1、 International Telecommunication Union ITU-T Y.2122TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2009) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Next Generation Networks Quality of Service and performance Flow aggregate information exch
2、ange functions in NGN Recommendation ITU-T Y.2122 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
3、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 capabil
4、ities 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.1900Y.1999 NEXT GENERATION NETWORKS
5、 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 Numbering, naming and addressing Y.23
6、00Y.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 the list of ITU-T Recommendations. R
7、ec. ITU-T Y.2122 (06/2009) i Recommendation ITU-T Y.2122 Flow aggregate information exchange functions in NGN Summary Recommendation ITU-T Y.2122 specifies the requirements and architecture for flow aggregate information exchange functions (FIXF). FIXF allows network domains to exchange flow aggrega
8、te information that reflects the current network conditions. In order to guarantee end-to-end QoS in NGN, cooperation among networks in an end-to-end path is necessary. Exchange of network configuration information is a key component of cooperation among participating networks. Flow aggregation has
9、been considered a scalable technique for traffic management. Additional information obtained through FIXF can improve the accuracy of performance estimation and effectiveness of resource management. Source Recommendation ITU-T Y.2122 was approved on 29 June 2009 by ITU-T Study Group 13 (2009-2012) u
10、nder Recommendation ITU-T A.8 procedures. ii Rec. ITU-T Y.2122 (06/2009) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization
11、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 Telecommunication Standardization Assembly (WTSA), which meets e
12、very 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 areas of information technology which fall within ITU-Ts purv
13、iew, 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 operating agency. Compliance with this Recommendation is volu
14、ntary. 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 “shall“ or some other obligatory language such as “must“ and th
15、e 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 practice or implementation of this Recommendation may involve
16、 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 development process. As of the date of approval of this Recomme
17、ndation, 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 therefore strongly urged to consult the TSB patent database at h
18、ttp:/www.itu.int/ITU-T/ipr/. ITU 2010 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.2122 (06/2009) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 4 Abbreviations and acronyms 2 5 Con
19、ventions 3 6 High level requirements for FA information exchange functions 3 7 Information exchange architecture . 3 7.1 Overall architecture 3 7.2 Modes of operation. 4 7.3 Operation of FA information exchange functions 6 7.4 Functional entities 7 7.5 Reference points . 9 8 Information to be exchan
20、ged 9 8.1 Parameters not specific to a FA 9 8.2 FA parameters 10 8.3 Parameters exchanged at the reference points 12 9 Security considerations. 12 Appendix I Typical network topology for FA parameter exchange . 14 Appendix II A usage example Admission decision process 15 II.1 DiffServ expedited forw
21、arding. 16 II.2 IntServ guaranteed rate service 16 II.3 Networks with various granularity flow aggregation (MPLS, FSA in b-ITU-T Y.2121, etc.) 17 II.4 Calculation of the burst-in or equivalently the burst-out 17 Appendix III A usage example Flow granularity and continuity decision process . 19 III.1
22、 FA granularity and continuity decision process . 19 Appendix IV FIM-FE usage scenarios 20 IV.1 FA table entry writing 20 IV.2 Information management mechanism for multiple ARs in a single network. 20 IV.3 Information management mechanism for a single AR over multiple networks . 20 Appendix V FIE-FE
23、 usage scenarios 21 V.1 Cases of information exchange for multiple-ARs in a network. 21 V.2 Cases of information exchange for a single AR in multiple networks. 21 Appendix VI Example allocation of FA parameter values. 22 VI.1 Mapping rule from flow ID to FA ID. 22 VI.2 Bandwidth allocation enforceme
24、nt method or scheduling method 22 iv Rec. ITU-T Y.2122 (06/2009) Page VI.3 Representative (R) 22 VI.4 FA identifier . 22 VI.5 Number of flows within the FA 23 VI.6 Maximum packet length divided by link capacity . 23 VI.7 Number of hops within the aggregation region or the policy region . 23 VI.8 Max
25、imum number of aggregation regions . 23 VI.9 Maximum sum of sustainable transfer rates (Rs) divided by link capacity . 23 VI.10 Maximum sum of sustainable burst sizes (Bs) divided by link capacity . 23 VI.11 Minimum guaranteed service rate divided by sum of Rs (if rate-based) or scheduling priority
26、24 VI.12 Packet discard priority 24 VI.13 Class (service context) 24 VI.14 Summary. 24 Appendix VII Network specific parameter values 25 VII.1 DiffServ network specific parameters 25 VII.2 DiffServ with traffic engineering (TE) network specific parameters. 25 VII.3 Flow state aware (FSA) network spe
27、cific parameters 26 Bibliography. 28 Rec. ITU-T Y.2122 (06/2009) v Introduction This Recommendation specifies the requirements and architecture for flow aggregate information exchange functions (FIXF). It addresses the flow or flow aggregate (FA) performance prediction by way of exchanging the netwo
28、rk operating parameters or unique parameters of flow aggregates. There are a few critical parameters (e.g., number of hops, link capacity, etc.) for the performance of a flow for a given QoS architecture, which are sometimes tuned dynamically (from time-to-time, from flow-to-flow) within a network.
29、By having the other networks parameters for the flow (or for the flow aggregate to which the flow belongs), one can infer the performance of the flow in these networks and in its own network. The estimation can be complemented by measurement, i.e., the estimation rules can be further adjusted by the
30、 measured performances. Consider the following example: A delay bound for an expedited forwarding (EF) flow in a differentiated services (DiffServ) network can be calculated by using parameters given from neighbouring networks. The initial delay estimation rule can be just to adopt the delay bound o
31、btained from the calculation. The bound, however, can be too conservative, compared to the measured delay, especially when the maximum burst sizes of flows in the same class are large. Then one can adjust the estimation rule to reduce the expected delay value under condition that the maximum burst s
32、izes are large. One obvious benefit of this approach is that upon a flow admission request, network operators can immediately decide whether the requested end-to-end performances can be met, based on the estimation rules that have been adjusted and stabilized. The frequency of the exchange, estimati
33、on, comparison, and adjustment can vary according to implementation. The frequency of exchange for a given flow aggregate, for example, depends on the parameter value precision, flow granularity, intended level of accuracy, etc. The overall process for the performance estimation is depicted in Figur
34、e Intro.1. Y.2122(09)_FIntro-1ExchangeparametersScope of theRecommendationDecideestimationrulesEstimateperformancesMeasureperformancesCompareAdjustrulesFigure Intro.1 Estimation process example based on exchanged parameters The network operating parameters to be exchanged vary according to network Q
35、oS architecture. For example, in the DiffServ b-IETF RFC 2475 architecture (or 802.1Q, 802.11e-type networks) the important parameters include the behaviour aggregate (BA) to which a packet belongs, and the bandwidth utilization of the BA based on the implied admission policy (e.g., not more than 10
36、% for EF BA). In another example, the flow aggregation granularity and the number of hops in an aggregation region, in case of a flow-based network such as flow state aware network b-ITU-T Y.2121, are the important parameters. vi Rec. ITU-T Y.2122 (06/2009) Y.2122(09)_FIntro-2Transport stratumServic
37、e stratumControl MediaNNIUNIManagementApplication support functions and service support functionsService controlfunctions Service userprofiles Transport userprofiles Resource andadmissioncontrol functions Network attachmentcontrol functions Transport control functions Transport functionsANIEnd-userf
38、unctionsManagementfunctionsOthernetworksApplicationsFAinformationexchangefunctions(FIXF)Figure Intro.2 Position of the FA information exchange functions in the NGN architecture ITU-T Y.2012 As depicted in Figure Intro.2, the FA information exchange functions defined in this Recommendation are one of
39、 the NGN management functions. The goal of the functions is to provide additional information to improve the accuracy of the admission decision. The FIXF collects the FA configuration information throughout the networks. The collected information can be used for estimating the end-to-end QoS, thus p
40、ossible applications of this function can be the resource and admission control functions (RACF) or other management functions that handle end-to-end QoS. Rec. ITU-T Y.2122 (06/2009) 1 Recommendation ITU-T Y.2122 Flow aggregate information exchange functions in NGN 1 Scope This Recommendation define
41、s the network operating parameters of a flow aggregate (FA) to be exchanged among different network domains for various types of FAs in NGN, and defines the architecture for exchanging these parameters. It also defines, for informational purposes, the mapping of the transport technology specific par
42、ameters to the defined network operating parameters. The details of the protocols are for further study and are out of the scope of this Recommendation. Usage examples of the exchanged operating parameters are shown in several appendices. 2 References The following ITU-T Recommendations and other re
43、ferences 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 i
44、nvestigate 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
45、 status of a Recommendation. ITU-T Y.2012 Recommendation ITU-T Y.2012 (2006), Functional requirements and architecture of the NGN release 1. ITU-T Y.2701 Recommendation ITU-T Y.2701 (2007), Security requirements for NGN release 1. 3 Definitions This Recommendation defines the following terms: 3.1 ag
46、gregation end point: The node where a flow aggregate is de-aggregated. Aggregate start and end points for a flow aggregate can collocate in the same node. 3.2 aggregation region: A set of neighbouring nodes within which every flow maintains its membership of a flow aggregate unaltered. For example,
47、in a DiffServ network, the aggregation region is usually limited to a single node, since at the very next node the membership within a behaviour aggregate is likely to be changed. An aggregation region is defined per flow aggregate. Typically, a node can belong to multiple aggregation regions at the
48、 same time. 3.3 aggregation start point: The node where flows are aggregated to form a flow aggregate. 3.4 flow: A set of IP packets that have the same IP 5-tuple in case of IPv4 packets, or have the same flow label in case of IPv6 packets. 3.5 flow aggregate: A set of flows treated in the same way
49、in terms of scheduling. 3.6 flow aggregate membership: The flows within the flow aggregate. The membership can be identified by the set of flow IDs within the flow aggregate. A given flow at a given node cannot be a member of different flow aggregates at the same time. 3.7 flow aggregate table: A set of flow aggregate table entries. 2 Rec. ITU-T Y.2122 (06/2009) 3.8 flow aggregate table entry: A set of information for a flow aggregate including flow aggregate specific configuration parameters. A flow aggregate table entry is
