1、 International Telecommunication Union ITU-T Y.2612TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2009) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Next Generation Networks Future networks Generic requirements and framework of addressing,
2、routing and forwarding in future, packet-based networks Recommendation ITU-T Y.2612 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.20
3、0Y.299 Network aspects Y.300Y.399 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 Arc
4、hitecture, access, network capabilities 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 IPTV over NGN Y.1
5、900Y.1999 NEXT GENERATION NETWORKS Frameworks and functional 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 Num
6、bering, naming and addressing Y.2300Y.2399 Network management Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Future networks Y.2600Y.2699 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 Carrier grade open environment Y.2900Y.2999 For further details, please refer to th
7、e list of ITU-T Recommendations. Rec. ITU-T Y.2612 (01/2009) i Recommendation ITU-T Y.2612 Generic requirements and framework of addressing, routing and forwarding in future, packet-based networks Summary Recommendation ITU-T Y.2612 describes the generic technical architecture, attributes and mechan
8、isms of future, packet-based networks (FPBN) addressing, mapping, translation, routing, and forwarding based on Recommendations ITU-T Y.2601 and Y.2611. This Recommendation can be provided as a reference to the future design and implementation of the FPBN network. Source Recommendation ITU-T Y.2612
9、was approved on 23 January 2009 by ITU-T Study Group 13 (2009-2012) under Recommendation ITU-T A.8 procedure. ii Rec. ITU-T Y.2612 (01/2009) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communica
10、tion 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 on them with a view to standardizing telecommunications on a worldwide basis. The Wo
11、rld 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 of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. I
12、n 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“ is used for conciseness to indicate both a telecommunication administration and a reco
13、gnized 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 wo
14、rds “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 of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility tha
15、t 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 Property Rights, whether asserted by ITU members or others outside of the Recommendat
16、ion 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, implementers are cautioned that this may not represent the latest information and a
17、re therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2009 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.2612 (01/2009) iii CONTENTS Page 1 Scope 1 2
18、 References. 1 3 Terms and definitions . 2 4 Abbreviations and acronyms 2 5 Conventions 3 6 Introduction 3 7 Addressing 3 7.1 Address attributes . 3 7.2 Structure of addresses. 4 7.3 Addressing objects 4 7.4 Allocation methods. 4 8 Mapping and translation . 5 8.1 Mapping 5 8.2 Translation 5 9 Routin
19、g . 6 9.1 Distributing/collecting topology information. 6 9.2 Calculating the routes. 6 9.3 Establishing/maintaining the routing table. 7 9.4 Establishment and maintenance of the FIB 7 10 Forwarding 7 10.1 Input procedure. 8 10.2 Enquiring the FIB. 8 10.3 Switching 8 10.4 Output procedure 8 Bibliogr
20、aphy. 9 Rec. ITU-T Y.2612 (01/2009) 1 Recommendation ITU-T Y.2612 Generic requirements and framework of addressing, routing and forwarding in future, packet-based networks 1 Scope This Recommendation describes the generic technical architecture, attributes and mechanisms of addressing, mapping, tran
21、slation, routing, and forwarding within a future, packet-based network (FPBN), including: Transport stratum addresses Allocation methods for addresses Mapping between service stratum names and transport stratum addresses Translation between different transport stratum technologies and administrative
22、 domains Mechanisms of routing and forwarding within the transport stratum. This Recommendation is restricted to describing some common technical requirements and framework of these above aspects. The specific technologies which can be used to implement these aspects are outside of the scope of this
23、 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 s
24、ubject 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 docume
25、nt within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.805 Recommendation ITU-T G.805 (2000), Generic functional architecture of transport networks. ITU-T Y.2601 Recommendation ITU-T Y.2601 (2006), Fundamental characteristics and requiremen
26、ts of future packet based networks. ITU-T Y.2611 Recommendation ITU-T Y.2611 (2006), High-level architecture of future packet-based networks. IETF RFC 2328 IETF RFC 2328 (1998), OSPF version 2. IETF RFC 2453 IETF RFC 2453 (1998), RTP version 2. IETF RFC 4271 IETF RFC 4271 (2006), A Border Gateway Pr
27、otocol 4 (BgP-4). IETF RFC 4291 IETF RFC 4291 (2006), IP version 6 Addressing Architecture. 2 Rec. ITU-T Y.2612 (01/2009) 3 Terms and definitions This Recommendation uses the following terms defined elsewhere: 3.1 address: See ITU-T Y.2601. 3.2 control plane: See ITU-T Y.2011. 3.3 data plane: See IT
28、U-T Y.2011. 3.4 identifier: See ITU-T Y.2601. 3.5 management plane: See ITU-T Y.2011. 3.6 name: See ITU-T Y.2611. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ACL Access Control List AP Access Point BGP Border Gateway Protocol CP Connection Point DC
29、E Data Circuit-terminating Equipment DNS Domain Name System DTE Data Terminal Equipment FIB Forwarding Information Base FIFO First In First Out FP Flow Point FPBN Future Packet-Based Network GFP Generic framing Procedure ICMP Internet Control Message Protocol ID Identifier IP Internet Protocol MAC M
30、edia Access Control NAT Network Address Translation NGN Next Generation Network OAM Operation, Administration as a result, the addressing of these layer networks is recommended to be independent from one another within the transport stratum. To satisfy the requirements of the FPBN defined in ITU-T Y
31、.2601, addresses in FPBN are required to have several desirable properties in their addressing domain. Some important attributes are listed as follows: Uniqueness: An address is required to be used reliably and deterministically for a single unique entity in one administrative domain. But an entity
32、can have more than one address. 4 Rec. ITU-T Y.2612 (01/2009) Persistence: If the location of an entity does not change, the address of the entity is required not to be changed frequently. Structured: The address is required to be structured, with the purpose of aggregation. It can facilitate the ro
33、uting and forwarding processes. 7.2 Structure of addresses There are two kinds of structured addresses in a packet based network: flat and hierarchical. Flat addressing: Address allocation is random from the aspects of routing and forwarding. Routing and forwarding mechanisms work on the whole bits
34、of target address in a packet header, rather than part of them in the address fields. Typical flat addressing is Ethernet MAC address. Hierarchical addressing: For the purpose of efficient routing and forwarding, address management follows a top down allocation process whereby intermediate levels ca
35、n sub-allocate to lower levels, portions of the address that was assigned to them by a higher level. Routing and forwarding will only work on parts of bit of the whole address, rather than the whole address. Typical hierarchical addressing is IP address. In the FPBN network, it is recommended to cho
36、ose hierarchical addressing, and the hierarchical address can be divided into several parts, each part of the address carries its own information. For example, one part of address specifies the network ID, another part specifies the host ID. Hierarchical address is required to support unicast and mu
37、lticast, and recommended to support anycast. 7.3 Addressing objects In FPBN, addressing objects can be a specific entity or a group of entities or one of a group of entities in layer networks of transport stratum, which are either DTE or DCE, such as network terminal(s), AP (access point), TCP (term
38、ination connection point), CP (connection point), FP (flow point), TFP (termination flow point) defined in ITU-T G.805. All of the addressing objects are required to be addressed to support unicast, multicast, and/or anycast communication. As recommended in ITU-T Y.2611, there are three planes (data
39、 plane, management plane and control plane) in the FPBN network and each plane is recommended to have its own address space. Each address space can be independent of the other address spaces, even if they use the same syntax or structure. When involved in more than one plane, each addressing object
40、is recommended to have an independent address for each plane correspondingly. Control plane address identifies the location of the addressing object in FPBN control plane which exchanges control information (for example, topological information, QoS policy) between network entities. Data plane addre
41、ss identifies the location of addressing object in FPBN data plane which transfers user packets among network terminals. Management plane address identifies the location of the managed addressing object in the FPBN network which exchanges OAM information, and can be used to locate and access the add
42、ressing object by operators or other transport entities in the management plane. 7.4 Allocation methods In FPBN, the allocation method is required to support one of the following options: provider-preference and geography-preference. Provider-preference and geography-preference are not mutually excl
43、usive. In certain circumstances, the address space can be first allocated by an address Rec. ITU-T Y.2612 (01/2009) 5 allocation authority to the network provider, and then it can be further allocated according to the regional locations in the network provider. Provider-preference implies that addre
44、ss space can be allocated by an address allocation authority to the network providers, not to a country or a region. Each network provider can apply and be assigned a part of address space which can be distinguished by different address prefix. Network providers can independently decide how to alloc
45、ate addresses in their own network. The current IP address allocation method is a typical example of provider-preference. Geography-preference implies that network addresses can be allocated according to the national or regional locations. Each nation or region has its own address space with a diffe
46、rent address prefix, and can independently allocate addresses by its own rule. 8 Mapping and translation There will be several independent addressing mechanisms existing in the different layers. For example, IP address and MAC address belong to different layers in the transport stratum. Even in the
47、same layer network of the transport stratum, it is also possible that different addressing mechanisms are used in the different administrative domains. For example, private IPv4 addresses can be used in enterprise network, while IPv6 or public IPv4 addresses can be used in the access and/or core net
48、work. The mapping mechanisms are required between different layers within an FPBN, and the translation mechanisms are required at the boundary of the different administrative domains in the FPBN network. The mapping and translation mechanisms are required within the data plane, control plane and man
49、agement plane in the FPBN network. 8.1 Mapping Mapping is to make a logical connection between two entities which belong to the different layers, for example, the logical connection from domain name to IP address or reversely, or the logical connection from IP address to MAC address or reversely. The mapping results can optionally be stored in a mapping table, a central database, or a distributed database. In order to enhance the efficiency, the mapping results are recommended to be cached in memory. It is r
