1、 International Telecommunication Union ITU-T Y.1315TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (09/2006) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Transport QoS support for VPN services Framework and characterist
2、ics ITU-T Recommendation Y.1315 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 pro
3、tocols 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 and resource
4、 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 architecture model
5、s 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.2400Y.2499 Netw
6、ork 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. ITU-T Rec. Y.1315 (09/2006) i ITU-T Recommendation Y.1315 QoS support for VPN services Framework and characteristics Su
7、mmary ITU-T Recommendation Y.1315 describes the characteristics and applicability of various QoS (quality of service) service scenarios in the VPN (virtual private network) environment. The QoS service scenarios cover various QoS models in single or multiple service provider configurations. The QoS
8、models described in this Recommendation encompass the pipe model, the hose model, and a combination and/or concatenation of both. Source ITU-T Recommendation Y.1315 was approved on 13 September 2006 by ITU-T Study Group 13 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. Y.131
9、5 (09/2006) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff qu
10、estions 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 Recommendati
11、ons 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 Recommendation
12、, 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. interoperability or
13、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 compliance w
14、ith 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, validity or app
15、licability 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 received notice of intellectual property, protected by patents, which may be required to impleme
16、nt 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 2007 All rights reserved. No part of this publication may be reproduced, by any mean
17、s whatsoever, without the prior written permission of ITU. ITU-T Rec. Y.1315 (09/2006) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 4 Abbreviations and acronyms 2 5 QoS definitions . 2 5.1 Packet-network-related QoS parameters 3 5.2 Basic QoS mechanisms 4 6 Network input and service s
18、pecification. 4 6.1 Input traffic characteristics. 4 6.2 Service specification. 5 7 QoS architectural components 6 7.1 Data plane architectural components 6 7.2 Control plane architectural components. 7 7.3 Management plane architectural components 8 7.4 Enhancements for Y.1291 8 8 VPN service based
19、 on the pipe model 8 8.1 Definition of pipe model 8 8.2 Customer edge characteristics 9 8.3 Provider equipment characteristics. 9 8.4 Applicability, complexity, and scalability 10 8.5 Constructing the VPN based on the pipe model. 11 9 VPN service based on the hose model 11 9.1 Definition of hose mod
20、el 11 9.2 Customer edge characteristics 12 9.3 Provider equipment characteristics. 12 9.4 Applicability, complexity, and scalability 13 10 VPN service based on both pipe and hose model. 14 11 Multiple service provider scenario . 14 Appendix I Pipe model-based implementation example of VPN with speci
21、fic QoS requirements . 16 I.1 Service requirements 16 I.2 Unified QoS-VPN architecture. 16 I.3 Considerations 17 Appendix II Service curve 19 Bibliography. 20 iv ITU-T Rec. Y.1315 (09/2006) Introduction There are several QoS models available for VPN services. In this Recommendation, the pipe model a
22、nd the hose model are studied. The objectives of such studies are to provide precise definitions for these QoS models, to construct the VPN using the toolset provided in ITU-T Y.1291, and to outline applicability of these QoS models in the VPN environment. The architectural components needed to buil
23、d these QoS models are defined in ITU-T Y.1291 while the mechanisms to coordinate the resources to ensure QoS between sites are defined in the related IETF and ITU-T documents. In order to provide VPN services with QoS, the first step is to define the QoS in parametric terms. This is construed as ob
24、jectives of the services to be provided. The next step is to use the architecture building blocks provided in ITU-T Y.1291 to construct the VPN with QoS, and the final step is to evaluate the service performance provided by the network. This Recommendation refers to ITU-T Y.1291 on the functions and
25、 features of the QoS architectural components. This Recommendation takes input from the various VPN related ITU-T deliverables, including approved Recommendations (e.g., ITU-T Y.1311, ITU-T Y.1311.1, ITU-T Y.1312, and ITU-T Y.1314). ITU-T Rec. Y.1315 (09/2006) 1 ITU-T Recommendation Y.1315 QoS suppo
26、rt for VPN services Framework and characteristics 1 Scope The scope of this Recommendation is to provide guidelines on how the QoS architecture tools, mostly provided in ITU-T Y.1291, can be used to support VPN services with QoS characteristics between the network ingress points to the network egres
27、s points. In this Recommendation, different QoS service models, including the pipe model and the hose model, are studied. The characteristics and applicability of VPN services using those QoS models and concatenation of multiple QoS models in a single or multiple provider scenarios are also studied,
28、 including some application examples. While this Recommendation discusses the QoS issues related to VPN applications, the mechanisms to ensure QoS assurance are out of the scope of this Recommendation. 2 References The following ITU-T Recommendations and other references contain provisions which, th
29、rough 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 investigate the possibility of applyin
30、g 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 status of a Recommendation. ITU-T E.
31、800 ITU-T Recommendation E.800 (1994), Terms and definitions related to quality of service and network performance including dependability. ITU-T G.1000 ITU-T Recommendation G.1000 (2001), Communications Quality of Service: A framework and definitions. ITU-T H.360 ITU-T Recommendation H.360 (2004),
32、An architecture for end-to-end QoS control and signalling. ITU-T Y.1291 ITU-T Recommendation Y.1291 (2004), An architectural framework for support of Quality of Service in packet networks. ITU-T Y.1311 ITU-T Recommendation Y.1311 (2002), Network-based VPNs Generic architecture and service requiremen
33、ts. ITU-T Y.1311.1 ITU-T Recommendation Y.1311.1 (2001), Network-based IP VPN over MPLS architecture. ITU-T Y.1312 ITU-T Recommendation Y.1312 (2003), Layer 1 Virtual Private Network generic requirements and architecture elements. ITU-T Y.1314 ITU-T Recommendation Y.1314 (2005), Virtual private netw
34、ork functional decomposition. 3 Definitions This Recommendation defines the following terms: 3.1 arrival curve: A mechanism to serve as a measure of traffic arriving at providers ingress network interface. 2 ITU-T Rec. Y.1315 (09/2006) 3.2 service curve: A mechanism to serve as a measure of the pack
35、et forwarding services provided by the service provider. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms. BE Best Effort CE Customer Edge CoS Class of Service CR-LDP Constraint-based Routing Label Distribution Protocol Diffserv Differentiated Services D
36、SCP DiffServ Code Point EF PHB Expedited Forwarding Per Hop Behaviour FIFO First In, First Out FILO First In, Last Out Intserv Integrated Services LAPS Link Access Procedure SDH LIFO Last In, First Out LILO Last In, Last Out LSP Label Switched Path MPLS Multi-Protocol Label Switching P Provider (nod
37、e) PE Provider Edge QoS Quality of Service RSVP Resource reSerVation Protocol SLA Service Level Agreement TE Traffic Engineering UNI User Network Interface VF Virtual Forwarder VPN Virtual Private Network 5 QoS definitions The concept of quality of service is a multi-dimensional measure of user sati
38、sfaction of the network. The various definitions of QoS have been discussed in different ITU-T Recommendations (e.g., ITU-T E.800 and ITU-T G.1000). Under those Recommendations, the network performance characteristics, network operability, network support, network serviceability, and network securit
39、y are all part of the quality of service. In this Recommendation, only the parametric aspects of QoS under the VPN environment for packet-based networks are discussed. The following subclauses provide details about the QoS metrics. ITU-T Rec. Y.1315 (09/2006) 3 5.1 Packet-network-related QoS paramet
40、ers Among various aspects of quality of service definitions, this Recommendation focuses on the performance aspects of the service providers network in the VPN environment for the packet-based networks. The measure of the QoS for a particular service providers packet network providing VPN services s
41、hould encompass the following aspects: Delay: There are various means to measure the time delay experienced by the user traffic. It should be noted that those definitions are not equivalent (e.g., consider if the packet is fragmented inside the network or LAPS-based framing). It should be noted that
42、 the service providers are free to use any of those definitions but a consistent definition needs to be provided to the clients if multiple service providers are involved. FIFO delay First-in, first-out: The time difference between the first bit accepted by the network and the first bit delivered to
43、 the user across the network. LILO delay Last-in, last-out: The time difference between the last bit accepted by the network and the last bit delivered to the user across the network. FILO delay First-in, last-out: The time difference between the first bit accepted by the network and the last bit de
44、livered to the user across the network. It is possible to define the FILO delay but should not be used because it is packet size sensitive. LIFO delay Last-in, first-out: The time difference between the last bit accepted by the network and the first bit delivered to the user across the network. It i
45、s possible to define the LIFO delay but should not be used because it is packet size sensitive. Delay variation (jitter): Once a specific type of delay is defined by the network, the delay variation may be further divided into the following sub-categories: Maximum delay variation: The difference bet
46、ween the maximum delay and minimum delay experienced by the user traffic within a specific time window. Mean delay variation: Within a specific time window 0,T, if each individual packet delay can be denoted as d(k) for the kth packet in the time window, the mean delay variation can then be denoted
47、as =NiTDidD0,0)( where N denotes that there are N packets arriving in the time interval 0,T and D is the average delay endured by each packet arriving in the time window 0,T (i.e., =NkkdD0)( where N is the total number of packets arrived in the time interval 0,T). Medium delay variations: ()M : With
48、in a specific time window 0,T, 50% of the packet have delay more than M and 50% packet will have delay less than M . Packet loss probability: The definition of packet loss probability (as opposed to the pure packet loss counts as some service providers are considering) is also subject to the time wi
49、ndow constraint. In this Recommendation, the “packet delivery probability“ is defined as the total number of packets successfully delivered divided by the total number of the eligible packets received by the network for a given and well-defined time interval. The eligible packets are then subject to the input constraint. Hence the “packet loss probability“ is one minus the “packet delivery probability“. The particular value of delay, delay variation, and packet
