1、 International Telecommunication Union ITU-T Y.2611TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2006) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Next Generation Networks High-level architecture of future packet-based networks ITU-T Reco
2、mmendation Y.2611 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 Interfaces and protocols Y.400Y.
3、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 and resource management Y.
4、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 architecture models Y.2000Y.2099
5、 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.2400Y.2499 Network control ar
6、chitectures 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. ITU-T Rec. Y.2611 (12/2006) i ITU-T Recommendation Y.2611 High-level architecture of future packet-based networks Summary ITU-T Recom
7、mendation Y.2611 specifies a high-level architecture for future packet-based networks (FPBNs). This Recommendation also specifies the relationship between an FPBN and the NGN strata and the interfaces in an FPBN. In order to be able to provide a full suite of services (examples of which include data
8、, video and voice telephony services) to their customers, operators may need to utilize both connectionless packet switched (cl-ps) and connection-oriented packet-switched (co-ps) transport modes. This is because each mode is well suited to the transport of some services and not so well suited to th
9、e transport of others. FPBNs provide the topmost layer(s) of the transport stratum as defined in ITU-T Recommendation Y.2011. The services mentioned above form part of the service stratum as defined in ITU-T Recommendation Y.2011. Source ITU-T Recommendation Y.2611 was approved on 14 December 2006 b
10、y ITU-T Study Group 13 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. Y.2611 (12/2006) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-
11、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 Telecommunication Standardization Assembly (WTSA), which meets every four ye
12、ars, 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 areas of information technology which fall within ITU-Ts purview, the nec
13、essary 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 operating agency. Compliance with this Recommendation is voluntary. Howev
14、er, 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 “shall“ or some other obligatory language such as “must“ and the negative eq
15、uivalents 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 practice or implementation of this Recommendation may involve the use of a
16、 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 development process. As of the date of approval of this Recommendation, ITU
17、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 therefore strongly urged to consult the TSB patent database at http:/www.itu.
18、int/ITU-T/ipr/. ITU 2007 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. Y.2611 (12/2006) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined i
19、n this Recommendation. 2 4 Abbreviations and acronyms 2 5 Conventions 3 6 High-level architecture of future packet-based networks. 3 6.1 FPBN architecture 3 6.2 User plane. 7 6.3 Control plane 7 6.4 Management plane 8 6.5 OAM, performance management and availability . 8 6.6 Relationship between laye
20、r networks and the OSI BRM. 12 6.7 Relationship with other strata. 13 6.8 Relationship between an FPBN and existing networks 13 6.9 Interfaces in an FPBN 13 6.10 Reference points in an FPBN . 14 6.11 Naming and addressing in an FPBN 15 6.12 Security considerations. 15 Appendix I Relationship between
21、 layer networks and the OSI BRM 17 I.1 The OSI BRM (X.200) model 17 I.2 The G.805/G.809 model. 17 I.3 Comparing the two models. 18 Bibliography. 21 ITU-T Rec. Y.2611 (12/2006) 1 ITU-T Recommendation Y.2611 High-level architecture of future packet-based networks 1 Scope This architecture for an FPBN
22、addresses both connectionless packet switched (cl-ps) and connection-oriented packet switched (co-ps) layer networks. Connection-oriented circuit switched (co-cs) layer networks used to provide the lower layer(s) of the transport stratum are outside of the scope of this Recommendation. The definitio
23、n and specification of specific services is left to other NGN Recommendations and is outside of the scope of an FPBN and this Recommendation. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this
24、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 r
25、eferences 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. ITU-T G.805 ITU-T Recommendation G.805 (2000), Generic functional ar
26、chitecture of transport networks. ITU-T G.809 ITU-T Recommendation G.809 (2003), Functional architecture of connectionless layer networks. ITU-T X.200 ITU-T Recommendation X.200 (1994), Information technology Open Systems Interconnection Basic Reference Model: The basic model. ITU-T X.800 ITU-T Reco
27、mmendation X.800 (1991), Security architecture for Open Systems Interconnection for CCITT applications. ITU-T Y.1710 ITU-T Recommendation Y.1710 (2002), Requirements for Operation b) provide mechanisms to protect the control plane communications from security threats (clause 7.8). An identical requi
28、rement also exists for protecting the FPBN management plane from security threats. The user, control, and management planes (of each layer network) should be segregated 4 ITU-T Rec. Y.2611 (12/2006) from each other in order to keep the performance, security and reliability of each plane (and that of
29、 the other planes) from being violated. Techniques for doing so include (but are not limited to) isolation between planes or special treatment of traffic belonging to the different planes. How a particular NGN network maintains the integrity of its planes is up to it, so long as the requirements det
30、ailed in ITU-T Y.2601 are met. It is a requirement identified in clause 6 of ITU-T Y.2601 that an FPBN: should support off-path control and management planes and therefore isolation is the preferred default mechanism that can meet the requirements for protecting the user, control and management plan
31、es (of each layer network) from each other. The user, control and management planes can be isolated from each other by the allocation of independent connection-oriented packet switched (co-ps) or connection-oriented circuit switched (co-cs) server layer network trails. The type of isolating technolo
32、gy is determined by several factors, such as location (e.g., access or core), network status, etc. It is up to the operator to decide to what degree they wish to operate their control and management planes off-path. Another motivation for isolating the control and management planes from the user pla
33、ne is to ensure that the FPBN control and management planes continue to operate even if the FPBN user plane is overloaded or faulty. An FPBN should seek to harmonize functional components (e.g., control and management plane design and operation) across the networking modes as far as practically poss
34、ible. Figures 6-1 and 6-2 show functional diagrams that depict the user plane of the FPBN architecture. The connectionless packet switched (cl-ps) network is drawn using G.809 conventions and the co-ps network is drawn using G.805 conventions. The transport stratum may be implemented by multiple dis
35、crete layer networks that form client/server relationships. A different networking mode (cl-ps, co-ps and co-cs) may be used for each of the layer networks (this is not shown in Figures 6-1 and 6-2). The number of layer networks and networking modes used is a choice for the particular operator deplo
36、ying the transport stratum and is beyond the scope of this Recommendation. In Figures 6-1 and 6-2, the cl-ps and co-ps layer networks are shown separately. This separation may be physical or logical. The cl-ps layer network may use co-cs server layer network trails that are separate from the server
37、co-cs layer network trails used by the co-ps layer network. Alternatively, the separation may be logical; i.e., the cl-ps and co-ps layer networks share the same server layer network trails. There may be some strict logical partitioning between them so that bandwidth sharing is impossible. Similarly
38、, the cl-ps layer network may use physically separate networking equipment (e.g., routers) to the co-ps layer network or both layer networks may use the same physical networking equipment but that equipment will be logically partitioned between the cl-ps and co-ps layer networks. ITU-T Rec. Y.2611 (
39、12/2006) 5 Figure 6-1 Functional diagram depicting the user plane of the FPBN architecture (cl-ps transport over co-ps layer network trails) Figure 6-2 Functional diagram depicting the user plane of the FPBN architecture (cl-ps transport over server layer network trails) In Figures 6-1 and 6-2, the
40、server layer network trail may be provided by any technology, switched or un-switched. Further client/server relationships may exist below the server layer network trail; however, it should be noted that client layers inherit the impairments of their server layer networks and that this inheritance i
41、s recursive down to the duct. In co-cs layer networks, each client is explicitly allocated a dedicated amount of bandwidth from the server layer network trail. The clients are fully isolated and therefore one clients loading cannot impact the performance of another client. This makes it simple to gu
42、arantee dedicated bandwidth for a client. 6 ITU-T Rec. Y.2611 (12/2006) In co-ps layer networks, each client is allocated bandwidth from a server layer network trail. However, as the clients are only logically isolated, one clients loading may directly impact the capacity available to another client
43、. The appropriate allocation of bandwidth and the use of ingress admission control and policing make it possible to guarantee dedicated bandwidth for a client. In cl-ps layer networks, flows are not normally explicitly allocated to server layer network trails. Therefore, the capacity available to on
44、e client flow may be impacted by the loading of other client flows. This may be mitigated by engineering the appropriate capacity in the server layer network (i.e., over-provisioning) or by establishing resource reservation state per-hop and pinning routes. This makes it possible to guarantee dedica
45、ted bandwidth for a client. This procedure is implicit in a co-ps layer network. However, these techniques are not generally used for the majority of traffic in cl-ps layer networks. NOTE Due to the different characteristics of each networking mode it is generally advisable to stack modes that less
46、efficiently provide dedicated bandwidth on top of modes that more efficiently provide dedicated bandwidth. Looking at the top of Figure 6-1 and working down the model shows cl-ps transport over cl-ps layer network connectionless trails, which are transported over co-ps layer network trails which are
47、 in turn transported over server layer network trails. co-ps transport is provided over co-ps layer network trails, which are in turn transported over server layer network trails. Looking at the bottom of Figure 6-1 and working up the model shows a server layer network trail providing transport for
48、a co-ps layer network. The co-ps layer network in turn provides transport for co-ps services as well as providing transport for the cl-ps layer network. Then the model shows that the cl-ps layer network provides transport for cl-ps services. Looking at the top of Figure 6-2 and working down the mode
49、l shows cl-ps transport over cl-ps layer network connectionless trails, which are in turn transported over server layer network trails. co-ps transport is provided over co-ps layer network trails, which are in turn transported over server layer network trails. Looking at the bottom of Figure 6-2 and working up the model shows a server layer network trail providing transport for a co-ps layer network and a cl-ps layer network. The cl-ps layer network provides cl-ps transport and the co-ps layer network provides co-ps transport. An oper
