1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T Y.2617 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2016) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS, INTERNET OF THINGS AND SMART CITIES Next Generation Netwo
2、rks Packet-based Networks Quality of service guaranteed mechanisms and performance model for public packet telecommunication data networks Recommendation ITU-T Y.2617 ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS, INTERNET OF
3、 THINGS AND SMART CITIES GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.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.70
4、0Y.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.1200Y.1299 Transport Y.1300Y.1399 Interworking Y.1400Y.1499 Quality of service and network performance Y.1500Y.159
5、9 Signalling Y.1600Y.1699 Operation, administration and maintenance Y.1700Y.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
6、and service architecture Y.2200Y.2249 Service aspects: Interoperability of services and networks in NGN Y.2250Y.2299 Enhancements to NGN 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 Gene
7、ralized mobility Y.2800Y.2899 Carrier grade open environment Y.2900Y.2999 FUTURE NETWORKS Y.3000Y.3499 CLOUD COMPUTING Y.3500Y.3999 INTERNET OF THINGS AND SMART CITIES AND COMMUNITIES General Y.4000Y.4049 Definitions and terminologies Y.4050Y.4099 Requirements and use cases Y.4100Y.4249 Infrastructu
8、re, connectivity and networks Y.4250Y.4399 Frameworks, architectures and protocols Y.4400Y.4549 Services, applications, computation and data processing Y.4550Y.4699 Management, control and performance Y.4700Y.4799 Identification and security Y.4800Y.4899 For further details, please refer to the list
9、 of ITU-T Recommendations. Rec. ITU-T Y.2617 (06/2016) i Recommendation ITU-T Y.2617 Quality of service guaranteed mechanisms and performance model for public packet telecommunication data networks Summary Recommendation ITU-T Y.2617 defines performance parameters including delay, jitter, and packet
10、 loss ratio, specifies end-to-end performance allocation when a public packet telecommunication data network (PTDN) interworks with other PTDNs or packet data networks (PDNs), describes service classification in terms of constant bit rate services and variable bit rate services and defines quality o
11、f service (QoS) guaranteed mechanisms in a PTDN. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T Y.2617 2016-06-13 13 11.1002/1000/12888 Keywords Delay, jitter, packet loss, performance allocation, performance parameter, PTDN, QoS, QoS guaranteed mechanism, VPN. * To access
12、the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T Y.2617 (06/2016) FOREWORD The International Telecommunication Union (ITU) is the United N
13、ations 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 tariff questions and issuing Recommendatio
14、ns 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 Recommendations on these topics. The approval
15、 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, the expression “Administration“
16、 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 applicability) and compliance w
17、ith 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 with the Recommendation is requi
18、red of any party. INTELLECTUAL PROPERTY RIGHTSITU 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 applicability of claimed Intellectu
19、al 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 required to implement this Recommendation. Howe
20、ver, 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 2016 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the pr
21、ior written permission of ITU. Rec. ITU-T Y.2617 (06/2016) 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 Conventions 3 6 Performance parameters . 3 7 Performance allo
22、cation . 4 7.1 End-to-end QoS in PTDN 4 7.2 End-to-end QoS with other PDNs 5 8 Service classification 6 9 QoS guaranteed mechanisms 6 9.1 Generic QoS guaranteed mechanisms 6 9.2 VPN QoS guaranteed mechanisms . 7 10 Security considerations . 7 Bibliography. 8 Rec. ITU-T Y.2617 (06/2016) 1 Recommendat
23、ion ITU-T Y.2617 Quality of service guaranteed mechanisms and performance model for public packet telecommunication data networks 1 Scope This Recommendation defines performance parameters, an end-to-end performance allocation approach, service classifications and quality of service (QoS) guaranteed
24、 mechanisms in a public packet telecommunication data network (PTDN) (defined in ITU-T Y.2613). 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, th
25、e 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 references listed below. A list of the currentl
26、y 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 Y.1541 Recommendation ITU-T Y.1541 (2011), Network performance objectives for IP-based services. ITU-T Y.261
27、3 Recommendation ITU-T Y.2613 (2010), General technical architecture for public packet telecommunication data network (PTDN). 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 constant bit rate service b-ITU-T I.113: A type of telecommuni
28、cation service characterized by a service bit rate specified by a constant value. 3.1.2 control plane b-ITU-T Y.2011: The set of functions that controls the operation of entities in stratum or layer under consideration, plus the functions required to support this control. 3.1.3 data plane b-ITU-T Y.
29、2011: The set of functions used to transfer data in stratum or layer under consideration. 3.1.4 management plane b-ITU-T Y.2011: The set of functions used to manage entities in the stratum or layer under consideration, plus the functions required to support this management. 3.1.5 packet loss b-ITU-T
30、 G.1050: The failure of a packet to traverse the network to its destination. Typically, packet loss is caused by packet discards due to buffer overflow. This model does not take into account packet loss due to discards in the terminal jitter buffer. 2 Rec. ITU-T Y.2617 (06/2016) 3.1.6 packet loss ra
31、tio (PLR) b-ITU-R BT.1720: The ratio between the number of the packets lost in the network and the total number of transmitted packets.1 3.1.7 queuing delay b-ITU-T E.600: In delay mode of operation, the time interval between the bid for a resource and its seizure. 3.1.8 variable bit rate service b-
32、ITU-T I.113: A type of telecommunication service characterized by a service bit rate specified by statistically expressed parameters which allow the bit rate to vary within defined limits. 3.2 Terms defined in this Recommendation This Recommendation defines the following term: 3.2.1 quality of servi
33、ce (QoS) domain: A collection of connected public packet telecommunication data network (PTDN) resources that are organized under common QoS policies and are under the control of the same network administration. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and ac
34、ronyms: ADT Address Translator ED Edge Device IP Internet Protocol IPER IP packet Error Ratio IPLR IP packet Loss Ratio NNI Network/Network Interface PD Propagation Delay PDN Packet Data Network PLR Packet Loss Ratio PTDN Public packet Telecommunication Data Network QoS Quality of Service RTP Real T
35、ime Protocol SLA Service Level Agreement TD Transmission Delay UDP User Datagram Protocol UNI User Network Interface VPN Virtual Private Network 1 According to the measurement scheme and the methodology proposed in b-ITU-R BT.1720, the total number of lost packets in the PLR parameter is the sum of
36、IP packet loss ratio (IPLR) and IP packet error ratio (IPER) as defined in ITU-T Y.1541. A more complete definition of this parameter is given in clause 7.7.1 of b-ITU-T G.1020, which defines “Overall (frame/packet) loss ratio“ for frames or packets. Being the measurement header on top of the transp
37、ort layer, if, for an IP packet, the IP or user datagram protocol (UDP) checksum fails, this packet will not be presented to the measurement (or real time protocol (RTP) layer. Rec. ITU-T Y.2617 (06/2016) 3 5 Conventions None. 6 Performance parameters In a PTDN, three performance parameters are spec
38、ified as given in clauses 6.1 to 6.3. 6.1 Delay Delay is the time between the first bit entering the network and the first bit arriving at the user across the network. It includes three factors: transmission delay, propagation delay and node processing delay (including queuing delay). Transmission d
39、elay (TD), in seconds, is the delay caused by the data rate of the link. When the link rate is given, the transmission delay is proportional to the packet length, it can be calculated as follows: TD = N/R where: N is the number of bits in the packet; R is the rate of transmission (in bits per second
40、). Propagation delay (PD), in seconds, is the amount of time spent for the traffic to travel from the sender to the receiver. It relates to the link distance and propagation speed. It can be calculated as follows: PD = L/S where: L is the length of the physical link (in kilometres); S is the propaga
41、tion speed in link (in kilometres per second). Node processing delay is the time spent for in-node processing, such as output link selection, bit errors check and queuing delay. More processes, such as address resolution, en/de-capsulation, examining the packet for security, are only done on a PTDN
42、edge device (ED). Therefore, the processing delay on an ED is larger than that on an intermediate PTDN node. In addition, the time spent for processing different packets may not be constant. For example, it will take a much longer time for address resolution by an address translator (ADT) than by a
43、local address cache. Queuing delay is the time spent between a packet arriving at a queue and it being transmitted out of the queue. If the number of incoming packets is bigger than that of outgoing packets, it causes queuing delay. Burst, load of a queue and packet length variance make queuing dela
44、y unstable; different queuing mechanisms (e.g., priority queue) and different schedule principles (e.g., weighted round robin) can affect queuing delay. Transmission and propagation delays are relatively stable, while node-processing and queuing delays may vary from packet to packet. 6.2 Jitter Jitt
45、er is the variation between the maximum delay and minimum delay within a specific time window. The node processing delay (including queuing delay) is the main factor of jitter. 6.3 Packet loss ratio Packet loss ratio (PLR) is the total number of packets failing to deliver through the network divided
46、 by the total number of transmitted packets within a specific time window. 4 Rec. ITU-T Y.2617 (06/2016) Packet loss can be caused by a number of factors including noise or signal degradation over the transmission link, packet drop because of congestion and hardware faults. Intentional packet droppi
47、ng also causes packet loss. In a PTDN, this intentional packet dropping happens when virtual private network (VPN) traffic or multicast traffic are above the preset threshold. 7 Performance allocation In a PTDN, an end-to-end network service may pass through concatenating QoS domains. End-to-end per
48、formance objectives are allocated to these QoS domains and interworking links between domains. 7.1 End-to-end QoS in PTDN Figure 7-1 End-to-end QoS model (without other types of PDNs) As shown in Figure 7-1, end-to-end QoS in PTDN is decided by (1n) PTDN QoS domains and (0(n1) network/network interf
49、ace(s) (NNI(s) between these QoS domains. In this case, the relationship between end-to-end performance parameters and those of QoS domains is as in clauses 7.1.1 to 7.1.3. 7.1.1 Delay The end-to-end PTDN packet delay is the sum of the delays experienced along the concatenating QoS domains from source user network interface (UNI) to destination UNI (not included), as follows: Dt = ni Ddi1+ ini DNNI11where: Dt is the packet delay of end-to-end QoS; Ddi is the packet delay of the PTDN QoS domain i
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