1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 8 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%27/2+).G0G0“%47%.G0G0.%47/2+3%.%2!,$%3#2)04)/.G0G0/(b) that Recommendation X.301 defines the general arrangements for call control within a subnetwork andbetween subnetworks for the provision of data tran
2、smission services;(c) that interworking with common channel signalling network (CCSN) needs to be considered, in view ofthe requirements for transferring operational information between Administrations;(d) the need that interconnected networks can communicate the necessary internal utilities related
3、 to theoperation of the data transmission services;(e) that Recommendations X.61, X.70, X.71 and X.75 already specify the detailed procedures applicable tocall control between two PDNs of the same type;(f) the need for arrangements for interworking between subnetworks;(g) the need, in particular, fo
4、r certain inter-network utilities defined between international exchange systemsfor the provision of data transmission services;(h) the need for compatibility and uniformity in the principle for realization of internal network utilitieswithin a subnetwork and between subnetworks for the provision of
5、 data transmission services,unanimously recommendsthat arrangements for internal utilities within a subnetwork and between subnetworks for the provision of datatransmission services, and that the necessary elements for realization of such internal network utilities be in accordancewith the principle
6、s and arrangements specified in this Recommendation.CONTENTS0 Introduction1 Scope and field of application2 References3 Definitions4 Abbreviations5 General aspects of call control6 Arrangements for internal network utilities2 Fascicle VIII.6 - Rec. X.3026.1 Network identification6.1.1 General6.1.2 O
7、riginating network identification6.1.3 Destination network identification6.1.4 Transit network identification6.1.5 Clearing network identification6.2 Call identifier6.3 Target quality of service parameters6.4 Tariffs6.5 Network user identification0 IntroductionThis Recommendation is one of a set of
8、Recommendations produced to facilitate consideration ofinterworking between networks. It is related to Recommendation X.300, which defines the general principles forinterworking between public networks, and between public networks and other networks for the provision of datatransmission services. Re
9、commendation X.300 indicates in particular combinations of physical equipment can berepresented as “subnetworks“ for consideration of interworking situations.This Recommendation describes utilities that can be used within a subnetwork and between subnetworks forthe provision of data transmission ser
10、vices. Only those utilities are described that are needed for the internal and inter-network operation, and that are not visible to the end users of a call. Facilities that are (also) visible to end users of acall are subject of other Recommendations (e.g. those arrangements described in Recommendat
11、ion X.301).1 Scope and field of applicationThe purpose of this Recommendation is to describe general arrangements for internal network utilitiesapplicable to interworking at the network layer. Such arrangements are not visible for the end users of the networklayer connection and apply within a subne
12、twork and between subnetworks.These arrangements are not applicable to interworking involving communication capability as described in 7of Recommendation X.300.2 ReferencesX.61 Signalling system No. 7 - Data user part.X.70 Terminal and transit control signalling system for start-stop services on int
13、ernational circuits betweenanisochronous data networksX.71 Decentralized terminal and transit control signalling system on international circuits between synchronousdata networksX.75 Packet switched signalling system between public networks providing data transmission servicesX.121 International num
14、bering plan for public data networksX.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 call control within a subnetwork and between subnetwor
15、ks forthe provision of data transmission services.3 DefinitionsThis Recommendation makes use of the following terms defined in Recommendation X.300:Fascicle VIII.6 - Rec. X.302 3a) transmission capability;b) communication capability;c) data transmission services.This Recommendation makes use of the
16、following terms defined in Recommendation X.301:a) call request phase;b) call information phase;c) data transfer phase;d) call clearing phase.4 AbbreviationsCCSN Common channel signalling networkCNIC Clearing network identification codeCSPDN Circuit switched public data networkDCC Data country codeD
17、CE Data circuit-terminating equipmentDNIC Data network identification codeDTE Data terminal equipmentIDSE International data switching exchangeINIC ISDN network identification codeISDN Integrated services digital networkNI Network identifierNUI Network user identificationPDN Public data networkPSPDN
18、 Packet switched public data network5 General aspectsThe network utilities described in this Recommendation can be applied for internal network operation and forarrangements between networks, and are not conveyed across the DTE/CDE interface.The general principles concerning inter-network signals ar
19、e defined in Recommendation X.301, in particularthe phases related to a call:- call request and call confirmation phases,- data transfer phase,- call clearing phase.4 Fascicle VIII.6 - Rec. X.302The corresponding model applicable to inter-network arrangements is reproduced in Figures 5-1/X.302 and5-
20、2/X.302.6 Arrangements for internal network utilities6.1 Network identification6.1.1 GeneralThe international network identification utilities provide information about the network(s) from, via or towhich an international call is routed. In the general case, the term network identifier (NI) is the n
21、ame of the numberthat identifies a network. Depending on the type of network and geographic location of the network, the format of theNI may vary.A PDN is identified by four decimal digits that indicate:a) in the case of the network of a country using the DCC format of the international data numberi
22、ng plan(see Recommendation X.121), the applicable DCC plus one digit consistent with the numbering plan;b) in the case of a network using the DNIC format of the international data numbering plan (seeRecommendation X.121), the applicable DNIC.Fascicle VIII.6 - Rec. X.302 5In the short term, an ISDN i
23、s identified by a 4-digit INIC (ISDN network identification code), that has beendesigned not to coincide with a valid PDN DNIC value (see Recommendation X.75).Note - The long term solution for network identification (NI) is for further study.6.1.2 Originating network identificationThe originating ne
24、twork identification utility identifies the originating network of a call.In the packet-switched data transmission service in PSPDNs, the identity of the originating network (DNIC) istransferred in the call request phase to the destination networks as part of the international data number (seeRecomm
25、endation X.75). To perform the function of the originating network identification utility this DNIC, which ispart of the international data number, is always either inserted or checked by the originating network.Provision of originating network identification as an optional network utility on reques
26、t by a transit ordestination network on a per call basis is mandatory for the circuit-switched data transmission service.In the case of common channel signalling (see Recommendation X.61), a network requiring identification ofthe originating network requests such identification by returning an origi
27、nating network identification requestindication. When receiving such a request the originating network responds by sending:a) the complete calling line identity in accordance with 6.2.4 of Recommendation X.301 in the case wherethe calling line identification facility is provided by the originating n
28、etwork and such identification isalso requested;b) the originating network identity in the case where calling line identification is not provided or requested.In the case of decentralized signalling (see Recommendations X.70 and X.71), a network requiringidentification of the originating network req
29、uests such identification by returning a calling line identification requestindication. When receiving such a request, the originating network responds with the calling line identity or theoriginating network identity depending on whether or not the calling line identification facility is provided b
30、y theoriginating network (see 6.2.4 of Recommendation X.301).6.1.3 Destination network identificationThe destination network identification utility identifies the destination network of a call.In the circuit-switched data transmission service in CSPDNs destination network identification for allinter
31、national calls is a mandatory network utility. Thus, for each international call the identity of the destinationnetwork is returned in accordance with the applicable signalling procedures (see Recommendations X.61, X.70 andX.71).In the packet-switched data transmission service, the identity of the d
32、estination network (DNIC) may betransferred in the call confirmation phase to the originating network as part of the international data number (seeRecommendation X.75). When transferred, this DNIC must either be inserted or checked by the destination network.6.1.4 Transit network identificationThe t
33、ransit network identification utility identifies the transit network(s) via which the call has been set up,and is conveyed during the call request phase.In the packet-switched data transmission service in PSPDNs and ISDNs transit network identification, in boththe forward and backward directions, is
34、 a mandatory network utility for international calls (see RecommendationX.75).In the circuit-switched data transmission service in CSPDNs transit network identification in the backwarddirection is a mandatory network utility for international calls (see Recommendations X.61, X.70 and X.71).In cases
35、where more than one transit network is identified, the identities are indicated in the order of transitnetworks traversed by the call following the established path from the calling user towards the called user.6 Fascicle VIII.6 - Rec. X.3026.1.5 Clearing network identificationThe CNIC utility ident
36、ifies the network that has cleared the call and is only used when the call clearing phasehas been initiated by a network during the data transfer phase.In the packet switched data transmission service in PSPDNs and ISDNS, the CNIC is an optional networkutility, subject to bilateral agreement between
37、 Administrations (see Recommendation X.75).The network initiating the call clearing phase is identified in PDNs and ISDNs by the NI (seeRecommendations X.75 and X.121). An IDSE receiving a CNIC will pass this code unchanged whenever applicable.6.2 Call identifierThe call identifier utility gives the
38、 identification of a call. When the utility is used in conjunction with thecalling DTE address, it uniquely identifies the call over a period of time, the duration of this time period is for furtherstudy. This utility is standardized for packet-switched data transmission service in PSPDNs and ISDNs
39、(seeRecommendation X.75).A significant call identifier may or may not be created for a given call (see also Note 2). This is theresponsibility of the originating network. Each transit network will always transfer a received significant call identifierwithout change. The definition of the content of
40、the call identifier, and further specification of the associated signallingmechanisms, require further study.Note 1 - However, it is for further study whether a transit network can create a significant call identifier, if itreceived a call identifier which was not significant.Note 2 - On links desig
41、ned according to Recommendation X.75, a call identifier utility of 4 octets is alwayspresent in the call request packet. The value of the 3 octet call identifier parameter may or may not be significant.In the permanent virtual circuit service, the call identifier might be systematically required. Ho
42、wever, it is leftfor further study.6.3 Target quality of service parametersIt is for further study whether or not a network utility is required to signal information related to theachievement of target quality of service parameters (e.g. target transit delay) for network purposes outside the control
43、of a user (see also 7.1 of Recommendation X.301).6.4 TariffsThe tariffs utility is an optional utility, standardized for PSPDNs and ISDN (PS). Support of this utility for agiven inter-network interface is subject to a bilateral agreement between Administrations.The utility is used to pass informatio
44、n from one network to one or more other networks participating in the callfor the purpose of implementating billing, accounting, or tariff arrangements that may exist among the respectiveAdministrations.The tariffs utility may appear in the call request, call confirmation and clear request phases of
45、 a call. If thisutility appears in the call confirmation or clear request phase, the information it contains relates to the ultimatedestination interface of the network. The utility may appear in the clear request phase only if that phase is initiated bythe destination DTE or DCE, in direct response
46、 to the call request phase.The content of this utility is determined by the originating or destination network and does not depend oninformation passed to the network by a DTE.Even if this utility is supported on the inter-network interface, it may not be present in a phase for a given callif there
47、is no need to exchange tariff-related information with that phase.Fascicle VIII.6 - Rec. X.302 76.5 Network user identification (NUI)The network user identification utility is an optional network utility standardized for PSPDNs and ISDNs(PS). The use of this utility is subject to bilateral agreement
48、 between Administrations.The utility may be present in the call request. Use of utility in the call confirmation phase is for further study.As agreed by the interfacing Administrations, the parameter field of this utility appearing in the call requestphase may contain:a) all, part or none of the parameter field of the NUI selection facility passed to the network by the DTE inthe call request phase, and/orb) an appropriate network-generated identification/verification/security code associated with thecorresponding end user.
