ISO-15055-1997.pdf
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1、INTERNATIONAL STANDARD lSO/IEC 15055 First edition 1997-05-l 5 Information technology - Telecommunications and information exchange between systems - Private Integrated Services Network - Specification, functional model and information flows - Transit counter additional network feature Technologies
2、de Iinforma tion - T6l6communica tions et sit count; 1 1 / Figure 1 - ANF-TC, overall SDL 7 ANF-TC stage 2 specification Throughout this clause, the term “call” shall be interpreted as meaning “call or signalling connection”. 7.1 Functional model 7.1.1 Functional model description The functional mod
3、el shall comprise the following functional entities: FE1 TC Initialize FE2 TC Execute The following functional relationship shall exist between these FEs: ra between FE1 and FE2 and between consecutive FE2s Figure 2 shows these FEs and relationship. LA- Figure 2 - Functional model for ANF-TC Copyrig
4、ht International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 02:45:21 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/IEC 15055:1997 (E) OISO/IEC 7.1.2 Description of f
5、unctional entities 7.1.2.1 TC Initialize, FE1 This FE recognises the invocation of ANF-TC, sets the transit counter to its initial value and passes it to FE2. 7.1.2.2 TC Execute, FE2 This FE receives the transit counter from FE1 or from another FE2. The following two types of FE2 exist: Intermediate
6、 FE2 An intermediate FE2 compares the transit counter to the allowed limit. If below the limit, FE2 increments the transit counter and passes it to the next FE2; otherwise it requests rejection of the call request. Final FE2 The final FE2 terminates ANF-TC. 7.1.3 Relationship of functional model to
7、basic call functional model FE1 shall be collocated with the Originating CC, an Incoming Gateway CC, or a Transit CC. An intermediate FE2 shall be collocated with a Transit CC. The final FE2 shall be collocated with the Terminating CC or an Outgoing Gateway CC. Figure 3 shows an example of the relat
8、ionship with the basic call functional model. ra Origin. r2 interm. 0 ra ra FE2 Transit,. r2 Transit r2 - Termin cc cc cc cc Figure 3 - Example relationship between models for ANF-TC and basic call 7.2 Information flows 7.2.1 Definition of information flows 7.2.1.1 ra-TC ra-TC is an unconfvmed infor
9、mation flow across ra from FE1 to FE2 and between FE2s. Table 1 lists the service elements within the ra-TC information flow. M in the column headed “Request” indicates that the service element is mandatory. Table 1 - Content of ra-TC Service element Transits count shall always be included in the ra
10、-TC request/indication information flow and contain the current value of the transit counter. 7.2.2 Relationship of information flows to basic call information flows ra-TC shall be sent in conjunction with an r2-Setup request/indication flow. 7.2.3 Examples of information flow sequences A stage 3 st
11、andard for ANF-TC shall provide signalling procedures in support of the information flow sequences specified below. In addition, signalling procedures should be provided to cover other sequences arising from error situations, interactions with other supplementary services, different topologies, etc.
12、 6 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 02:45:21 MDTNo reproduction or networking permitted without license from IHS -,-,- 01!30l-IEc ISOAEC 15055:1997 Q In the figure
13、s, ANF-TC information flows are represented by solid arrows and basic call information flows are represented by broken arrows. An ellipse embracing two information flows indicates that the two information flows occur simultaneously. Within a column representing an ANF-TC functional entity, the numbe
14、rs refer to functional entity actions listed in 7.3. The following abbreviations are used: req request ind indication 7.2.3.1 Normal operation of ANF-TC Figure 4 shows the information flow sequence for normal operation of ANF-TC. ra ra r-t -r2 - - - l- -0 cc cc Figure 4 - Information flow sequence -
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