1、 International Telecommunication Union ITU-T Y.1566TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2012) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Quality of service and network performance Quality of service map
2、ping and interconnection between Ethernet, Internet protocol and multiprotocol label switching networks Recommendation ITU-T Y.1566 ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100
3、Y.199 Services, applications and middleware Y.200Y.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
4、.1099 Services and applications Y.1100Y.1199 Architecture, 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.1599Signalling Y.1600Y.1699 Operation, administration and maintenance Y.170
5、0Y.1799 Charging Y.1800Y.1899 IPTV over NGN Y.1900Y.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 o
6、f services and networks in NGN Y.2250Y.2299 Numbering, naming and addressing Y.2300Y.2399 Network management Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Packet-based Networks Y.2600Y.2699 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 Carrier grade open environment
7、 Y.2900Y.2999 FUTURE NETWORKS Y.3000Y.3499 CLOUD COMPUTING Y.3500Y.3999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T Y.1566 (07/2012) i Recommendation ITU-T Y.1566 Quality of service mapping and interconnection between Ethernet, Internet protocol and multiprotoc
8、ol label switching networks Summary Existing quality of service (QoS) class standardization for packet-based layer 2 and layer 3 services is largely non binding or missing. Recommendation ITU-T Y.1566 intends to simplify technical Ethernet, multiprotocol label switching (MPLS) and internet protocol
9、(IP) QoS interconnection negotiations. Four ordinary classes and four auxiliary classes have been defined. This set of classes covers a wide range of transport service offerings. The Recommendation gives guidance on how to deal with issues resulting from differences in QoS deployments of interconnec
10、ting service providers, aiming at the preservation of the original intent of the service. History Edition Recommendation Approval Study Group 1.0 ITU-T Y.1566 2012-07-14 12 Keywords Interconnection, interworking, mapping, matching, QoS. ii Rec. ITU-T Y.1566 (07/2012) FOREWORD The International Telec
11、ommunication Union (ITU) is the United Nations 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 ta
12、riff 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 years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recom
13、mendations 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 necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recomme
14、ndation, the expression “Administration“ is 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., interoperab
15、ility 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 equivalents are used to express requirements. The use of such words does not suggest that com
16、pliance 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 claimed Intellectual Property Right. ITU takes no position concerning the evidence, validi
17、ty 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 had not received notice of intellectual property, protected by patents, which may be requir
18、ed 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.int/ITU-T/ipr/. ITU 2013 All rights reserved. No part of this publication may be reproduced
19、, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T Y.1566 (07/2012) iii Table of 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 The Ordinary class prop
20、osal . 2 6 Simplifying QoS mapping by a standard interconnection class and codepoint scheme 7 Appendix I Example codepoint mapping for 3-bit codepoint classes 9 Appendix II Example class mapping for ITU-T Y.1541 to ITU-T Y.1566 10 Appendix III Single class transport of multiclass traffic 12 Bibliogr
21、aphy. 13 Rec. ITU-T Y.1566 (07/2012) 1 Recommendation ITU-T Y.1566 Quality of service mapping and interconnection between Ethernet, Internet protocol and multiprotocol label switching networks 1 Scope This Recommendation defines a limited set of classes that provide a basis for interworking between
22、the different traffic class aggregates of different service providers, while preserving the original intent of the service (although packet markings might change). The scope includes interworking between layers and between networks using similar technologies. Each QoS class is defined by its qualita
23、tive performance characteristics and the suggested groups of applications whose performance requirements match the characteristics of one or more classes. The limit on the number of classes is imposed by the space available in the widely-used three-bit codepoint space. End-to-end QoS requires a comm
24、on understanding of the QoS class properties in all involved domains. While many similarities are expected between the deployed or planned QoS architectures of different providers, these are often not obvious when starting interconnection negotiations. This specification aims on enabling end-to-end
25、QoS (by preserving the intended service properties) across different packet networks and on simplification of the technical QoS interconnection negotiations between providers. Informational examples in the appendices provide: Codepoint to class association, with an interworking example ITU-T Y.1541
26、QoS class mapping to interworking classes The allocation of numerical performance budgets among interworking networks in the user network interface to user network interface (UNI-UNI) path is out of the scope of this Recommendation. The issue of matching b-3GPP TS 23.203 standardized QoS class ident
27、ifier (QCI) characteristics to interworking classes is for further study. 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 w
28、ere 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 valid ITU-T Recommen
29、dations 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 I.371 Recommendation ITU-T I.371 (2000), Traffic control and congestion control in B-ISDN. ITU-T Y.1541 Recommendation ITU-T Y.154
30、1 (2006), Network performance objectives for IP-based services. 3 Definitions 3.1 Terms defined elsewhere None. 2 Rec. ITU-T Y.1566 (07/2012) 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 mapping table: A table with entries for each class exchanged a
31、t an interconnecting point between service providers, with a row indicating the codepoint of each service class, the matching Ordinary class (or Auxiliary class), and the codepoint of the class used by the other service provider on the interconnecting link. 3.2.2 matching: An operation performed to
32、associate existing service classes with the Ordinary class set (or Auxiliary class set), and ultimately associate the classes of two different service providers. 3.2.3 remarking: An operation performed to replace the codepoint of an existing service class with the codepoint of the matching class use
33、d by another service provider on the interconnecting link. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: AF Assured Forwarding CPE Customer Premises Equipment CS Class Selector DSCP Differentiated Services Codepoint EF Expedited Forwarding GSMA Globa
34、l System for Mobile Communications Alliance IP Internet Protocol MPLS Multiprotocol Label Switching QCI QoS Class Identifier QoS Quality of Service TCP Transmission Control Protocol UNI User to Network Interface 5 The Ordinary class proposal Prior to development of this Recommendation, there was no
35、single standard which provided: 1) qualitative QoS class definitions 2) example classification of widely-deployed applications and services 3) coverage of interconnection and interworking of the most popular packet-based communication layers (IP, MPLS and Ethernet) and enabling transport technologie
36、s. The last aspect is twofold: first, class properties need to match across interconnection boundaries and second, codepoint mapping should be deterministic and non-ambiguous (identical codepoints are not required). The aim of this Recommendation is to simplify the production and negotiation of end-
37、to-end QoS over a chain of retail, wholesale and inter-provider transport products. The Recommendation accomplishes this goal by defining a set of “ordinary“ classes with the capability to support groups of commonplace user applications and/or services (with similar performance needs). This clause R
38、ec. ITU-T Y.1566 (07/2012) 3 briefly introduces existing standards and then proceeds to a proposal of classes, their properties and example uses. Codepoint and mapping proposals may be found in several appendices. On IP and MPLS, IETFs Differentiated Services (Diffserv) architecture b-IETF RFC 2475
39、resulted in first commercial deployments of QoS differentiating IP services. Diffserv tries to respect prior standardization of IP precedence b-IETF RFC 791. Some informative work has been produced suggesting mappings of services to QoS classes and aggregation of IP classes to MPLS classes b-IETF RF
40、C 4594, b-IETF RFC 5127. ITU-T Y.1541 standardizes several generic QoS classes and specifies UNI-to-UNI performance objectives ITU-T I.371. IEEE standardized quality differentiating LAN services with strict priority scheduling, which was picked as a simple solution viable in local networks. While a
41、QoS class concept similar to that of Diffserv was not mandatory within IEEE, an optional specification was provided (see Annex G of b-IEEE 802.1Q). b-MEF 23.1 proposes three service oriented classes including an IP to Ethernet mapping. b-GSMA IR.34 alliance IR.34 proposes four service oriented inter
42、connection IP QoS classes b-GSMA IR.34. b-3GPP TS 23.203 defines nine classes with different properties and example usages. All of these standards have commonalities. But attempting to produce end-to-end QoS by simply combining the available standards is a challenge. QoS schemes independently develo
43、ped by separate providers usually are not identical (although most have many commonalities). The inter-layer QoS mappings to be covered are IP over Ethernet, IP over MPLS, Ethernet over MPLS and Ethernet over IP. These mappings cover the most widespread layer 2 and layer 3 service deployments. In ge
44、neral, codepoints of an interconnecting party whose QoS markings are trusted (i.e., the receiving network providers are sure that a given codepoint identifies a specific class) may only be re-marked, if the class interpretation remains absolutely identical after re-marking. This is required to allow
45、 non ambiguous reversion of the re-marking at other points in a communication path. If this cannot be done, end-to-end QoS with pre-defined performance properties cannot be guaranteed. No suggestions are made here how to remark codepoints of parties to which a provider has no trust relation. In some
46、 cases, the number of classes may differ at an interconnection point. It is then up to the interconnecting parties to agree class mappings and non-revertible re-marking of traffic, if it cannot be avoided. Note that re-marking IP precedence within a DSCP offers limited chances for class transparency
47、, if only a single precedence codepoint is re-marked and an AF class like DSCP differentiation is applied. Any mapping of a QoS traffic to a class with different properties should be revertible by conserving the original codepoint. Tunnelling (and may be header stacking) may be appropriate mechanism
48、s. To simplify mapping of QoS classes, while being aware that neither classes nor codepoints are widely standardized, two tables below introduce lists of class definitions with properties of these classes and some usage examples. Table 5-1 starts with well-defined QoS classes and their properties. I
49、t is expected that support of classes with the properties and usage examples shown in Table 5-1 are a commodity to a majority of carriers and service providers. 4 Rec. ITU-T Y.1566 (07/2012) Table 5-1 Ordinary packet service QoS classes, their properties and matching suggestions Class properties Class name (usage example) Recommended matching to connecting provider class (if per class mapping applies) Extremely low loss. Very low bandwidth per flow or session. Critical (Network management)See b-IETF RFC
