1、Standard ECMA-252December 1996Standardizing Information and Communication SystemsPhone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http:/www.ecma.ch - Internet: helpdeskecma.chBroadband Private IntegratedServices Network (B-PISN) -Inter-Exchange SignallingProtocol -Transit CounterAdditional Net
2、work Feature.Standard ECMA-252December 1996Standardizing Information and Communication SystemsPhone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http:/www.ecma.ch - Internet: helpdeskecma.chGL Ecma-252.doc 28-02-97 11,54Broadband Private IntegratedServices Network (B-PISN) -Inter-Exchange Signal
3、lingProtocol -Transit CounterAdditional Network Feature(B-QSIG-TC).Brief HistoryThis Standard is one of a series of ECMA standards defining services and signalling protocols applicable to Broadband PrivateIntegrated Services Networks. The series uses the B-ISDN concepts as developed by ITU-T (former
4、ly CCITT) and is alsowithin the framework of standards for open systems interconnection as defined by ISO.This Standard specifies the signalling protocol for use at the Q reference point in support of the Transit Counter additionalnetwork feature.The Standard is based upon the practical experience o
5、f ECMA member companies and the results of their active andcontinuous participation in the work of ISO/IEC JTC1, ITU-T, ETSI and other international and national standardizationbodies. It represents a pragmatic and widely based consensus.This ECMA Standard is contributed to ISO/IEC JTC1 under the te
6、rms of the fast-track procedure for adoption as an ISO/IECInternational Standard.This Standard has been adopted by the ECMA General Assembly of December 1996.- i -Table of contents1 Scope 12 Conformance 13 References (normative) 14 Definitions 14.1 External definitions 15 List of acronyms 26 Signall
7、ing protocol for the support of ANF-TC 26.1 ANF-TC description 26.2 ANF-TC operational requirements 36.2.1 Requirements on the Originating PINX 36.2.2 Requirements on the Terminating PINX 36.2.3 Requirements on a Transit PINX 36.3 ANF-TC coding requirements 36.3.1 Transit counter information element
8、 36.3.2 Messages 46.4 ANF-TC signalling procedures 46.4.1 Actions at the Originating PINX 46.4.2 Actions at the Terminating PINX 46.4.3 Actions at a Transit PINX 46.4.4 At an Incoming Gateway PINX 46.4.5 At an Outgoing Gateway PINX 4Annex A - Protocol Implementation Conformance Statement (PICS) prof
9、orma 5- ii -1ScopeThis Standard specifies the signalling protocol for the support of the Transit Counter additional network feature (ANF-TC) at the Q reference point between Private Integrated Services Network Exchanges (PINXs) connected togetherwithin a Broadband Private Integrated Services Network
10、 (B-PISN).ANF-TC is a feature that limits the number of Transit PINXs that a call/connection setup request may be routedthrough e.g., to protect the network against indefinite looping.The Q reference point is defined in ISO/IEC 11579-1.Service specifications are produced in three stages and accordin
11、g to the method specified in CCITT Rec. I.130. ThisStandard contains the stage 3 specification for the Q reference point and satisfies the requirements identified by thestage 1 and stage 2 specifications in ECMA-224.The signalling protocol for ANF-TC operates in association with the signalling proto
12、cols for basic call/connectioncontrol (as specified in ISO/IEC DIS 13247) and call independent (connection oriented) signalling connections (asspecified in ECMA-254).This Standard is applicable to PINXs that can interconnect to form a PISN.2 ConformanceIn order to conform to this Standard, a PINX sh
13、all satisfy the requirements identified in the Protocol ImplementationConformance Statement (PICS) proforma in annex A.3 References (normative)The following standards contain provisions which, through reference in this text, constitute provision of this Standard.All standards are subject to revision
14、, and parties to agreements based on this Standard are encouraged to investigate thepossibility of applying the most recent editions of the standards indicated below.ECMA-224 Private Integrated Services Network (PISN) - Specification, Functional Model and InformationFlows - Transit Counter Additiona
15、l Network Feature (1995)ECMA-254 Broadband Private Integrated Services Network (B-PISN) - Inter-Exchange Signalling Protocol- Generic Functional Protocol (1996)ISO/IEC 11579-1 Information technology - Telecommunications and information exchange between systems -Private Integrated Services Network -
16、Part 1: Reference configuration for PISN Exchanges(PINX) (1994)ISO/IEC DIS 13247 Information technology - Telecommunications and information exchange between systems -Broadband Private Integrated Services Network - Inter-exchange signalling procedures andprotocol - Basic CallCCITT Rec. I.112 Vocabul
17、ary of terms for ISDNs (1988)CCITT Rec. I.130 Method for the characterization of telecommunication services supported by an ISDN andnetwork capabilities of an ISDN (1988)CCITT Rec. I.210 Principles of telecommunication services supported by an ISDN and the means to describe them(1988)4 DefinitionsFo
18、r the purpose of this Standard the following definitions apply.4.1 External definitionsThis Standard uses the following terms defined in other documents: Basic Service (CCITT Rec. I.210) Call, Basic Call (ECMA-254)- 2 - Call Independent Signalling Connection (ECMA-254) Incoming Gateway PINX (ISO/IEC
19、 DIS 13247) Incoming Side (ISO/IEC DIS 13247) Inter-PTNX Link (ISO/IEC DIS 13247) Originating PINX (ISO/IEC DIS 13247) Outgoing Gateway PINX (ISO/IEC DIS 13247) Outgoing Side (ISO/IEC DIS 13247) Preceding PINX (ISO/IEC DIS 13247) Private Integrated Services Network (PISN) (ISO/IEC 11579-1) Private I
20、ntegrated Services Network Exchange (PINX) (ISO/IEC 11579-1) Signalling (CCITT Rec. I.112) Subsequent PINX (ISO/IEC DIS 13247) Supplementary Service (CCITT Rec. I.210) Terminating PINX (ISO/IEC DIS 13247) Transit PINX (ISO/IEC DIS 13247)5 List of acronymsANF Additional Network FeatureANF-TC Transit
21、Counter Additional Network FeatureB-ISDN Broadband Integrated Services Digital NetworkB-PISN Broadband Private Integrated Services NetworkPICS Protocol Implementation Conformance StatementPINX Private Integrated Services Network ExchangePISN Private Integrated Services Network6 Signalling protocol f
22、or the support of ANF-TC6.1 ANF-TC descriptionANF-TC is invoked when it is desired to limit the number of Transit PINXs that a call/connection setup request maybe routed through.This additional network feature is applicable to the broadband connection oriented bearer service.ANF-TC may be used in co
23、njunction with either a Basic call setup request or a setup request for a call independent(connection oriented) signalling connection.Use of ANF-TC is a network option. The criteria for determining: when ANF-TC should be invoked; the number of PINXs through which a call may be routed; and, the means
24、 by which the feature is activated or deactivatedare network dependant and outside the scope of this Standard.- 3 -6.2 ANF-TC operational requirements6.2.1 Requirements on the Originating PINXCall/connection establishment procedures for the outgoing side of an inter-PINX link and call/connection rel
25、easeprocedures, as specified in ISO/IEC DIS 13247, shall apply.If the PINX supports connection-oriented APDU transport, then the generic procedures for the call independentcontrol (connection oriented) of supplementary services, as specified in ECMA-254 for an Originating PINX,shall apply.6.2.2 Requ
26、irements on the Terminating PINXCall/connection establishment procedures for the incoming side of an inter-PINX link and call/connection releaseprocedures, as specified in ISO/IEC DIS 13247, shall apply.If the PINX supports connection-oriented APDU transport, then the generic procedures for the call
27、 independentcontrol (connection oriented) of supplementary services, as specified in ECMA-254 for a Terminating PINX,shall apply.6.2.3 Requirements on a Transit PINXBasic call procedures for call/connection establishment and call/connection clearing at a Transit PINX, asspecified in ISO/IEC DIS 1324
28、7, shall apply.If the PINX supports connection-oriented APDU transport, then the generic procedures for the call independentcontrol (connection oriented) of supplementary services, as specified in ECMA-254 for a Transit PINX, shallapply.6.3 ANF-TC coding requirements6.3.1 Transit counter information
29、 elementANF-TC shall be encoded as a discrete information element (called Transit counter) within codeset 4 (ISOcodeset), according to the rules for the general format and coding of variable length information elements definedin 8.5.1 of ISO/IEC DIS 13247.The Transit counter information element shal
30、l be a variable length category 1 (see 12.1.9.2 of ISO/IEC DIS13247) information element with the format shown in figure 1 and coded as shown in table 1.8 7 6 5 4 3 2 1 OctetTransit counter001100011Information element identifier1 Coding IE compatibility instr. indicator 2ext standard Flag Res. IE Ac
31、tion Ind.Length of transit counter contents 341 0 0 Transit count 5ext Reserved (binary value)Figure 1 - Transit counter information elementTable 1 - Transit counter information elementTransit count (octet 3)A binary value (in the range 0 - 31) that indicates the number ofTransit PINXs through which
32、 the SETUP request has alreadypassed.The maximum number of Transit PINXs through which a SETUPrequest may pass is a network dependant value.- 4 -6.3.2 MessagesIf used, the Transit counter information element shall be conveyed in a SETUP message.One of the shift information elements (see 8.5.3 and 8.
33、5.4 of ISO/IEC DIS 13247) shall precede the Transitcounter information element in the SETUP message.6.4 ANF-TC signalling proceduresThe signalling protocol for Transit counter functionality operates in association with the signalling protocols forbasic call/connection control (as specified in ISO/IE
34、C DIS 13247) and call independent (connection oriented)signalling connections (as specified in ECMA-254).NOTE 1The actions specified in the following subclauses are applicable to both cases.Where a reference is made to procedures specified in ISO/IEC DIS 13247 and ECMA-254, the interpretation ofsuch
35、 reference should be made according to whether the call concerned is a basic call or a call independentsignalling connection.6.4.1 Actions at the Originating PINXAn Originating PINX may include a Transit counter information element in the SETUP message sent across aninter-PINX link. The value of the
36、 transit count field shall be set to zero.6.4.2 Actions at the Terminating PINXA Terminating PINX shall ignore the Transit counter information element if it is contained in any receivedSETUP message.6.4.3 Actions at a Transit PINX6.4.3.1 Normal proceduresOn receipt of a SETUP message from the Preced
37、ing PINX, the call/connection request shall be processedaccording to the procedures specified in ISO/IEC DIS 13247 and ECMA-254.If the received SETUP message contains a Transit counter information element in which the transit count fieldhas a value that is less than the acceptable (network dependent
38、) limit, that information element shall beincluded in the SETUP message sent to the Subsequent PINX. The value of the transit count field in theoutgoing Transit counter information element shall be set to one greater than the value received.If the received SETUP message does not contain a Transit co
39、unter information element, the Transit PINX mayinclude a Transit counter information element in the SETUP message sent to the Subsequent PINX. The valueof the transit count field in this element shall be set to a value not less than 1.6.4.3.2 Exceptional proceduresIf the SETUP message received from
40、the Preceding PINX contains a Transit counter information element inwhich the transit count field has a value that is greater than or equal to the acceptable (network dependent)limit of Transit PINXs through which the call may be routed, and the PINX is unable to become aTerminating or Outgoing Gate
41、way PINX, the call shall be rejected. The acceptable limit shall not exceed 31.6.4.4 At an Incoming Gateway PINXWhen routeing a call entering the PISN an Incoming Gateway PINX may include a Transit counter informationelement in the SETUP message sent across the inter-PINX link. The value of the tran
42、sit count field shall be set toan initial value. This initial value shall be zero unless knowledge of the history of the call enables a higher valueto be chosen.6.4.5 At an Outgoing Gateway PINXAn Outgoing Gateway PINX shall ignore the Transit counter information element if it is contained in anyrec
43、eived SETUP message.- 5 -Annex A(normative)Protocol Implementation Conformance Statement (PICS) proformaA.1 IntroductionThe supplier of a protocol implementation which is claimed to conform to this Standard shall complete the followingProtocol Implementation Conformance Statement (PICS) proforma.A c
44、ompleted PICS proforma is the PICS for the implementation in question. The PICS is a statement of whichcapabilities and options of the protocol have been implemented. The PICS can have a number of uses, including use: by the protocol implementor, as a check list to reduce the risk of failure to conf
45、orm to the Standard throughoversight; by the supplier and acquirer, or potential acquirer, of the implementation, as a detailed indication of the capabilitiesof the implementation, stated relative to the common basis for understanding provided by the Standards PICSproforma; by the user or potential
46、user of the implementation, as a basis for initially checking the possibility of interworkingwith another implementation - while interworking can never be guaranteed, failure to inter-work can often bepredicted from incompatible PICSs; by a protocol tester, as the basis for selecting appropriate tes
47、ts against which to assess the claim for conformance ofthe implementation.A.2 Instructions for completing the PICS proformaA.2.1 General structure of the PICS proformaThe PICS proforma is a fixed format questionnaire divided into sub-clauses each containing a group of individualitems. Each item is i
48、dentified by an item number, the name of the item (question to be answered), and thereference(s) to the clause(s) that specifies (specify) the item(s) in the main body of this Standard.The “Status“ column indicates whether an item is applicable and if so whether support is mandatory or optional. The
49、following terms are used:m mandatory (the capability is required for conformance to the protocol);o optional (the capability is not required for conformance to the protocol, but if the capability isimplemented it is required to conform to the protocol specifications);o. optional, but support of at least one of the group of options labelled by the same numeral isrequired;x prohibited;c. conditional requirement, depending on support for the item or items listed in condition ;:m simple conditional requirement, the capability being mandatory if item number issuppor
