INTERNATIONAL TELECOMMUNICATION UNION STUDY GROUP 13TELECOMMUNICATIONSTANDARDIZATION SECTOR

STUDY PERIOD 2005-2008

TD 212 (WP 3/13)English only

Original: English

Question(s): 2/13 Geneva, 17-28 July 2006

TEMPORARY DOCUMENT

Source: Rapporteur Q.2/13

Title: Provisional text of draft new ITU-T Recommendation Y.ngn-mcast (NGN multicast Service capabilities with MPLS-based QoS support) – Kobe, 22-27 April 2006

Editor’s Note: This document was developed during the Q.2/13 Rapporteur group meeting in Kobe from 22 April to 27 April 2006 based on TD 172R1(3/13) of January 2006 SG13 meeting.

This output text reflects the proposals from Kobe-q2-13-23, -24, -29, and -33 (Korea), however these input contributions were just roughly scanned at the Q.2/13 meeting due to lack of time.

This update has to be considered provisional as it was not reviewed for lack of meeting time. It constitutes a major input for developing the next version of this draft Recommendation.

Contact: Marco CarugiNortel Networks EuropeUK

Tel: +33 1 6955 7027Fax: +33 1 6955 3115Email marco.carugi@nortel.com

Attention: This is not a publication made available to the public, but an internal ITU-T Document intended only for use by the Member States of ITU, by ITU-T Sector Members and Associates, and their respective staff and collaborators in their ITU related work. It shall not be made available to, and used by, any other persons or entities without the prior written consent of ITU-T.

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NGN Multicast Service Capabilities with MPLS-based QoS Support

Justification of this recommendation:

- It describes scenarios for NGN multicast services with QoS support, with MPLS as converged technology to run these services. It also shows value add of MPLS as converged technology to support these NGN services.

It might generate new multicast capabilities which are not supported in current MPLS specifications. (Editor’s note: to be completed)

Editor’s N ote :

Areas of improvement for this document in order of priority include:

- Functional architecture

- Protocol procedures

- Implementation scenarios:

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Draft ITU-T Recommendation Y.ngn-mcast

NGN Multicast service capabilities with MPLS-based QoS support

Summary

<TBD>

Keywords

UPT

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CONTENTS

Introduction............................................................................................................................6

1. Scope...........................................................................................................................7

2. References...................................................................................................................7

2.1 Normative References...........................................................................................7

2.2 Informative References.........................................................................................8

3. Terms and definitions..................................................................................................9

4. Abbreviations............................................................................................................10

5. Service Definition and Requirements for NGN Multicast Services with MPLS-based QoS Support....................................................................................................10

5.1 Example Services of NGN multicast service......................................................10

5.2 Service Requirements for NGN Multicast services with QoS Support..............11

5.3 Functional Requirements for NGN Multicast Services with MPLS-based QoS Support........................................................................................................12

6. Overview of general architecture for NGN multicast services with MPLS-based QoS support...............................................................................................................13

6.1 Service Stratum...................................................................................................14

6.1.1 Multicast application functions........................................................................14

6.1.2 Multicast service control functions..................................................................14

6.1.3 Multicast service profile functions...................................................................14

6.2 Transport stratum................................................................................................14

6.2.1 MPLS multicast transport control functions....................................................14

6.2.2 Multicast transport functions...........................................................................15

6.3 Management functions........................................................................................16

6.3.1 Multicast management functions.....................................................................16

6.4 Multicast end-user functions...............................................................................17

6.5 Reference interfaces in general architecture for NGN Multicast service architecture..................................................................................................17

7. Generalized functional architecture for NGN multicast services with MPLS-based QoS Support..............................................................................................................17

8. Functional scenarios and protocol procedures for NGN multicast services at the transport stratum.......................................................................................................17

8.1 Functional Scenarios...........................................................................................17

8.1.1 Multicast QoS connection registration scenarios.............................................18

8.1.2 Multicast QoS connection management scenarios...........................................18

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8.2 MPLS-based functional protocol procedures......................................................21

8.2.1 Multicast join mechanism................................................................................21

8.2.2 Group identifier distribution mechanism.........................................................22

8.2.3 Multicast resource reservation mechanism......................................................23

8.2.4 QoS level modification mechanism.................................................................24

8.2.5 Multicast leave mechanism..............................................................................24

9. Interaction between the service and the transport stratum for MPLS multicast.......24

9.1 Functional requirement of Reference Point C2(same as Rs in Y.RACF) for MPLS multicast..........................................................................................26

9.2 Functional requirement of PD-FE for MPLS multicast at the service stratum...27

10. Implementation scenarios for NGN multicast services with MPLS-based QoS support.......................................................................................................................28

10.1 Multicast service and implementation scenario using FTTH/PON..................28

10.2 Multicast service and implementation scenario using Wireless LAN..............28

10.3 Implementation scenario of multicast service through multiple heterogeneous transport networks.......................................................................................28

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NGN Multicast Service Capabilities with MPLS-based QoS Support

Justification of this recommendation:

- It describes scenarios for NGN multicast services with QoS support, with MPLS as converged technology to run these services. It also shows value add of MPLS as converged technology to support these NGN services.

- It might generate new multicast capabilities which are not supported in current MPLS specifications. (Editor’s note: to be completed)

Introduction

In the classifications of NGN services and applications, there are a number of multicast services and applications such as Digital Multimedia Broadcasting (DMB) service, high quality IP TV service, E-learning application and on-line gaming application, which require high bandwidth and efficient multicast mechanisms because of high traffic volume and number of receivers. The network capabilities for multicast services are different with those for point-to-point and interactive services. Their control mechanisms and protocol procedures are complicate and difficult to implement. Therefore, multicast mechanisms should be simple for implement scalable and robust implementations. And, they also support QoS and traffic engineering in heterogeneous network environments.

The Multi-Protocol Label Switching (MPLS) technology has many advantages such as forwarding speed, scalability, QoS and traffic engineering. These advantages have been proved in the real market. It describes how MPLS technology and capabilities may support the multicast services with certain QoS levels in the NGN environment.

In the NGN environment, various access technologies might be connected to a common, flexible MPLS core network.

Figure 1 illustrates an example of network architecture for NGN multicast services with MPLS-based QoS support. It consists of a number of access networks which are organized on the basis of access technology and/or geographical region. An end user can communicate with MPLS core network through various access networks with wireless access technology (2G, 3G, WLAN, Wibro) or wireline access technology (PON, ADSL, VDSL, Ethernet).

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Figure 1. Example of network architecture for NGN multicast service over MPLS network

1. Scope

The scope of this recommendation covers:

Requirements for NGN multicast services with MPLS-based QoS support

Reference model for NGN multicast service architecture

Functional architecture for NGN multicast services with MPLS-based QoS support

Functional scenarios and procedures for NGN multicast services with MPLS-based QoS support

Implementation scenarios for NGN multicast services with MPLS-based QoS support

(Editor’s note: Protocol procedures for NGN multicast services with MPLS-based QoS will be described)

Out of scope of this recommendation covers:

( Editor’s note : to be completed)

2. References

2.1 Normative References

[1] ITU-T Recommendation G.1010, Multimedia QoS/Performance requirements.

[2] ITU-T Recommendation Y.2001 (2004), General overview of NGN.

[3] ITU-T Recommendation Y.2011 (Y.NGN-GRM), General principles and general reference model for NGN.

MPLS Multicast Core Network

Wireless Multicast Access Network

WirelineMulticast Access Network

IP TV Server

DMBServer

VoDServer

Multicast Server Farm

IP TV LocalServer

Multicast Local Server Farm

VoD LocalServer

MPLS Core Node

MPLS Edge Node

ONU

Wireless AP

Multicast Resource and Admission Control Functions

Transport User Profile

Service User ProfileService Control Functions

MPLS Edge NodeMPLS Edge Node

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[4] ITU-T Draft RecommendationFGNGN Document, Draft Baseline For Recommendation on Terminology and DefinitionsTerminological Framework for NGN, TR.TERM, FGNGN-OD-261TD-WP1-54r1, December 2005January 2006, London, Terminological Framework for NGNGeneva.

[5] ITU-T FGNGN Draft RecommendationDocument, Functional Requirements and Architecture for Resource and Admission Control in Next Generation Network, draft Draft TR-Y.RACF, FGNGN-OD-241TD-WP4-81r2, January 2006December 2005, LondonGeneva.

[6] ITU-T Draft RecommendationFGNGN Document, Functional architecture of Next Generation Networks, Y.NGN-FRA Version 1, FGNGN-OD-244R2TD-WP2-133, December January 20052006, LondonFunctional Geneva. architecture of Next Generation Networks.

[7] ITU-T Draft RecommendationFGNGN Document, NGN Release 1 Requirements document, draft Y.NGN-R1-Reqts, TD-WP3-167FGNGN-OD-252, January 2006December 2005, GenevaLondon.

[8] ITU-T Draft RecommendationFGNGN Document, NGN Release 1 scope documentDescription, draft Y.NGN-R1, TD-WP1-40FGNGN-OD-253, December January 20052006, LondonGeneva.

[9] ITU-T Draft RecommendationFGNGN Document, Draft FGNGN-IFN, FGNGN-OD-245r1, IMS for Next Generation Networks, December 2005, London

[10] IETF RFC 1112, Deering, S., "Host extensions for IP multicasting", STD 5, August 1989.

[11] IETF RFC 3031, E. Rosen, et. al., “Multiprotocol Label Switching Architecture,” January 2001.

[12] IETF RFC 3036, L. Andersson, et. al., "LDP Specification", January 2001.

[13] IETF RFC 3209, D. Awduche, et. al.. “RSVP-TE: Extensions to RSVP for LSP Tunnels", December 2001.

[14] IETF RFC 3212, B. Jamoussi, et. al., “Constraint-Based LSP Setup using LDP”, January 2002.

[15] IETF RFC 3376, Cain, B., et. al., "Internet Group Management Protocol, Version 3", October 2002.

[16] IETF RFC 3810, Vida, R. and L. Costa, "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", June 2004.

2.2 Informative References

(Editor note : The following references are not the relevant part of this Recommendation. They are just for information only.)

[17] IETF RFC 2365, Meyer, D., "Administratively Scoped IP Multicast", BCP 23, July 1998.

[18] IETF RFC 2375, Hinden, R. and S. Deering, "IPv6 Multicast Address Assignments", July 1998.

[19] IETF RFC 2702, D. Awduche, et. al., “Requirements for Traffic Engineering over MPLS”, September 1999.

[20] IETF RFC 3353, D.Ooms, et al., “Overview of IP Multicast in a Multi-Protocol Label Switching (MPLS) Environment”, August 2002.

[21] IETF RFC 3569, Bhattacharyya, S., "An Overview of Source-Specific Multicast (SSM)", July 2003.

[22] IETF RFC 3973, A. Adams, J. Nicholas, W. Siadak, “Protocol Independent Multicast - Dense Mode (PIM-DM): Protocol Specification (Revised)”, January 2005.

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[23] Bill Fenner, et. al., “Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)”, Internet Draft, draft-ietf-pim-sm-v2-new-11.txt, October 2004.

[24] A/92 "Delivery of IP Multicast Sessions over ATSC Data Broadcast", Advanced Television Systems Committee (ATSC), Doc. A/92, 2002

[25] EN 300 800, "Digital Video Broadcasting (DVB); DVB interaction channel for Cable TV distribution systems (CATV)", European Telecommunications Standards Institute (ETSI).

[26] EN 301 790, "Digital Video Broadcasting (DVB); Interaction channel for satellite distribution systems", European Telecommunications Standards Institute (ETSI).

[27] ETSI TS 101 812, "Digital Video Broadcasting (DVB); Multimedia Home Platform (MHP) Specification", v1.2.1, European Telecommunications Standards Institute (ETSI), June 2002.

[28] 3GPP TS 22.246, “Multimedia Broadcast/Multicast Service; Stage 1”, December 2005.

[29] 3GPP TS 23.246, “Multimedia Broadcast/Multicast Service (MBMS), Architecture and functional description”, December 2005.

[30] "IP Datacast Specification", DVB Interim Specification CNMS 1026 v1.0.0,(Work in Progress), April 2004.

[31] MSF-ARCH-001.00-FINLA IA, “System Architecture Implementation Agreement” May 2000

[32] PacketCable 1.5 Specifications, Dynamic Quality-of-Service, PKT-SP-DQOS1.5-I02-050812, August 2005.

[33] PacketCable 1.5 Specifications, “Multimedia Architecture Framework”, PKT-TR-MM-ARCH-V01-030627, June 26, 2003.

[34] PacketCable 1.5 Specification, “Archtecture Framework Technical Report”, PKT-TR-ARCH1.5-V01-050128, January 28, 2005.

3. Terms and definitions

( Editor’s note : to be completed

These terms should be considered the relationship with other multicast documents.)

This Recommendation defines the following terms.

- Multicast Group

(to be included)A multicast group usually consist of a multicast source and many multicast receivers and optionally the intermediate nodes from source to receivers. The source sends multicast traffic and the receivers receive concurrently multicast traffic after joining a multicast group. Therefore, each multicast group should be identified with its own group identifier.

- Multicast Domain

A multicast domain is boundary of a group identifier among a contiguous set of nodes which operate with same routing and forwarding mechanism. There can be several domains between a multicast source and many multicast receivers; for example, one multicast service domain and three multicast transport domains.

(to be included)

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- Group Identifier

A group identifier is used to establish and maintain the multicast connection configuration by using a unique identifier within the same administrative domain. Each multicast group at the same domain is distinguished by a group identifier.

4. Abbreviations

A-TRCF Access TRansport Control Functional entity

C-TRCF Core TRansport Control Functional entity

DiffServ Differential Service

DMB Digital Multimedia Broadcasting

FTTH Fiber To The Home

IP TV Internet Protocol Television

L2 Layer 2

MCU Multipoint Control Unit

MPLS Multiprotocol Label Switching

NGN Next Generation Network

P2MP Point to Multipoint

P2P Point to Point

PDF Policy Decision Functional entity

PON Passive Optical Network

RACF Resource and Admission Control Function

SLA Service Level Agreement

QoS Quality of Service

5. Service Definition and Requirements for NGN Multicast Services with MPLS-based QoS Support

At first, example services of NGN multicast service are described. The requirements for NGN multicast services are drawn out from these example services. The requirements for NGN multicast services are divided into service requirements and functional requirements.

5.1 Example Services of NGN multicast service

There are many NGN multicast services. Some example services of NGN multicast service are described in this section. The typical examples of multicast QoS service over MPLS are IP TV service, DMB service, and Video-on-Demand service, etc.

IP TV Service

IP TV service distributes broadcasting data to multiple users through NGN. This service can have a main IP TV server in multicast server farm and several mirror servers in multicast local server farms. The data of this service can be live data or recording data. A user can enjoy and change a channel in several channels of service provider. This service uses a multicast technology because of the number of user and data volume and it is very sensitive in delay and delay jitter.

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DMB service

DMB service is very similar with IP TV service except it is for only mobile user and it uses broadcasting technology. This service provides mobile broadcasting service with terrestrial equipment or satellite equipment. If DMB service uses a NGN network to distribute to streaming data from DMB server to users, it is more efficient and economical.

Video on Demand Service

This service is to distribute streaming service to a user on demand. A central VoD streaming server is located in multicast server farm and provides services using unicast method. Then, several mirror servers are located in multicast local sever farm. In this case, load becomes significantly larger at central server; mirror servers are required in order to decentralize the load because many users can request the service to a mirror server. Then, the connections from the central server to several mirror servers had better to use multicast connection to reduce traffic volume. When the central server sends data to mirror servers, these data should be guaranteed the time delay.

5.1 2 Service Requirements for NGN Multicast services with QoS Support

( Editor’s note : The following list of requirements has not been reviewed in detail. The items should be checked one by one and completed (including compatibility with various services, interworking with IP multicast and overlay multicast, etc.).

This section describes the requirements for the NGN multicast services from the user’s point of view.

Join / leave multicast groups or services with security

It supports for users to join and leave the specific multicast groups and services. Also it ensures that only authenticated users are entitled to receive multicast service.

It implies that the joining procedure involves checking authorization based on membership with considerations of operator specific policy rules and resource availability.

Differentiated QoS levels

According to SLA negotiation, the multicast groups or services supports differentiated QoS levels. In case, it provides the guaranteed QoS levels to all the members within a multicast group.

Initiating and dynamic changing of the QoS levels by user’s request The QoS levels between users and service provider can be initialized at the subscription time or the joining time. But, the QoS level could be dynamically changed by on-demand requests.

Traffic monitoring for SLA commitments

The traffic monitoring concerns checking the temporal properties (e.g., rate) of multicast traffic stream against the agreed SLAs. It involves observing traffic characteristics at a given interface point, collecting and storing the traffic information for analysis and further action, such as validation and verification of QoS level.

Multicast service information request and notification

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Each multicast service information notices to all users. All users could join the multicast service after acknowledging multicast service information such as TV contents and video materials. If the users want to join a multicast service, they request the multicast service information.

5.2 3 Functional Requirements for NGN Multicast Services with MPLS-based QoS Support

This section describes the functional requirements for multicast. Specifically, it covers the functional requirements of both service control (at the service stratum) and transport control (at the transport stratum) to support the NGN multicast services by using MPLS technologies.

Identifications of multicast group and service

A multicast group and service should be identified by the relevant mapping mechanisms with physical or logical identifiers. In case, the label information of the MPLS packet format can be used to uniquely identify a specific multicast group or service in an administrative domain of network.

(Editor ’ s note : The meaning of physical and logical identifier requests to be provided.)

Advertisements of multicast group membership

It provides the announcements of the multicast group membership for a multicast service. This advertisement includes the flow identification of multicast group while applying the MPLS technologies.

Solicitations of multicast service information

A user shall request multicast service information in order to join multicast service. This solicitation could request only one multicast service information or a group of multicast services information.

Multicast session management

The network provider manages the multicast session information including multicast tree information, which includes the number of multicast users, multicast domain, the QoS levels per multicast group, and accounting information per user, etc.

It may support a multicast tree configuration for a specific multicast group. The multicast tree can be dynamically updated when joining and leaving users. Each multicast group can be identified by a unique group identifier. In case, more than one session for a multicast user can be configured depending on manageability of multicast group.

Depending on network topology and physical media, multicast tree path can be easily implemented by utilizing physical access media in nature such as FTTH/PON (Fiber To The Home/Passive Optical Network) and wireless LAN technologies, which are useful to configure multicast tree configuration and reduce network resources.

Network resource controls to support QoS classes

It supports a number of QoS levels for a multicast group while network resources are limited. It controls network resources and traffics with combinations of admission control and congestion control mechanism.

The traffic engineering capability of MPLS can provide the certain QoS classes to support various multicast applications. It supports the differentiated service with priority and QoS control mechanism (including the flow description and QoS parameters). It processes the incoming traffics at the different flow aggregation levels. In case, it may guarantee the multicast QoS according to SLA.

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Traffic measurement function

It requires the traffic measurement functions to support the charging and billing mechanism. It traces traffic flows of multicast tree paths whether it meets the negotiated QoS class. It involves observing traffic behaviors at the given interfaces. By collecting and storing the traffic information, further actions such as validation and verification of QoS levels may be taken.

6. Overview of general architecture for NGN multicast services with MPLS-based QoS support

Figure 2 shows an overview of general architecture with reference interfaces for NGN multicast service over MPLS-based QoS support. It divided into service stratum, transport stratum and management functions according to Y.2011. The service stratum functions can support the guaranteed delivery of end-user services according to the application service functions, IP-TV, DMB etc. The transport stratum functions provide the guaranteed connectivity and transfer the media data within the MPLS based networks. The management stratum functions support various multicast management schemes of NGN multicast service.

Boxes in figure2 identify functional groups for which an overall description is given later in this section. The control links between the functional groups represent high level logical interactions.

MulticastEnd-UserFunctions

ManagementFunctions

MulticastManagement

Functions

Transport Stratum

MulticastAccess Transport

Functions

MulticastAccess Node

Functions

MPLS MulticastEdge NodeFunctions

MPLS MulticastCore Transport

Functions

MulticastTransportProfiles

MPLS Multicast Transport Control Functions

Multicast Network

AttachmentFunctions

Multicast Resource and Admission

Control Functions

Multicast Service Control FunctionsMulticastServiceProfiles

Multicast Application Functions

Service Stratum

I1 I2

C1

T1 T2

C2

Figure 2. The overview of general architecture with reference interfaces for NGN multicast service over MPLS network

( Editor’s note : to relate the general architecture from FRA with this Figure)

( Editor’s Note : Multicast Access Transport Functions could be covered non-MPLS based access network such as Wireless Lan, Wibro, etc.)

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6.1 Service Stratum

The service stratum provides the multicast service level functions such as multicast application functions and multicast service control functions.

6.1.1 Multicast application functions

These includes a lot of functions for various NGN multicast services in IP TV, DMB, e-learning and etc. Therefore, they could be implemented specific functions dependent on the each service and could provide an interface to multicast user to notice the multicast service information and accept the service request of multicast user. These are available to the end user functions.

6.1.2 Multicast service control functions

The Multicast service control functions provide multicast session control, service user profile management and group identifier management and QoS negotiation in the service stratum.

- A multicast session is controlled with a point-to-multipoint session ins service level. This function should manage user’s multicast session information for charging, authentication and QoE after a multicast user joins. Before a multicast user joins the multicast session, it can request and/or receive multicast service information in service level.

- Service user profile management provides registration, authentication and authorization at the service level according to the application services.

- U nique group identifier is provided Multicast session management provides unique group identifier in a MPLS multicast service domain and interact with MPLS multicast transport control functions to assign group identifier in transport stratum. Each multicast flowservices is distinguished by a these group identifiers.

- QoS negotiation provides a negotiation procedure of various QoS levels between a multicast user and a multicast service provider; then, the QoS level can be modified by the request of multicast user..

6.1.3 Multicast service profile functions

Multicast service profile functions are based on the user subscription data and network data. It is a database based on a service user and shall be provided in support of:

- Multicast user authentication and authorization

- Multicast service subscription information

6.2 Transport stratum

The transport stratum provides the multicast transport level functions such as multicast traffic forwarding, multicast tree configuration, a multicast QoS supporting mechanism and media handling function. It is divided into MPLS multicast transport control functions, MPLS multicast end functions, MPLS multicast access transport functions, MPLS multicast edge functions, MPLS multicast core transport control functions.

6.2.1 MPLS multicast transport control functions

MPLS multicast transport control functions include Resource and Admission Control Functions and Network Attachment Control Functions.

6.2.1.1 Multicast resource and admission control functions

Multicast resource and admission control functions provide multicasting resource management to support multicast QoS and group identifier control in the transport stratum.

- Multicasting resource management provides admission control and gate control according to multicast service control functions and allocates transport resources including QoS

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control according to the Service Level Agreement (SLA) which is performed to each multicast flow. It interacts with transport functions to control QoS support functions in transport stratum.

- Group identifier control assigns a group identifier to each multicast flow. Before the first resource is allocated, the group identifier could be assigned in transport stratum and the group identifier could be pre-assigned per a multicast service. The group identifier is related with a multicast session at multicast service functions.

- These functions control the dynamic multicast tree with access transport control functions and core transport control functions according to join/leave of multicast user.

- These functions receive and respond the delivery request of multicast service request from multicast service control functions. Then, they should map between service dependent information from multicast service control functions and transport dependent information from multicast transport control functions.

- These functions do QoS routing, resource reservation and admission control on transport network. These functions collect and maintain the network topology and resource status information in access network.

- Multicast tree is changed dynamically according to join and leave procedure of multicast user. Therefore, these functions should support a group identifier announcement mechanism in transport stratum.

6.2.1.2. Multicast network attachment functions

Network Attachment functions provide a registration at the access level and initialization of end-user functions for accessing the NGN multicast service. The functions provide network-level multicast group announcement, identification in the access transport network.

- These functions provide a dynamic multicast tree management in access transport network according to join/leave of multicast user. Therefore, these functions should support a group identifier information announcement mechanism to a multicast user in the access transport network.

6.2.1.3 Multicast transport profile functions

Multicast transport profiles are based on the user flow data and network data. It is a database based on a user data flow and shall be provided in support of;

- Multicast identification information- QoS control information (traffic parameters, etc.)

6.2.2 Multicast transport functions

These functions provide connectivity with multicast tree for all multicast users. These functions include multicast access transport functions, MPLS multicast core transport functions, MPLS edge functions, multicast access functions and multicast gateway functions. The multicast transport functions can support priority based forwarding mechanism, resource reservation mechanism, and traffic control mechanism for multicast QoS.

6.2.2.1 Multicast access transport functions

Theses functions is established the multicast delivery path with tree structure in access network. When a new multicast user joins a multicast tree in access network, the multicast tree could be extended. When a user leaves a multicast tree in access network, the multicast tree could be pruned.

Then, multicast traffic is forwarded by a group identifier through multicast tree and these functions should manage and control the parameters in the access network to support QoS, security and accounting related to the multicast traffic.

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These transport functions could be support a various types of access network (e.g. FTTH/PON, Wireless LAN, xDSL and Cable access technologies).

6.2.2.2 MPLS multicast core transport functions

Theses functions are established the multicast delivery path with tree structure in core network. When a new access network joins multicast tree, the multicast tree could be extended to the access network. When an access network leaves multicast tree, the access network is pruned. When multicast tree is extended, a group identifier announcement mechanism is needed in a new access network.

6.2.2.3 MPLS multicast edge node functions

MPLS multicast edge node functions are used for media and traffic. These are supported by the MPLS label switching. If a multicast access network would not support MPLS technology, these functions should provide interpret a MPLS group identifier to group identifier of other technologies. MPLS multicast edge node functions also perform QoS and traffic control such as buffer management, queuing, scheduling, marking, policing and shaping.

6.2.2.4 Multicast access functions

Multicast access node functions provide a group identifier tagging and QoS control based on MPLS multicast flow.

- QoS control performs traffic control functions such as priority control, packet filtering, traffic classification, rate limiting, minimum bandwidth guarantee, etc.

6.2.2.5 Multicast gateway functions

Multicast gateway functions provide capabilities to interwork with end-user functions and other networks.

6.2.2.6 Media handling functions

These functions provide multimedia resource processing for NGN multicast service provision, such as trans-coding which can adjust the data rate in specific node to support different QoS of heterogeneous network or can support different codec between multicast transport domains..

6.3 Management functions

The management functions provide ability to manage the NGN multicast capabilities in order to provide NGN multicast services with QoS, security, and reliability. These functions are allocates in each network node and interact with several nodes. These various management functions are such as the fault management, accounting management, performance management, and security management. A traffic measurement mechanism is needed to support accounting management by checking traffic volume and is needed to support performance management by monitoring traffic parameter in SLA.

6.3.1 Multicast management functions

These functions present the multicast management functions. They manage the customer information that is used to authenticate when the customer joins multicast service.

After end-user joins in multicast group as a receiver, this receiver’s information is managed.

These functions maintain the information of multicast flow traffic such as multicast receiver, multicast flow status, multicast rendezvous points and the information of network based on measurement. From this information, they can support various accounting functions, fault management and performance management in transport network.

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6.4 Multicast end-user functions

Multicast end-user can request the multicast service information or solicit the multicast transport information to join multicast service. After receiving this information, it request joins the multicast join group mechanism with its wanted QoS requirements. Then, it receives multicast data through multicast tree.

6.5 Reference interfaces in general architecture for NGN Multicast service architecture

( Editor’s note : This section has to be reviewed. Developing the reference interfaces with functional architecture should be further study.)

C interfaces are the service control interfaces for the general multicast application services. Service control messages and QoS control parameters are delivered by means of this interface between service and transport layer.

T interfaces are the transport control interfaces for the MPLS-based QoS support.

I interfaces are the transport interfaces for the delivery of guaranteed multicast media information between each networks.

- C1 End user’s service interface for control messages. Multicast application service request messages with SLA parameters are delivered through this interface.

- C2 Service control interface between the service and the transport stratum. Multicast service user profile information and QoS parameters are delivered through this interface.

- T1 Transport control interface to MPLS based access network. - T2 Transport control interface to MPLS based core network- I1 End user’s access interface for media information based on MPLS group identifier. - I2 Access network to core network interface for merged media.

7. Generalized functional architecture for NGN multicast services with MPLS-based QoS Support

( Editor’s note : The generalized functional architecture describes the MPLS-based NGN multicast capabilities for QoS support. These capabilities are divided into vertically and horizontally. They are divided into service stratum and transport stratum in vertical domain and end-user domain, access domain, core domain and source domain in horizontally.

This section should be describes with transport capabilities based on MPLS technology. Then, this capabilities are defined in next section to provide NGN multicast service over MPLS network. )

8. Functional scenarios andAND protocol procedures PROCEDURES for NGN multicast services at the transport stratum

( Editor’s note : possible required changes to MPLS technology/protocols will require coordination with current MPLS standardization efforts. )

8.1 Functional Scenarios

These protocol procedures provide the detailed description of information exchange between functional entities for the multicasting application services. However, prior to this protocol description, the functional scenarios should be described. These functional scenarios provide the global figure of the protocol procedures.

The following functional scenarios are described for the multicasting application services.

1) Multicast QoS connection registration scenarios

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- Multicast service registration with requested QoS negotiation 2) Multicast QoS connection management scenarios - Multicast QoS connection request - Multicast QoS connection release

8.1.1 Multicast QoS connection registration scenarios

This scenario describes the multicast QoS connection registration procedures for the multicasting application service. The service registration includes the requested explicit QoS requirement.

8.1.1.1 Multicast service registration with requested QoS negotiation

Figure 4 depicts the flow diagram of multicast connection registration.

Figure 4. The flow diagram of multicast connection registration

(1) The multicast end user requests the multicast service registration by HTTP in website or off-line to the Service Control Functions. This registration request contains the explicit QoS requirement (e.g. QoS class) for this service.

(2) The Service Control Functions determine the QoS parameters (Bandwidth, delay, jitter and loss etc.) of the requested service QoS level, and send registration request which contains these explicit QoS requirement parameters to the Multicast Resource Allocation Control Function.

(3) The Multicast Resource Allocation Control Function checks that the requested registration with QoS parameters can be acceptable within MPLS transport domain, and if admitted, modify the user profile held in the NAAF based on operator specific policy rules and on resource availability. It response the requested QoS requirement can be accepted or not.

8.1.2 Multicast QoS connection management scenarios

This scenario describes the multicast QoS connection management procedures for the multicasting application service request. (e.g. IPTV Channel Zapping) According to the existing of requested multicast connection in access network, two scenarios can be identified.

Service Control Functions

Multicast Resource Allocation

Control Function

MPLS Transport Functions

Multicast End User

(1)

(2) (3)

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8.1.2.1 Multicast QoS connection request

Scenario 1 : Requested multicast connection exists in access network

A flow diagram of scenario 1 for the multicast QoS connection request is provided in Figure 5.

Figure 5. The flow diagram of multicast connection request (Scenario 1)

(1) The multicast end user requests the multicast connection by sending a “Channel Request” (e.g. IPTV channel zapping message) to the MPLS Transport Functions.

(2) On receipt of the Channel Request, the MPLS transport functions at the network edge send this message to the Multicast Resource Allocation Control Function.

(3) The Multicast Resource Allocation Control Function checks authorization based on user profile. If admitted and the requested multicast connection exists in this access network domain, it sends the multicasting join control information, traffic control parameters to the MPLS transport functions.

Scenario 2 : Requested multicast connection is a new multicast connection in access network

A flow diagram of scenario 2 for the multicast QoS connection request is provided in Figure 6.

Figure 6. The flow diagram of multicast connection request (Scenario 2)

Service Control Functions

Multicast Resource Allocation

Control Function

MPLS Transport Functions

Multicast End User

(1)

(2)

(3)

Service Control Functions

Multicast Resource Allocation

Control Function

MPLS Transport Functions

Multicast End User

(1)

(2)

(5)

(3)

(4)

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(1) The multicast end user requests the multicast connection by sending a “Channel Request” (e.g. IPTV channel zapping message) to the MPLS Transport Functions.

(2) On receipt of a Channel Request, the MPLS transport functions at the network edge send this message to the Multicast Resource Allocation Control Function.

(3) The Multicast Resource Allocation Control Function checks authorization based on user profile. If the requested multicast connection does not exist in this access network domain, the Multicast Resource Allocation Control Function sends this message to the Service Control Functions for the setup of requested new multicast connection.

(4) The Service Control Functions initiate the new multicast connection through MPLS signaling within MPLS domain, and send the multicast connection information (e.g. the MPLS multicast label, MPLS multicast path) to the Multicast Resource Allocation Control Function.

(5) The Multicast Resource Allocation Control Function modifies the user profile, and sends the multicasting control information, traffic control parameters to the MPLS transport functions.

8.1.2.2 Multicast QoS connection release

Figure 7 shows the flow diagram of the multicast QoS connection release.

Figure 7. The flow diagram of multicast connection release

(1) The multicast end user requests the multicast connection by sending a “Channel Release” to the MPLS Transport Functions.

(2) On receipt of a Channel Release, the MPLS transport functions at the network edge send this message to the Multicast Resource Allocation Control Function.

(3) The Multicast Resource Allocation Control Function modifies the user profile, and sends the multicasting leave control information, release traffic control parameters to the MPLS transport functions.

Service Control Functions

Multicast Resource Allocation

Control Function

MPLS Transport FunctionsMulticast

End User

(1)

(2)

(3)

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8.2 MPLS-based functional protocol procedures

( Editor’s note : This section describes the 5 protocol procedures to provide NGN multicast services with MPLS based QoS support. These functional protocol procedures are based on MPLS protocol to support multicast delivery and multicast QoS in transport stratum.

)

8.2.4 1 Multicast join mechanism

( Editor’s note : This mechanism is to request multicast services by joining multicast tree. When a new multicast user requests a join procedure, a multicast tree can be extended. by distributing a group identifier to deliver multicast data to the multicast user. Before the multicast user joins a multicast tree, it should get multicast service information. A multicast user can join twice in service stratum and transport stratum.(it depends on the policy of service provider and network provider.)

8.2.41.1 Requirements ofMessage information of multicast join message information

(Editor’s note: This section defines the requirements of exchanged message parameters in a multicast join procedure.)

In this mechanism, some messages are needed such as ‘Service Information Request’, ‘Service information’, ‘Multicast Service Join’, ‘Multicast Service Join Ack’, and ‘Multicast Tree Join’.

- Service Information Request

This message contains information of a multicast user and a multicast server.

- Service Information

This message contains various multicast service lists with multicast server information, multicast session numbers, description of multicast sessions (media types, codecs, data rates, and etc) in the multicast server.

- Multicast Service Join

This message contains wanted multicast session information including multicast server information, a multicast session number (wanted media type, codec, priority, and data rate), and multicast user information to join multicast service such as user’s security information.

- Multicast Service Join Ack

This message contains result of multicast service join whether a join request is succeed or failed it including information of serviced multicast session, multicast user, and multicast server. If the request was failed, the reason of service fail should be contained.

- Multicast Tree Join

This message contains the multicast session information to join a multicast tree in transport stratum.

8.2.41.2 The flow of Protocol procedure of multicast join procedure

Figure 8 shows the flow of multicast join mechanism. Before the multicast user joins a multicast tree, it should get multicast service information. Therefore, the multicast user can request service information by sending ‘Service Information Request’ message to a multicast server and the multicast server sends ‘Service information’ message with all service information; then, the multicast user can select a wanted service in this service list and sends ‘Multicast Service Join’ to the multicast server. The multicast server decides whether accepting this request with its own service profile and sends ‘Multicast Service Join Ack’ as its result. After receiving this message, a multicast user can know where it can join by requesting a group identifier. The multicast user sends

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‘Multicast Tree Join’ to an access network node and the access network node start to group identifier distribution mechanism with PDF to join core network node. After distributing a group identifier between the access network node and a join point, a multicast branch is extended to support a multicast tree for the multicast user. A group identifier distribution mechanism will explain in next section.

Figure 8. The flow of multicast join

( Editor’s note : This section describes the detail message flow between functional entities and the operation of functional entities for a multicast join procedure.)

8.2.1 2 Group identifier distribution mechanism

( Editor’s note : This mechanism is to distribute a group identifier between a joining point to a multicast user to extend multicast tree. A group identifier allows a network node to identify each multicast flow including MPLS group identifier in transport stratum. The transport group identifier has a relation with a session group identifier in service stratum and has including MPLS group identifier. If a multicast tree does not use MPLS technology, group identifier should have an association with other types of group identifier if a multicast tree does not use MPLS technology. The group identifier distribution mechanism is very important because multicast tree management is based on the group identifier. A group identifier is distributed after a multicast user joins a specific multicast group. A group identifier can be distributed with centralized method or distributed method..

- MPLS group identifier

- Other types of group identifier)

8.2.12.1 Requirements of message Message information of group identifier distribution

A group identifier is managed by a PDF and is a unique value in a domain. Then, PDF starts to distribute a group identifier between join point and access network node. In this mechanism, the

Multicast user Access network Node Core network Node Application Server

Service Information Request

Service Information

Multicast Service Join

Multicast Service Join Ack

Multicast Tree Join

PDF

Group Identifier Distribution

Multicast Traffic Flow

Multicast Traffic Flow

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multicast session information such as session group identifier is needed to request a transport group identifier.

- Group Identifier Request

This message contains the multicast session information to find transport group identifier.

- Group Identifier Report

This message contains transport group identifier and media profile of multicast traffic to reserve transport network resource.

( Editor’s note: This section defines the requirements of exchanged message parameters in a group identifier distribution procedure.)

8.2.12.2 The flow of protocolProtocol procedure of group identifier distribution procedure

Figure 9 shows the flow of the group identifier distribution mechanism. When a multicast user joins multicast tree at core network node, an access network node sends ‘Group Identifier Query’ message to PDF because PDF manages all group identifier. PDF sends ‘Group Identifier Report’ message to a core network node because it is a joining point in this procedure and the core network node relays ‘Group Identifier Report’ to the access network node. By doing so, a new multicast tree branch is established from the core access network node to the access network node.

Figure 9. The flow of group identifier distribution

( Editor’s note : This section describes the detail message flow between functional entities and the operation of functional entities for a group identifier distribution procedure.)

8.2.2 3 Multicast resource reservation mechanism

( Editor’s note : This mechanism is to support MPLS-based QoS support. When a multicast user requests a NGN multicast service, MPLS-based transport functions should guarantee QoS. Therefore, it needs a resource reservation.)

8.2.23.1 Requirements of message Message information of multicast resource reservation

( Editor’s note : This section defines the requirements of exchanged message parameters in a resource reservation mechanism.)

8.2.23.2 The flow of pProtocol procedure of multicast resource reservation

( Editor’s note : This section describes the detail message flow between functional entities and the operation of functional entities for a resource reservation mechanism.)

Access network Node

Core network Node

Multicast Tree Join

PDF

Group Identifier Request

Group Identifier ReportGroup Identifier

Report

Multicast user

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8.2.3 4 QoS level modification mechanism

( Editor’s note : This mechanism is to modify a QoS level. If a multicast user wants to upgrade or degrade the service quality of multicast service, it may use this mechanism.)

8.2.34.1 Requirements of message Message information of QoS level modification

(Editor’s note: This section defines the requirements of exchanged message parameters in a QoS level modification procedure.)

8.2.34.2 The flow of pProtocol procedure of QoS level modification

( Editor’s note : This section describes the detail message flow between functional entities and the operation of functional entities for a QoS level modification.)

9.2.4 Multicast join mechanism

( Editor’s note : This mechanism is to request multicast services. When a multicast user requests a join procedure, a multicast tree can be extended.)

9.2.4.1 Requirements of message information

(Editor’s note: This section defines the requirements of exchanged message parameters in a multicast join procedure.)

9.2.4.2 The flow of protocol procedure

( Editor’s note : This section describes the detail message flow between functional entities and the operation of functional entities for a multicast join procedure.)

8.2.5 Multicast leave mechanism

( Editor’s note : This mechanism is to exit multicast services. When a multicast user requests a leave procedure, a multicast tree can be pruned.)

8.2.5.1 Requirements of mMessage information of multicast leave

(Editor’s note: This section defines the requirements of exchanged message parameters in a multicast leave procedure.)

8.2.5.2 The flow of pProtocol procedure of multicast leave

( Editor’s note : This section describes the message flow between functional entities and the operation of functional entities for a multicast leave procedure.)

9. Interaction between the service and the transport stratum for MPLS multicast

( Editor’s note : This section will deals with interaction procedures between MPLS transport control functions and service stratum. This section has a relation with reference interface C2, service

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control interface.)

For multicast function in the SCF, there consists of a session manager (SM) and a multicast agent (MA). The SM takes charge on group membership management and monitoring transport state while MA takes charge on send or receive application and forwarding function of IP multicast router. Both of MA and SM can be implemented by host or separate server.

The MA transfers resource control parameters (e.g. Flow direction, IP Address, Protocol Number, Bandwidth, MPLS Label.) to the PD-FE. The PD-FE establishes a negotiation based on these parameters.

It is necessary for session manager (SM) to provide a management functions for multicasting in wired and wireless and customer premises environment. Thus, SM interacts with multiple MAs (Multicasting Agents), for example MA-1 for wired environment, MA2 for wireless environment, and MA-3 for customer premises environment at transport stratum.

Multicast End-User Functions

Multicast Application Functions

Multicast Service Profiles

Multicast Network

Attachment Functions

Multicast Resource and Admission

Functions Multicast Transport ProfilesMPLS Multicast Transport Control Functions

MulticastAccess Node Functions

MPLS Multicast Edge Node Functions

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Functions

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Functions

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C1

C2 (RS in Y.RACF)

T1 T2

I1 I2

SM

MA-1 MA-2 MA-3

Service Control Functions

Management Functions

Multicast Management

Functions

Figure 10. Interaction between service and transport stratum for MPLS multicast

Each of Multicast Agents in SCF can interact with PD-FE via the C2 (same as Rs in Y.RACF) reference point.

MPLS multicast service user profile information and QoS parameters are delivered through C2 interface. Multicast session management provides unique group identifier in MPLS domain and interact with MPLS multicast transport control functions to assign group identifier. Each multicast flow is distinguished by a group identifier.

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The MAs provide information to the PD-FE to maintain the status information for multicast QoS service, performance, etc.

Multicast Agents (MAs) provide information to the PD-FE to identify media flows and their required resource (e.g. service QoS class, bandwidth) for multicast QoS service.

The MAs may provide service information to the PD-FE to facilitate handling (e.g. wired, wireless, customer premises network).

The MAs may request resource usage information through the PD-FE for accounting.

9.1 Functional requirement of Reference Point C2(same as Rs in Y.RACF) for MPLS multicast

It is necessary for SCF to send and receive following messages via C2 to PD-FE. For identify multicast group and service, the PD-FE may need to receive following messages from SCF.

- Application Identifier, Resource Control Session Identifier, and Transport Subscriber Identifier message can be used to uniquely identify a specific multicast group or service by PD-FE.

- Advertisements of multicast group membership may necessary Application Identifier, Media Profile messages.

- Solicitations of multicast service information could request only one multicast service information or a group of multicast services information. Application Identifier, Media Profile, and Resource Control Session Identifier messages can be used for this operation.

- Multicast session management is necessary for PD-FE to manage the multicast session information including multicast tree information. Resource Control Session Identifier and Resource Control Session Information, Media Profile messages can be used for this operation.

- Network resource controls to support QoS classes support a number of QoS levels for a multicast group while network resources are limited. Resource Reservation Mode, Media Profile messages can be used for this operation.

- In case of MAs support the interaction between wired network and wireless network. (e.g MA-1 and MA-2 in Figure x)

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Figure 11. Interaction between wired and wireless environment

When the PD-FE in Multicast Transport Function receives resource authorization and reservation from the SCF, PD-FE (with Access Network) performs authorization and admission control based on operator policy rules in the Multicast Network Attachment Functions. These control messages derived to the other access network via MPLS core network.

PD-FE with MPLS core network is connected with MA-1. It may acts like an interface between PD-FEs in wired and wireless network.

9.2 Functional requirement of PD-FE for MPLS multicast at the service stratum

To support multicast service at the service stratum, PD-FEs may have a function that interacts with other PD-FE in other network. Between different networks, PD-FE communicates with others through Rd interface for sharing multicast QoS control received from SCF. PD-FE inspects both TRC-FEs in same network and other nearby network. This interaction may occur eventually at any time, so that PD-FEs can have information about QoS control over the different or same networks.

MA-1 can be applied existing multicasting mechanism in service stratum, but MA-2 must support following functional requirements because it must provide multicast mechanism in mobile environment.

For MA-2(mobile environment) interact with PD-FE, it is necessary considering the following. MA-2 should have MAID(Multicast Agent Identifier) of mobile device for smooth

handover mechanism. This unique identifier enables the group administrator to know the location of each PD-

FE. When MA-2 moves from one wireless network to another one, supporting smooth and

fast handover is highly needed. PD-FE and MA-2 for wireless environment must be free from network fault such as loop

and partitioning.

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When a PD-FE uses bidirectional tunnelling, mechanism, undesirable data duplication may occur inside wireless environment. To prevent this, PD-FE guarantees only one MA inside local network.

10. Implementation scenarios for NGN multicast services with MPLS-based QoS support

10.1 Multicast service and implementation scenario using FTTH/PON

(Editor’s note: the benefit of the MPLS technologies have to be described and justified.)

( Editor’s N ote : This section will deal with multicast service architecture and scenario by using FTTH/PON, their operation and QoS provisioning mechanism. The protocol procedure also includes NGN multicast service scenario in FTTH/PON network. )

10.2 Multicast service and implementation scenario using Wireless LAN

(Editor’s note: the benefit of the MPLS technologies have to be described and justified.)

( Editor’s N ote : This section will deal with multicast service architecture and scenario by using wireless LAN, their operation and QoS provisioning mechanism. The protocol procedure also includes NGN multicast service scenario in wireless LAN.

In wireless LAN, an access point has a role of the edge point of MPLS domain. To support multicast service, access point controls the membership of multicast user, maps a group identifier between MPLS domain and wireless domain. It may include to control wireless resources to support multicast QoS.)

10.3 Implementation scenario of multicast service through multiple heterogeneous transport networks

(Editor’s note : The MPLS technologies can apply to multiple heterogeneous transport networks (such as IP, ATM, frame relay, TDM and Ethernet) to provide multicast QoS capabilities.

For example of video streaming service, the MPLS technologies can provide multicast capabilities through various transport network environments. Contributions are requested on the implementations of MPLS-based multicast QoS capabilities scenario through heterogeneous transport networks.

In order to provide MPLS-based multicast services over different transport networks. the interworking situations are requested for further study. It requests for additional clarifications.)

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