SIST ETS 300 259 E1:2005
(Main)Private Telecommunication Network (PTN); Inter-exchange signalling protocol; Path replacement additional network feature
Private Telecommunication Network (PTN); Inter-exchange signalling protocol; Path replacement additional network feature
Stage 3 of additional network feature path replacement at Q ref pt. See DTR/ECMA-0002 (ECMA-TR/SVC) for service description. See ENV41005 for definition of stage 3. See ENV41004 for definition of Q reference point. To contain PICS proforma.
Zasebno telekomunikacijsko omrežje (PTN) – Medcentralni signalizacijski protokol - Dodatna omrežna lastnost (ANF): nadomestitev poti
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-maj-2005
Zasebno telekomunikacijsko omrežje (PTN) – Medcentralni signalizacijski protokol
- Dodatna omrežna lastnost (ANF): nadomestitev poti
Private Telecommunication Network (PTN); Inter-exchange signalling protocol; Path
replacement additional network feature
Ta slovenski standard je istoveten z: ETS 300 259 Edition 1
ICS:
33.040.35 Telefonska omrežja Telephone networks
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN ETS 300 259
TELECOMMUNICATION November 1993
STANDARD
Source: ETSI TC-ECMA Reference: DE/ECMA-00055
ICS: 33.080
PTN, ECMA-176, QSIG-PR
Key words:
Private Telecommunication Network (PTN);
Inter-exchange signalling protocol
Path replacement additional network feature
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - secretariat@etsi.fr
X.400: Internet:
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1993. All rights reserved.
New presentation - see History box
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ETS 300 259: November 1993
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.
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ETS 300 259: November 1993
Contents
Foreword .5
1 Scope .7
2 Conformance.7
3 References.7
4 Definitions.8
4.1 External definitions.8
4.2 Branching PTNX .8
4.3 Co-operating PTNX .8
4.4 End PTNX.8
4.5 Preceding PTNX .9
4.6 Replaced connection .9
4.7 Requesting PTNX .9
4.8 Retained connection .9
4.9 Subsequent PTNX .9
5 List of acronyms .9
6 Signalling protocol for the support of ANF-PR .10
6.1 ANF-PR description .10
6.2 ANF-PR operational requirements.10
6.2.1 Requirements on the Co-operating PTNX .10
6.2.2 Requirements on the Requesting PTNX .10
6.2.3 Requirements on a Transit PTNX .11
6.2.3.1 Transit PTNX Involved in the replaced connection.11
6.2.3.2 Transit PTNX Involved in the new connection.11
6.2.3.3 Transit PTNX Involved in the retained connection .11
6.2.3.4 Branching PTNX.12
6.3 ANF-PR coding requirements.13
6.3.1 Operations.13
6.3.2 Information elements.16
6.3.2.1 Facility information element.16
6.3.2.2 Other information elements .16
6.3.3 Messages.16
6.4 ANF-PR state definitions.17
6.4.1 States at the Requesting PTNX .17
6.4.1.1 State PR-Req-Idle.17
6.4.1.2 State PR-Req-Initiated.17
6.4.1.3 State PR-Req-Completing .17
6.4.2 States at the Co-operating PTNX.17
6.4.2.1 State PR-Coop-Idle.17
6.4.2.2 State PR-Coop-Establishment.17
6.4.2.3 State PR-Coop-Retain.17
6.4.3 States at a Transit PTNX on the retained path, including the Branching
PTNX.17
6.4.3.1 State PR-Transit-Idle .17
6.4.3.2 State PR-Transit-Establishment .17
6.4.3.3 State PR-Transit-Retain .17
6.5 ANF-PR signalling procedures.18
6.5.1 Actions at the Requesting PTNX.18
6.5.1.1 Normal procedures.18
6.5.1.2 Exceptional procedures .19
6.5.2 Actions at the Co-operating PTNX .19
6.5.2.1 Normal procedures.20
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6.5.2.2 Exceptional procedures . 21
6.5.3 Actions at a Co-operating/Requesting PTNX in the case of a trombone
connection . 21
6.5.4 Actions at a Transit PTNX . 21
6.6 ANF-PR optional signalling procedures for retention of part of the old connection. 21
6.6.1 Actions at the Requesting PTNX . 21
6.6.2 Actions at the Co-operating PTNX. 21
6.6.2.1 Normal procedures . 22
6.6.2.2 Exceptional procedures . 22
6.6.3 Actions at a Transit PTNX on the retained connection. 22
6.6.3.1 Able to retain old connection as far as Subsequent PTNX. 23
6.6.3.2 Unable to retain old connection as far as Subsequent
PTNX . 23
6.6.4 Actions at a Transit PTNX on the new connection or replaced connection. 24
6.7 ANF-PR impact of interworking with public ISDNs. 25
6.8 ANF-PR impact of interworking with non-ISDNs. 25
6.9 ANF-PR parameter values (timers). 25
6.9.1 Timer T1 . 25
6.9.2 Timer T2 . 25
6.9.3 Timer T3 . 26
6.9.4 Timer T4 . 26
Annex A (normative): Protocol Implementation Conformance Statement (PICS) proforma . 27
A.1 Introduction. 27
A.2 Instructions for completing the PICS proforma . 27
A.2.1 General structure of the PICS proforma. 27
A.2.2 Additional Information. 28
A.2.3 Exception Information. 28
A.3 PICS Proforma for prETS 300 259. 28
A.3.1 Implementation identification . 28
A.3.2 Protocol summary. 29
A.3.3 General . 29
A.3.4 Procedures . 30
A.3.5 Coding . 31
A.3.6 Timers. 31
Annex B (informative): Imported ASN.1 definitions . 32
Annex C (informative): Examples of message sequences. 34
C.1 Example message sequence for normal operation. 35
C.2 Example message sequence for case of congestion encountered at Transit PTNX. 36
C.3 Example message sequence for normal operation, retaining part of the old connection . 37
C.4 Example message sequence for case of congestion encountered at Transit PTNX,
after attempting to retain part of the old connection. 38
C.5 Example message sequence for normal operation, retaining all of the old connection. 39
Annex D (informative): Specification and Description Language (SDL) representation of procedures. 40
D.1 SDL representation of ANF-PR at the Requesting PTNX. 40
D.2 SDL representation of ANF-PR at the Co-operating PTNX . 42
D.3 SDL representation of ANF-PR at a Transit PTNX on the retained connection. 43
History. 44
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Foreword
This European Telecommunication Standard (ETS) has been produced by the European Computer
Manufacturers Association (ECMA) on behalf of its members and those of the European
Telecommunications Standards Institute (ETSI).
This ETS is one of a series of standards defining services and signalling protocols applicable to Private
Telecommunication Networks (PTNs). The series uses the ISDN concepts as developed by CCITT and is
also within the framework of standards for open systems interconnection as defined by ISO.
This particular ETS specifies the signalling protocol for use at the Q reference point in support of the Path
Replacement additional network feature.
The ETS is based upon the practical experience of ECMA member companies and the results of their
active and continuous participation in the work of ISO, CCITT, ETSI and other international and national
standardisation bodies. It represents a pragmatic and widely based consensus.
This ETS was produced by ECMA using the ECMA guidelines for the production of standards and using
the ECMA stylesheet. In order to avoid undue delays in the voting process for this ETS it has been agreed
that this ETS will not be converted to the ETSI stylesheet.
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1 Scope
This ETS specifies the signalling protocol for the support of the Path Replacement additional
network feature (ANF-PR) at the Q reference point between Private Telecommunication Network
Exchanges (PTNXs) connected together within a Private Telecommunication Network (PTN).
ANF-PR is a feature which applies to an established call, allowing that call's connection through
the PTN to be replaced by a new connection.
The Q reference point is defined in ENV 41004. This ETS contains the stage 3 specification for the
Q reference point and satisfies the requirements identified by the stage 1 and stage 2
specifications in prETS 300 258.
Service specifications are produced in three stages and according to the method specified in
ENV 41005.
The signalling protocol for ANF-PR operates on top of the signalling protocol for basic circuit
switched call control, as specified in ETS 300 172, and uses certain aspects of the generic
procedures for the control of supplementary services specified in ETS 300 239.
The impact on the protocol of interactions between the ANF specified in this ETS and other
supplementary services and ANFs is outside the scope of this ETS.
This ETS is applicable to PTNXs which can interconnect to form a PTN.
2 Conformance
In order to conform to this ETS, a PTNX shall satisfy the requirements identified in the Protocol
Implementation Conformance Statement (PICS) proforma in annex A.
3 References
ENV 41004 Reference configuration for connectivity relations of private
telecommunication network exchanges (1989).
ENV 41005 Method for the specification of basic and supplementary services of
private telecommunication networks (1989).
ENV 41007 Definition of terms in private telecommunication networks (1989).
ETS 300 171 Private Telecommunication Network (PTN); Specification, functional
models and information flows, Control aspects of circuit mode basic
services (1992).
ETS 300 172 Private Telecommunication Network (PTN); Inter-exchange signalling
protocol, Circuit mode basic services (1992).
ETS 300 189 Private Telecommunication Network (PTN); Addressing (1992).
ETS 300 196 ISDN - Generic Functional Protocol for the Support of Supplementary
Services - DSS1 Protocol
ETS 300 239 Private Telecommunication Network (PTN); Signalling between
private telecommunication exchanges, Generic functional protocol for
the support of supplementary services (1993).
prETS 300 258 Private Telecommunication Networks (PTN); Specification, functional
models and information flows, Path replacement additional network
feature (1993).
prETS 300 261 Private Telecommunication Networks (PTN); Inter-exchange
signalling protocol, Call transfer supplementary service (1993).
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CCITT Recommendation I.112 Vocabulary of terms for ISDNs (1988).
CCITT Recommendation I.210 Principles of telecommunication services supported by an ISDN
and the means to describe them (1988).
CCITT Recommendation Z.100 Specification and description language (1988).
4 Definitions
For the purpose of this ETS the following definitions apply.
4.1 External definitions
This ETS uses the following terms defined in other documents:
- ANF-PR user (prETS 300 258);
- Application Protocol Data Unit (APDU) (ETS 300 239);
- Basic Service (CCITT Recommendation I.210);
- Call, Basic Call (ETS 300 239);
- Connection (prETS 300 258);
- Incoming Gateway PTNX (ETS 300 172);
- Interpretation APDU (ETS 300 239);
- Network Facility Extension (NFE) (ETS 300 239);
- New Connection (prETS 300 258);
- Old Connection (prETS 300 258);
- Originating PTNX (ETS 300 172);
- Outgoing Gateway PTNX (ETS 300 172);
- Private (ENV 41007);
- Private Telecommunication Network Exchange (PTNX) (ENV 41007);
- Public ISDN (ENV 41007);
- Signalling (CCITT Recommendation I.112);
- Supplementary Service (CCITT Recommendation I.210);
- Supplementary Services Control Entity (ETS 300 239);
- Telecommunication Network (ENV 41007);
- Terminating PTNX (ETS 300 172);
- Transit PTNX (ETS 300 172);
- Trombone Connection (prETS 300 258);
- User (except in the context of ANF-PR user) (ETS 300 171).
4.2 Branching PTNX
The Transit PTNX at which the retained connection finishes and the new connection starts.
4.3 Co-operating PTNX
The End PTNX which initiates the establishment of the new connection towards other End
PTNX involved in the call.
4.4 End PTNX
Within the context of a call, a PTNX which is not acting as a Transit PTNX, i.e. an Originating
PTNX, a Terminating PTNX, an Incoming Gateway PTNX or an Outgoing Gateway PTNX.
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4.5 Preceding PTNX
The adjacent PTNX in the direction of the Co-operating PTNX, relative to a particular PTNX
involved in the old connection.
NOTE 1
This can be the Co-operating PTNX itself or a Transit PTNX.
4.6 Replaced connection
That part of the old connection which is not retained and is replaced by the new connection.
4.7 Requesting PTNX
The End PTNX which invokes ANF-PR and towards which the new connection is routed.
4.8 Retained connection
That part of the old connection which is retained and not replaced by the new connection.
4.9 Subsequent PTNX
The adjacent PTNX in the direction of the Requesting PTNX, relative to a particular PTNX
involved in the old connection.
NOTE 2
This can be the Requesting PTNX itself or a Transit PTNX.
5 List of acronyms
ANF Additional Network Feature
ANF-PR Path Replacement Additional Network Feature
APDU Application Protocol Data Unit
ASN.1 Abstract Syntax Notation no. 1
ISDN Integrated Services Digital Network
NFE Network Facility Extension
PICS Protocol Implementation Conformance Statement
PTN Private Telecommunication Network
PTNX Private Telecommunication Network Exchange
SDL Specification and Description Language
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6 Signalling protocol for the support of ANF-PR
6.1 ANF-PR description
ANF-PR is invoked by an ANF-PR user for an established call, allowing that call's connection
through the PTN to be replaced by a new connection. If the new connection is required to satisfy
certain criteria, ANF-PR should be used in conjunction with other supplementary services
and/or ANFs. In the absence of specific criteria, the new connection should be established
using the routing rules which apply to basic call establishment.
NOTE 3
Annex A of prETS 300 258 gives examples of the circumstances under which ANF-PR can be
used and criteria which can govern the selection of the new connection.
The Requesting PTNX shall request the Co-operating PTNX to attempt the establishment of a
new connection from the Co-operating PTNX to the Requesting PTNX. If successful, the new
connection shall replace the old connection.
NOTE 4
The Requesting PTNX can be either End PTNX involved in a call, i.e. the Originating PTNX or
the Terminating PTNX or, in the case of interworking with another network, the Incoming
Gateway PTNX or Outgoing Gateway PTNX.
Optional procedures and coding are specified for allowing the retention of one or more elements
of the old connection, starting from the Co-operating PTNX and continuing as far as a Transit
PTNX, subject to any given criteria being achievable in that way. A new connection is
established from the Transit PTNX to the Requesting PTNX instead of from the Co-operating
PTNX to the Requesting PTNX.
6.2 ANF-PR operational requirements
6.2.1 Requirements on the Co-operating PTNX
ANF-PR shall be applicable to a call whose protocol control state, as defined in ETS 300 172,
is Active.
NOTE 5
State Active will have been reached as a result of ETS 300 172 call establishment
procedures, possibly in conjunction with supplementary service and/or ANF procedures.
ETS 300 172 protocol control procedures for call establishment at the outgoing side of an
inter-PTNX link shall apply to the establishment of the new connection. ETS 300 172 protocol
control procedures for call clearing shall apply to the release of the old connection in the
event of successful switch over to the new connection.
Generic procedures for the call-related control of supplementary services, as specified in
ETS 300 239 for an End PTNX, shall apply.
6.2.2 Requirements on the Requesting PTNX
ANF-PR shall be applicable to a call whose protocol control state, as defined in ETS 300 172,
is Active.
NOTE 6
State Active will have been reached as a result of ETS 300 172 call establishment
procedures, possibly in conjunction with supplementary service and/or ANF procedures.
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ETS 300 172 protocol control procedures for call establishment at the incoming side of an
inter-PTNX link shall apply to the establishment of the new connection. ETS 300 172 protocol
control procedures for call clearing shall apply to the release of the old connection in the
event of successful switch over to the new connection.
Generic procedures for the call-related control of supplementary services, as specified in
ETS 300 239 for an End PTNX, shall apply.
6.2.3 Requirements on a Transit PTNX
6.2.3.1 Transit PTNX Involved in the replaced connection
ANF-PR shall be applicable to a call whose protocol control state, as defined in ETS 300
172, on each of the two links (incoming and outgoing) is Active and whose call control
state, as defined in ETS 300 172 is TCC_Call_Active.
NOTE 7
State Active will have been reached as a result of ETS 300 172 call establishment
procedures, possibly in conjunction with supplementary service and/or ANF procedures.
ETS 300 172 protocol control and call control procedures for call clearing at a Transit
PTNX shall apply to the release of the old connection in the event of successful switch
over to the new connection.
Generic procedures for the call-related control of supplementary services, as specified in
ETS 300 239 for a Transit PTNX, shall apply. For ANF-PR the requirements are limited to
the passing on of Facility information elements for which the destination, as indicated in
the Network Facility Extension (NFE), is not the Transit PTNX.
6.2.3.2 Transit PTNX Involved in the new connection
ETS 300 172 protocol control and call control procedures for call establishment at a
Transit PTNX shall apply to the establishment of the new connection.
ETS 300 172 protocol control and call control procedures for call clearing at a Transit
PTNX shall apply to the release of the new connection in the event of failure to complete
ANF-PR successfully.
Generic procedures for the call-related control of supplementary services, as specified in
ETS 300 239 for a Transit PTNX, shall apply. For ANF-PR the requirements are limited to
the passing on of Facility information elements for which the destination, as indicated in
the Network Facility Extension (NFE), is not the Transit PTNX.
6.2.3.3 Transit PTNX Involved in the retained connection
The procedures below are applicable only if the optional procedures for retention of part of
the old connection (see subclause 6.6) are supported.
ANF-PR shall be applicable to a call whose protocol control state, as defined in ETS 300
172, on each of the two links (incoming and outgoing) is Active and whose call control
state, as defined in ETS 300 172 is TCC_Call_Active.
NOTE 8
State Active will have been reached as a result of ETS 300 172 call establishment
procedures, possibly in conjunction with supplementary service and/or ANF procedures.
Generic procedures for the call-related control of supplementary services, as specified in
ETS 300 239 for a Transit PTNX, shall apply.
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6.2.3.4 Branching PTNX
The procedures below are applicable only if the optional procedures for retention of part of
the old connection (see subclause 6.6) are supported.
ANF-PR shall be applicable to a call whose protocol control state, as defined in ETS 300
172, on each of the two links (incoming and outgoing) is Active and whose call control
state, as defined in ETS 300 172 is TCC_Call_Active.
NOTE 9
State Active will have been reached as a result of ETS 300 172 call establishment
procedures, possibly in conjunction with supplementary service and/or ANF procedures.
ETS 300 172 protocol control procedures for call establishment at the outgoing side of an
inter-PTNX link shall apply to the establishment of the new connection. ETS 300 172
protocol control procedures for call clearing shall apply to the release of the replaced
connection in the event of successful switch over to the new connection.
Generic procedures for the call-related control of supplementary services, as specified in
ETS 300 239 for a Transit PTNX, shall apply.
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6.3 ANF-PR coding requirements
6.3.1 Operations
The operations defined in Abstract Syntax Notation number 1 (ASN.1) in table 10 shall apply.
Table 11 - Operations in support of ANF-PR
Path-Replacement-Operations
{ccitt (0) identified-organisation (3) etsi (0)
qsig-path-replacement (259) pr-operations (0)}
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
IMPORTS OPERATION, ERROR FROM Remote-Operation-Notation
{joint-iso-ccitt(2) remote-operations(4) notation (0)}
Extension FROM Manufacturer-specific-service-extension-definition
{ccitt(0) identified-organisation(3) etsi(0)
qsig-generic-procedures (239) msi-definition (0)}
notAvailable, supplementaryServiceInteractionNotAllowed FROM General-Errors
{ccitt(0) identified-organisation(3) etsi(0) 196 general-errors (2)}
invalidReroutingNumber, unrecognizedCallIdentity,
establishmentFailure, CallIdentity FROM Call-Transfer-Operations
{ccitt(0) identified-organisation (3) etsi(0) qsig-call-transfer (261)
call-transfer-operations (0)}
PartyNumber FROM Addressing-Data-Elements
{ccitt (0) identified-organisation (3) etsi(0)196 addressing-data-elements(6)};
-- Note. The definition of PartyNumber is reproduced in annex B.
ptn OBJECT IDENTIFIER ::= {iso(1) identified-organisation(3) icd-ecma (0012)
private-isdn-signalling-domain (9)}
PathReplacePropose ::= OPERATION
ARGUMENT PRProposeArg
ERRORS {
notAvailable,
temporarilyUnavailable,
criteriaPermanentlyUnachievable,
criteriaTemporarilyUnachievable,
invalidReroutingNumber,
unrecognizedCallIdentity,
establishmentFailure,
collision,
supplementaryServiceInteractionNotAllowed,
unspecified
}
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Table 1 - Operations in support of ANF-PR (continued)
PathReplaceSetup ::= OPERATION
ARGUMENT PRSetupArg
RESULT DummyResult
ERRORS {
criteriaPermanentlyUnachievable,
criteriaTemporarilyUnachievable,
invalidReroutingNumber,
unrecognizedCallIdentity,
temporarilyUnavailable,
unspecified
}
PathReplaceRetain ::= OPERATION
ARGUMENT PRRetainArg
RESULT DummyResult
ERRORS {
notAvailable,
temporarilyUnavailable,
criteriaPermanentlyUnachievable,
criteriaTemporarilyUnachievable,
invalidReroutingNumber,
unrecognizedCallIdentity,
establishmentFailure,
supplementaryServiceInteractionNotAllowed,
unspecified
}
PRProposeArg ::= SEQUENCE {
callIdentity CallIdentity,
reRoutingNumber PartyNumber,
extension CHOICE {
[1] IMPLICIT Extension,
[2] IMPLICIT SEQUENCE OF Extension
} OPTIONAL
}
PRSetupArg ::= SEQUENCE {
callIdentity CallIdentity,
extension CHOICE {
[1] IMPLICIT Extension,
[2] IMPLICIT SEQUENCE OF Extension
} OPTIONAL
}
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Table 1 - Operations in support of ANF-PR (concluded)
PRRetainArg ::= SEQUENCE {
callIdentity CallIdentity,
reRoutingNumber PartyNumber,
extension CHOICE {
[1] IMPLICIT Extension,
[2] IMPLICIT SEQUENCE OF Extension
} OPTIONAL
}
DummyResult ::= CHOICE {
NULL,
[1] IMPLICIT Extension,
[2] IMPLICIT SEQUENCE OF Extension
}
pathReplacePropose PathReplacePropose ::= {ptn pr-propose (4)}
pathReplaceSetup PathReplaceSetup ::= {ptn pr-setup (5)}
pathReplaceRetain PathReplaceRetain ::= {ptn pr-retain (6)}
temporarilyUnavailable
ERROR ::= {ptn 1000}
-- used when the operation is temporarily not available and none of
-- the other errors applies - a later attempt could be successful
collision ERROR ::= {ptn 1001}
-- used when a pathReplacePropose invoke APDU is received by a PTNX
-- which has sent a pathReplacePropose invoke APDU
criteriaPermanentlyUnachievable
ERROR ::= {ptn 1002}
-- used when the special criteria requested cannot be achieved
-- because the necessary resources are permanently unavailable
criteriaTemporarilyUnachievable
ERROR ::= {ptn 1003}
-- used when the special criteria requested cannot be achieved
-- because the necessary resources are temporarily unavailable
-- a later attempt could be successful
Unspecified ERROR PARAMETER Extension
unspecified Unspecified ::= {ptn 1008}
-- used to convey a manufacturer specific error, possibly with other
information
END -- of Path-Replacement-Operations
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6.3.2 Information elements
6.3.2.1 Facility information element
APDUs of the operations defined in 6.3.10 shall be coded in the Facility information
element in accordance with ETS 300 239.
When conveying APDUs of operations pathReplacePropose and pathReplaceSetup, the
NFE shall be included.
When conveying the invoke APDU of operation pathReplacePropose, the destinationEntity
data element of the NFE shall contain value endPTNX.
When conveying the invoke APDU of operation pathReplaceSetup, the destinationEntity
data element of the NFE shall contain value endPTNX.
When conveying the invoke APDU of operation pathReplaceRetain, the NFE shall be
omitted.
When conveying the invoke APDU of operation pathReplaceSetup, the Interpretation
APDU shall be included and shall have the value clearCallIfAnyInvokePduNotRecognised.
When conveying any other Remote Operations APDU, the Interpretation APDU shall either
be omitted or have the value rejectAnyUnrecognisedInvokePdu.
6.3.2.2 Other information elements
The following information elements used during establishment of the new connection and
release of the old connection shall be coded as specified in ETS 300 172:
- Bearer capability;
- Called party number;
- Cause;
- Sending complete;
- Transit counter.
6.3.3 Messages
Except for cases where a basic call message is to be conveyed at the same time, the
Facility information shall be conveyed in a FACILITY message as specified in ETS 300
239.
The following messages used during establishment of the new connection and release of
the old connection shall be as specified in ETS 300 172:
- CALL PROCEEDING;
- CONNECT;
- CONNECT ACKNOWLEDGE;
- DISCONNECT;
- RELEASE;
- RELEASE COMPLETE;
- SETUP.
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6.4 ANF-PR state definitions
6.4.1 States at the Requesting PTNX
The procedures for the Requesting PTNX are written in terms of the following conceptual
states existing within the ANF-PR functional entity in that PTNX in association with a
particular call.
6.4.1.1 State PR-Req-Idle
ANF-PR is not operating.
6.4.1.2 State PR-Req-Initiated
A pathReplacePropose invoke APDU has been sent to the Co-operating PTNX.
6.4.1.3 State PR-Req-Completing
The new connection has been established and a pathReplaceSetup return result APDU
has been sent to the Co-operating PTNX.
6.4.2 States at the Co-operating PTNX
The procedures for the Co-operating PTNX are written in terms of the following conceptual
states existing within the ANF-PR functional entity in that PTNX in association with a
particular call.
6.4.2.1 State PR-Coop-Idle
ANF-PR is not operating.
6.4.2.2 State PR-Coop-Establishment
A pathReplaceSetup invoke APDU has been sent in conjunction with the establishment of
the new connection.
6.4.2.3 State PR-Coop-Retain
A pathReplaceRetain invoke APDU has been sent to the Subsequent PTNX.
6.4.3 States at a Transit PTNX on the retained path, including the Branching PTNX
The procedures for a Transit PTNX on the retained path are written in terms of the following
conceptual states existing within the ANF-PR functional entity in that PTNX in association
with a particular call.
6.4.3.1 State PR-Transit-Idle
ANF-PR is not operating.
6.4.3.2 State PR-Transit-Establishment
A pathReplaceSetup invoke APDU has been sent in conjunction with the establishment of
the new connection.
6.4.3.3 State PR-Transit-Retain
A pathReplaceRetain invoke APDU has been sent to the Subsequent PTNX.
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6.5 ANF-PR signalling procedures
The signalling procedures specified below are in support of replacement of the entire
connection. Additional optional procedures for retention of part of the old connection are
specified in 6.61.
Examples of message sequences are shown in C.1 and C.2 of annex C.
6.5.1 Actions at the Requesting PTNX
The SDL representation of procedures at the Requesting PTNX is shown in D.1 of annex D.
6.5.1.1 Normal procedures
On determining that ANF-PR is to be invoked during a call whose protocol control state is
Active, the Requesting PTNX shall send a pathReplacePropose invoke APDU in a
FACILITY message to the Co-operating PTNX and enter state PR-Req-Initiated. Within
the argument, the reRoutingNumber data element shall contain a number from one of the
native numbering plans of the PTN (see ETS 300 189). The number, when used as the
contents of information element Called party number in a SETUP message, shall be
sufficient to cause routing of the new connection to the Requesting PTNX. The callIdentity
data element shall contain a number which, in conjunction with the reRoutingNumber data
element, identifies the particular ANF-PR entity, and therefore the call on which ANF-PR is
being invoked. This number need not have significance outside the Requesting PTNX.
NOTE 10
The number in the callIdentity data element should be sufficient to distinguish the call
concerned from any other call for which the PTNX is acting as an ANF-PR Requesting
PTNX at that time.
Having agreed the B-channel and sent back a CALL PROCEEDING message in response
to an incoming SETUP message, in accordance with the procedures of ETS 300 172, if
the SETUP contains a pathReplaceSetup invoke APDU the Requesting PTNX shall
proceed as follows. If the callIdentity data element in the argument of pathReplaceSetup,
in conjunction with the number information in the Called party number information element,
identifies an ANF-PR entity in state PR-Req-Initiated, the Requesting PTNX shall
associate the new connection (as requested by the SETUP message) with the call on
behalf of which that ANF-PR entity is acting.
The Requesting PTNX shall connect the calling / called user to the B-channel of the new
connection and terminate the B-channel of the old connection in a suitable manner
(pending its release).
NOTE 11
The method of terminating the old connection's B-channel is an implementation matter.
Annex B of prETS 300 258 contains more information on this subject.
A pathReplaceSetup return result APDU shall be sent in a CONNECT message using the
call reference of the new connection and state PR-Req-Completing shall be entered.
NOTE 12
On sending CONNECT, the protocol control state for the new connection will become
Active.
While in state PR-Req-Completing, if a DISCONNECT message is received using the call
reference of the old connection, the Requesting PTNX shall complete the release of the
old connection in accordance with the procedures of ETS 300 172, and enter state
PR-Req-Idle. The call shall continue as an active call using the new connection.
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ETS 300 259: November 1993
6.5.1.2 Exceptional procedures
Receipt of a FACILITY message containing a pathReplacePropose return error APDU or
reject APDU during state PR-Req-Initiated shall cause entry to state PR-Req-Idle, thereby
abandoning ANF-PR. The call shall continue to use the old connection.
NOTE 13
Depending on the error, it may be appropriate to invoke ANF-PR again later. If the error is
collision, steps should be taken to reduce the probability of a further collision, e.g. by using
a random delay before invoking again.
Failure to associate an incoming SETUP message containing a pathReplaceSetup invoke
APDU with an ANF-PR entity in state PR-Req-Initiated shall result in the sending of a
DISCONNECT message to initiate the clearing of the new connection. Depending on
implementation, the DISCONNECT message shall contain either:
- a suitable cause number in the Cause information element, e.g. 1 "unallocated
(unassigned) number"; or
- cause number 29 "facility rejected" in the Cause information element and a return error
APDU containing error invalidReroutingNumber; or
- cause number 29 "facility rejected" in the Cause information element and a return error
APDU containing error unrecognizedCallIdentity.
If the incoming SETUP message containing a pathReplaceSetup invoke APDU is
successfully associated with an ANF-PR entity in state PR-Req-Initiated but the new
connection is unsuitable for some reason, e.g. criteria not satisfied, a DISCONNECT
message shall be sent to initiate clearing of the new connection. The disconnect message
shall contain cause number 29 "facility rejected" in the Cause information element and a
return error APDU containing an appropriate error. The ANF-PR entity shall remain in state
PR-Req-Initiated.
NOTE 14
Receipt of a pathReplacePropose return error APDU can be expected.
On receipt of a FACILITY message containing a pathReplacePropose invoke APDU while
in state PR-Req-Initiated, a pathReplacePropose return error APDU containing error
collision shall be returned. No state change shall occur.
NOTE 15
Receipt of a pathReplacePropose return error APDU containing error collision can be
expected.
6.5.2 Actions at the Co-operating PTNX
The SDL representation of procedures at the Co-operating PTNX is shown in D.2 of annex D.
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ETS 300 259: November 1993
6.5.2.1 Normal procedures
On receipt of a FACILITY message containing a pathReplacePropose invoke APDU while
in protocol control state Active and ANF-PR state PR-Coop-Idle, the Co-operating PTNX
shall determine whether it can proceed with ANF-PR. If so, it shall attempt to establish a
new connection by selecting an outgoing B-channel on a route determined by the contents
of the reRoutingNumber data element within the received argument. If a B-channel is
available, a SETUP message shall be sent using a new call reference in accordance with
the procedures of ETS 300 172. The SETUP shall contain a new call reference and the
following information elements:
- Bearer capability, containing bearer capability information as for the old connection;
- Called party number, containing the number received in the reRoutingNumber data
element within the received argument;
- Sending complete;
- Transit counter, with value zero (optional);
- Facility.
The Facility information element shall contain a pathReplaceSetup invoke APDU. Within
the argument, data element callIdentity shall have the same contents as the corresponding
data element in the argument of the received pathReplacePropose invoke APDU.
The Co-operating PTNX shall terminate the new connection's B-channel suitably.
NOTE 16
The method of terminating the new connection's B-channel is an implementation matter.
Annex B of prETS 300 258 contains more information on this subject.
State PR-Coop-Establishment shall be entered.
The protocol control procedures of ETS 300 172 shall apply during the establishment of
the new connection.
NOTE 17
Initially protocol control will enter state Call Initiated. On receipt of a CALL PROCEEDING
message, state Outgoing Call Proceeding will be entered and on receipt of CONNECT,
state Active will be entered.
On receipt of a CONNECT message (using the call reference of the new connection)
containing a pathReplaceSetup return result APDU, the Co-operating PTNX shall
disconnect the B-channel of the old connection and connect the calling / called user
instead to the B-channel of the new connection. A DISCONNECT message shall be sent
using the call reference of the old connection, thereby initiating the clearing procedures of
ETS 300 172 for the old connection. State PR-Coop-Idle shall be entered. The call shall
continue as an active call using the new connection.
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ETS 300 259: November 1993
6.5.2.2 Exceptional procedures
If the Co-operating PTNX is unable to comply with the pathReplacePropose invoke APDU,
it shall send back a FACILITY message containing a pathReplacePropose return error
APDU with a suitable error.
If the new connection fails to be established for any reason, the Co-operating PTNX shall
send using the old connection a FACILITY message containing a pathReplacePropose
return error APDU with a suitable error. Reasons can include:
- unable to select a B-channel for the new connection;
- receipt of a call clearing message using the new connection's call reference without a
pathReplaceSetup return error APDU or reject APDU;
- receipt of a call clearing message using the new connection's call reference with a
pathReplaceSetup return error APDU or reject APDU;
- timer expiry at the Co-operating PTNX.
In each case state PR-Coop-Idle shall be entered and the call shall continue as an active
call using the old connection.
6.5.3 Actions at a Co-operating/Requesting PTNX in the case of a trombone connection
On receipt of a FACILITY message containing a pathReplacePropose invoke APDU, the Co-
operating PTNX can determine from the reRoutingNumber data element in the argument
whether the Requesting PTNX is the same
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