITU-T RECMN*I.376 95 4862593 0600245 377 Pdling period d a
42、n EUT - Poll PollAck Info U Info * CPT Info Information message InfoAck Infomation acknovvledgement message T-lack Time for information transfer procedure FIGURE 3A.376 Service information transfer 5.3 Teleaction service attributes For further study. - NOTE -Appendix I contains preliminary material.
43、 6 Service aspects 6.1 A distinction between the Teleaction service, using high layer functions in the TMF, and services based on network bearer services using only layers 1-3 of the TMF has to be made and reflected by the selected protocol stack, in order to: restrict the relatively heavy traffic b
44、etween the TMF and the terminal, when permanent monitoring is required, to the local link between the TMF and the terminal, thus saving the significant cost of end-to-end secure inactivity control for all the terminals by minimizing the use of network resources; improve throughput due to priority-or
45、iented service in the TMF; reduce system traffic by means of distributing broadcast capabilities within the network. Bearer services and supplementary services - - - Recommendation 1.376 (03/95) 5 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling
46、 ServicesThe TMF can be used as an OS1 level 3 concentrator supporting for example IS0 8473 (connectionless protocol) encapsulated into X.25 PLP. thereby keeping only layers 1-3 of the Th4F active, reducing the complexity of the terminal and traffic costs. In that case, the ELFs of the Teleaction te
47、leservice can be based on a connection-oriented secure class 4 transport layer providing a network service in accordance with Recommendation X.213. These protocols can use connectionless network service, X.25 PLP or frame relay service. Figure 4 describes one possible implementation of the teleactio
48、n service protocol stack. . L7 P Application specific - L7 L7 + Message Handler -j L7 4 Message Handler * L7 L4 4 B- or D-channel based packet-mode and frame-mode bearer services, and within this category, several sub-options are available: Option - Virtual call or permanent virtual circuit bearer s
49、ervice (according to Recommenda- tion X.31.462). Opdon 2 - User signalling bearer service on the D-channel. Option 3 - Frame relay/frame switching of teleaction data-frame according to Recommenda- - tions Q.922 and 1.233. Option 4 - Connectionless bearer service. The teleservice is the normal way of communication, also for EUT to SPT alarms. The polling and authentication of the EUT and SPT are offered as a supplementary service feature. The additional capability of receiving a status report from the TMF called Terminal Stabs Reporting, must be defined along with other suppl
