1、 International Telecommunication Union ITU-T Y.2051TELECOMMUNICATION 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 General overview of
2、IPv6-based NGN Recommendation ITU-T Y.2051 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.399 Interfa
3、ces 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 capabilities a
4、nd 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 functional archite
5、cture 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 management Y.2400
6、Y.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.2051 (02/2008) i Recommendation ITU-T Y.2051 General overview of IPv6-based NGN Summary Recomme
7、ndation ITU-T Y.2051 identifies a next generation network (NGN) which mainly operates with Internet Protocol version 6 (IPv6) features. This Recommendation provides the general requirements of IPv6-based NGN and its overall architecture. Source Recommendation ITU-T Y.2051 was approved on 29 February
8、 2008 by ITU-T Study Group 13 (2005-2008) under Recommendation ITU-T A.8 procedure. Keywords IPv6, NGN. ii Rec. ITU-T Y.2051 (02/2008) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication t
9、echnologies (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 on them with a view to standardizing telecommunications on a worldwide basis. The World Te
10、lecommunication 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 of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some
11、 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“ is used for conciseness to indicate both a telecommunication administration and a recognized
12、 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 the Recommendation is achieved when all of these mandatory provisions are met. The words “s
13、hall“ 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 of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the
14、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 Property Rights, whether asserted by ITU members or others outside of the Recommendation de
15、velopment 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, implementers are cautioned that this may not represent the latest information and are the
16、refore 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 written permission of ITU. Rec. ITU-T Y.2051 (02/2008) iii CONTENTS Page 1 Scope 1 2 Refere
17、nces. 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 2 6 Overview of IP-based networks 2 6.1 Classification of IP-based networks . 2 6.2 Key features of IPv6-based networks compared with IPv4-based. 3 7 Overvie
18、w of IPv6-based NGN 5 7.1 Definition of IPv6-based NGN. 5 7.2 Functional architecture of IPv6-based NGN 6 7.3 Impact of using IPv6 to NGN. 7 7.4 Relationships with other IP-based networks 7 8 General requirements of IPv6-based NGN. 8 9 Security considerations. 8 Bibliography. 9 iv Rec. ITU-T Y.2051
19、(02/2008) Introduction Internet Protocol version 6 (IPv6) is emerging to form the basis of the next generation networks (NGNs). It is expected that IPv6-based networks will replace IPv4-based networks in order to overcome the ultimate limitations of Internet Protocol version 4 (IPv4). That is, NGNs
20、will gradually migrate to IPv6-based NGNs. The NGN is a packet-based network to provide telecommunication services with the help of underlying transport-related technologies and various access technologies. IPv6 is a well-defined transport protocol to support the NGN transport functions. It provides
21、 considerable flexibility to NGN. These flexibilities are beneficial for improving network provisioning and operations, as well as the services to be offered to the NGN providers and users. Rec. ITU-T Y.2051 (02/2008) 1 Recommendation ITU-T Y.2051 General overview of IPv6-based NGN 1 Scope This Reco
22、mmendation defines an IPv6-based NGN to support IPv6 addressing, signalling, multi-homing, and migration. Additionally, it identifies the overall architecture and general requirements for IPv6-based NGN. The scope of this Recommendation covers: classification of IP-based networks definition of IPv6-
23、based NGN functional architecture for IPv6-based NGN general requirements for IPv6-based NGN 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 e
24、ditions 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 v
25、alid 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. ITU-T Y.2001 Recommendation ITU-T Y.2001 (2004), General overview of NGN. ITU-T Y.2011 Recommendation ITU-T Y.2011 (2
26、004), General principles and general reference model for Next Generation Networks. ITU-T Y.2012 Recommendation ITU-T Y.2012 (2006), Functional requirements and architecture of the NGN release 1. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following term defined elsewhere:
27、3.1.1 next generation network ITU-T Y.2001: A packet-based network able to provide telecommunication services and to make use of multiple broadband, (QoS)-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies. It enables
28、unfettered access for users to networks and to competing service providers and/or services of their choice. It supports generalized mobility which will allow consistent and ubiquitous provision of services to users. 2 Rec. ITU-T Y.2051 (02/2008) 3.2 Terms defined in this Recommendation This Recommen
29、dation defines the following terms: 3.2.1 IPv6-based NGN: This refers to NGN that supports addressing, routing protocols, and services associated with IPv6. An IPv6-based NGN shall recognize and process the IPv6 headers and options, operating over various underlying transport technologies in the tra
30、nsport stratum. 3.2.2 IPv6-based functions and FEs: These are NGN functions and FEs which recognize and process the IPv6 protocol with its headers and options. They have their own specific roles including IPv6. 3.2.3 IPv6-enabled functions and FEs: These are NGN functions and FEs which recognize the
31、 IPv6 protocol with its headers and options. They have their own specific roles in NGN except IPv6. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: AH Authentication Header ESP Encapsulating Security Payload FE(s) Functional Entity(-ies) ICMPv6 Interne
32、t Control Message Protocol for the Internet Protocol Version 6 IP Internet Protocol IPsec Internet Protocol Security IPv4 Internet Protocol Version 4 IPv6 Internet Protocol Version 6 NAC Network Attachment Control NAPT Network Address and Port Translation NGN Next Generation Network QoS Quality of S
33、ervice RA Router Advertisement RAC Resource and Admission Control RSVP Resource ReserVation Protocol SIP Session Initiation Protocol 5 Conventions None. 6 Overview of IP-based networks 6.1 Classification of IP-based networks IP-based networks are classified into IPv4 and IPv6 according to the IP pro
34、tocol types used. Their behaviours differ according to the features of each protocol version. This criterion to classify IP-based networks is also applied to differentiate instantiations of NGN, since NGN is based mainly on transport technologies employing IP. Rec. ITU-T Y.2051 (02/2008) 3 Taking co
35、nsideration of this, IP-based networks relevant to NGN should be classified according to the following: IPv6-based NGN: This is a NGN which supports addressing, routing, protocols and services associated with IPv6. IPv4-based NGN: This is a NGN which supports addressing, routing protocol and service
36、s associated with IPv4. IPv6-based non-NGN: This is an IPv6-based packet network which does not comply with NGN. IPv4-based non-NGN: This is an IPv4-based packet network which does not comply with NGN. Figure 1 shows the various IP-based networks from a NGN point of view. Figure 1 Classification of
37、IP-based networks 6.2 Key features of IPv6-based networks compared with IPv4-based Clarifying the differences between IPv4 and IPv6 is very useful for identifying the operations of IPv4 and IPv6, which influence network design and service operations. Key features of IPv4 and IPv6 are summarized in T
38、able 1. Table 1 Key features of IPv4 and IPv6 IPv4 IPv6 Size of IPv6 header Variable size Constant size Packet Format Optional headers Optional headers Extension headers and options Addressing spaces Lack of address spaces Large address spaces End-to-end communications No Yes Types of addresses Unic
39、ast, multicast and broadcast Unicast, multicast and anycast Scopes of addresses Local and global Link-local, local and global Address configuration to an interface A address Multiple addresses Address allocation to an equipment Multiple interface/addresses Multiple interfaces/addresses Addressing Ad
40、dress Autoconfiguration Using private addresses Using public addresses 4 Rec. ITU-T Y.2051 (02/2008) Table 1 Key features of IPv4 and IPv6 IPv4 IPv6 Hierarchical addressing Yes Address Renumbering Yes Management of service conflicts Type of Service field Traffic class field Identification of traffic
41、 flows None Flow label field QoS Recognition of control/expedite data None Hop-by-Hop extension header AH header Optional Mandated Security ESP header Optional Mandated Detection of new networks RA messages Generation of new addresses Autoconfiguration Mobility headers Mandated Mobility Option heade
42、r: Destination option, routing, etc. Optional Mandated There are key features of IPv6 which may significantly impact NGN in various ways, such as addressing schemes, QoS, security and mobility. Simplified packet format IPv6 headers are simplified from IPv4 headers. Some IPv4 header fields have been
43、dropped or made optional to limit their bandwidth cost. They also have a constant size to reduce the common processing cost of packet handling. Expanded addressing scheme IPv6 addressing schemes have a large addressing space due to an increased size of the IP address fields to support more levels of
44、 addressing hierarchy, a much greater number of addressable nodes and interfaces, and a simpler autoconfiguration of addresses. The scalability of multicast routing is improved by adding a “scope“ field to multicast addresses. In addition, a new type of address called an “anycast address“ is defined
45、 and is used to send a packet to any of a group of nodes. QoS A flow label and traffic class fields in IPv6 header are added to enable the labeling of packets belonging to particular traffic “flows“ for which the sender requests special handling, such as non-default quality of service or “real-time“
46、 service. In addition, IPv6 hop-by-hop header with router-alert option will indicate the contents of IPv6 packets to support the selective processing of the intermediate nodes. Security support IPv6 supports built-in IPsec services such as authentication, data integrity and data confidentiality usin
47、g authentication header (AH) and encapsulating security payload (ESP) extension headers. These enable end-to-end security services via global IP addresses even though intermediate nodes do not understand the IPsec headers. Rec. ITU-T Y.2051 (02/2008) 5 Mobility support IPv6 capabilities such as neig
48、hbour discovery, address resolution and reachability detection support the mobility services using destination option, routing and mobility extension headers. 7 Overview of IPv6-based NGN 7.1 Definition of IPv6-based NGN IPv6-based NGN is defined as a NGN which supports addressing, routing, protocol
49、s and services associated with IPv6. This applies not only to transport aspects in access and core networks but also includes other functions such as end user, transport control and application/service support functions in ITU-T Y.2011 and ITU-T Y.2012. Taking into consideration these definitions and features, IPv6-based NGN could be identified as illustrated in Figure 2. Figure 2 Overview of IPv6-based NGN As shown in Figure 2, there are three relationships among the NGN functions and FEs in order to descr
