SIST-TP ETSI/ETR 157-1 E1:2005
(Main)Broadband Integrated Services Digital Network (B-ISDN); Signalling requirements for B-ISDN services; Part 1: Capability Set 2 (CS2)
- Abstract
To investigate the requirements for the evolution of access and network protocols for B-ISDN services, to act as the coordination point in SPS for such studies and to contribute to CCITT WP XI/4 & 6 question 11, for signalling requirements on release 1 & 2
- Status
- Published
- Publication Date
- 31-Mar-2005
- Withdrawal Date
- 30-Sep-2003
- Technical Committee
- SPN - Services and Protocols for Networks
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Apr-2005
- Due Date
- 01-Apr-2005
- Completion Date
- 01-Apr-2005
SIST-TP ETSI/ETR 157-1 E1:2005 is the Slovenian edition of ETSI ETR 157-1 Edition 1, issued by SIST as an informative ETSI Technical Report. It sets out B-ISDN signalling requirements for Capability Set 2 (CS2), including the service model, signalling flows, and interworking cases used to develop access and network protocols. It is written for people designing, assessing, or implementing B-ISDN signalling and interworking with N-ISDN.
What does SIST-TP ETSI/ETR 157-1 E1:2005 specify?
SIST-TP ETSI/ETR 157-1 E1:2005 specifies the signalling requirements for B-ISDN services in CS2 and organizes them as a study of access and network protocol evolution. The report ties the service requirements to stage 2 functional modelling, information flows, and interworking with related broadband and narrowband services.
The document is arranged in these main parts:
| Annex | What it covers |
|---|---|
| Annex A | SDL diagrams supporting atomic actions |
| Annex B | General connection types for possible future application |
| Annex C | Bibliography |
The main body moves from scope and abbreviations to service objectives, the information model, the functional signalling model, information flow elements, functional entity actions, and signalling interworking requirements. In practice, that means the report does not stay at a high-level service description - it also shows how calls, parties, and connections are represented and how signalling procedures are expected to behave.
What are the key requirements of SIST-TP ETSI/ETR 157-1 E1:2005?
SIST-TP ETSI/ETR 157-1 E1:2005 defines the CS2 signalling behaviour around service setup, connection structure, ownership, notification, and interworking. The most important points are the service capabilities that must be supported, the allowed connection topologies, and the procedures used when calls or connections are created, modified, or released.
Service support and bearer behaviour
Clause 3 identifies the service capabilities that drive the signalling design. These include bearer service classes X, A, B, C, and D, support for point-to-point and point-to-multipoint configurations, symmetric and asymmetric connections, adding bearers after a call has been established, and specifying Quality of Service (QoS) class information.
In practice, this tells a protocol designer what kinds of user sessions the signalling must carry: simple two-party calls, multiparty distribution, and calls where capacity and QoS are negotiated rather than fixed from the start.
Clause 3 also ties CS2 to interworking with N-ISDN supplementary services and with Frame Relay, X.25, and 64 kbit/s circuit-mode bearer services. That matters because a B-ISDN implementation is expected to coexist with older networks and related service environments.
Connection types, routing rules, and ownership
Clause 3.2 distinguishes two connection topology types: Type 1 point-to-point connection and Type 2 point-to-multipoint connection. It also introduces Virtual Channel Connection, CRCG bearer connection, and Virtual Path bearer connection, while noting that Virtual Path bearer connections are not supported in CS2.
The CRCG rules are especially important in practice:
- no rerouting is allowed when adding a party or a Network Connection Group
- a CRCG may contain different connection types
- all roots of a Type 2 connection must be attached at the same party
- each connection belongs to only one CRCG
These rules control how the network keeps related media paths aligned. For implementers, they define when paths may be shared and when they must remain fixed.
Clause 3.2 also defines the ownership model:
- call owner
- party owner
- connection owner
- branch owner
This ownership model matters because it determines who may release a call, release a party, release a connection, or detach a party from a connection. The report also states that any party may release itself from the call or detach itself from the connection.
General CS2 rules for call and connection handling
Clause 3.2 lists the general CS2 rules that shape the signalling exchange. The most practical ones are that the Network Connection owner is the initiating party, the root party of a Type 2 connection is not necessarily the Network Connection owner, and a third party may establish and add a Network Connection Group and attach an existing party to it.
The report also allows a party to have no connections, requires that any additional Network Connection be awarded only to the terminal equipment that received the first Network Connection in the call, and states that Type 2 connections assume automatic answer machines. These details matter when mapping service logic to real terminals and network nodes.
Other notable CS2 rules are that all multiple parties in an information flow are mandatory, ATM bearer connection characteristics are negotiated during call establishment, a connection can belong to only one Network Connection Group at a time, and all attached parties must be notified when a connection changes type. Modification from Type 1 to Type 2 is allowed only when the Type 1 connection is unidirectional.
Look Ahead and control-plane modelling
Clause 3.4 defines Look Ahead as a procedure with two variants: without state change and with state change. Look Ahead without state change tests whether the terminal and connection are suitable before the action proceeds. Look Ahead with state change lets the network reserve resources at the terminating end point before the request arrives.
This matters because it separates user acceptance checks from resource reservation. The report also says that Gateway exchanges may optionally reject interrogation requests and that a selection mechanism offers sets of capabilities to the terminating end point.
Clause 5 and clause 6 describe the functional signalling model and the information flow sequences. The model splits the control plane into signalling functional entities coordinated by Application Control (AC), and the flows use one-phase and two-phase request mechanisms with READY, COMMIT, BEGIN, and CANCEL behaviour. In practice, this is the procedural backbone for implementation and protocol mapping.
Interworking with other signalling environments
Clause 8 gives the interworking requirements for N-ISDN at 64 kbit/s and for Release 1 and Release 2 coexistence. It presents two interface scenarios for N-ISDN access and network interworking, and it stresses that existing operations must not be impaired when new signalling is introduced.
For engineers, this means the CS2 design must preserve compatibility while allowing broadband signalling to carry older services and to evolve toward Release 2 behaviour.
What terms does SIST-TP ETSI/ETR 157-1 E1:2005 define?
- B-ISDN - Broadband Integrated Services Digital Network, the broadband service and signalling environment covered by the report.
- CS2 - Capability Set 2, the signalling capability set addressed by the technical report.
- QoS - Quality of Service, used for characterizing service and connection requirements during establishment and modification.
- CRCG - Common Route Connections Group, a grouping where connections share route characteristics under the rules given in clause 3.2.
- Look Ahead - A procedure for checking terminal or connection suitability, either without state change or with state change.
- FE - Functional Entity, one of the signalling entities used in the functional model.
- FEA - Functional Entity Agent, the user-associated form of a functional entity in the SDL annexes.
- AC - Application Control, the coordination function that manages the signalling functional entities.
Who uses SIST-TP ETSI/ETR 157-1 E1:2005?
SIST-TP ETSI/ETR 157-1 E1:2005 is used by signalling protocol engineers, network architects, and implementers of B-ISDN access and core network control. It is also useful for vendors and integrators working on interworking with N-ISDN, ATM-based bearer services, and multiparty call control.
Quality and conformance teams can use it to understand the intended call ownership, notification, and release behaviour before they verify protocol design or interoperability. Service designers can also use it to see how CS2 supports point-to-point and point-to-multipoint services, add/drop behaviour, and QoS-related negotiation.
Which standards are used with SIST-TP ETSI/ETR 157-1 E1:2005?
SIST-TP ETSI/ETR 157-1 E1:2005 refers to several related Recommendations and service studies:
- Recommendation Q.71 - provides the Release 1 information flows and functional entity actions referenced in clause 6.1.
- Recommendation Q.73 - appears in the stage 2 functional model figures as the model basis for the B-ISDN CS2 signalling structure.
- Recommendation Q.767 - defines the narrowband ISDN supplementary services used in the interworking discussion.
- Recommendations F.310, F.722, F.732, F.811, F.812, F.821, and F.822 - are listed as related B-ISDN service studies that help explain the service context behind CS2.
- Recommendations I.122, I.555, I.580, and X.2 - are listed as interworking-related studies for Frame Relay, N-ISDN, and data communication services.
These references help place the signalling requirements in the wider B-ISDN and interworking environment rather than treating CS2 as a standalone design.
What does the SIST-TP ETSI/ETR 157-1 E1:2005 document contain?
The document contains tables, figures, procedures, and SDL descriptions rather than a short checklist of requirements. Clause 3 uses tables to classify bearer service classes, connection types, and release-1 versus release-2 capability areas. Clause 4 defines the information model with objects such as Call, Remote Party, Service Module, Service Component, Network Connection, and Network Connection Group.
Clause 6 maps information flow names and parameters to the stage 2 model, including setup, add, attach, detach, release, renegotiate, modify, interrogation, look-ahead, and notification flows. Clause 7 then works through example signalling actions for call establishment, adding connections or parties, detachment, release, and look-ahead procedures. Clause 8 gives interworking scenarios between B-ISDN and 64 kbit/s based ISDN.
Annex A contains SDL diagrams for generic information model objects and the FEA, co-ordinator, subordinate, and superior roles used in atomic actions. Annex B gives connection types for possible future application, which helps readers see how CS2 fits into a broader connection model.
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Frequently Asked Questions
SIST-TP ETSI/ETR 157-1 E1:2005 is a technical report published by the Slovenian Institute for Standardization (SIST). Its full title is "Broadband Integrated Services Digital Network (B-ISDN); Signalling requirements for B-ISDN services; Part 1: Capability Set 2 (CS2)". This standard covers: To investigate the requirements for the evolution of access and network protocols for B-ISDN services, to act as the coordination point in SPS for such studies and to contribute to CCITT WP XI/4 & 6 question 11, for signalling requirements on release 1 & 2
To investigate the requirements for the evolution of access and network protocols for B-ISDN services, to act as the coordination point in SPS for such studies and to contribute to CCITT WP XI/4 & 6 question 11, for signalling requirements on release 1 & 2
SIST-TP ETSI/ETR 157-1 E1:2005 is classified under the following ICS (International Classification for Standards) categories: 33.080 - Integrated Services Digital Network (ISDN). The ICS classification helps identify the subject area and facilitates finding related standards.
SIST-TP ETSI/ETR 157-1 E1:2005 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-april-2005
Širokopasovno digitalno omrežje z integriranimi storitvami (B-ISDN) -
Signalizacijske zahteve za storitve B-ISDN - 1. del: Nabor zmožnosti 2 (CS2)
Broadband Integrated Services Digital Network (B-ISDN); Signalling requirements for B-
ISDN services; Part 1: Capability Set 2 (CS2)
Ta slovenski standard je istoveten z: ETR 157-1 Edition 1
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
ETSI ETR 157-1
TECHNICAL March 1996
REPORT
Source: ETSI TC-SPS Reference: DTR/SPS-03008-1
ICS: 33.080
B-ISDN, signalling, CS2
Key words:
Broadband Integrated Services Digital Network (B-ISDN);
Signalling requirements for B-ISDN services;
Part 1: Capability Set 2 (CS2)
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 1996. All rights reserved.
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ETR 157-1: March 1996
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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ETR 157-1: March 1996
Contents
Foreword .9
1 Scope .11
2 Abbreviations.11
3 B-ISDN signalling requirements objectives .12
3.1 B-ISDN Services Requirements .12
3.2 B-ISDN Bearer Services Signalling Requirements .13
3.3 ITU-T SG 13 Proposed Schedule for B-ISDN Signalling Capabilities .17
3.4 B-ISDN Signalling Capabilities.18
4 Information model .25
4.1 General .25
4.1.1 Object Modelling and Signalling Requirements.25
4.1.2 Views of a Call.25
4.2 Description of Objects in Information Model.26
4.2.1 Call .27
4.2.2 Remote Party .27
4.2.3 Attachment .27
4.2.4 Service Module.27
4.2.5 Service Component.27
4.2.6 Network Connection.28
4.2.7 Network Connection Group.28
4.2.8 Participation.28
4.3 Descriptions of Attributes.28
4.3.1 Attributes of Call Objects.28
4.3.1.1 Call Identifier (Call ID).28
4.3.1.2 List of Remote Parties .28
4.3.1.3 Local Party Address.28
4.3.1.4 Telecommunications Service Type.28
4.3.1.5 List of Service Components.28
4.3.1.6 List Network Connection Groups.28
4.3.2 Attributes of Remote Party Objects.28
4.3.2.1 Remote Party Reference Identifier .28
4.3.2.2 Remote Party Address.28
4.3.2.3 Remote Party Type.29
4.3.3 Attributes of Attachment Objects.29
4.3.4 Attributes of Service Module Objects .29
4.3.4.1 Service Module Identifier .29
4.3.4.2 List of Service Components.29
4.3.4.3 Multiplexing Method.29
4.3.5 Attributes of Service Component Objects .29
4.3.5.1 Service Component Identifier .29
4.3.5.2 Service Component Characteristics .29
4.3.5.3 Service Traffic Descriptor Requirements.29
4.3.5.4 Service QoS Descriptor Requirements.29
4.3.6 Attributes of Network Connection Objects .29
4.3.6.1 Network Connection Identifier .29
4.3.6.2 List of Service Modules.30
4.3.6.3 User (TE) - Oriented Low Layer Information .30
4.3.6.3.1 Network Layer Information.30
4.3.6.3.2 AAL Layer Information .30
4.3.6.4 Network-Oriented Low Layer Information.30
4.3.6.4.1 Network Layer Information.30
4.3.6.4.2 AAL Layer Information .30
4.3.6.4.3 ATM Layer Information .30
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ETR 157-1: March 1996
4.3.6.4.4 Bearer Service Subcategory . 30
4.3.6.5 Directionality Indicator. 30
4.3.6.6 Transit Network Identifier. 30
4.3.6.7 ATM Connection Topology Type. 31
4.3.6.8 Local Attachment . 31
4.3.7 Attributes of Network Connection Group Objects. 31
4.3.7.1 Network Connection Group Identifier. 31
4.3.7.2 List of Network Connection Identifiers . 31
4.3.8 Attributes of Participation Objects. 31
5 Functional signalling model . 31
5.1 Description of the Stage 2 Functional Model. 31
5.2 Description of Functional Entities. 35
5.3 Information Flow Strata for Capability Set 2. 36
6 Information flow elements. 37
6.1 Information Flows and FE actions for Release 1 services . 37
6.2 Information Flow Conventions for Capability Set 2 services . 37
6.2.1 Convention of Reference Direction. 37
6.2.2 Convention for ATM Switch Through. 38
6.3 Description of Information Flows. 38
6.3.1 Call-&-Bearer-Setup Information Flow Sequence. 43
6.3.2 Call-Setup Information Flow Sequence . 43
6.3.3 Add-Bearer-to-Call Information Flow Sequence. 43
6.3.4 Add-Party-to-Bearer Information Flow Sequence. 43
6.3.5 Attach-Party-to-Bearer Information Flow Sequence. 43
6.3.6 Add-Party-to-Call Information Flow Sequence . 43
6.3.7 Add-Party-&-Bearer-to-Call Information Flow Sequence. 43
6.3.8 Detach-Party-from-Bearer . 43
6.3.9 Release-Bearer. 43
6.3.10 Release-Party-from-Call . 43
6.3.11 Release-Call . 43
6.3.12 Re-Negotiate-Bearer. 43
6.3.13 Modify-Bearer . 44
6.3.14 Call-&-Bearer-Setup-Remote. 44
6.3.15 Add-Bearer-to-Call-Remote. 44
6.3.16 Add-Party-to-Bearer-Remote. 44
6.3.17 Attach-Party-to-Bearer-Remote. 44
6.3.18 Add-Party-&-Bearer-to-Call-Remote. 44
6.3.19 Detach-Party-from-Bearer-Remote . 44
6.3.20 Release-Bearer-Remote. 44
6.3.21 Interrogation-Terminating-End-Point . 44
6.3.22 Look-Ahead . 44
6.3.23 Report-End/Edge . 45
6.3.24 Report-Link . 45
6.3.25 Notify-Party-Change . 45
6.3.26 Notify-Bearer-Change. 45
6.3.27 Notify-Bearer-Modified. 45
6.4 Relationship between Parameters of Information Flows and Stage 2 model . 45
6.5 Information Flow and Stage 2 Model. 47
6.6 Information Parameters for Information Flows. 48
7 Functional entity actions . 61
7.1 Simultaneous Call and Connection Establishment . 62
7.1.1 Call and Network Connection Group Establishment of Type 1
Connections. 62
7.1.1.1 Call and Network Connection Group Establishment -
Single Network Connection Group - Without "Look
Ahead". 62
7.1.1.2 Call and Network Connection Group Establishment -
Single Network Connection Group - With "Look Ahead" . 64
7.1.1.3 Call and Network Connection Group Establishment -
Single Network Connection Group - Third Party. 66
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ETR 157-1: March 1996
7.1.2 Call and Network Connection Group Establishment of Type 2 Network
Connection Groups .69
7.1.2.1 Call and Network Connection Group Establishment Single
Network Connection Group - Originating Node Branch
Root Party.69
7.1.2.2 Call and Network Connection Group Establishment Single
Network Connection Group - Relay Node Branch Root .71
7.1.2.3 Call and Network Connection Group Establishment Single
Network Connection Group - Relay Node Branch Leaf.73
7.1.2.4 Call and Network Connection Group Establishment Single
Network Connection Group - Relay Node Branch Third.76
7.2 Addition of a new Network Connection (Group) to an existing Call with attachment of
existing Parties to the Network Connection (Group).78
7.2.1 Addition of a Type 1 Network Connection Group to an existing call .78
7.2.1.1 Addition of one point-to-point Network Connection Group
requested by the Call Initiating Party .79
7.2.1.2 Addition of an Network Connection Group to an existing
Call - Without "Look Ahead" and with Notify - With
Establishment of a new Route in the Network.80
7.2.1.3 Addition of an Network Connection Group to an existing
Call - Third Party.82
7.2.2 Addition of a Type 2 Network Connection Group to an existing call .85
7.2.2.1 Addition of an Network Connection Group to an existing
Call - Requesting Serving Node Branch Root Party .85
7.2.2.2 Addition of an Network Connection Group to an existing
Call - Relay Node Branch Root.87
7.3 Addition of one Network Connection to an Existing Network Connection Group with
attachment of existing Parties to the new Network Connection.89
7.3.1 Addition of one Type 1 Network Connection .89
7.3.1.1 Addition of one point-to-point Network Connection
requested by the Call Initiating Party .90
7.3.2 Addition of one Type 2 Network Connection .91
7.3.2.1 Addition of one point to multipoint Network Connection
requested by the Root of the new Network Connection .91
7.4 Addition of one or more new Parties to an Existing Call with Attachment to an Existing
Network Connection - With or without network Look-ahead.93
7.4.1 Addition of one or more new Parties and attachment to a Type 1 Network
Connection .93
7.4.1.1 Add one new Party requested by a Party which will be the
Root of the Type 1 Network Connection (without network
Look Ahead) .93
7.4.2 Addition of one or more new Parties and attachment to a Type 2 Network
Connection .95
7.4.2.1 Add one or more new Parties requested by the call
initiating Party .95
7.5 Attachment of one or more existing Parties to an existing Network Connection.95
7.5.1 Attachment of one or more existing Parties to a Type 1 Network
Connection .95
7.5.1.1 Attachment of one existing Party requested by a Party
which will be the Root of the Type 1 Network Connection.96
7.5.2 Attachment of one or more existing Parties to a Type 2 Network
Connection .97
7.5.2.1 Attachment of one existing Party requested by the call
initiating Party .97
7.6 Call Establishment without any Network Connection Group(s) .97
7.6.1 Two-Party Call-Only Establishment.98
7.6.2 Three-or-More-Party Call-Only Establishment .99
7.7 Addition of a Party to a Call without Attachment to any Network Connection Group(s) .100
7.8 Detachment of a Party from an Existing Connection.100
7.8.1 Detachment Requested by the Root of the Connection.100
7.8.1.1 Root Party Requests Detachment from the Connection.101
7.8.1.2 Root Party Requests that a Leaf be Detached from the
Connection.102
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ETR 157-1: March 1996
7.8.2 Detachment Requested by a Leaf of the Connection. 102
7.8.2.1 A Leaf Party Requests that it be Detached from a
Connection. 103
7.8.2.2 A Leaf Party Requests that the Root be Detached from
the Connection. 104
7.8.2.3 A Leaf Party Requests a Leaf be Detached from the
Connection. 105
7.8.3 Detachment Requested by a Party not Attached to the Connection . 106
7.8.3.1 A Party Not Attached to a Connection Requests that the
Root Party be Detached. 106
7.8.3.2 A Party Not Attached to a Connection Requests that a
Leaf be Detached. 107
7.9 Release of the Connection from an Existing Call. 108
7.9.1 Release of a Point-to-point Connection from an existing Call . 108
7.9.2 Release of a Point-to-multi-point Connection from an Existing Call. 108
7.9.2.1 Release of a Connection requested by the Party
Associated with the Root. 109
7.9.2.2 Release of a Connection Requested by a Leaf Party that
is the Connection Owner. 110
7.9.2.3 Release of a Connection Requested by a Leaf Party that
is not the Connection Owner. 111
7.9.2.4 Release of a Connection Requested by a Party not
attached to the Connection . 112
7.10 Release of a Party from an existing call. 112
7.10.1 General rules for release of a Party. 112
7.10.2 Release of a Party from a Call requested by the Call or Party Owner. 113
7.10.2.1 Release of a Party that is the leaf party of a Type 2
Connection by the Call Owner . 113
7.10.3 Release of a Party from a Call requested by the Party to be released. 114
7.10.3.1 Release of a Party that is the Connection owner but not
the root of a Type 2 Connection. 114
7.11 Release of a Call. 114
7.11.1 General rules for releasing a call. 114
7.11.2 Release of a Call without any connections . 115
7.11.3 Release of a Call with multiple Type 1 connections . 116
7.11.3.1 Release of a Call with two Type 1 connections between
different Parties. 116
7.11.3.2 Release of a Call Requested by the Connection owner. 117
7.11.4 Release of a Call with Point to multipoint connections . 118
7.11.4.1 Release of a Call where the call owner is not the root of
the connection. 118
7.12 Look Ahead Procedures. 118
7.12.1 Look Ahead without State Change . 119
7.12.2 Look Ahead with State Change . 121
7.12.2.1 Human User Version. 121
7.12.2.2 Non-Human User Version. 123
8 Signalling interworking requirements. 124
8.1 Introduction. 124
8.1.1 Possible solutions . 124
8.1.2 Communication scenarios . 125
8.2 N-ISDN (64 kbit/s based) Interface Requirements. 126
8.2.1 Interworking requirements for Access signalling . 129
8.2.2 Interworking requirements for Network signalling. 129
8.3 Interworking of Release 1 and Release 2 . 130
8.3.1 Requirements for B-ISDN signalling protocol evolution. 130
8.3.2 Scenarios for Interworking. 130
8.3.2.1 Scenario A. 130
8.3.2.2 Scenario B. 131
8.3.2.3 Scenario C . 131
8.3.2.4 Scenario D . 132
8.3.3 Support of Release 2 services by using Release 1 equipment . 132
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ETR 157-1: March 1996
Annex A: SDL diagrams supporting atomic actions .133
A.1 Introduction.133
A.2 Generic Information Model Object .135
A.3 FEA Application Part .137
A.4 SDL for Co-ordinators .139
A.5 SDL for a Subordinate.143
A.6 SDL for Superior.145
Annex B: General connection types for possible future application .146
Annex C: Bibliography .150
History.151
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ETR 157-1: March 1996
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ETR 157-1: March 1996
Foreword
This ETSI Technical Report (ETR) has been produced by the Signalling Protocols and Switching (SPS)
Technical Committee of the European Telecommunications Standards Institute (ETSI). It is based on
contribution to ITU-T Study Group 11.
ETRs are informative documents resulting from ETSI studies which are not appropriate for European
Telecommunication Standard (ETS) or Interim European Telecommunication Standard (I-ETS) status. An
ETR may be used to publish material which is either of an informative nature, relating to the use or the
application of ETSs or I-ETSs, or which is immature and not yet suitable for formal adoption as an ETS or
an I-ETS.
This ETR is part 1 of a multi-part ETR covering the signalling requirements for B-ISDN services as
described below:
Part 1: "Capability Set 2 (CS2)";
NOTE: Additional parts may cover the further development of the B-ISDN services.
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ETR 157-1: March 1996
Blank page
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ETR 157-1: March 1996
1 Scope
This ETSI Technical Report (ETR) contains a description of the Broadband Integrated Services Digital
Network (B-ISDN) signalling requirements for Capability Set 2 (CS2). These requirements are to be used
in the development of the appropriate peer-to-peer and layer-to-layer signalling protocols. These
requirements are based on the requirements from ITU-T Study Groups 1 and 13, especially the available
stage 1 definitions listed in subclause 3.1.
The following services/capabilities are identified. These will impose signalling requirements in B-ISDN.
a) Establishment of on demand connections.
Demand a call between exactly two users which is supported by a single point-to-point connection.
b) Support of connections configurations on a point-to-point and point-to-multipoint basis.
c) Support of symmetric and asymmetric connections (e.g. low or zero bandwidth in one direction and
high bandwidths in the other).
d) To be able to establish a call and then later add bearers.
e) Specification of Quality of Service (QoS) class, etc.
NOTE: For integration of 64 kbit/s based N-ISDN services and B-ISDN with a broadband
signalling protocol, the supplementary services itemized in CCITT Recommendation
Q.767 according to the most recent stage 1 and stage 2 recommendation should be
supported.
2 Abbreviations
For the purposes of this ETR, the following abbreviations apply:
AAL ATM Adaptation Layer
AC Application Control
ATM Asynchronous Transfer Mode
B-ISDN Broadband Integrated Services Digital Network
BCLB Broadband ConnectionLess Bearer
BCOB Broadband Connection Oriented Bearer
CBR Constant Bit Rate
CC Call Control
CCR Commitment, Concurrency and Recovery
CRCG Common Route Connections Group
CS2 Capability Set 2
DC enD-to-end Control
DCA enD Control Agent
EC Edge-to-edge Control
FE Functional Entity
ID IDentifier
IN Intelligent Network
IWU Inter Working Unit
LBA Local Bearer Access
LC Link-by-link Control
LCA Link Control Agent
LEX Local EXchange
LLC Lower Layer Component
N-ISDN Narrowband ISDN
NA Not Applicable
NNI Network-Network Interface
NSAP Network Service Access Point
NT Network Termination
OAM Operations, Administration and Management
PC Presentation Control
PCA Presentation Control Agent
PDH Pleisiochronous Digital Hierarchy
PSTN Public Switched Telephone Network
QoS Quality of Service
RLS Release
SAP Service Access Point
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SAR Segmentation And Reassembly
SC Service Component
SDH Synchronous Digital Hierarchy
SDL Specification and Description Language
SDU Service Data Unit
SM Service Module
SMDS Switched Multi-megabit Data Service
TE Terminal Equipment
TEI Terminal Equipment Identifier
TMN Telecommunication Management Network
UNI User-Network Interface
VBR Variable Bit Rate
VC Virtual Channel
VCC Virtual Channel Connection
VCI Virtual Channel Identifier
VP Virtual Path
VPC Virtual Path Connection
VPI Virtual Path Identifier
3 B-ISDN signalling requirements objectives
3.1 B-ISDN Services Requirements
General service characteristics that need to be addressed in the development of B-ISDN Signalling CS2
are as follows:
- signalling Support for Bearer Service Classes X, A, B, C, and D for the connection types identified
below. The connection types are defined in table 3.
Table 1: Bearer Service Classes and Connection Types
Bearer Service Connection Types
Sub-categories Type 1 Type 2
Class X, A, B
Class C assured service --
Class C unassured service
Class D (dial up only)
- service Interworking with N-ISDN which is presently restricted to the 10 Supplementary Services
defined in Broadband Release 1:
- Calling Line Identification Presentation;
- Calling Line Identification Restriction;
- Connected Line Presentation;
- Connected Line Restriction;
- Direct Dialling In;
- Multiple Subscriber Number;
- Terminal Portability;
- Closed User Group;
- Subaddressing;
- User to User Signalling Service 1;
- Interworking with Frame Relaying, X.25 and 64 kbit/s circuit mode bearer services of N-ISDN.
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For additional information about the service specific requirements driving Broadband CS2, the following
draft Recommendations for B-ISDN services should be considered:
F.310 (Broadband Videotex Service)
F.722 (Broadband Videotelephony)
F.732 (Broadband Videoconference)
F.811 (Broadband connection oriented bearer service)
F.812 (Broadband connectionless data bearer service)
F.821 (Broadband TV distribution service)
F.822 (Broadband HDTV)
On an interworking basis, the following services should also be considered:
I.122 (Frame Relay Service)
I.555 (Interworking with Frame Relay)
I.580 (Interworking with N-ISDN)
X.2 (Data Communications Services)
3.2 B-ISDN Bearer Services Signalling Requirements
The broadband connection oriented bearer service categories provide unrestricted transfer of user
information over a B-ISDN Virtual Path, Virtual Channel, or Common Route Connection Group (CRCG)
connection between two or more parties connected at the Sb/Tb reference points. The three forms of
B-ISDN connections are illustrated in figure 1.
Virtual Path Common Route Virtual Channel
Bearer Connection Connection Group Bearer Connection
Bearer Connection
Figure 1: B-ISDN Bearer Connections
- Virtual Channel Connection: A single Virtual Channel is provided by the network as a separate
entity.
- CRCG Bearer Connection: CRCGs provide a constrained differential delay service for a selected
group of connections. This is accomplished by using the same route for VC connections in a CRCG
from the requesting party to a requested party. Not all connections in a CRCG need to be
established simultaneously. A user may wish to establish a video connection in addition to an
already existing speech connection. It should be possible to indicate, that the video connection will
be routed via the same route as the existing speech connection. Within Capability Set 2, the
following rules apply:
- no re-routeing is allowed when adding a party or a Network Connection Group; and
- a CRCG may have VC connections of different connection types; however all roots of Type 2
connection must be attached at the same party;
- a CRCG may consist of one connection only;
- every connection belongs to only one CRCG.
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- Virtual Path Bearer Connection: an entire Virtual Path is provided by the network. The Virtual
Channels and their content is transparent to the network (Virtual Path Bearer Connections are not
supported in Capability Set 2).
The Bearer Connection (Bearer Service) provides cell based communication in a bi-directional symmetric,
bi-directional asymmetric or uni-directional fashion for various Bearer Connection topology types. Those
connection topology types that are applicable for Capability Set 2 are illustrated in table 3; a more general
representation showing possible future extensions is provided in annex B. The user specifies several
parameters at connection establishment to characterize the communications. The Virtual Channel may
carry one service component or may carry several service components multiplex together. When the
Virtual Channel is used in this fashion, the method of multiplexing must be indicated to the addressed
parties associated with this virtual channel at the time of connection establishment. The information rate
may be characterized by a group of parameters such as peak cell rate or peak bit rate, average cell rate
or bit rate, etc. When a connection is being requested, the admission control within the network will check
if this connection type is allowed and then may employ "Look Ahead" procedures in order to determine if
the addressed parties associated with the connection are willing to accept the connection. If the service
class and the addressed parties are willing to accept the connection, the network will attempt to establish
the connection. If there is sufficient physical bandwidth within the network to carry this connection, the
connection will be established.
The following definitions about the ownerships capabilities will apply:
call owner: One that initiates a call is the call owner. There is only one call owner per call.
party owner: One that adds a party to a call is the owner of that party. There may be several party owners
within a call.
connection owner: One that initiates a connection is the connection owner. There is only one connection
owner per connection. There may be several connection owner per call. A connection owner may be
associated with the root, a leaf, or be a party not attached to the connection.
branch owner: One that adds a branch to a connection is the owner of that branch. There may be several
branch owners per connection. A branch owner may be associated with the root, a leaf, or be a party not
attached to the connection.
Table 2
Permission Call Owner Party Owner Connection Branch Owner
Owner
Release a Call
Release Party from Call
Release a Connection
Detach a Party from a
Connection
Any party has the permission to release itself from the call or to detach itself from the connection.
The transfer of ownership is not included in the Capability Set 2 requirements.
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The B-ISDN services allows for the inclusion of several connections per "call." An example of a call with
several connections is shown in figure 2.
Network
o
a
o
B
b o
o
b
o
R d
A o
c b
o
o
o
C
D
NOTE: Lines a, b, c, and d = connections.
Figure 2: Example Four Party Call containing Four Connections
- "R" is a replication function which may be implemented in multiple nodes within the network.
- Connection "a" is a Type 1 connection between Party "A" and Party "B".
- Connection "b" is a Type 2 connection between the "Root" Party "A" and the "Leaf" Parties "B" and
"C".
- Connection "c" is a Type 1 connection between Party "A" and Party "C".
- Connection "d" is a Type 1 connection between Party "B" and Party "C".
- Party D is a member of the call but is not attached to any of the four connections.
Table 3: Connection Topology Types
Network
Type 1: Point-to-point Connection - a unidirectional or
Connection
bi-directional connection between two terminals.
B
A Point-to-point Connection may provide uni-
A
directional or Bi-directional asymmetric
communications between parties "A" and "B".
C
D
Point-to-point Connection
Network
Leaf
Type 2: Point-to-multi-point Connection - a
Connection
unidirectional connection from a single source to two
Root
B
or more sinks (note 1).
R
A
A Point-to-multi-point Connection provides uni-
directional communications from the "Root" Party "A" C
to "Leaf" Parties "B" and "C."
Leaf
D
"R" = Replication Function (note 2).
Uni-Directional Point-to-multi-point
Connection
(continued)
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Table 3 (concluded): Connection Topology Types
NOTE 1: Type 2 connections may be used to support multicast or broadcast services.
A multicast connection is one in which sink parties are specified before the connection
is established, or by subsequent operations to add or remove parties from the
connection. The source of the connection will always be aware of all parties to which the
connection travels.
EXAMPLES: A connection that is established to a list of end addresses.
A connection that broadcasts to a community of terminals by some criteria other
than network parties.
A connection that is associated with a "distribution list" not visible to the source,
such as an e-mail exploder.
A broadcast connection is one in which the sink parties are not always known to
the source. The major difference from multicast is that for a broadcast
connection, the connection to individual sink parties is not under the control of the
source, but is by request of the each sink party.
A broadcast connection to which any terminal can subscribe without reference to
the source, perhaps subject to subscription restrictions.
Broadcast connections are not required for Capability Set 2.
NOTE 2: Replication may occur in one or more network nodes to provide the multiple routes. A
Replication point is a point in a connection where user plane data received from one
incoming data flow is replicated on two or more outgoing data flows. Replication is
possible in the ATM Layer, within the AAL or in higher layers.
Replication takes place within the ATM switch based on the VPI:VCI fields in the cell
header. Each such cell arriving at the switch is copied onto one or more outgoing ATM
cell streams, and within each cell stream onto one or more ATM virtual paths or virtual
channels. Cell information field contents are not altered by this copying process. This
form of Replication is simple to implement but is not suitable for those AALs that rely on
point-to-point retransmission for recovery of lost data. ATM Replication points may
occur in any node of the network. This type of Replication point is required for CS2.
Replication takes place within an AAL handler attached to or integrated with the ATM
switch. Each AAL packet is assembled from incoming cells, the user information is
extracted, and this is then segmented again onto two or more outgoing AAL
connections. Because the AAL is terminated and regenerated in this case,
retransmission is handled directly by the Replication point, not passed back to the origin
of the information. This type of Replication point is not supported by Capability Set 2.
Higher Layer Replication takes places within a specialist server function of some kind.
This type of Replication point is not supported by CS2.
Within CS2, the following general requirements apply:
1) the Network Connection owner shall be the connection initiating party;
2) the root party of a Type 2 connection is not necessarily the Network Connection owner;
3) a party that is not a connection owner can add a new party to the existing connection;
4) a third party may establish and add a Network Connection Group and attach an existing party to a
Network Connection Group to which this party is not attached although it is the Network Connection
Group owner;
5) it is possible for a party to have no connections;
6) when an attempt to add an additional Network Connection is made, the Network Connection will
only be awarded to the terminal equipment which was awarded the first Network Connection within
the call;
7) whenever type 2 connections are used, automatic answer machines are assumed;
8) when multiple parties are contained in an information flow, they are all considered mandatory;
9) the negotiation of ATM bearer connection characteristics (e.g. ATM cell rate) during the call
establishment phase shall be provided;
10) a particular connection can belong to no more than one Network Connection Group at a certain
point in time: A connection has one particular route through the network at a certain point of time,
so it cannot belong at the same moment to multiple Network Connection Groups;
11) it should be possible to control the Network Connection Group as a whole for establishment;
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12) it is necessary to be able to specify, within a single information flow, single or multiple parties,
service components, service module and network connections;
13) all attached parties must be notified about type changes of the connection;
14) all serving nodes associated with parties that may invoke capabilities related to parties, connections
or attachments that are modified should be notified of these modifications;
15) modification from type 1 to 2 connections are only allowed if the type 1 connection is unidirectional.
3.3 ITU-T SG 13 Proposed Schedule for B-ISDN Signalling Capabilities
Major areas of study for the initial B-ISDN access and network signalling Recommendations prepared by
Study Group 13 are listed in table 4.
Table 4: Proposed Schedule for B-ISDN Signalling Capabilities
Release 1 (note 1) Release 2 (note 2)
<- as for Release 1 with additions:
1 B-ISDN Bearer services (note 3)
BCOB-A (CBR, CO with end-to-end timing) peak BCOB-B (VBR, CO, with end-to-end timing)
traffic parameter, emulation (speech, 3,1 kHz
audio & 64 kbit/s unrestricted and higher rates)
BCLB (VBR, CLS, no end-to-end timing) peak BCOB-C (VBR, CO, no end-to-end timing)
traffic parameter
BCOB-X (unrestricted, proprietary AAL) peak Resource allocated according to statistical
traffic parameter multiplexing scheme (VBR services)
Information transfer capability: unrestricted Relationship of CLP to QoS & Indication of QoS by
user
<- as for Release 1 with additions:
2 Network Architecture (refer I.311 par.2)
For both UNI and NNI Connectionless servers (switched access)
VPC cross connect only VP Resource management systems
VCC Switching (ATM switching) Service Control Point (IN) access
non-intelligent multiplexing Intelligent multiplexing (note 10)
Connectionless servers interconnected with semi- Switched access to connectionless servers
permanent VCC/VPC. Access to connectionless
services wit
...