SIST-TS TS 101 885 V1.1.1:2004

• Abstract:

  This WI will deliver a mapping of the reference points N1, N2, N3, N4 and UI in WI 2003 to H.248/MEGACOP.

• Status: Published
• Publication Date: 31-Mar-2004
• ICS: 33.020 - Telecommunications in general
• Technical Committee: SPN - Services and Protocols for Networks
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Apr-2004
• Due Date: 01-Apr-2004
• Completion Date: 01-Apr-2004
• Ref Project: ETSI TS 101 885 V1.1.1 (2002-03) - Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON) Release 3; Technology Mapping; Technology Mapping of TIPHON reference point N to H.248/MEGACO protocol

SIST-TS TS 101 885 V1.1.1:2004 is the Slovenian adoption of ETSI TS 101 885 V1.1.1 (2002-03) for TIPHON Release 3. It specifies how TIPHON reference point N is mapped to the H.248/MEGACO protocol, so media gateways, controllers, terminals, gatekeepers and related IP-network entities can use the same control model.

What does SIST-TS TS 101 885 V1.1.1:2004 specify?

SIST-TS TS 101 885 V1.1.1:2004 defines how H.248/MEGACO is used to implement the TIPHON Release 3 architecture from TS 101 314 and the primitives, information elements and behaviours from TS 101 882. It maps the TIPHON Media Control meta-protocol to H.248, and it is written for equipment that plays the Terminal, Gateway, Gatekeeper and supporting IP-network roles.

The document is organized into an introduction and clauses on scope, references, definitions, H.248 usage, scenario templates, options, and management operations. It then adds two normative annexes for mappings and one informative bibliography.

Annex	What it covers
Annex A	Normative mapping from TS 101 882 to H.248, including primitive mappings and error reasons
Annex B	Normative meta-protocol to SDP mapping, including fields that can and cannot be represented
Annex C	Informative bibliography

What are the key requirements of SIST-TS TS 101 885 V1.1.1:2004?

Control interface and supported packages

SIST-TS TS 101 885 V1.1.1:2004 says that the MGC-MG control interface follows clause 11 of ITU-T Recommendation H.248 without restrictions for TIPHON Release 3. In practice, that means an implementation should use the H.248 control model as written, unless later TIPHON releases change it.

Clause 6 requires TIPHON to use the basic H.248 messages, with additional semantic alignment where TIPHON is stricter than H.248. It also requires a transaction-level timer, and it says ReserveGroup and ReserveValue are needed to keep the TIPHON choice-and-confirm behavior consistent across alternative media descriptions.

Clause 6.1 defines the packages that must be supported for all TIPHON reference point N implementations: Generic, Base Root, Network and RTP. For N3, the TDM circuit package is also required; for N2, no additional package is listed. That tells an implementer which H.248 capabilities must be present before interoperability testing.

Media setup, scenarios and resource handling

Clause 7.2 describes the default TIPHON media setup procedure. The media gateway establishes the media elements needed for the call, and when the call control protocol identifies a QoS class, the gateway sets up a QoS-controlled transport capability. In practice, this is the part that turns call setup into concrete media reservation, confirmation, establishment and release actions.

Annex A maps the TIPHON primitives to H.248 commands: MediaReservationRequest and MediaReservationConfirm map to Add, MediaEstablishmentRequest and MediaEstablishmentConfirm map to Modify, and MediaReleaseRequest and MediaReleaseConfirm map to Subtract. The annex also maps the associated data elements such as LocalDescriptor, RemoteDescriptor, ContextId, StreamID and TerminationID. For implementers, this is the core message mapping that must be followed when translating TIPHON flows into H.248 transactions.

Clauses 7.3 to 7.6 give template scenarios for N2 and N3, with and without source filtering. The scenarios show IP-to-IP media gateway behavior, IP-to-SCN and SCN-to-IP trunk behavior, and how the MGC and MG exchange Add, Modify and Subtract transactions. These examples matter because they show which descriptors are populated first, when the controller resolves alternatives, and how media starts or stops flowing.

Error handling, compliance and QoS

Clause 4.2 limits TIPHON compliance to the options named in the document. Clause 4.3 gives the error-handling rule set: elements outside the profile are ignored, unknown commands are rejected with the appropriate H.248 error, and missing or invalid mandatory elements are handled by defaulting or failure depending on whether a default value exists. This gives a clear interoperability rule - follow the profile, ignore what is outside it, and use the named error reasons for non-conforming requests.

Clause 4.4 states that TIPHON Release 3 does not prescribe security measures. Clause 8.2 states that QoS parameters are carried only in binary encoding because SDP does not support them in this profile. For readers, that means QoS information must be handled in the H.248 binary path, not expected from SDP alone.

Clause 8.1 defines the media activation option, where the forward media path can stay muted until the call is established. That option changes the LocalControl mode during setup and later switches the flow to duplex when the call is accepted.

What terms does SIST-TS TS 101 885 V1.1.1:2004 define?

• Call - any fixed or temporary connection that can transfer information between two or more users.
• Flow - a single data stream identified by source and destination address and port, plus protocol number.
• Bearer Control (BC) - the control function that decides whether a bearer is needed and requests media support.
• Call Control (CC) - the control function that handles the call-level decision-making around bearer use.
• Media Control (MC) - the function in the media gateway that manages media resources and media flow control.
• Quality of Service (QoS) - the quality specification of a telecommunications channel, system or session.
• Switched Circuit Network (SCN) - a circuit-switched network such as PSTN, ISDN or GSM used for voice calls.
• TIPHON compliant - an entity that meets the mandatory TIPHON requirements and the embodied specification parts.

Who uses SIST-TS TS 101 885 V1.1.1:2004?

SIST-TS TS 101 885 V1.1.1:2004 is used by engineers and architects building TIPHON Release 3 equipment, especially media gateways, controllers and related IP telephony components. It is also relevant to quality managers and test teams who need to verify that an implementation supports the required H.248 packages, mappings and error handling.

Service providers and equipment vendors use it when they need interworking between TIPHON networks and existing PSTN, ISDN or GSM environments. It is also useful for teams that must map SDP, configure media descriptors, or validate call setup and release behavior across reference point N.

Which standards are used with SIST-TS TS 101 885 V1.1.1:2004?

• ITU-T Recommendation H.248 - provides the gateway control protocol, the command structure, descriptors, error codes and ServiceChange/Restart behavior used by this document.
• ETSI TS 101 882 - provides the TIPHON meta-protocol framework, the primitives, information elements and annex C flows that are mapped here.
• ETSI TS 101 314 - defines the TIPHON abstract architecture and reference points that this document implements at reference point N.
• ETSI TR 101 311 - gives the transport-plane requirements used by the TIPHON Release 3 architecture.
• ETSI TS 101 878 - defines the simple-call service capabilities that the mapping supports.
• ETSI TS 101 315 - gives guidelines for applying the TIPHON functional architecture to inter-domain services.
• ETSI TS 101 883 and ETSI TS 101 884 - provide the related H.323 and SIP profile mappings in the same TIPHON Release 3 family.
• ETSI TR 101 301 and ETSI TR 102 008 - define the release scope and the TIPHON terms and definitions.
• ETSI TS 101 520, TS 101 521, TS 101 522 and TS 101 804 - provide conformance proformas and technology compliance specifications for related TIPHON implementations.
• IETF RFC 1890 - provides the RTP profile used for the audio payload mapping in Annex A and Annex B.

What does the SIST-TS TS 101 885 document contain?

The document contains the TIPHON architecture overview, the scope, references, definitions and abbreviations, then a detailed explanation of H.248 usage on reference point N. It includes template scenarios for N2 and N3 with and without source filtering, plus the media activation and QoS options.

Annex A gives the code point mapping between TIPHON primitives and H.248 messages, including error reasons and the binary and text encodings for IP-based and SCN media flows. Annex B maps the meta-protocol to SDP, including the fields that can be represented, the Originator MpoA encoding approach, and the values that cannot yet be mapped. The figures show example H.248 contexts and message exchanges for the main scenarios, which makes the document practical for implementation and interoperability work.

SLOVENSKI STANDARD
01-april-2004
+DUPRQL]DFLMDWHOHNRPXQLNDFLMLQLQWHUQHWQHJDSURWRNRODSUHNRPUHåLM7,3+21
L]GDMD7HKQRORJLMDSUHVOLNDYH7HKQRORJLMDSUHVOLNDYHUHIHUHQþQHWRþNH1SUL
7,3+21YSURWRNRO+0(*$&2
Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON)
Release 3; Technology Mapping; Technology Mapping of TIPHON reference point N to
H.248/MEGACO protocol
Ta slovenski standard je istoveten z: TS 101 885 Version 1.1.1
ICS:
33.020 Telekomunikacije na splošno Telecommunications in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

Technical Specification
Telecommunications and Internet Protocol
Harmonization Over Networks (TIPHON) Release 3;
Technology Mapping;
Technology Mapping of TIPHON reference point N
to H.248/MEGACO protocol
2 ETSI TS 101 885 V1.1.1 (2002-03)

Reference
DTS/TIPHON-03019
Keywords
architecture, configuration, internet, network,
protocol, telephony
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© European Telecommunications Standards Institute 2002.
All rights reserved.
ETSI
3 ETSI TS 101 885 V1.1.1 (2002-03)
Contents
Intellectual Property Rights.5
Foreword.5
Introduction .5
1 Scope.7
2 References.7
3 Definitions and abbreviations.8
3.1 Definitions.8
3.2 Abbreviations.9
4 Introduction.10
4.1 Supported service capabilities .11
4.2 General note on compliance .11
4.3 Error handling.11
4.4 Security.12
5 Setting up of MGC-MG control interface .12
6 General notes about the TIPHON H.248 usage.12
6.1 Packages supported.13
7 TIPHON template usage scenarios.13
7.1 Process used.13
7.1.1 General note on source filtering used in the scenarios.13
7.2 Default TIPHON media setup procedure .13
7.3 IP to IP media gateway without source filtering .14
7.4 IP to IP media gateway with source filtering.17
7.5 IP-SCN Flow without source filtering.21
7.6 SCN to IP media gateway without source filtering .23
8 Options on the basic scenarios .26
8.1 Media activation option.26
8.2 QoS on media flows .27
8.3 Media events.27
9 Management operations.27
Annex A (normative): Mapping from TS 101 882.28
A.1 Code point mapping .28
A.1.1 Primitive mappings.28
A.1.2 Binary Encoding.29
A.1.2.1 For an IP-based media flow .29
A.1.2.2 For an SCN media flow .29
A.1.3 Text Encoding.30
A.1.3.1 For an IP-based media flow .30
A.1.3.2 For an SCN media flow .30
A.2 Error reasons.30
Annex B (normative): Meta-protocol to SDP mapping.31
B.1 Mappable fields.31
B.2 Specifying the OriginatorMpoA.32
B.3 Unmappable fields.32
Annex C (informative): Bibliography.33
ETSI
4 ETSI TS 101 885 V1.1.1 (2002-03)
List of figures.34
History .35

ETSI
5 ETSI TS 101 885 V1.1.1 (2002-03)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server)
which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Project Telecommunications and Internet Protocol
Harmonization Over Networks (TIPHON).
Introduction
The approach being taken to standardization in TIPHON represents a departure from that used in the past for PSTN,
ISDN and GSM. Its aim is to allow much greater scope for competition through innovation in the design of equipment
and services. Its aim is also to provide adequate standardization to facilitate the operation of services across
interconnected networks, even networks that use different technologies. The present document presents the initial core
set of service capabilities envisaged to be required to enable service providers to offer services on TIPHON networks
that may safely interwork with existing PSTN services while enabling more advanced services to be subsequently
developed.
ETSI
6 ETSI TS 101 885 V1.1.1 (2002-03)
Figure 1 shows the relationship of the present document with other TIPHON Release 3 deliverables.
TR 101 301 Release 3: Scope & Definition
TR 102 008
Definition of Terms
Transport Plane
Service Capabilities
TR 101 311 TS 101 878
Architecture & Reference
TS 101 314
configurations
Protocol
Implementer’s
TS 101 882 TS 101 315
Framework
guide
TS 101 885
TS 101 883 TS 101 884
H.323 profile SIP profile H.248 profile
TS 101 520 TS 101 521 TS 101 522 TS 101 804
H.323 PICS SIP PICS H.248PICS
TS, ATS, PIXIT
Figure 1: Relationship with other TIPHON Release 3 documents
• TR 101 311 [4] provides the requirements on the transport plane,
• TS 101 878 [5] defines service capabilities that are used in the TIPHON Release 3 for a simple call,
• TS 101 882 [2] provides the Protocol Framework based on the TIPHON Release 3 architecture to implement the
simple call service capabilities as defined in the present document,
• TS 101 315 [6] is an implementer's guide that shows how to use of the meta-protocol to realize the capabilities as
defined in TS 101 878 [5],
• TS 101 883 [7] provides the protocol mappings for the ITU-T H-323 profile,
• TS 101 884 (see bibliography) provides the protocol mappings for the SIP profile,
• TS 101 885 (the present document) provides the protocol mappings for the ITU-T H-248 profile,
• TS 101 314 [3] provides the architecture and reference configurations for TIPHON Release 3.
ETSI
7 ETSI TS 101 885 V1.1.1 (2002-03)
1 Scope
The present document describes how the H.248/MEGACO [1] protocol can be used to implement the architecture,
defined in TS 101 314 [3] and the primitives, information elements and behaviours, defined in TS 101 882 [2].
The present document defines the mapping of the Media Control meta-protocol.
The document is applicable to equipment performing the roles of Terminal, Gateway, Gatekeeper and also to entities
within the IP network that are necessary to support TIPHON Release 3.
NOTE: Where the text indicates the status of a requirement (i.e. as strict command or prohibition, as
authorizations leaving freedom or as a capability or possibility), this may modify the nature of a
requirement within a referenced standard used to provide the capability.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
• References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies.
[1] ITU-T Recommendation H.248 (2000): "Gateway control protocol".
[2] ETSI TS 101 882: "Telecommunications and Internet protocol Harmonization Over Networks
(TIPHON) Release 3; Protocol Framework Definition and Interface Requirement Definition;
General (meta-protocol)".
[3] ETSI TS 101 314 (V2.1.1): "Telecommunications and Internet Protocol Harmonization Over
Networks (TIPHON) Release 3; Abstract Architecture and Reference Points Definition; Network
Architecture and Reference Points".
[4] ETSI TR 101 311: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; Service Independent requirements definition; Transport Plane".
[5] ETSI TS 101 878: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; Service Capability Definition; Service Capabilities for a simple call".
[6] ETSI TS 101 315: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; Functional Entities, Information Flow and Reference Point Definitions;
Guidelines for application of TIPHON functional architecture to inter-domain services".
[7] ETSI TS 101 883: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; Technology Mapping; Implementation of TIPHON architecture using
H.323".
[8] ETSI TR 101 301: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; Release Definition; TIPHON Release 3 Definition".
[9] ETSI TR 102 008: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON) Release 3; Terms and Definitions".
[10] ETSI TS 101 520: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON); Implementation Conformance Statement (ICS) proforma for the support of packet
based multimedia communications systems; Support of ITU-T Recommendation H.323".
ETSI
8 ETSI TS 101 885 V1.1.1 (2002-03)
[11] ETSI TS 101 521: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON); Protocol Implementation Conformance Statement (PICS) proforma for the support of
call signalling protocols and media stream packetization for packet-based multimedia
communication systems; Support of ITU-T Recommendation H.225.0".
[12] ETSI TS 101 522: "Telecommunications and Internet Protocol Harmonization Over Networks
(TIPHON); Protocol Implementation Conformance Statement (PICS) proforma for the support of
control protocol for multimedia communication; Support of ITU-T Recommendation H.245".
[13] ETSI TS 101 804 (all parts): "Telecommunications and Internet Protocol Harmonization Over
Networks (TIPHON) Release 3; Technology compliance specifications".
[14] IETF RFC 1890: "RTP Profile for Audio and Video Conferences with Minimal Control".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
call: any connection (fixed or temporary) capable of transferring information between two or more users of a
telecommunications system
NOTE: In this context a user may be a person or a machine.
charging: process of determining the amount of money a user shall pay for usage of a certain service
codec: combined speech encoder and decoder
flow: single data stream, identified by a tuple of characteristic values (source address, source port, destination address,
destination port, protocol number)
functional entity: entity in a system that performs a specific set of functions
functional group: collection of functional entities within a domain
NOTE: In TIPHON systems Functional Groups are used to structure the necessary functionality to offer IP
telephony services across domains.
IP address: each network unit connected to an IP network must have a unique Internet or IP address
NOTE: Today's IP addresses is based on IPv4 and are 32-bit numbers with its predefined structure. The IP
address (IPv4) is written as four decimal numbers separated by a point.
IP endpoint: device that originates or terminates the IP based part of a call
NOTE: Endpoints include H.323 clients, and IP telephony gateways.
IP network: packet transport network comprising one or more transport domains each employing the IP protocol
network: telecommunications network that provides telecommunications services
protocol: set of semantics, syntax and procedures which govern the exchange of information across an interface
Quality of Service (QoS): quality specification of a telecommunications channel, system, virtual channel,
computer-telecommunications session, etc.
NOTE: Quality of Service may be measured, for example, in terms of signal-to-noise ratio, bit error rate, message
throughput rate or call blocking probability.
ETSI
9 ETSI TS 101 885 V1.1.1 (2002-03)
Switched Circuit Network (SCN): telecommunications network, e.g. Public Switched Telephone Network (PSTN),
Integrated Services Digital Network (ISDN), and General System for Mobile communications (GSM), that uses
circuit-switched technologies for the support of voice calls
NOTE: The SCN may be a public network or a private network.
telephone call: two-way speech communication between two users by means of terminals connected via network
infrastructure
terminal: endpoint within the user equipment on which signalling and media flows originate and/or terminate
TIPHON compliant: entity that complies with the mandatory requirements identified in the TIPHON requirements
documents together with compliance to the parts of the TIPHON specifications in which these requirements are
embodied
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
BC Bearer Control
CC Call Control
IP Internet Protocol
MC Media Control
QoS Quality of Service
SCN Switched Circuit Networks
SDL Specification and Description Language
SIP Session Initiation Protocol
ISDN Integrated Services Digital Network
GSM General System for Mobile communications
PSTN Public Switched Telephone Network
ETSI
SCN Plane
10 ETSI TS 101 885 V1.1.1 (2002-03)
4 Introduction
Originating/
Originating/Terminating Network FG Terminating/
Intermediate
Terminating
Originating
Network FG
Terminal FG
Serving Home
Gateway FG
Network FG Network FG
User
Service
CR QoSPE CR QoSPE CR QoSPE
profile
Profile QoSPE
S3 S4 S3 S4 S3 S4
S4
S1 S2
S1
SC2’ SC2’ SC2’
SC
SC SC
SC SC
R1 R2
TREG SREG HREG
SC1 SC2 SC2 SC2
SC2
C3
C1 C1 C2 C2
CC CC CC CC CC
C2
C1 C3
C1
C2
BC
BC BC BC BC
N1 N2 N2 N3
N2
M3
M1 M2 M2 M2
MC MC MC MC MC
T2
T2
T1 T2 T1
TU TPE TU TPE
TU TPE
I6 I4 I6 I4 I6 I4
I1
I1
I2 I2
TRM TRM TRM TRM TRM
I3 I5 I3 I3 I3
I5
I3
I3 I5
ICF TF ICF ICF TF ICF ICF TF ICF
Terminating/
Originating/
Originating
Core transport
Terminating
Ingress/Egress Egress/Ingress
Gateway FG
domain
Terminal FG transport domain transport domain

Figure 2: TIPHON architecture with reference points N highlighted
The present document describes an implementation of reference point N of the meta-protocol described in annex C of
TS 101 882 [2], producing an interoperable profile of H.248/MEGACO. Figure 2 shows the TIPHON architecture
copied from [3] with the reference points N highlighted.
H.248/MEGACO has been created to control a range of media devices. For the purpose of the present document we
address several categories:
• Residential gateways implementing reference point N1 and a user interface. The user interface component is not
addressed in this version of the present document.
• IP-IP Media devices for the control, transcoding and monitoring of media streams in TIPHON networks. These
devices implement reference point N2.
• Trunk gateways, between TIPHON networks and the SCN implementing reference point N3.
ETSI
Servi e
c
Media Bearer
Transport Transport Transport
flows Control Service
Call
control
Service
control
11 ETSI TS 101 885 V1.1.1 (2002-03)

Controller
CC
BC
Nx
Media Gateway
MC
Figure 3: Entities involved
The mapping described in the present document describes the messages between a media gateway and its controller.
The media gateway implements the MC functional entity as described in TS 101 314 [3] the controller implements at
least a BC and CC entity as described in TS 101 314 [3].
4.1 Supported service capabilities
This release defines media setup for basic bearers.
QoS bearers supported in the binary encoding ONLY due to lack of support of QoS parameters in SDP.
4.2 General note on compliance
Any options in the H.248 protocol not mentioned in the present document MAY be supported by MG or MGC, however
are outside the scope of TIPHON compliance and testing.
4.3 Error handling
The present document describes a profile that mandates certain optional parts of the H.248 protocol and does not
mandate certain other options. General use of the error codes can be found in clause A.2.
If an H.248 information element is received (descriptor or parameter), which is not within the context of this profile, the
receiver shall ignore the information element and act as if the information element were not received.
If an unknown H.248 command or an information element not within the context of this profile, the receiver shall
ignore the command and send an appropriate error (443 - unsupported or unknown command or 444 - unsupported or
unknown descriptor, 445 - unsupported or unknown property, 446 - unsupported or unknown parameter).
If an H.248 command with a mandatory information element missing is received, the receiver shall act as if the
information element was received carrying the default values, or reject with the appropriate error message if there is no
default value specified in the ITU-T Recommendation H.248 [1].
ETSI
12 ETSI TS 101 885 V1.1.1 (2002-03)
If an H.248 information element is received with syntactically invalid contents the receiver shall:
• If the information element is optional, ignore the information element;
or
• If the information element is mandatory, act as if the information element was received correctly coded carrying
the default values and reject/Fail if there is no default value specified in the present document.
If an H.248 information element is received with a value not allowed within the context of the present document, the
receiver shall:
• If the information element is optional, pass on, but otherwise ignore the information element;
or
• If the information element is mandatory reject/fail.
NOTE: The security policy of an operator's network or the security policy implemented in a network element may
override the error handling as described above.
4.4 Security
TIPHON does not prescribe security measures in Release 3.
5 Setting up of MGC-MG control interface
For TIPHON Release 3 clause 11 of ITU-T Recommendation H.248 [1] shall apply without restrictions. This may
change in future releases of the present document.
6 General notes about the TIPHON H.248 usage
TIPHON prescribes the basic messages of H.248 and prescribes the support of certain packages depending on the
reference point that is implemented. This clause describes the messages used, the exact encoding is given in annex B.
The TIPHON semantics require that when multiple alternatives are returned by the MG to the MGC for a termination
the MG shall support whichever one the MGC chooses. Failure to support parameters for a termination offered earlier is
considered a fault.
H.248 does not have semantics as strict as those prescribed by TIPHON. To align the semantics, ReserveGroup needs
to be set for all alternative media flow descriptions that are requested from the MC entity and that ReserveValue needs
to be set for all requests where the MC entity is given the choice to provide flow descriptions.
The optional ModemDescriptor, MuxDescriptor. EventsDescriptor, DigitMapDescriptor, AuditDescriptor are not
prescribed in this profile.
A transaction level timer shall be provided.
The flows in TS 101 882 [2] use an InvokingControllerReference, is mapped to StreamID in
ITU-T Recommendation H.248 [1]
The contextID is a value that is local to the MG-MGC relationship and is not mapped to the meta-protocol.
The TIPHON type mcReservedMediaReference and mcEstablishedMediaReference shall be mapped to the H.248
TerminationID.
Code point mapping for the Local and Remote Descriptors is provided in the annexes.
The error codes are taken from ITU-T Recommendation H.248 [1], annex L, error codes applicable to the present
document are described in clause A.2.
ETSI
13 ETSI TS 101 885 V1.1.1 (2002-03)
6.1 Packages supported
The following packages shall be supported for all TIPHON Reference point N implementations:
• Generic package (ITU-T Recommendation H.248 [1], clause E.1)
• Base Root package (ITU-T Recommendation H.248 [1], clause E.2)
• Network package (ITU-T Recommendation H.248 [1], clause E.11)
• RTP package (ITU-T Recommendation H.248 [1], clause E.12)
The following packages are to be supported for each of the reference points mentioned:
- N2 -
- N3 TDM circuit package (ITU-T Recommendation H.248 [1], clause E.13)
7 TIPHON template usage scenarios
This clause provides template TIPHON messages for the use of H.248 on reference points N.
The process used is given in clause 7.1.
The generic TIPHON media flows are summarized from [2] in clause 7.2.
In the remainder of the clause three scenarios are shown:
7.3 Reference point N2 (IP to IP) Media Gateway without source address filtering.
7.4 Reference point N2 (IP to IP) Media Gateway with source address filtering.
7.5 Reference point N3 (IP to SCN) Media Gateway without source address filtering.
7.6 Reference point N3 (SCN to IP) Media Gateway without source address filtering.
7.1 Process used
This clause provides the mapping of the flows in TS 101 882 [2], annex C, to H.248 message flows. Please note that the
source is ITU-T Recommendation H.248 [1] and hence parts of H.248 may not be covered in the present document
where they do not contribute to the requirements of TIPHON deployments. The present document also aligns the
parameter and error reason definitions in TS 101 882 [2], annex C to ensure interoperability of these values across the
mappings of these reference points. In general each of the primitives defined on the N reference points in
TS 101 882 [2] each map to one or more commands in ITU-T Recommendation H.248 [1]. Please note that additional
messaging may be necessary where applicable for the correct execution of the protocol.
7.1.1 General note on source filtering used in the scenarios
SDP specifies in clause B.2.1 a means for specifying unicast sessions. This provides the means to encode the Originator
MpoA. In clause B.2 it is shown how the recvonly and sendonly attribute are used for specifying the sender side
behaviour of media flows.
7.2 Default TIPHON media setup procedure
Media control allows reservation and allocation of resources for formatting of the media stream (e.g. to reserve
processing capability for soft codecs, or to switch into the path hard codecs). See TS 101 882 [2] for a full definition of
the primitives involved.
NOTE: The following text is derived from the SDL in TS 101 882 [2]. Should there be discrepancies between
TS 101 882 [2] and the present document, the text in TS 101 882 [2] is authoritative.
ETSI
14 ETSI TS 101 885 V1.1.1 (2002-03)
The Media Gateway shall establish the media elements required to support the media flows required for the call. If so
required, the media gateway shall establish a QoS controlled transport capability in accordance with the QoS class
identified by the call control protocol.
Step TS 101 882 [2] Primitive Meaning
BC layer decides it needs a bearer.
Asks the MC to support it with a QoS-enabled media stream (a
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