INTERNATIONAL TELECOMMUNICATION UNION STUDY GROUP 15TELECOMMUNICATIONSTANDARDIZATION SECTOR

STUDY PERIOD 2005-2008

TD 294R2 (WP 1/15)English only

Original: English

Question(s): 1/15 Geneva, 11-22 February 2008

TEMPORARY DOCUMENT

Source: Rapporteur Q1/15

Title: Draft new Recommendation G.hnta – Generic Home Network Transport Architecture (working text)

This document contains the Draft Recommendation G.hnta: Generic Home Network Transport Architecture as submitted in document TD 294 (WP1/15) and includes the amendments agreed in the Q1/15 meeting February 2008.

G.hnta: Generic Home Network Transport Architecture

Summary

This Recommendation describes a generic architecture for home networks and their interfaces to the operators' broadband access networks.

Introduction

As the use of electronics and communications equipment proliferates in the home, as well as their technologies and protocols, there have been several proposals for standardization of equipment, transport and networking within the “home network”. This recommendation proposes a generic home network architecture for the Transport Stratum Layer that can be the platform for the development of home networking standards.

1 ScopeConsidering that in the future the Home Network will be interconnected with the Next Generation Network (NGN) in future, this Recommendation describes the generic Home Network architecture from the view point of NGN architecture. Recommendation Y.2012 “Next Generation Networks – Frameworks and functional architecture models” defines the Transport Stratum as well as the Service Stratum. Considering these, the generic Home Network architecture can be separately discussed both in the Transport layer categorized in the Transport Stratum and the Application layer categorized in the Service Stratum. This recommendation references the former model. Note that the latter model is specified in the companion recommendation, H.ghna “A Generic Home Network Architecture with Support for Multimedia Services”. Its detail will be described in Clause 6.

Contact: John A. JayCorning, Inc.USA

Tel: +1 607 974 4288Fax: +1 607 974 7648Email: jayja@corning.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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This Recommendation discusses the interfaces between access networks and home networks, including interfaces within home networks as well as legacy interfaces. However, interfaces for off-air broadcast services are not considered in this Recommendation. Interfaces in the home network as well as the interface to the access network are shown as reference points, while proposed demarcation points for the customer and the operator are also shown in this Recommendation. Moreover, this Recommendation identifies key transport technologies for an operator to consider when providing services relevant to home networking.

In summary, this recommendation addresses layer 3 Home Network architecture, while Recommendation G.hn addresses layers 2 and 1 Home Network architecture. Moreover, this recommendation describes the high level requirements for the layer 2 and 3 transport technologies from the viewpoint of the interaction between Access Network and Home Network, while one of the detailed requirements and specifications for the layer 2 transport technologies within the Home Network can be found in G.hn. The detailed explanation regarding the relationship between Recommendations G.hnta and G.hn can be found in the annex of this recommendation.

2 References

The following ITU-T Recommendations and other references contain provisions, which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published.

The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation

[1] ITU-T Rec. H.610 (2003), Full service VDSL – System architecture and customer premises equipment.

[2] ITU-T Rec. J.190 (2002), Architecture of MediaHomeNet that supports cable-based services.

[3] DSL Forum TR-094 (2004), Multi-Service Delivery Framework for Home Networks.

[4] ITU-T Rec. Y.2012 (2006), Next Generation Networks – Frameworks and functional architecture models.

[5] ITU-T Rec. Y.1541 (2006), Network performance objectives for IP-based services.

[6] ITU R Rec. M.1450 (2008), Draft revision of Recommendation ITU-R M.1450-2 - Characteristics of broadband radio local area networks

[7] ITU R Rec. M.1801 (2007), Radio interface standards for broadband wireless access systems, including mobile and nomadic applications, in the mobile service operating below 6 GHz

[8] DSL Forum TR-069 Amendment 1 (2006), “CPE WAN management protocol”

[9] ITU-T Rec. X.1111 (2007), “Framework of security technologies for home network”

[10] ISO/IEC 15045-1 (2004), “Information technology – Home electronic system (HES) gateway – Part 1: A residential gateway model for HES”

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3 Definitions

The new terminologies are defined in clause 6.

4 Abbreviations

This Recommendation uses the following abbreviations:

ASG Application Service Gateway

B-NT Broadband Network Termination

DHCP Dynamic Host Configuration Protocol

EUT End User Terminal

FPD Functional Processing Device

FPD/T Functional Processing Device and Terminal

GW Gateway

HA Home Access

HB Home Bridge

HC Home Client

HD Home Decoder

ICMP: Internet Control Message Protocol

IMS: IP Multimedia Subsystem

IP Internet Protocol

IPTV: Internet Protocol Television Set

NGN: Next Generation Network

OSGi: Open Service Gateway initiative

PC Personal Computer

PLC: Power Line Communication

PPP: Point to Point Protocol

PS POTS Splitter

QoS Quality of Service

RG Routing Gateway

RSVP Resource ReSerVation Protocol

SIP: Session Initiation Protocol

SNMP: Simple Network Management Protocol

STB Set Top Box

TV Television Set

UPnP Universal Plug and Play

VTP/D VDSL Termination Processing or VDSL Termination Processing and Decoding

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5 Conventions

None

6. Generic Home Network architecture

6.1 Application layer Generic Home Network model

Before discussing a Generic Home Network architecture in the Transport layer, the Application layer architecture will be described in this Clause. Draft ITU-T Recommendation H.ghna “A generic Home Network architecture with support for multimedia services” in SG16 addresses the Home Network architecture for the Application Model, as shown in Figure 6-1.

Access GW

Access NW Primary

Terminal Primary Domain

Secondary Domain

Secondary Terminal

Figure 6-1 - Application model of Home Network

- Primary Terminal is a terminal device that can interact with the Access Network or service functionality beyond the Access Network without having the assistance of another Terminal and is the service end-point where the service from the service provider is terminated.

- Secondary Terminal is a terminal device that has no direct interactive capability with network side entities or needs to rely on another terminal to do so.

- Primary Domain is the logically defined area of the Home Network that interconnects the Primary Terminal and the Access GW.

- Secondary Domain is a logically defined area of the Home Network that interconnects Terminals. The devices and traffic dedicated to Secondary Domain do not need to be configured to be reachable to/from Access Network.

6.2 Transport layer Generic Home Network model

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Figure 6-2 - Generic Home Network functional architecture for the Transport layer

In Figure 6-2, the home network is shown as an “IP Home Network” using IP and a “Non-IP Home Network” using other specific technologies or protocols. A Gateway between the “Access Network” and the “IP Home Network” is called the “Access Gateway Transport layer Function (AGTF)”, while a Gateway between an “IP Home Network” and a “Non-IP Home Network” is called a “Non-IP GW”. Non-IP Terminal at the right-hand-side bottom is a legacy terminal, such as an analogue CPE, which is directly connected to the Access Network, bypassing the home network.

The following sections will describe the terminology relevant to the home network architecture for the Transport layer.

Note that this is functional architecture. For example, both “IP Home Network” and “Non-IP GW” can be collapsed in case that the “Non-IP Home Network” is directly connected to “AGTF”. In such a case, “IP Home Network” and “Non-IP GW” functions are contained in one physical Access Gateway device. Moreover, one port of the physical Access Gateway device may serve “IP Home Network”, while another port of the same physical Access Gateway device may serve “Non-IP Home Network”.

6.2.1 IP Home Network

The “IP Home Network” is the network that carries IPv4 or IPv6 data. That is, it corresponds to “IPCable2Home Domain” in ITU-T Rec. J.190 or “Premises Distribution” in DSL Forum TR-094. Note that the HB in ITU-T Rec. J.190 can be one of the elements composing the “IP Home Network”.

6.2.2 Non-IP Home Network

A “Non-IP Home Network” is composed of one or more networks, each of which has its own non-IP technology or protocol. “Non-IP Home Network” corresponds to “Proprietary Domain” in ITU-T Rec. J.190, and also corresponds to “Supplementary Application Network” or the connectivity between FPD and EUT in DSL Forum TR-094. Note that HD in ITU-T Rec. J.190 can be one of the elements composing “Non-IP Home Network”.

6.2.3 IP Terminal

An “IP Terminal” is a terminal function that is directly connected to an “IP Home Network”, for example an IP-interface-equipped STB or telephone. “IP Terminal” corresponds to HC or a set of HC and HD in ITU-T Rec. J.190 as well as FPD/T in DSL Forum TR-094.

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As shown in Figure 6-3, there are three types of IP terminals depending on which kind of Terminal it resides in, Primary or Secondary. IP Terminal (a) retrieves the payload from the received IP packets (from the left) for the Application layer and then sends the Non-IP Layer 3 packets for the Application layer. Similarly to this, IP Terminal (b) sends the IP packets for the Application layer. On the other hand, IP Terminal (c) just retrieves the payload from the received IP packets for the Application layer.

Figure 6-3 – Three types of IP Terminal

6.2.4 Non-IP Terminal- There are examples of customer premise terminal functions that cannot be directly connected to

“IP networks”, such as legacy TV, telephone and PC peripheral equipment, such as printers. Such terminals are called “Non-IP Terminals” in this Recommendation. “Non-IP Terminal” corresponds to HD in ITU-T Rec. J.190 as well as EUT in DSL Forum TR-094.

Moreover, analogue CPE connected directly to the access network, - so thus bypassing the home network, - supporting legacy non-IP services like POTS or broadcast analogue television, is also a “Non-IP Terminal”.

6.2.5 Non-IP Gateway (GW)

A “Non-IP GW” connects the “IP Home Network” and “Non-IP Home Networks”.

“Non-IP GW” corresponds to HC in ITU-T Rec. J.190 as well as FPD or ASG in DSL Forum TR-094. Moreover, it may correspond to FPD in ITU-T Rec. H.610 when the architecture in Figure 6-2 is applied to it.

On the contrary to IP Terminal (type a), Non-IP GW directly converts the received IP packets to the Non-IP Layer 3 packets without the Application layer, which is shown in Figure 6-4.

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Figure 6-4 – Non-IP Gateway

6.2.6 Access Network

The Access Network is terminated by NT (Network Termination) function, as shown in Figure 6-5. In general, IP terminal and non-IP terminal is connected to the Access Network via AGTF. However, some Non-IP, or legacy, Terminals are sometimes directly connected to the access network for historical reasons. Typical examples are a telephone directly connected to a metallic cable or an STB directly connected to a coaxial cable. In such cases, a non-IP terminal should be connected to a Splitter in the Access Network via a Splitter (see Figure 6-5)..

Figure 6-5 - Access Network to support Non-IP Terminal

The Splitter separates the signals for legacy services from the aggregate signal stream from the central office. A Splitter in this Recommendation corresponds to PS in both ITU-T Rec. H.610 and DSL Forum TR-094. Moreover, ITU-T Rec. J.190 implicitly shows the signal splitter function that is connected to an STB.

6.2.7 Access Gateway Transport layer Function (AGTF)

The “AGTF” connects the “Access Network” to the “IP Home Network”. This Recommendation does not specify its detailed implementation aspects. The relationship between AGTF and the physical Access Gateway (AGW) device as well as how they are handled by some referenced documents will be discussed in this clause.

The definition of AGTF is shown in Figure 6-6. Layer 1 and 2 of Access Network are terminated at NT (Network Termination). “Access Gateway Transport layer Function (AGTF)” specified in this recommendation terminates layer 1 and 2 of WAN side by using WANT (WAN-side Termination), while it terminates layer 1 and 2 of LAN side by using LANT (LAN-side Termination). “IP/PPP processing” may be executed above these WANT and LANT functions. On the other hand, “Access Gateway Application layer Function (AGAF)” specified in H.ghna works above AGTF. “Access Gateway (AGW)” is a physical device that contains at least AGTF and AGAF, as shown in this

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figure. Note that it may also contain NT function as optional. In such a case, WANT is not needed, because NT also plays the role of WANT.

This recommendation identifies two types of AGW: one is called “aggregate type AGW” that contains NT, while the other is called “separate type AGW” that does not contain NT, as shown in Figure 6-6.

Figure 6-6 - Decomposition of Access Gateway

Figure 6-7 shows the types of AGW in comparison with some documentscommon industry standards for the home-access network interface, while Table 6-1 shows the relationship between two types of AGW and the corresponding entities of some these documents. The entities described in DSL Forum TR-094, B-NT and RG, represent the separate type of AGW. On the other hand, VTP/D in ITU-T Rec. H.610 and HA in ITU-T Rec. J.190 represent the aggregate type of AGW.

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Figure 6-7 - The configuration of AGW in comparison with some documents

Table 6-1 - Relationship between two types of AGW and the corresponding entities of some documents

6.3 The relationship between the Home Network architecture for the Transport layer and that of the Application layer

The main objective of the Home Network Architecture for the Transport layer is to ensure that communication in the Application layer can be carried over the Transport layer. To better

Type of AGW

Document

Aggregate type AGW Separate type AGW

NT/AGTF/AGAF NT AGTF/AGAF

DSL-F TR-094 --------------------- B-NT RG

ITU-T H.610 VTP/D --------------------- ---------------------

ITU-T J.190 HA --------------------- ---------------------

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understand the relationship between the two Home Network Architectures, one physical configuration is provided in Figure 6-8. This includes the following features. - The Primary Terminal contains both IP Terminal (type a) and Application Layer Device Func-

tion (ALDF), while the Secondary Terminal contains both Non-IP Terminal and ALDF. AGW, which is the aggregated type in this example, contain NT, AGTF and AGAF.

- AGW terminates the public IP address and interacts with an IP Terminal (type a) by local IP ad-dress, while IP Terminal (type a) interacts with Non-IP Terminal by non-IP (L3) protocol. Both IP Terminal (type a) and Non-IP Terminal lie within the Transport layer in the Home Network.

- On the other hand, ALDF in the Primary Terminal interacts with functions in the Application layer of the carrier’s network via AGAF in AGW. It also interacts with that in the Secondary Terminal at the application level.

- The Primary Domain is provided over an IP Home Network, while the Secondary Domain is provided over Non-IP Home Network.

-

Figure 6-8 - One physical configuration based on the two Generic Home architectures

Considering the above, you can find three typical flows in layer 3, as shown in Figure 6-9. Note that this figure shows a physical configuration. Concretely speaking, AGW is the aggregated type device, while IP Terminal (type a) is the device that contains IP Terminal (type a) function.- Flow 1: IP Terminal (type a) acting as Primary Terminal receives packets from AGW via IP

Home Network and then distributes them to Non-IP Terminal acting as Secondary Terminal via Non-IP Home Network.

- Flow 2: IP Terminal (type b) acting as Primary Terminal receives packets from AGW via IP Home Network and then distributes them to IP Terminal (type c) acting as Secondary Terminal also via IP Home Network.

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- Flow 3: Non-IP GW receives packets from AGW via IP Home Network and then forwards them to Non-IP Terminal acting as Primary Terminal via Non-IP Home Network.

Note that Appendix I shows various use cases applying this generic home network architecture for the Transport layer in Home Networks.

Figure 6-9 – Three typical flows over Generic Home Network Transport physical architecture

Figure 6-10 summarises the two layered two generic Home Network models. AGW is a physical device that contains at least AGTF and AGAF. Moreover, as it may also contain NT function as optional. Both Primary Terminal and Secondary Terminal are physical devices that contain Application Layer Device Functions as well as Transport Layer Terminal functions, such as IP Terminal or Non-IP Terminal. Primary Terminal may contain either IP Terminal or Non-IP Terminal. As the sameSimilarly, Secondary Terminal may also contain either IP Terminal or Non-IP Terminal.

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Figure 6-10 - The conceptual diagram of layered two generic Home Network models

7 Possible demarcation points

As described in Clause 6, service is provided to the Primary Terminal in the Application layer, which is supported by either the IP Terminal or the Non-IP Terminal in the Transport layer. Therefore, the interfaces to reach each Terminal are potential demarcation points between the user and operator domain of responsibility. Possible demarcation points for an IP Terminal are described in Section 7.1, while those for a Non-IP Terminal are described in Section 7.2. One of these demarcation points would be selected by a user and an operator, considering the service model deployed. Moreover, we must take into account that there are two types of AGW, aggregation type and separate type.

7.1 Possible demarcation points for IP Terminals

Points A, B, C, D1 and D2 in Figure 7-1 are the possible demarcation points for an IP Terminal (type a) and IP Terminal (type b), which act as Primary Terminal.

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Figure 7-1 - Possible demarcation points for IP Terminals

7.2 Possible demarcation points for Non-IP Terminals

Existing non-IP services should be provided to the Non-IP Terminals, such as TV, STB, telephone, PC peripherals etc., that do not have IP capability. Points A, B, C, E, F, G and H in Figure 7-2 are the possible demarcation points for Non-IP Terminals.

Figure 7-2 - Possible demarcation points for Non-IP Terminals

8 High level requirements

8.1 QoS control

The functionality to realize QoS control over IP network is important to accomplish stable quality in case of offering streaming-based multi-media services on the IP Network. One QoS control domain, at the edge of which two kinds of QoS services can be defined: parameterized QoS and prioritized QoS. ITU-T Y.1541 specifies IP-based parameterized QoS. Parameterized QoS is realized by some control protocols, such as SIP utilized in NGN and RSVP mentioned in J.190. Dynamic parameterized QoS control can be provided by using these protocols, while static parameterized QoS can be provided by management functions. On the other hand, prioritized QoS is realized by DSCP for IP or Ethernet VLAN, which attaches a priority level to each packet. R QoS described in DSL Forum TR-094 also is a kind of prioritized QoS. Moreover, TR-098 includes configuration of many QoS parameters.

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In case of studying the requirements for the Access GW (or AGW) to realize end-to-end QoS control between two remote IP Terminals in different IP Home Networks via Network Operator’s network, we must consider that they communicate with each other over multiple QoS control domains. We can identify three types of service scenarios in terms of QoS control domain.

- Type 1: One QoS control domain exists for IP Home Network, but no QoS control domain for Network Operator’s network including Access Network

- Type 2: QoS control domains exist each for Network Operator’s network including Access Network and for IP Home Network

- Type 3: One QoS control domain exists through Network Operator's network including Access Network as well as IP Home Network

Type 1 is the non-NGN case that the Network Operator’s network including Access Network provides only best-effort service, which means not to provide any QoS control, such as parameterized or prioritized. As QoS control is provided only within each IP Home Network, end-to-end QoS control between two remote IP Terminals cannot be achieved. On the other hand, Types 2 and 3 are the NGN case.

Figure 8-1 shows Type 2. QoS mapping function is required for the Access GW, because each QoS control in one Network Operator’s network including Access Network and two IP Home Networks may be different from each other. After QoS mapping, admission control is performed by the Access GW to check whether the network resources are enough to achieve the required QoS. After the communication is established between two remote IP Terminals, some traffic control, such as priority control, policing or shaping, will be also performed by the Access GW.

The QoS mapping should be performed, considering the following three cases.

- In case that the Access Network is IP (Layer 3) QoS control domain, while the IP Home Network is Ethernet (Layer 2) QoS control domain, Layer 3 and Layer 2 QoS mapping should be performed.

- Even if both the Access Network and the IP Home Network are IP (Layer 3) QoS control domains, one may be parameterized QoS control domain, while the other may be prioritized QoS control domain.

- Even if both the Access Network and the IP Home Network are the parameterized QoS control domain, each may have different QoS specifications.

Figure 8-1 also shows Type 3. QoS mapping function is not required for the Access GW, because one unique QoS control service is provided through IP Home Network as well as Network Operator’s network including Access Network. However, admission control, as well as some traffic control functions, will be needed for the Access GW.

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Figure 8-1 - QoS control for Network Operator’s network and IP Home Networks

8.2 Device management

As described in Clause 7, the Primary Terminal in the Application layer, which is the service end-point, is supported by either the IP Terminal or the Non-IP Terminal in the Transport layer. Therefore, the devices from the Access Network communicating to either the IP Terminal or the Non-IP Terminal should be managed by the Remote Management Server (RMS) owned by the Network Operator or Service Provider. Management functions include configuration, local monitoring and maintenance.

AGW will be directly managed by RMS. The protocols to be used are the generic management protocol based on IP, such as ICMP and SNMP. Moreover, one more promising candidate is TR-069 Amendment 1 [A8] specified in DSL Forum ( http://www.dslforum.org/techwork/treports.shtml ) , which provides configuration and monitoring functions. Note that TR-098 is a companion specification for TR-069 which specifies configuration parameters for AGW.

There will be two schemes to manage end devices, such as IP Terminal, Non-IP Terminal or Non-IP GW, as shown in Figure 8-2. Scheme A is the one that in which RMS directly manages individual end devices, while Scheme B is the one that in which RMS only manages an AGW that manages individual end devices instead of RMS it. Note that AGW contains both NT and AGTF in this figure.

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Figure 8-2 - Two schemes to remotely manage end devices

As for scheme A, the protocols to manage IP Terminal and Non-IP GW are the same ones to manage AGW, described above. However, proprietary management protocols are applied for managing Non-IP Terminal because there is Non-IP Home Network before it.

Scheme B can also use the generic management protocol based on IP, such as ICMP and SNMP, for the protocol between AGW and IP Terminal or Non-IP GW. Moreover, since this sScheme requires plug and play to enhance usability, specifications discussed in UPnP Forum (http://www.upnp.org) can be applied. However, proprietary management protocols are applied for managing Non-IP Terminal by AGW because there is Non-IP Home Network before it. AGW plays the role of adaptation between RMS and end devices in such a way that AGW notifies RMS of the end device information by using protocols, such as ICMP, SNMP or TR-069.

It depends on the situation in the home network which scheme should be deployed, Scheme A or B. Scheme A will be useful when the Home Network contains few as far as the number of end devices and their kinds are few. However, when they increase, the load of the RMS will increase accordingly. Scheme B will be useful in such a case. As AGW manages end devices instead of RMS, the load distribution balancing can be accomplished. Moreover, even if a new kind of end device is connected to the home network, the interface between RMS and AGW will be changed less, because AGW hides the new operations to manage it. This is also applied to the proprietary management for Non-IP Terminal.

In case that the management protocols between AGW and end devices are changed frequently due to their version change and so on, OSGi (http://www.osgi.org) base technology can be applicable for AGW. The software for AGW to manage end devices can be implemented as software bundle on OSGi platform, if it is installed in AGW. OSGi platform provides an open interface for each software bundle, independent of hardware, operating system and other conditions of AGW. Therefore, RMS does not have to care for the specifications of AGW to dynamically download such software bundles managing end devices.

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As DSL Forum has other documents that specify management of SIP endpoints (TR-104) and Set-Top Boxes (STBs) (WT-135, which will soon be undergoing final approval), they can be referred to, if necessary.

8.3 IP addressing

One of the important functions provided by NGN is IP address management. As shown in Figure 8-3, the ports connected to the Access Network (referred to as “Access network attached port”) and the ones connected to the IP Home network (called “IP Home network attached port”) are identified by IP addresses. Note that IP address types are categorized into IPv6, IPv4 Global and IPv4 Local. The owners for IP address assignment are classified into Network Operators (NPs), Service Providers (SPs) or End Users (EUs). IP addresses for “Access network attached port” are normally assigned by NPs. However, IP addresses for “IP Home network attached port” are assigned by NPs or SPs or EUs. In the case of NPs, the AGW would not need to translate the assigned IP address, because the owner assignment of IP addresses for the Access network and the IP Home network is done by one NP. On the other hand, in the case of SPs or EUs, the AGW should translate the IP addresses for the Access Network and the IP Home Network. However, even in this case, when PPP is provided by NPs to reach the Access Network, the AGW would not need to translate the IP addresses, because it only encapsulates IP packets by PPP.

Figure 8-3 - Definition of IP addressing schemes

Based on the above description, typical combinations of IP addressing schemes are listed in Table 8-1. This table will need to be updated when new addressing schemes or usages are identified. IP address types as well as the owners for IP address assignment, which are written in parentheses, are described as follows.

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- IPv6 (by NP): A Network Operator assigns the IP address by IPv6.

- IPv6 (by SP or EU): A Service Provider, such as ISP, assigns the IP address to access servers managed by this Service Provider. Otherwise, an End User assigns the IP address for IP Home Network, dynamically. In this case, DHCP or IPCP will be required. In general, the static assignment by users is not recommended.

- IPv4 Global (by NP): A Network Operator assigns the IP address by IPv4.

- IPv4 Global (by SP): A Service Provider, such as ISP, assigns the IP address to access servers managed by this Service Provider.

- IPv4 Local (by EU): An End User assigns the IP address for IP Home Network, dynamically. In this case, DHCP or IPCP will be required. In general, the static assignment by users is not recommended.

The last column of this table shows what kinds of functions AGTF in AGW should possess, such as IP address translation function or IP en-/de-capsulation function. The AGTF should support these functions according to service policy and/or End Users’ preferences.

Table 8-1 Typical combinations of IP addressing schemes

Case Access network attached port

IP Home network attached port

Functions required for AGTF

1 IPv6 (by NP) IPv6 (by NP) None

2 IPv6 (by NP) IPv6 (by SP or EU) Note 1

3 IPv6 (by NP) IPv4 Global (by SP) Note 1

4 IPv6 (by NP) IPv4 Local (by EU) Note 1

5 IPv4 Global (by NP) IPv4 Global (by NP) None

6 IPv4 Global (by NP) IPv4 Global (by SP) IP address translation

7 IPv4 Global (by NP) IPv4 Local (by EU) IP address translation

8 PPP IPv6 (by SP or EU) PPP en-/de-capsulation

9 PPP IPv4 Global (by SP) PPP en-/de-capsulation

10 PPP IPv4 Local (by EU) PPP en-/de-capsulation

Note 1: IP address translation between Access Network and IP Home Network, or IP en-/de-capsulation, such as IPv6 over IPv6 or IPv4 over IPv6, is provided.

8.4 Security

Security features are categorized into various types, such as establishment of secure communication paths, prevention from attack, and so on. Home Network should be secured from/to the Access Network. The detailed requirements can be referred to ITU-T X.1111[B] and ISO/IEC15045-1 [C].

______________

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8 Key technical issues

To specify home network architecture, some key technical issues should be discussed. These issues are summarized in the following sections.

8.1 QoS control

QoS control is evaluated according to the NGN release. In non-NGN network services, only best effort service is provided in the access network. In NGN Release 1, QoS can be guaranteed between edges of the access networks. In NGN Release 2, it can also be guaranteed between some end terminals. Therefore, QoS control is categorized into 3 types as follows.

Type 1: QoS control within the home network (in case of the best available network service)

Type 2: QoS control between access network and home network (in the case of the network service described by NGN Release 1)

Type 3: QoS control for End-to-End communication (in the case of the network service described by NGN Release 2)

Technical issues in each category are described as follows.

(1) Type 1: QoS control within a home network

In this type, the access network provides only best-effort service which does not provide any guarantee of QoS. Home network controls QoS by internal methods. This control does not impact the access network. Therefore, this type is out of the scope of this recommendation which deals with interface and interworking between a home network and an access network.

(2) Type 2: QoS control between an access network and a home network

Architecture and required functions in this category are illustrated in Figure 0-12.This category requires independent QoS management in the access network and in the home network. However, when several guaranteed QoS services are specified in an access network, such as NGN QoS services which are specified by ITU-T Y.1541 based on IP, QoS mapping between the access network and the home network is required. For example, IP communication with guaranteed QoS in a home network is translated for communication in the access network. Access GW performs this mapping according to defined policies. Moreover, for QoS mapping between the access network and a home network, the Access GW has traffic control functions, including traffic engineering, Admission control for dynamic resource allocation, Priority control.

Proprietary home networks using physical and data link layers which may include traffic control facilities are out of the scope of this recommendation because these mechanisms do not impact the access network, for example IEEE802.11e, IEEE1394, and PLC.

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Accessnetwork

Access GW

IP Home

network

IP Terminal(type B)

Proprietary GW

Proprietary Terminal

Proprietary Home

Network

Guarantee of QoSService (e.g., comply with Y.1541)

Guarantee of QoS services

Traffic engineering, Admission control for dynamic resource allocation, priority control, etc

QoS translator and Mapper IP Terminal (type A)

Proprietary Terminal

Proprietary Home

Network

Out of scope for QoS guarantee

Out of scope for QoS guarantee

(3) Type 3: QoS control for End-to-End communication

Architecture and required functions in this category are illustrated in Figure 0-34. This category is applicable, if some IP terminals require the same QoS in the home network as they require in the access network. In this case, the Access GW is a nodal point, providing admission control for this communication, in addition to some traffic control functions.

Proprietary home networks using physical and data link layers which may include traffic control facilities are out of the scope of this recommendation because these mechanisms do not impact the access network, for example IEEE802.11e, IEEE1394, and PLC.

Figure 0-12 - Architecture and required functions in Type 2 case

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Accessnetwork

Access GW

IP Home

network

IP Terminal(type B)

Proprietary GW

Proprietary Terminal

Proprietary Home

Network

Guarantee of QoS Service (e.g., comply with Y.1541)

Traffic engineering, Admission control for dynamic resource allocation, priority control, etc

IP Terminal (type A)

Proprietary Terminal

Proprietary Home

Network

Out of scope for QoS guarantee

Out of scope for QoS guarantee

8.2 Management Functionality

Management functions for home networking include configuration, local monitoring and maintenance for home network terminals. To provide these functions, for an IP-based terminal, conventional protocols such as ICMP or SNMP can be applied. To enhance usability, “plug and play” specified by UPnP facilitates configuration. Moreover, OSGi architecture (http://www.osgi.org/) is useful for flexible management. This architecture provides detailed configuration, remote management, and software download for version maintenance. This also provides these functions, independent of the device hardware and operating system, using an open interface.

8.3 IP address management

An important function provided by NGN is address management. The IP home network, Access GW, and Proprietary GW are identified by IP addresses. Assignment of IP addresses for end terminals, such as IP terminals and Proprietary terminals consist of network assignment and local assignment. In the case of network assignment, the Access GW would not need to translate the assigned IP address. In the case of local assignment, the Access GW translates the IP address. However, even in the network assignment case, when PPP is required to reach the access network, the Access GW should encapsulate IP packets by PPP.

Therefore, typical combinations of IP addressing schemes are listed in Table 2. This table will need to be updated when new addressing schemes or usages are specified in NGN releases. The Access GW should support combinations in Table 2 according to service policy and user preferences.

Figure 0-34 - Architecture and required functions for the Type 3 case

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Table 2 Examples of IP address combination

Case Access network IP home network

Case 1 IPv6 IPv6

Case 2 IPv6 IPv4 (Local)

Case 3 IPv4 (Global) IPv4 (Local)

Case 4 PPP IPv6

Case 5 PPP IPv4 (Local)

In Case 1, Access GW transfers IP packets from an IP home network to an access network. Otherwise, Access GW may encapsulate IP packets with IPv6 addresses by other IPv6 addresses specified by the access network. In Cases 2, 3, and 5, Access GW assigns IP devices and Proprietary GW using DHCP. In Cases 4 and 5, IP packets from a home network are encapsulated by PPP at Access GW.

8.4 Security aspects

Security features are categorized into various types, such as establishment of secure communication paths, prevention from attack, and so on. Home networks should be secured from/to the access network. However, security features in the transport stratum are for further study.

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Annex A - The relationship between G.hnta and G.hn

Figure 1/Annex A shows the scope of G.hnta, G.hn and some other Alien Home Networks that is are out of scope of G.hnta and G.hn. Note that each technology to be handled, such as Power Line Wiring, is an example. Moreover, the interaction, as shown in the arrow, does not mean the traffic flow but the traffic control function, such as QoS mapping.

The scope of G.hn can be found below:

- As shown in Figure 1/Annex A, the scope of G.hn is the G.hn-specific Physical layers for each of Power Line Wiring, Telephone Wiring and Coaxial Cable. Moreover, G.hn-MAC, and G.hn-LLC, and G.hn-APC on top of each Physical layer are also in the scope of G.hn.

- G.hn utilizes MAC Bridge (802.1D) for interaction between two adjacent G.hn domains, as shown in bigby the large dark arrow. Therefore, each G.hn-APC exposes A-reference point compliant with MAC part of 802.3.

- Each Standard or Non-standard Alien Home Network also interactions with MAC Bridge (802.1D), as shown in small arrow, via A-reference point, but it is out of the scope of G.hn.

- There may be the case that G.hn-APC exposes A-reference point directly to IP without MAC Bridge (802.1D). However, such an A-reference point is not currently defined in current G.hn.

- In summary, G.hn studies layers 1 and 2 technical requirements and specifications, which are derived from the interaction between the devices within one G.hn Home Network domain. Moreover, G.hn studies some specific requirements for MAC Bridge (802.1D) implementation, which are derived from the interaction between the devices of the different G.hn Home Network domains, although inter-domain bridging is out of scope of G.hn.

The scope of G.hnta can be found below.

- As shown in Figure 1/Annex A, the scope of G.hnta is IP as well as MAC Bridge /VLAN layers.

- G.hnta studies layers 2 and 3 high level requirements, which are derived from the interaction between Access Network and Home Network. Concretely speaking,

- The IP layer interaction, as shown in big by the large white arrow, is the main traffic control function to study. QoS mapping is an example, in case thatsuch as when two IP layers uses different QoS specifications. Note that there is no IP layer interaction in case that the IP layer in the Access Network directly reaches the IP Terminal in the Home Network.

- The interactions between IP and MAC Bridge /VLAN layers, as well as between MAC Bridge /VLAN layers, as also shown iby the large n big white arrow, are also the traffic control functions to study in order to guarantee the end-to-end IP layer communication. For example, when IP packets enter the right-hand-side IP layer from the Access Network, QoS mapping will be executed from the IP layer to MAC Bridge /VLAN layer in the middle. As the sameSimilarly, the QoS mapping will be also executed from the IP layer to MAC Bridge /VLAN layer in the most right-hand-side. These are shown as two vertical big large white arrows. On the other hand, in case that the QoS mapping cannot be executed from the IP layer to MAC Bridge /VLAN layer in the most right-hand-side, the QoS mapping

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will be executed between two MAC Bridge /VLAN layers, which is shown as horizontal big large white arrow.

1

Non-standard Alien Home NetworkAccess Network

Layer 1

Layer 2

G.hn

G.hnta

G.9954 Standard Alien Home Network

MAC Bridge (802.1D) / VLAN (802.1Q, 802.1ad, 802.1ah)

Power LineWiring

PHY

LLC

MAC

APC

A-reference point for MAC part of 802.3

IP

Telephone Wiring

LLC

MAC

PHY

APC

Coaxial Cable

LLC

MAC

PHY

APC

IP

MAC Bridge (802.1D) / VLAN (802.1Q, 802.1ad, 802.1ah)

MAC Bridge (802.1D) / VLAN (802.1Q, 802.1ad, 802.1ah)

Power LineWiring

LLC

MAC

PHY

APC

Telephone Wiring

LLC

MAC

PHY

APC

Coaxial Cable

LLC

MAC

PHY

APC

Figure 1/Annex A The scope of G.hnta and G.hn

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Appendix I – Example Applications of the Generic Home Network Architecture Use cases applying this architecture

IPTV traffic is first stored in a Primary Terminal by its interaction with an IMS or an IPTV Head End system and then distributed to a Secondary Terminal. The following cases use this as an example.

Case 1 shown in Figure 1/Appendix I: The figure shows the Flow 1 in Figure 6-9. The AGTF of AGW terminates the public IP address and then translates it into local IP addresses. While the IP Terminal (type a) of Primary Terminal terminates the local IP, its Application Layer Device Functions (ALDF) terminates IPTV traffic. This IPTV traffic can be distributed to ALDF of Secondary Terminal over Non-IP L3 protocol.

Figure 1/Appendix I Generic Home Network Architecture: Case 1

Use Case 2 shown in Figure 2/Appendix I: The figure shows the Flow 2 in Figure 6-9. This Use Case focuses on the interaction between the two IP Terminals, IP Terminal (type b) of Primary Terminal and IP Terminal (type c) of Secondary Terminal. The two IP Terminals may directly interact with each other in the IP Home Network, but it is preferable that this interaction takes place via the AGTF. This is because the AGTF can control the QoS of each IP flow. Specifically, it is assumed that the flow from the Head End system travels downstream to other IP Terminals, which are not shown in this figure. This downstream flow may be affected by the flow from IP Terminal (type b) to IP Terminal (type c), unless this latter flow is controlled. The AGTF may control the QoS in such a case, where QoS control may be either IP level or Ethernet level.

Figure 2/Appendix I Generic Home Network Architecture: Use Case 2

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Use Case 3 shown in Figure 3/Appendix I: The figure shows the Flow 3 in Figure 6-9. As in Use Case1, the AGTF of AGW terminates the public IP address and then translates it into local IP addresses. However, Non-IP GW terminates the local IP address and then directly translates it into Non-IP L3 protocol. Therefore, IPTV traffic is terminated at the Non-IP Terminal of Primary Terminal.

Figure 3/Appendix I Generic Home Network Architecture: Case 3

Case 4 shown in Figure 4/Appendix I: This is different from Case1 in that the IP Terminal (type a) terminates the public IP address rather than the AGTF of AGW. Note that this case represents the Case 1 in Table 8-1, where Network Provider (NP) assigns IP addresses of AGW as well as Primary Terminal.

Figure 4/Appendix I Generic Home Network Architecture: Case 4

Case 5 shown in Figure 5/Appendix I: This is different from Case1from Case1 in that the AGTF of AGW terminates PPP. Therefore, IP packets with local IP addresses in IP Home Network are en-/de-capsulated in this PPP. Note that this case represents the Case 8, 9 and 10 in Table 8-1.

Figure 5/Appendix I Generic Home Network Architecture: Case 5

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