1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 8 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%27/2+).G0G0“%47%.G0G0.%47/2+3%.%2!,%.%2!,G0G0!22!.%-%.43G0G0(b) that Recommendation X.301 defines the general arrangements for call control within a subnetwork andbetween subnetworks for the provision of
2、data transmission services;(c) that Recommendation X.302 defines the general arrangements for internal network utilities within asubnetwork and between subnetworks for the provision of data transmission services;(d) that Recommendation X.75 defines procedures for PSPDN/PSPDN interworking and thatRec
3、ommendations X.61 and X.71 define procedures for CSPDN/CSPDN interworking;(e) that Recommendation X.10 describes categories of access to PDNs and ISDNs for the provision of datatransmission services;(f) that Recommendation X.213 describes the network service definition for open systems interconnecti
4、onfor CCITT applications;(g) that Recommendation X.305 describes functionalities of subnetworks relating to the support of the OSInetwork service;(h) the desirability to maintain compatibility in the procedures used at layers 1, 2 and 3 on CSPDN, for currentand future telematic terminals, and also f
5、or terminals in non-telematic applications;(i) that Recommendation X.223 defines the use of X.25 to provide the OSI connection-mode network service;(j) that Recommendation T.70 defines the network-independent basic transport service for the telematicservices;(k) that Recommendation X.32 defines the
6、interface between DTE and DCE for terminals operating in thepacket-mode and accessing a PSPDN through a PSTN or an ISDN or a CSPDN;(l) that Recommendation X.82 defines detailed arrangements for interworking between CSPDNs and PSPDNsbased on Recommendation T.70;(m) the need for arrangements when inte
7、rworking between PSPDNs and CSPDNs for the provision of datatransmission services,unanimously recommendsthat arrangements for the interworking between PSPDNs and CSPDNs for the provision of data transmissionservices be in accordance with the principles and arrangements specified in this Recommendati
8、on.2 Fascicle VIII.6 - Rec. X.322CONTENTS0 Introduction1 Scope and field of application2 References3 Definitions4 Abbreviations5 General aspects6 Specific interworking arrangements0 IntroductionThis Recommendation is one of a set of Recommendations produced to facilitate considerations of interworki
9、ngbetween networks. It is based on Recommendation X.300, which defines the general principles for interworking betweenpublic networks, and between public networks and other networks for the provision of data transmission services.Recommendation X.300 indicates in particular how collections of physic
10、al equipment can be represented as“subnetworks“ for consideration in interworking situations.This Recommendation describes the interworking arrangements between CSPDNs and PSPDNs for the provisionof data transmission services.1 Scope and field of applicationThe purpose of this Recommendation is to d
11、escribe the general arrangements for the interworking betweenPSPDNs and CSPDNs for the provision of data transmission services (Note 1). These arrangements are applicable onlyto the interworking involving transmission capabilities, and not to interworking involving communication capabilities asdescr
12、ibed in Recommendation X.300.Note 1 - These arrangements could also be used for the support of telematic services.Note 2 - The typing of subnetworks in this Recommendation is based on the support for the OSI connection-mode network service and is therefore only valid in that context.Other types of s
13、ubnetworks supporting other services and applications are for further study.2 ReferencesX.300 General principles for interworking between public networks, and between public networks and othernetworks for the provision of data transmission servicesX.301 Description of the general arrangements for ca
14、ll control within a subnetwork and between subnetworks forthe provision of data transmission servicesX.302 Description of the general arrangements for internal network utilities within a subnetwork and intermediateutilities between subnetworks for the provision of data transmission servicesX.305 Fun
15、ctionalities of subnetworks relating to the support of the OSI connection-mode network serviceX.1 International user classes of service in public data networks and integrated services digital networks (ISDNs)X.2 International data transmission services and optional user facilities in public data net
16、works and ISDNsX.10 Categories of access for data terminal equipment (DTE) to public data transmission servicesX.71 Decentralized terminal and transit control signalling system on international circuits between synchronousdata networksX.75 Packet switched signalling system between public networks pr
17、oviding data transmission servicesX.82 Detailed arrangements for interworking between CSPDNs and PSPDNs based on Recommendation T.70X.121 International numbering plan for public data networksX.223 Use of X.25 to provide the OSI connection-mode network service for CCITT applicationsT.70 Network indep
18、endent basic transport service for telematic servicesFascicle VIII.6 - Rec. X.322 33 DefinitionsThis Recommendation makes use of the following terms defined in Recommendation X.300:a) transmission capability,b) communication capability,c) subnetwork functionality,d) data transmission service,e) netw
19、ork*,f) interworking by call control mapping,g) interworking by port access.4 AbbreviationsCSPDN Circuit switched public data networkDTE Data terminal equipmentISDN Integrated services digital networkIWF Interworking functionLAN Local area networkMSS Maritime satellite servicePBX Private branch exch
20、angePSPDN Packet switched public data networkPSTN Public switched telephone networkQOS Quality of serviceTNIC Transit network identification code5 General aspectsThis Recommendation, in describing interworking arrangements between two subnetworks for the provision ofdata transmission services, adher
21、es to the general principles of Recommendation X.300. The environments of these twosubnetworks are described in the following sections.5.1 PSPDNThe PSPDN provides packet switched data transmission services described in Recommendations X.1 and X.2.For the provision of data transmission services, the
22、PSPDN may be accessed by DTEs by the categories of access Cand D as defined in Recommendation X.10. In addition, the PSPDN may also be accessed via other networks, i.e., PSTN(X.10 category L, P), CSPDN (X.10 category K, O and this Recommendation), PSPDN (Recommendation X.75), MSS(Recommendation X.75
23、), or ISDN (Recommendation X.325). Private networks access the PSPDN via X.10 category ofaccess D.5.2 CSPDNThe CSPDN provides circuit switched data transmission services described in Recommendations X.1 and X.2.For the provision of data transmission services, the CSPDN may be accessed by DTEs by the
24、 categories of access B asdefined in Recommendation X.10. In addition, the CSPDN may also be accessed via other networks, i.e., PSPDN (thisRecommendation), CSPDN (Recommendation X.71), or ISDN (Recommendation X.321). Access of private networksand mobile systems to the CSPDN is for further study (see
25、 Recommendation X.300).5.3 Call control between the PSPDN and CSPDNThe general arrangements for call control between the PSPDN and CSPDN are as defined inRecommendation X.301. Network utilities used between the PSPDN and CSPDN are as defined inRecommendation X.302 (not visible for users).4 Fascicle
26、VIII.6 - Rec. X.3225.4 Functionalities of the PSPDN and CSPDNThe functionalities of different types of subnetworks are described in Recommendation X.300. Thefunctionalities of the PSPDN and CSPDN differ. Therefore, in order to enable interworking, procedures must beoperated over the CSPDN to achieve
27、 functional compatibility.Two different sets of procedures are considered for this purpose:a) T.70 based procedures for the support of telematic procedures (see 6.1);b) X.25 based procedures (see Recommendation X.32); (see 6.2).However, the T.70 based procedures do not provide full functional compat
28、ibility; some protocol elements fromthe PSPDNs cannot be mapped by the IWF (see Recommendation X.82).TABLE 1/X.322Comparison of general characteristics of PSPDN and CSPDNGeneral characteristics PSPDN CSPDNData transmission service/Bearer serviceX.1, X.2 X.1, X.2Optional user facilities/Supplementary
29、 servicesX.2 X.2Categories of access X.10 categories C, D X.10 category BAccess via other networksPSTNCSPDNPSPDNMSSISDNPrivate networksX.10 categories L, PThis RecommendationX.323X.324X.325X.327-X.71This Recommendation-X.321Further study5.5 Routing5.5.1 Routing considerations related to the use of T
30、.70a) When crossover from packet switched to circuit switched PDNs is needed, this changeover should occur aslate as possible:i.e., going from A to D, crossover at (3) is preferred.Fascicle VIII.6 - Rec. X.322 5b) The T.70 ( 3.3.3) based solution should not be used for cases where the CSPDN acts as
31、transit network incases where the preservation of functional compatibility is necessary to the highest possible extent.c) It is for further study whether beyond an X.21 subscriber interface, typically private networks may need to beexpected other than PBX type (circuit switched) of networks (e.g., n
32、ot LANs). This assumption isparticularly relevant for the treatment of QOS parameters in the IWF.5.5.2 IWF selectionWhen the crossover from PSPDN to CSPDN is needed, the appropriate IWF must be selected, i.e., X.25based IWF, or the T.70 based IWF. (In case the IWFs are physically collocated, still t
33、he proper procedures must beselected.) The appropriate selection can be made on the basis of the called DTE address.6 Specific interworking arrangements6.1 Interworking by call control mappingThe interworking arrangement is illustrated in Figure 2/X.322.In this interworking arrangement:a) the intern
34、ational arrangement between both subnetworks (i.e., in the figures between the interworkingfunctions and the PSPDN) is based on Recommendation X.75;b) the interworking function (IWF) provides conversion between signalling system X.71 or X.61, and X.75.During data transfer phase, and for telematic te
35、rminals mentioned in Recommendation T.70, the protocolsdefined in 3.3.2 and 3.3.3 of T.70 are used on CSPDN at layers 2 and 3; for other terminals on CSPDN,the application of these protocols or alternative protocols is possible.Note 1 - In establishing international accounting principles in relation
36、 with this interworking arrangement,consideration should be given to the distribution of the functional elements involved in this interworking arrangement(e.g., cost/revenues of the IWF).Note 2 - For any of the cases in 6.1, the Administrations involved may agree exceptionally that theinterworking f
37、unction or crossover point between the CSPDN and PSPDN be placed in a country different thanthe CSPDN.The detailed procedures for interworking are defined in Recommendation X.82 (does not yet cover the X.61case). In particular, the following applies:6.1.1 Transfer of addressing informationFor furthe
38、r study.6.1.2 Arrangements for facilities related to the QOS of the callFor further study.6.1.3 Arrangements for facilities relating to charging conditions applying to the callFor further study.6.1.4 Arrangements for facilities relating to specific routing conditions applying to the callFor further
39、study.6 Fascicle VIII.6 - Rec. X.3226.1.5 Arrangements for facilities related to protection mechanisms requested by the user of the callFor further study.6.1.6 Arrangements for facilities to convey user data in addition to the normal data flow in the data transfer phaseFor further study.6.1.7 Arrang
40、ements for other facilitiesFor further study.6.1.8 Arrangements for internal network utilities (not visible for users)These arrangements are as described in Recommendation X.302.6.2 Interworking by port accessThe interworking arrangement is illustrated in Figure 3/X.322.The detailed procedures for i
41、nterworking are defined in Recommendation X.32. In particular, the followingapplies:6.2.1 Transfer of addressing informationThese arrangements are described in Recommendation X.301.6.2.2 Arrangements for facilities related to QOS of the callThese arrangements are described in Recommendation X.301.6.
42、2.3 Arrangements for facilities relating to charging conditions applying to the callThese arrangements are described in Recommendation X.301.6.2.4 Arrangements for facilities relating to specific routing conditions applying to the callThese arrangements are described in Recommendation X.301.6.2.5 Ar
43、rangements for facilities related to protection mechanisms requested by the user of the callThese arrangements are described in Recommendation X.301.Fascicle VIII.6 - Rec. X.322 76.2.6 Arrangements for facilities to convey user data in addition to the normal data flow in the data transfer phaseThese arrangements are described in Recommendation X.301.6.2.7 Arrangements for other facilitiesThese arrangements are described in Recommendation X.301.6.2.8 Arrangements for internal network utilities (not visible for users)These arrangements are as described in Recommendation X.302.
