ITU-T X 340-1993 General Arrangements for Interworking between a Packet Switched Public Data Network (PSPDN) and the International Telex Network - Interworking between Networks Gen.pdf

1、CCITT RECflN*X-340 93 4862573 0578223 bOT I NTE R NATI O N AL TELECOM MU N IC AT1 O N U N I ON ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU INTERWORKING BETWEEN NETWORKS: GENERAL X.340 (03/93) GENERAL ARRANGEMENTS FOR INTERWORKING BETWEEN A PACKET SWITCHED PUBLIC DATA NETWORK (PSPDN) AND TH

2、E INTERNATIONAL TELEX NETWORK ITU-T Recommendation X.340 (Previously “CCITT Recommendation”) CCITT RECMN*X*340 93 4862591 0578222 546 H FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The IT-T is responsible for s

3、tudying technical, operating 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

4、 Groups which, in their turn, produce Recommendations on these topics. W-T Recommendation X.340 was prepared by the IT-T Study Group VI1 (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Unio

5、n (ITU), the CCITT ceased to exist as of 28 February 1993. In its place, the IT Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCJR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publica

6、tion of this Recommendation, 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 tbe proper terminology related to the new ITU stru

7、cture. 2 telecommunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O IT 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electr

8、onic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. CONTENTS Page Inuoduction 11 1 Scope and field of application 2 2 References 2 3 Definitions . 2 4 Abbreviations . 3 5 General aspects 3 6 Specific interworking arrangements . 5 . Recommendation X.3

9、40 (03/93) 1 I CCITT RECMN*X-340 73 = 9862593 0578229 319 INTRODUCTION This Recommendation is one of a set of Recommendations introduced to facilitate considerations of interworking between networks. It is based on Recommendation X.300, which defines the general principles for interworking between p

10、ublic data networks, and between public data networks and other networks for the provision of data transmission service. Recommendation X.300 indicates in particular bow collections of physical equipment can be represented as “sub-networks”C for consideration in interworking situations. The Recommen

11、dation describes the interworking arrangements between a PSPDN and the intemational telex network. In this case, the service provided to users is neither a data transmission service (see Recommendation X.300) nor is it the international telex service (see Recommendation F.60). 11 Recommendation X.34

12、0 (03193) CCITT RECMNUX.340 93 m 4862593 0578225 255 Recommendation X.340 GENERAL ARRANGEMENTS FOR INTERWORKING BETWEEN A PACKET SWITCHED PUBLIC DATA NETWORK (PSPDN) AND THE INTERNATIONAL TELEX NETWORK (Helsinki, 1993) Preface The establishment in various countries of public data networks providing

13、packet switched data transmission service creates a need to produce standards to facilitate interworking with the international telex network. The CCITT, considering (a) telex network; the urgent need to allow packet switched public data networks (PSPDNs) to interwork with the international cb) and

14、other networks; that Recommendation X.300 defines the general principles for interworking between public data networks (4 between subnetworks for the provision of data transmission services; that Recommendation X.301 defines the general arrangements for call control within a subnetwork and (d) subne

15、twork and between subnetworks for the provision of data transmission services; that Recommendation X.302 defines the general arrangements for internal network utilities within a (e) data networks and integrated service digital network (ISDNs); that Recommendation X.l defines intemational user classe

16、s of service in, and categories of access to, public (0 that Recommendation X.3 defuies the packet assembly/disassembly facility (PAD) in a public data network; (8) accessing the packet assembly/disassembly facility (PAD) in a public data network situated in the same country; that Recommendation X.2

17、8 specifies DTE/DCE interface for a start-stop mode data terminal equipment (h) between a packet assembly/disassembly (PAD) facility and a packet mode DTE or another PAD; that Recommendation X.29 specifies procedures for the exchange of control information and user data (i) between public networks p

18、roviding data transmission services; that Recommendation X.75 specifies detailed procedures applicable to packet switched signalling system ti) that Recommendation F.59 lists the general characteristics of the international telex service; (k) that Recommendation F.60 describes operational provisions

19、 for the international telex service; (1) international telex service and other services; that Recommendation F.80 defines the basic requirements to be met for interworking relations between the (m) international telex network and data terminal equipment on packet switched public data network; that

20、Recommendation F.83 defines the operational principles for communication between terminals of the Recommendation X.340 (03193) 1 CCITT RECMN*X.340 93 m 4862591 0578226 191 m (n) that R, S and U-Series Recommendations define the technical aspects of the international telex network; (0) that Recommend

21、ation U.203 specifies technical requirements to be met when providing real-time bothway communications between terminals on the international telex network and data terminal equipment on a packet switched public data network or via the PSTN, (unanimously) declares the view that arrangements for the

22、interworking between a PSPDN and the international telex network be in accordance with the principles and arrangements specified in this Recommendation. 1 The purpose of this Recommendation is to describe the general arrangements for the interworking between a PSPDN and the international telex netwo

23、rk. Scope and field of application 2 References The following Recommendations, and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other ref

24、erences are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references Listed below. A list of the currently valid Recommendations is regularly published. 1 Recommendati

25、on F.59 2 Recommendation F.60 3 Recommendation F.69 4 Recommendation F.80 5 Recommendation F.83 6 Recommendation S.l 7 Recommendation U.l 8 Recommendation U. 1 1 9 Recommendation U. 12 10 Recommendation U.203 1 1 Recommendation X. 1 12 Recommendation X.2 13 Recommendation X.3 14 Recommendation X.25

26、15 Recommendation X.28 16 Recommendation X.29 17 Recommendation X.75 18 Recommendation X.300 19 Recommendation X.301 20 Recommendation X.302 21 Recommendation X.305 3 Definitions This Recommendation makes use of the following terms defined in Recommendation X.300: a) subnetwork functionality; b) dat

27、a transmission service; c) interworking by port access. 2 Recommendation X.340 (03/93) CCITT RECMNmX.340 93 48b25L 0578227 O28 4 Abbreviations For the purpose of this Recommendation the following abbreviations are used: AU Access unit DTE Data terminal equipment ITA2 IWF Interworking function MSS Ma

28、ritime satellite service OS1 Open systems interconnection PAD Packet assembly/disassembly facility PSPDN Packet Switched Public Data Network TPIWF Telex-Packet interworking function International Telegraph Alphabet No. 2 5 General aspects This Recommendation, in describing interworking arrangements

29、between two networks, adheres to the general principies of Recommendation X.300. 5.1 Reference configuration The reference configuration for interworking between a PSPDN and the telex network is shown in Figure 1. DTfi*n PSPDN r DTm X.2E IWF Telex terminal FIGURE 1/X340 Reference configuration 5.2 T

30、he PSPDN provides packet switched data transmission services as defined in Recommendations X.1 and X.2 for the provision of data transmission services. The PSPDN may be accessed by DTEs through start-stop or synchronous direct connection (categories of access C and D as defined in Recommendation X.1

31、). In addition, the PSPDN may also be accessed via other networks i.e. PSTN (X.1 category L, P), CSPDN (X.1 category K, O), PSPDN (Recommendation X.73, MSS (Recommendation X.75), ISDN (Recommendation X.325), or the international telex network (this Recommendation). Packet switched public data networ

32、k (PSPDN) Recommendation X.340 (03193) 3 CCITT RECMN*X.340 93 4862591 0578228 T64 5.3 International telex network The international telex service is described in Recommendations F.59 and F.60. Signalling as applied within the international telex service is described in Recommendations U., U.ll andU.

33、12. In addition, the international telex network may also be accessed via a PSPDN (this Recommendation). 5.4 Call control between a PSPDN and the international telex network The general arrangements for call control between a PSPDN and the international telex network are as defined in this Recommend

34、ation. 5.5 Functionalities of the PSPDNs and the international telex network The functionalities of different types of subnetworks relating to the support of OS1 connection mode network service are described in Recommendation X.305. However, it should be noted that it is inappropriate in applying th

35、e functionalities of sub-networks to the international telex network since the international telex network cannot support the OS1 connection mode network service as defined in Recommendation X.213. 5.6 Characteristics of the interworking between PSPDN and the international telex network The internat

36、ional telex network supports the intemational telex service as described in Recommendations F.59 and F.60. A PSPDN provides packet switched data uansmission service which may be used to transfer various kinds of higher layer services such as Teletex and Videotex. Interworking between the internation

37、al telex service both with Teletex and Videotex is described in Recommendation F.201KJ.201 and F.86N.206, respectively and is not a part of this Recommendation. See Table 1 for a comparison of general characteristics of PSPDN and the intemational telex network. (the name of INTEX is given provisiona

38、lly). NOTE - Tbe international telex network may also support other standardized services, for example, the INTEX service 5.6.1 Interworking to provide the service specified in Recommendation F.83 In this mode of interworking, interworking via non-OS1 adaptor may be applied among the categories of i

39、nterworking described in Recommendation X.300. A TPIWF in accordance with Recommendation U.203 will perform as a non-OS1 adaptor which provides a PAD function for communication between a terminal of the international telex service and a DTE on a PSPDN. 5.6.2 Interworking by port access In this mode

40、of interworking, interworking via a non-OS1 adaptor may be applied among the categories of interworking described in Recommendation X.300. This interworking function is subdivided into a PAD function either in the PSPDN or stand-done and an Access unit (AU) which provides adaptation to/from telex si

41、gnalling and formats. 5.6.3 Interworking to provide end-to-end international telex service The arrangements for this type of interworking which are not included in Recommendation F.83 are for further study. 5.7 Interworking functions The interworking functions (Ws) considered in this Recommendation

42、are functional entities involved for the establishment of calls and the interchange of data between DTEs on a PSPDN and terminals on the international telex network. A general description of an IWF is given in Recommendation X.300. However, because of the service characteristics being addressed here

43、 (e b) TPWF provides conversion between telex signalling and protocols referred to in a) during call set up phase. FIGURE 2m.340 Interworking using one stage selection from the telex side 6 Recommendation X.340 (03/93) CCITT RECflN*X*340 93 48b2.591 O578233 559 W International telex service Port Acc

44、ess , Port a !) End- :ess c end call n International (Note 1) or internal Telex 1 terminal I TPIWF II -n TO71 73MT93/d03 NOTES 1 subscriber interface or a telex trunk interface. 2 3 Recommendation X.29. 4 This type of interworking is covered in 3.2m.203 “Two stage selection“ in this interworking arr

45、angement: The arrangement between the international telex network and the TPIWF can be either a telex Procedures for access into the international telex network as described in the U-Series Recommendations. Procedures described in Recommendation U.203. a) the arrangement between the TPIWF and the PS

46、PDN may be based on Recommendation X.75, or on Recommendation X.25, or on internal protocols; b) the TPIWF provides conversion between a protocol used at the interface between the PSPDN and the TPIWF, and international telex network signalling to set up the call from a DTE on the PSPDN to a terminal

47、 on the international telex network and vice versa. FIGURE 3m.340 Interworking using two stage selection from telex side Recommendation X.340 (03/93) 7 CCITT RECMN*X.340 93 4862591 0578232 475 m 6.3 Interworking by port access In this interworking method, the IWF is subdivided into a PAD function ei

48、ther in the PSPDN or stand-alone, and an access unit (AU) which provides the necessary conversion functions to gain access to and from the international telex network. The functions of the access unit include emulation of a telex terminal to the international telex network and of a start-stop mode D

49、TE which supports X.28 procedures to the PAD; code conversion in accordance with Recommendation S.18; handling of WU signals, answerbacks, ENQ and ACK characters. - - - The establishment of the connection through the intemational telex network may be initiated either by the telex terminal (“dial in to the PSPDN”) or by the AU following the reception by the PAD of an X.25 Cai1 Request packet from a DTE (“dial out to the international telex network). After establishing a connection through the international telex network between the AU and the telex terminal, X.28 procedures apply between