1、 International Telecommunication Union ITU-T Y.2052TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2008) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Next Generation Networks Frameworks and functional architecture models Framework of multi-h
2、oming in IPv6-based NGN Recommendation ITU-T Y.2052 ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Services, applications and middleware Y.200Y.299 Network aspects Y.300Y.39
3、9 Interfaces and protocols Y.400Y.499 Numbering, addressing and naming Y.500Y.599 Operation, administration and maintenance Y.600Y.699 Security Y.700Y.799 Performances Y.800Y.899 INTERNET PROTOCOL ASPECTS General Y.1000Y.1099 Services and applications Y.1100Y.1199 Architecture, access, network capab
4、ilities and resource management Y.1200Y.1299 Transport Y.1300Y.1399 Interworking Y.1400Y.1499 Quality of service and network performance Y.1500Y.1599 Signalling Y.1600Y.1699 Operation, administration and maintenance Y.1700Y.1799 Charging Y.1800Y.1899 NEXT GENERATION NETWORKS Frameworks and functiona
5、l architecture models Y.2000Y.2099 Quality of Service and performance Y.2100Y.2199 Service aspects: Service capabilities and service architecture Y.2200Y.2249 Service aspects: Interoperability of services and networks in NGN Y.2250Y.2299 Numbering, naming and addressing Y.2300Y.2399 Network manageme
6、nt Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T Y.2052 (02/2008) i Recommendation ITU-T Y.2052 Framework of multi-homing in IPv6-based N
7、GN Summary Recommendation ITU-T Y.2052 describes a framework of multi-homing in Internet Protocol version 6 (IPv6)-based next generation network (NGN). This Recommendation identifies the requirements, the usage models, the functional architecture, and the applications of multi-homing in IPv6-based N
8、GN. Source Recommendation ITU-T Y.2052 was approved on 29 February 2008 by ITU-T Study Group 13 (2005-2008) under Recommendation ITU-T A.8 procedure. Keywords IPv6, IPv6-based NGN, multi-homing. ii Rec. ITU-T Y.2052 (02/2008) FOREWORD The International Telecommunication Union (ITU) is the United Nat
9、ions specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations
10、 on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval o
11、f ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ i
12、s used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with
13、the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required
14、of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual
15、Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However
16、, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2008 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior
17、 written permission of ITU. Rec. ITU-T Y.2052 (02/2008) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation. 2 4 Abbreviations and acronyms 2 5 Conventions 3 6 Features of multi-homing in IPv6-based NGN. 3 7 Requirements
18、of multi-homing in IPv6-based NGN 5 7.1 General requirements of multi-homing in IPv6-based NGN . 5 7.2 Requirements of site multi-homing 5 7.3 Requirements of host multi-homing. 6 8 Multi-homing models in IPv6-based NGN. 9 8.1 Usage model of multi-homing in a network layer 10 8.2 Usage model of mult
19、i-homing in a transport layer. 11 9 Functional architecture to support multi-homing in IPv6-based NGN 12 9.1 Overall architecture to support multi-homing 12 9.2 Functional architecture to support multi-homing. 13 10 Applications of multi-homing in IPv6-based NGN 15 10.1 Always-on connectivity 15 10.
20、2 Load sharing . 17 10.3 Traffic engineering . 17 10.4 Fault tolerance with redundancy 18 10.5 Session continuity across access networks. 19 11 Security considerations. 20 Appendix I Session continuity using multi-homing . 21 Bibliography 23 Rec. ITU-T Y.2052 (02/2008) 1 Recommendation ITU-T Y.2052
21、Framework of multi-homing in IPv6-based NGN 1 Scope One of the primary features of Internet Protocol version 6 (IPv6) is multi-homing. Using IPv6 multi-homing features, a network (or site) and/or a user terminal (or host) is able to have multiple network connections with multiple network interfaces
22、and multiple IPv6 addresses. In IPv6-based next generation network (NGN), NGN users will have, using multi-homing features, always-on connectivity, improved fault tolerance, performance improvement by load balancing, and session continuity, etc. This Recommendation describes a framework of multi-hom
23、ing in IPv6-based NGN. For this purpose, this Recommendation identifies the requirements, the usage models, the functional architecture, and some applications of multi-homing so as to facilitate the deployment of the enhanced services in IPv6-based NGN. The scope of this Recommendation includes: req
24、uirements of multi-homing in IPv6-based NGN; usage models of multi-homing in IPv6-based NGN; functional architecture to support multi-homing in IPv6-based NGN; applications of multi-homing in IPv6-based NGN. 2 References The following ITU-T Recommendations and other references contain provisions whi
25、ch, 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 a
26、pplying 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. IT
27、U-T Y.2012 Recommendation ITU-T Y.2012 (2006), Functional requirements and architecture of the NGN release 1. ITU-T Y.2051 Recommendation ITU-T Y.2051 (2008), General overview of IPv6-based NGN. ITU-T Y.2201 Recommendation ITU-T Y.2201 (2007), NGN release 1 requirements. ITU-T Y.2701 Recommendation
28、ITU-T Y.2701 (2007), Security requirements for NGN release 1. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 fault tolerance ITU-T E.800: An attribute of an item that makes it able to perform a required function in the presence of cert
29、ain given sub-item faults. 3.1.2 IPv6-based NGN ITU-T Y.2051: This refers to NGN that supports addressing, routing protocols and services associated with IPv6. An IPv6-based NGN shall recognize and process the 2 Rec. ITU-T Y.2052 (02/2008) IPv6 headers and options, operating over various underlying
30、transport technologies in the transport stratum. 3.1.3 session continuity b-ITU-T Q.1702: The ability of the user to maintain continuity of ongoing sessions while changing between terminal devices and across various access and core networks. 3.2 Terms defined in this Recommendation This Recommendati
31、on defines the following terms: 3.2.1 always-on connectivity: A capability that a NGN user or user equipment can connect to the networks at any time and at any place. 3.2.2 host multi-homing: A multi-homing feature that a host has multiple connections to networks. 3.2.3 IPv6 multi-homing: A feature
32、of an IPv6 host and/or IPv6 network that enables the host or network to be multi-homed to networks through multiple network interfaces and multiple IPv6 addresses. 3.2.4 IPv6 network provider: An entity that provides IPv6 network connection by advertising IPv6 prefix information (e.g., ISP). 3.2.5 l
33、oad balancing: A scheme by which the traffic load could be separated and balanced to effectively utilize the network resources (e.g., link bandwidth). 3.2.6 network interface: A device to be used by a node to connect to a network. 3.2.7 site: An entity autonomously operating a network using IP. 3.2.
34、8 site multi-homing: A multi-homing feature that a site (network) has multiple connections to other networks. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: BGP Border Gateway Protocol DCCP Datagram Congestion Control Protocol DHCPv6 Dynamic Host Conf
35、iguration Protocol for IPv6 FE Functional Entity IPv4 Internet Protocol version 4 IPv6 Internet Protocol version 6 ISP Internet Service Provider NACF Network Attachment Control Function NGN Next Generation Network RACF Resource and Admission Control Function SCTP Stream Control Transmission Protocol
36、 TCP Transmission Control Protocol UDP User Datagram Protocol Rec. ITU-T Y.2052 (02/2008) 3 5 Conventions None. 6 Features of multi-homing in IPv6-based NGN The primary purpose of multi-homing is to provide multiple network connections to increase the reliability of network connections. Besides incr
37、easing reliability, the multi-homing feature enables the site and/or host to effectively utilize network connections to provide load balancing, session continuity, etc. In Internet Protocol version 4 (IPv4)-based networks, multi-homing is mainly deployed by using border gateway protocol (BGP) mechan
38、ism between network domains b-IETF RFC 2260. In IPv6-based NGN, multi-homing should be given more importance due to the following observations: A node has multiple IPv6 addresses for different scope and renumbering. A node has multiple network interfaces (physical interfaces by heterogeneous access
39、networks and tunnelling interfaces). A node has multiple network prefixes for routing scaling. IPv6 can provide a user terminal with multiple IPv6 addresses, which are allocated hierarchically by network providers. Although the purpose of multi-homing in IPv6-based NGN is the same as IPv4-based netw
40、ork, the requirements/considerations and mechanisms are different. In IPv6-based NGN, it disallows IPv4-style multi-homing b-IETF RFC 2772. IPv6 network providers (e.g., Internet service provider (ISP) cannot advertise prefixes of other network providers. Sites cannot advertise to upstream providers
41、 prefixes longer than their assigned prefix. Because of these restrictions and the requirement of session continuity during the change of network connection by multi-homing, different mechanisms are needed for IPv6 multi-homing. The Internet Engineering Task Force (IETF) has carried out many studies
42、 for developing solutions, see b-IETF RFC 3582, b-IETF RFC 4116, b-IETF RFC 4177, b-IETF RFC 4218, b-IETF RFC 4219. In IPv6-based NGN, a NGN transport stratum comprises a wide variety of IPv6-based access networks and IPv6-based core network. IPv6-based access networks may be heterogeneous using dif
43、ferent access technologies ITU-T Y.2012. Figure 1 shows an example of an IPv6-based NGN network architecture that consists of an IPv6-based core network and heterogeneous access networks which support IPv6-based IP connectivity. Those access networks use different access technologies and are interco
44、nnected with each other through IPv6-based core network. 4 Rec. ITU-T Y.2052 (02/2008) Y.2052(08)_F01IPv6-based core networkIPv6-basedcellular radioaccess networkIPv6-basedfixed accessnetworksIPv6-basedInternetLegacy networksIPv6-basedmobilenetworksOther NGNnetworksIPv6-basedWLAN accessnetworksUser
45、terminal (host)Figure 1 Overall configuration model of IPv6-based NGN In this configuration, a user terminal could use multiple IPv6 addresses and multiple network interfaces and be multiply connected to IPv6-based NGN. Also, each access network could use multiple network connections through multipl
46、e network prefixes. In this way, multi-homing features in IPv6-based NGN could be used to provide more enhanced services and connectivity for the users. Figure 2 Example of multi-homing in IPv6-based NGN Rec. ITU-T Y.2052 (02/2008) 5 In Figure 2, a user terminal is connected to three different acces
47、s networks using different access technologies. Each access network is also connected to different IPv6-based networks. In this case, the user terminal could simultaneously use multiple network connections to communicate with the other network nodes. The user terminal could use two network connectio
48、ns through access network 1 with two different IPv6 addresses, and it could use each network connection through access network 2 and access network 3. Also, access network could be multiply connected to other networks. Access network 1 could use two network connections (using different IPv6 prefixes
49、 through IPv6-based network 1). Also, access network 2 could use two network connections (one is through IPv6-based network 2 and the other through IPv6-based network 3). 7 Requirements of multi-homing in IPv6-based NGN 7.1 General requirements of multi-homing in IPv6-based NGN To provide more enhanced services and applications for the users, IPv6-based NGN shall be considered to support multi-homing. In this respect, the following are defined as general requirements to support multi-homing in IPv6-based N
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