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 already specifies detailed procedures applicable to call co
3、ntrol betweentwo PDNs of the same type;(e) that Recommendation X.10 describes categories of access to PSPDNs and ISDNs for the provision of datatransmission services;(f) that Recommendation X.213 describes the network service definition for open systems interconnection forCCITT applications;(g) that
4、 Recommendation X.305 describes functionalities of subnetworks relating to the support of the OSIconnection-mode network service;(h) that Recommendations Q.711 to 716 describe the signalling connection control part (SCCP) for commonchannel signalling;(i) the need to operate operations, administratio
5、n and maintenance (OA and M) applications over a variety ofnetworks, including CCSN and PSPDNs; and consequently the need for CCSN and PSPDNs to be able to interwork,unanimously recommendsthat arrangements for the interworking between PSPDNs and CCSN be in accordance with the principles andarrangeme
6、nts specified in this Recommendation.CONTENTS0 Introduction1 Scope and field of application2 References3 Definitions4 Abbreviations5 General aspects of interworking between CCSN and PSPDN6 Connection establishment phase7 Connection release phase8 Data transfer phase2 Fascicle VIII.6 - Rec. X.3260 In
7、troductionThis Recommendation is one of a set of Recommendations produced to facilitate considerations of interworkingbetween networks. It is based on Recommendation X.300, which defines the general principles for interworking betweenpublic data networks, and between public data networks and other n
8、etworks. Recommendation X.300 indicates inparticular how collections of physical equipment can be represented as “subnetworks“ for consideration in interworkingsituations.This Recommendation describes the interworking arrangements between PSPDNs and CCSN. Theseinterworking arrangements should includ
9、e all the capabilities required to support the network service for open systemsinterconnection for CCITT applications as described in Recommendation X.213.1 Scope and field of application1.1 Network operations, administration and maintenance (OA and M) applications need to be able to operate over av
10、ariety of networks, including public data networks.1.2 This Recommendation describes the interworking between CCSN and packet switched public data networks(PSPDNs), which may be needed for the transmission of operational information between Administrations, as a means ofdata transmission between ope
11、rational centres and/or terminals for those Administrations. This is illustrated in thefollowing Figure 1/X.326.1.3 It should be noted that, when dealing with OA and M protocols, a great confusion may appear between:- the network which is used to convey the OA and M information (e.g. CCSN or PDN in
12、Figure 1/X.326above);- the network which is controlled by the CCSN, with the support of the OA and M applications.It may furthermore happen that the controlled network interwork with a PDN, as illustrated in the followingFigure 2/X.326. Such an interworking is not considered as interworking between
13、CCSN and PDN; consequently it is notdescribed in the present Recommendation.Fascicle VIII.6 - Rec. X.326 32 References1 Recommendation X.200 Reference model of open systems interconnection for CCITT applications.2 Recommendation X.213 Network layer service definition for open systems interconnection
14、 (OSI) for CCITTapplications.3 Recommendation X.300 General principles for interworking between public networks, and between publicnetworks and other networks for the provision of data transmission services.4 Recommendation X.305 - Functionalities of subnetworks relating to the support of the OSI co
15、nnection-modenetwork layer service.5 Recommendation Q.711 - Functional description of the SCCP.6 Recommendation Q.712 - Definitions and functions of SCCP messages.7 Recommendation Q.713 - SCCP formats and codes.8 Recommendation Q.714 - SCCP procedures.9 Recommendation Q.716 - SCCP performances.3 Def
16、initions3.1 This Recommendation makes use of the following terms defined in Recommendations X.300 and X.305:a) Type I subnetworkb) Subnetworkc) Interworking function (IWF)d) OSI Network-connectione) (OSI) Network layerf) OSI) Network layer service3.2 This Recommendation makes use of the following te
17、rms defined in Recommendations Q.711, Q.712, Q.713and Q.714:a) (SCCP) Message (see Note)b) Message typec) Local reference4 Fascicle VIII.6 - Rec. X.326Note - The use of the concept of “Message“ in this Recommendation is not to be confused with other uses of thesame term “Message“ in different areas
18、(e.g., in the context of Message Handling Systems-MHS developed inthe X.400-series Recommendations).4 AbbreviationsCCSN Common channel signalling networkPDN Public data networkPSPDN Packet switched public data networkIWF Interworking functionOSI Open systems interconnectionOA- a type of packet, on P
19、SPDN side.Each type is recognized by:- the “message type“ parameter, on CCSN (SCCP) side;- the “packet type“ parameter, on PSPDN side.5.8 Each disconnection is identified by:- Source and destination local reference number, on CCSN (SCCP) side;- a logical channel number, on PSPDN side.Note - On PSPDN
20、 side, a logical channel number is usually local to an X.25 or X.75 interface. On the sameconnection, its value usually changes between two interfaces.6 Fascicle VIII.6 - Rec. X.3266 Connection establishment phase6.1 The following Tables 1/X.326 and 2/X.326 show the relationships between the primiti
21、ves used during theestablishment of an OSI network connection through interconnection CCSN (SCCP) and PSPDN, and the SCCPmessages and X.25/X.75 packets associated with that connection establishment.6.2 The actions and events at the interfaces to CCSN or PSPDN which correspond to those primitives are
22、 alsodescribed in 6 of Recommendation X.305.6.3 In the context of interworking between CCSN (SCCP) and PSPDN, Tables 1/X.326 and 2/X.326 describe amapping to be performed between SCCP messages and X.25/X.75 packets in relation with the OSI network layerservice.6.4 Since protocol class 3 of SCCP appl
23、ies to the interworking, any connection request SCCP message sent orreceived by the interworking function (IWF) should contain a “proposed protocol class“ set to 3. The action to be takenby the interworking function (IWF) if receiving a connection request SCCP message which proposes a protocol class
24、different from 3, is for further study.Any connection confirm (SCCP) message should contain a “selected protocol class“ set to 3. The action to betaken by the interworking function (IWF) if receiving a connection confirm SCCP message selecting a protocol class lessthan 3 is for further study.6.5 A c
25、onnection request SCCP message sent or received by the interworking function (IWF) should convey OSInetwork layer addresses, as needed to identify the called and calling parties involved in the connection.Note 1 - The extent of the requirement to support part or all of OSI network layer addresses is
26、 for further studyin relation to the interworking between CCSN and PSPDNs.Note 2 - The exact mapping of the OSI network layer addresses used at the interworking between CCSN andPSPDNs, into SCCP messages on one side, and into X.25/X.75 packets on the other side, is for further study.6.6 Since severa
27、l simultaneous connections may be required, it is necessary to identify each of these connections atthe interworking between CCSN and PSPDN (see also 5.8). In order to map the logical channel numbering schemes onboth sides, the interworking function (IWF) should connect a logical circuit on one side
28、 to a logical circuit on the otherside, as illustrated in Figure 4/X.326.6.7 During the establishment of a connection, quality of service (QOS) parameters are used to adjust the quality ofthe connection.Note - The exact mapping between the mechanisms used to adjust QOS, in SCCP on one side, and in X
29、.27/X.75on the other side, is for further study.Fascicle VIII.6 - Rec. X.326 77 Connection release phase7.1 Tables 1/X.326 to 3/X.326 show the relationships between the primitives used during the release of an OSInetwork connection through the interconnected CCSN (SCCP) and PSPDN, and the SCCP messa
30、ges and X.25/X.75packets associated with that connection release.7.2 The actions and events at the interfaces to CCSN or PSPDN which correspond to those primitives are alsodescribed in 7 of Recommendation X.305.7.3 In the context of interworking between CCSN (SCCP) and PSPDN, Table 3/X.326 describes
31、 a mapping to beperformed between SCCP messages and X.25/X.75 packets in relation with the OSI network layer service.Note - The exact mapping of OSI disconnect originators and reasons used at the interworking between CCSNand PSPDNs, into SCCP messages on one side, and into X.25/X.75 packets on the o
32、ther side, is for further study.TABLE 1/X.326OSI network layer service SCCP X.25/X.75PRIMITIVES :- Connect request- Connect indicationMESSAGES :- Connection request- Connection requestPACKETS :- Call request- Incoming callPARAMETERS:- (a) Called address- (b) Calling address- (c) Receipt confirmation
33、selection- (d) Expedited data selection- (e) QOS parameter set- (f) NS user dataPARAMETERS:- (a) Called party address- (b) Calling party address- (c) (for further study)- (d) (see Note)- (e) Credit, protocol class- (f) User-dataPARAMETERS (INCLUDINGFACILITIES):- (a) Called DTE addressCalled address
34、extension- (b) Calling DTE addressCalling address extension- (c) General format identifier field- (d) Expedited data negotiationfacility- (e) Throughput class negotiationfacilitiesTransit delay negotiationfacilities- (f) Call and called user data(fast select facility)Note - Expedited data is an intr
35、insic capability for all class 3 connections; therefore there is no need to explicitly indicate it in themessages.8 Fascicle VIII.6 - Rec. X.326TABLE 2/X.326OSI network layer service SCCP X.25/X.75PRIMITIVES :- Connect response- Connect confirmMESSAGES :- Connection confirm- Connection confirmPACKET
36、S :- Call accepted- Call connectedPARAMETERS:- (a) Responding address- (b) Receipt confirmationselection- (c) Expedited data selection- (d) QOS parameter set- (e) NS user dataPARAMETERS:- (a) Called party address- (b) (for further study)- (c) (for further study)- (d) Credit, protocol class- (e) User
37、-dataPARAMETERS (INCLUDINGFACILITIES):- (a) Called DTE addressCalled address extension- (b) General format identifier field- (c) Expedited data negotiationfacility- (d) Throughput class negotiationfacilitiesTransit delay negotiationfacilities- (e) User data(fast select facility)TABLE 3/X.326OSI netw
38、ork layer service SCCP X.25/X.75PRIMITIVES :- Disconnect request- Disconnect indicationMESSAGES :- Connection refused/released- Connection refused/releasedPACKETS :- Clear request- Clear indicationPARAMETERS:- (a) Originator- (b) Reason- (c) NS user-data- (d) Responding addressPARAMETERS:- (a)- (b)R
39、efusal / release cause+ Diagnostic(for further study)- (c) User data- (d) Called party addressPARAMETERS (INCLUDINGFACILITIES):- (a)- (b)Cause code anddiagnostic code- (c) Clear user data- (d) Called DTE addressCalled address extension8 Data transfer phase8.1 Tables 4/X.326 to 6/X.326 show the relat
40、ionships between the primitives used for the transfer of data on an OSInetwork connection through interconnected CCSN (SCCP) and PSPDN, and the SCCP messages and X.25/X.75 packetsassociated with that data transfer.8.2 The actions and events at the interfaces to CCSN or PSPDN which correspond to thos
41、e primitives are alsodescribed in 8 of Recommendation X.305.Fascicle VIII.6 - Rec. X.326 98.3 In the context of interworking between CCSN (SCCP) and PSPDN, Tables 4/X.326 to 6/X.326 describe amapping to be performed between SCCP messages and X.25/X.75 packets in relation to the OSI network layer ser
42、vice.TABLE 4/X.326OSI network layer service SCCP X.25/X.75PRIMITIVES :- Data request- Data indicationMESSAGES :- Data form- Data formPACKETS :- Data- DataPARAMETERS:- (a) NS user-data- (b) Confirmation requestPARAMETERS:- (a) User data- (b) Sequencing/segmenting(see Note)PARAMETERS (INCLUDINGFACILIT
43、IES):- (a) User dataM-bit- (b) D-bitP(S)Note - Since delivery confirmation is not provided, D-bit functions are not present in the parameterTABLE 5/X.326OSI network layer service SCCP X.25/X.75PRIMITIVES :- Reset request- Reset indicationMESSAGES :- Reset request- Reset requestPACKETS :- Reset reque
44、st- Reset indicationPARAMETERS:- (a) Originator- (b) ReasonPARAMETERS:(a)(b)Reset cause and diagnostic(for further study)PARAMETERS (INCLUDINGFACILITIES):- (a)- (b)Cause code anddiagnostic codePRIMITIVES :- Reset responseMESSAGES :- Reset confirmationPACKETS :- Reset confirmationPARAMETERS: No - -10
45、 Fascicle VIII.6 - Rec. X.326TABLE 6/X.326OSI network layer service SCCP X.25/X.75PRIMITIVES :- Expedited data request- Expedited data indicationMESSAGES :- Expedited data- Expedited dataPACKETS :- Interrupt- InterruptPARAMETERS:- (a) NS-user dataPARAMETERS:- (a) User dataPARAMETERS (INCLUDINGFACILI
46、TIES):- (a) Interrupt user data8.4 On an OSI network layer connection established through the interworking between CCSN and PSPDNs,network service data units (NSDUs) or any size may need to be conveyed. Consequently, segmenting and reassemblingis needed.The mechanism used to perform such segmenting
47、and reassembling are:- the more data bit (M bit) on PSPDN side;- the more data indicator (M bit) on CCSN (SCCP) side.8.5 On an OSI network layer connection established through the interworking between CCSN and PSPDNs, a dataflow control is exercised.Note - The exact mapping between the flow control
48、mechanisms used in SCCP protocol class 3 on one side,and X.25/X.75 on the other side, requires further study.8.6 Resets may occur during the data transfer phase of a connection.Note - The exact mappings of the OSI reset originators and reasons used at the interworking between CCSN andPSPDNs, into SCCP messages on one side, and into X.25/X.75 packets on the other side, is for further study.
