Standard ECMA-224 2nd E dition - J une 1997
Standardizing
Information
and
Communication
Systems
Private Integrated Services Network (PISN) Specification, Functional Model and Information Flows Transit Counter Additional Network Feature
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Standard ECMA-224 2nd E dition - J une 1997
Standardizing
Information
and
Communication
Systems
Private Integrated Services Network (PISN) Specification, Functional Model and Information Flows Transit Counter Additional Network Feature (ANF-TCSD)
P h o n e : + 4 1 2 2 8 4 9 . 6 0 . 0 0 - F a x : + 4 1 2 2 8 4 9 . 6 0 . 0 1 - U R L : h t t p : / / www. e c m a . c h - I n t e r n e t : h e l p d e s k @ e c m a . c h IW Ecma-224.doc
25-08-97 14,17
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Brief History
This Standard is one of a series of ECMA Standards defining services and signalling protocols applicable to Private Integrated Services Networks (PISNs). The series uses ISDN concepts as developed by ITU-T and conforms to the framework of International Standards for Open Systems Interconnection as defined by ISO/IEC. It has been produced under ETSI work item DE/ECMA-00145. This particular Standard specifies the Transit Counter additional network feature. This Standard is based upon the practical experience of ECMA member companies and the results of their active and continuous participation in the work of ISO/IEC JTC1, ITU-T, ETSI and other international and national standardization bodies. It represents a pragmatic and widely based consensus. Compared to the 1st Edition of Standard ECMA-224 (published by ECMA in June 1995), this 2nd Edition incorporates changes in order to achieve complete alignment with International Standard ISO/IEC 15055:1997(E) published by ISO/IEC in May 1997. Differences between this ECMA Standard and the ISO/IEC International Standard with which it is aligned are clearly identified.
Adopted as 2nd Edition of Standard ECMA-224 by the General Assembly of June 1997.
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Table of contents 1 Scope
1
2 Conformance
1
3 References (normative)
1
4 Definitions
2
4.1 External definitions
2
4.2 Other definitions
2
4.2.1 Additional network feature
2
4.2.2 Call, basic call
2
4.2.3 Signalling connection
2
4.2.4 Transit counter
2
5 List of acronyms
2
6 ANF-TC stage 1 specification
3
6.1 Description
3
6.1.1 General description
3
6.1.2 Qualifications on applicability to telecommunication services
3
6.2 Procedure
3
6.2.1 Provision/withdrawal
3
6.2.2 Normal procedures
3
6.2.3 Exceptional procedures
3
6.3 Interaction with other supplementary services and ANFs
3
6.3.1 Calling Line Identification Presentation (SS-CLIP)
3
6.3.2 Connected Line Identification Presentation (SS-COLP)
3
6.3.3 Calling/Connected Line Identification Restriction (SS-CLIR)
3
6.3.4 Calling Name Identification Presentation (SS-CNIP)
3
6.3.5 Connected Name Identification Presentation (SS-CONP)
3
6.3.6 Calling/Connected Name Identification Restriction (SS-CNIR)
4
6.3.7 Completion of Calls to Busy Subscriber (SS-CCBS)
4
6.3.8 Completion of Calls on No Reply (SS-CCNR)
4
6.3.9 Call Transfer (SS-CT)
4
6.3.10 Call Forwarding Unconditional (SS-CFU)
4
6.3.11 Call Forwarding Busy (SS-CFB)
4
6.3.12 Call Forwarding No Reply (SS-CFNR)
4
6.3.13 Call Deflection (SS-CD)
4
6.3.14 Path Replacement (ANF-PR)
4
6.3.15 Call Interception (ANF-CINT)
4
6.3.16 Advice of Charge (SS-AOC)
4
6.3.17 Recall (SS-RE)
4
6.3.18 Call Offer (SS-CO)
4
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6.3.19 Call Intrusion (SS-CI)
4
6.3.20 Do Not Disturb (SS-DND)
4
6.3.21 Do Not Disturb Override (SS-DNDO)
4
6.3.22 Cordless Terminal Location Registration (SS-CTLR)
4
6.3.23 Cordless Terminal Mobility Incoming Call (ANF-CTMI)
4
6.4 Interworking considerations
5
6.5 Overall SDL
5
7 ANF-TC stage 2 specification
5
7.1 Functional model
5
7.1.1 Functional model description
5
7.1.2 Description of functional entities
6
7.1.3 Relationship of functional model to basic call functional model
6
7.2 Information flows
6
7.2.1 Definition of information flows
6
7.2.2 Relationship of information flows to basic call information flows
7
7.2.3 Examples of information flow sequences
7
7.3 Functional entity actions
8
7.3.1 Functional entity actions of FE1
8
7.3.2 Functional entity actions of FE2
8
7.4 Functional entity behaviour
8
7.4.1 Behaviour of FE1
8
7.4.2 Behaviour of FE2
9
7.5 Allocation of functional entities to physical equipment
10
7.6 Interworking considerations
10
1
Scope This Standard specifies the Transit Counter additional network feature (ANF-TC), which is applicable to various basic services supported by Private Integrated Services Networks (PISN). Basic services are specified in ECMA-142. ANF-TC is an additional network feature which limits the number of network exchanges that a call request may transit during call establishment, e.g. to protect the network against indefinite looping. There is no user involved in the provision or operation of ANF-TC. Additional network feature specifications are produced in three stages, according to the method described in ETS 300 387. This Standard contains the stage 1 and stage 2 specifications of ANF-TC. The stage 1 specification (clause 6) specifies the general feature principles and capabilities. The stage 2 specification (clause 7) identifies the functional entities involved in the feature and the information flows between them.
2
Conformance In order to conform to this Standard, a stage 3 standard shall specify signalling protocols and equipment behaviour that are capable of being used in a PISN which supports the feature specified in this Standard. This means that, to claim conformance, a stage 3 standard is required to be adequate for the support of those aspects of clause 6 (stage 1) and clause 7 (stage 2) which are relevant to the interface or equipment to which the stage 3 standard applies.
3
References (normative) The following standards contain provisions which, through reference in this text, constitute provisions of this Standard. All standards are subject to revision, and parties to agreements based on this Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. In the case of references to ECMA Standards that are aligned with ISO/IEC International Standards, the number of the appropriate ISO/IEC International Standard is given in brackets after the ECMA reference. ECMA-142
Private Integrated Services Network - Circuit-mode 64 kbit/s Bearer Services - Service Description, Functional Capabilities and Information Flows (International Standard ISO/IEC 11574)
ECMA-173
Private Integrated Services Network - Specification, Functional Model and Information Flows Call Diversion Supplementary Services (International Standard ISO/IEC 13872)
ECMA-175
Private Integrated Services Network - Specification, Functional Model and Information Flows Path Replacement Additional Network Feature (International Standard ISO/IEC 13863)
ECMA-177
Private Integrated Services Network - Specification, Functional Model and Information Flows Call Transfer Supplementary Service (International Standard ISO/IEC 13865)
ECMA-185
Private Integrated Services Network - Specification, Functional Model and Information Flows Call Completion Supplementary Services (International Standard ISO/IEC 13866)
ISO/IEC 11579-1
Information technology - Telecommunications and information exchange between systems Private Integrated Services Network - Part 1: Reference configuration for PISN Exchanges (PINX)
ETS 300 387
Private Telecommunication Network (PTN); Method for the specification of basic and supplementary services (1994)
ITU-T Rec. I.112
Vocabulary of terms for ISDNs (1993)
ITU-T Rec. I.210
Principles of telecommunication services supported by an ISDN and the means to describe them (1993)
ITU-T Rec. Z.100
Specification and description language (1993)
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4
Definitions For the purposes of this Standard, the following definitions apply.
4.1
External definitions This Standard uses the following terms defined in other documents: − Basic service
(ITU-T Rec. I.210)
− Private Integrated Services Network (PISN)
(ISO/IEC 11579-1)
− Private Integrated Services Network Exchange (PINX)
(ISO/IEC 11579-1)
− Service
(ITU-T Rec. I.112)
− Signalling
(ITU-T Rec. I.112)
− Supplementary Service
(ITU-T Rec. I.210)
− User
(ECMA-142)
This Standard refers to the following basic call functional entity (FE) defined in ECMA-142: − Call Control (CC) This Standard refers to the following basic call inter-FE relationship defined in ECMA-142: − r2 This Standard refers to the following basic call information flows defined in ECMA-142: − Setup request/indication − Setup-Reject request/indication
4.2
Other definitions
4.2.1
Additional network feature A capability over and above that of a basic call, but not provided directly to a user.
4.2.2
Call, basic call An instance of the use of a basic service.
4.2.3
Signalling connection A connection used to exchange information between peer supplementary service protocol control entities independently of a basic call.
4.2.4
Transit counter A counter for the number of transit exchanges involved in a call or signalling connection during the establishment phase.
5
List of acronyms ANF(-TC)
Additional Network Feature (Transit Counter)
CC
Call Control (functional entity)
FE
Functional Entity
ISDN
Integrated Services Digital Network
PINX
Private Integrated Services Network Exchange
PISN
Private Integrated Services Network
SDL
Specification and Description Language
SS
Supplementary Service
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6
ANF-TC stage 1 specification Throughout this clause, the term “call” shall be interpreted as meaning “call or signalling connection”.
6.1
Description
6.1.1
General description ANF-TC may be invoked in conjunction with a call request when it is desired to limit the number of network exchanges that the call can transit. The maximum number of network exchanges that the call can transit is network dependent, in the range 1 to 31.
6.1.2
Qualifications on applicability to telecommunication services ANF-TC is applicable to all basic services defined in ECMA-142.
6.2
Procedure
6.2.1
Provision/withdrawal ANF-TC shall be generally available for all calls that involve more than one network exchange.
6.2.2
Normal procedures
6.2.2.1
Activation/deactivation/registration/interrogation Not applicable.
6.2.2.2
Invocation and operation ANF-TC may be invoked in conjunction with a call request. When invoked, the transit counter shall be set to an initial value and then incremented with every network exchange that the call request transits. The initial value shall be zero unless any knowledge available about the history of the call (e.g. route taken, interworking, diversions) is used to choose a higher initial value. ANF-TC shall terminate when the call request reaches its destination, is released, or leaves the PISN.
6.2.3
Exceptional procedures
6.2.3.1
Activation/deactivation/registration/interrogation Not applicable.
6.2.3.2
Invocation and operation If the transit counter exceeds a PISN specific limit (which takes any value in the range 1 to 31) before the call reaches its destination or leaves the PISN, the call shall be aborted. NOTE Other actions that the PISN may take are outside the scope of this Standard.
6.3
Interaction with other supplementary services and ANFs Interactions with other supplementary services and ANFs for which PISN standards were available at the time of publication of this Standard are specified below.
6.3.1
Calling Line Identification Presentation (SS-CLIP) No interaction.
6.3.2
Connected Line Identification Presentation (SS-COLP) No interaction.
6.3.3
Calling/Connected Line Identification Restriction (SS-CLIR) No interaction.
6.3.4
Calling Name Identification Presentation (SS-CNIP) No interaction.
6.3.5
Connected Name Identification Presentation (SS-CONP) No interaction.
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6.3.6
Calling/Connected Name Identification Restriction (SS-CNIR) No interaction.
6.3.7
Completion of Calls to Busy Subscriber (SS-CCBS) ANF-TC may apply to a call resulting from the use of SS-CCBS.
6.3.8
Completion of Calls on No Reply (SS-CCNR) ANF-TC may apply to a call resulting from the use of SS-CCNR.
6.3.9
Call Transfer (SS-CT) ANF-TC may apply to the establishment of the new connection during transfer by rerouteing.
6.3.10
Call Forwarding Unconditional (SS-CFU) ANF-TC may be invoked when establishing the diverted call.
6.3.11
Call Forwarding Busy (SS-CFB) 6.3.10 shall apply.
6.3.12
Call Forwarding No Reply (SS-CFNR) 6.3.10 shall apply.
6.3.13
Call Deflection (SS-CD) 6.3.10 shall apply.
6.3.14
Path Replacement (ANF-PR) ANF-TC may apply to the establishment of the new connection.
6.3.15
Call Interception (ANF-CINT) ANF-TC may be invoked when establishing the intercepted call.
6.3.16
Advice of Charge (SS-AOC) No interaction.
6.3.17
Recall (SS-RE) No interaction.
6.3.18
Call Offer (SS-CO) No interaction.
6.3.19
Call Intrusion (SS-CI) No interaction.
6.3.20
Do Not Disturb (SS-DND) No interaction.
6.3.21
Do Not Disturb Override (SS-DNDO) No interaction.
6.3.22
Cordless Terminal Location Registration (SS-CTLR) No interaction.
6.3.23
Cordless Terminal Mobility Incoming Call (ANF-CTMI) ANF-TC may be invoked when establishing the call to the CTM user. Difference from ISO/IEC 15055 Subclauses 6.3.22 and 6.3.23 do not exist in the ISO/IEC International Standard. End of Difference
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6.4
Interworking considerations ANF-TC may apply to calls entering the PISN from another network or to calls going to another network.
6.5
Overall SDL Figure 1 contains the dynamic description of ANF-TC using the Specification and Description Language (SDL) defined in ITU-T Rec. Z.100 (1993). The SDL process represents the behaviour of the PISN in providing ANF-TC. Input symbols from the left and output symbols to the left represent internal stimuli.
T C -ID LE
C all request present
initialize trans it counter
T C -C O U N T IN G
C all request at trans it node
lim it exceeded?
C all clearing initiated
C all reached destination or left the netw ork
YES
NO
A b o rt c a ll
increm ent transit counter
T C -C O U N TIN G
T C -ID LE
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 7.1.1
Functional model Functional model description The functional model shall comprise the following functional entities: FE1
TC Initialize
FE2
TC Execute
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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.
ra
FE1
ra
FE2
FE2
Figure 2 - Functional model for ANF-TC 7.1.2
Description of functional 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 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 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 relationship with the basic call functional model.
FE1
ra
interm.
ra
r2
Origin. CC
Transit CC
interm.
ra
final
FE2
FE2 r2
Transit CC
FE2 r2
Termin. CC
Figure 3 - Example relationship between models for ANF-TC and basic call
7.2
Information flows
7.2.1 7.2.1.1
Definition of information flows ra-TC ra-TC is an unconfirmed information 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
Allowed Value
Request
Transits count
Integer (Note)
M
Note: The allowed range is (0, .., max) where max is a network dependent maximum value.
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Service element Transits count shall always be included in the ra-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 standard 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. In the figures, 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 numbers refer to functional entity actions listed in 7.3. The following abbreviations are used:
7.2.3.1
req
request
ind
indication
Normal operation of ANF-TC Figure 4 shows the information flow sequence for normal operation of ANF-TC. FE1 CC 101
ra
ra
FE2
r2
FE2 r2
CC
CC
ra-TC req/ind ra-TC req/ind
201
202
r2-SETUP req/ind
r2-SETUP req/ind
Figure 4 - Information flow sequence - normal operation of ANF-TC 7.2.3.2
Transit counter limit exceeded Figure 5 shows the information flow sequence for the case that the allowed limit of the transit counter is exceeded. FE2 CC
ra FE2 r2
CC
ra-TC req/ind r2-SETUP req/ind
203
r2-SETUP-REJECT req/ind
Figure 5 - Information flow sequence - transit counter limit exceeded
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7.3
Functional entity actions The following FE actions shall occur at the points indicated in the figures of 7.2.
7.3.1
Functional entity actions of FE1 101
7.3.2
7.4
Recognize the invocation of ANF-TC, set the transit counter to the initial value and send ra-TC request/indication to FE2.
Functional entity actions of FE2 201
Acting as an intermediate FE2, on receiving ra-TC request/indication with a transit counter value below the limit, increment the value and send ra-TC request/indication to the next FE2.
202
Acting as the final FE2, on receiving ra-TC request/indication, terminate ANF-TC.
203
Acting as an intermediate FE2, on receiving ra-TC request/indication with a transit counter value equal to or higher than the allowed limit, reject the call setup request.
Functional entity behaviour The FE behaviours shown below are intended to illustrate typical FE behaviour in terms of information flows sent and received. The behaviour of each FE is shown using the Specification and Description Language (SDL) defined in ITU-T Rec. Z.100 (1993).
7.4.1
Behaviour of FE1 Figure 6 shows the normal behaviour of FE1. Input symbols from the left represent internal stimuli. Output symbols to the right represent information flows to FE2.
FE1-IDLE
C all request present
initialize transit counter
ra -T C re q u e s t
F E1-IDLE
Figure 6 - ANF-TC, SDL for functional entity FE1
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7.4.2
Behaviour of FE2 Figure 7 shows the normal behaviour of FE2. Input symbols from the left represent information flows from other FEs. Output symbols to the right represent information flows to another FE2. Output symbols to the left represent internal stimuli. F E2-ID LE
r a -T C in d ic a tio n
final FE2?
YES
NO
lim it exceeded?
YES
NO
increm ent transit counter
Abort call
ra -T C re q u e s t
FE 2-ID LE
Figure 7 - ANF-TC, SDL for functional entity FE2
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7.5
Allocation of functional entities to physical equipment Table 2 shows the allocation of functional entities to physical equipment. Table 2 - Scenarios for the allocation of FEs to physical equipment
7.6
FE1
FE2 (intermediate)
FE2 (final)
Scenario 1
Originating PINX
Transit PINX
Terminating PINX
Scenario 2
Transit PINX
Transit PINX
Terminating PINX
Interworking considerations ANF-TC applies only to portions of a call that lie within the PISN. For calls to and from other networks the functional entities are allocated to physical equipment as shown in table 3. Table 3 - Scenarios for the allocation of FEs to physical equipment in interworking situations FE1
FE2 (intermediate)
FE2 (final)
Scenario 3
Originating PINX
Transit PINX
Outgoing Gateway PINX
Scenario 4
Transit PINX
Transit PINX
Outgoing Gateway PINX
Scenario 5
Incoming Gateway PINX
Transit PINX
Terminating PINX
Scenario 6
Incoming Gateway PINX
Transit PINX
Outgoing Gateway PINX
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