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 G.8264/Y.1364 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 1 (01/2015) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Packet over Transport aspects Synchronization, quality and availabil
2、ity targets SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Transport Distribution of timing information through packet networks Amendment 1 Recommendation ITU-T G.8264/Y.1364 (2014) Amendment 1 ITU-T G-SERIES RECOMMENDATI
3、ONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES
4、G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TE
5、RMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PA
6、CKET OVER TRANSPORT ASPECTS G.8000G.8999 Ethernet over Transport aspects G.8000G.8099 MPLS over Transport aspects G.8100G.8199 Synchronization, quality and availability targets G.8200G.8299 Service Management G.8600G.8699 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of
7、ITU-T Recommendations. Rec. ITU-T G.8264/Y.1364 (2014)/Amd.1 (01/2015) i Recommendation ITU-T G.8264/Y.1364 Distribution of timing information through packet networks Amendment 1 Summary Amendment 1 to Recommendation ITU-T G.8264/Y.1364 amends clause 11.1 and introduces clause 11.1.1. History Editio
8、n Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.8264/Y.1364 2008-10-29 15 11.1002/1000/9420 1.1 ITU-T G.8264/Y.1364 (2008) Cor. 1 2009-11-13 15 11.1002/1000/10433 1.2 ITU-T G.8264/Y.1364 (2008) Amd. 1 2010-09-22 15 11.1002/1000/10927 1.3 ITU-T G.8264/Y.1364 (2008) Cor. 2 2012-02-13 15 1
9、1.1002/1000/11526 1.4 ITU-T G.8264/Y.1364 (2008) Amd. 2 2012-02-13 15 11.1002/1000/11525 2.0 ITU-T G.8264/Y.1364 2014-05-14 15 11.1002/1000/12192 2.1 ITU-T G.8264/Y.1364 (2014) Amd. 1 2015-01-13 15 11.1002/1000/12390 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address
10、 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 G.8264/Y.1364 (2014)/Amd.1 (01/2015) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecom
11、munications, 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 Recommendations on them with a view to standardizing telecommu
12、nications 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 of ITU-T Recommendations is covered by the proce
13、dure 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“ is used for conciseness to indicate both a telec
14、ommunication 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 with the Recommendation is achieved when all of th
15、ese 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 required of any party. INTELLECTUAL PROPERTY RIGHTSITU
16、 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 Intellectual Property Rights, whether asserted by ITU membe
17、rs 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. However, implementers are cautioned that this may not
18、 represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2015 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 G.8264/
19、Y.1364 (2014)/Amd.1 (01/2015) 1 Recommendation ITU-T G.8264/Y.1364 Distribution of timing information through packet networks Amendment 1 1) Clause 11.1 Move the last two paragraphs of clause 11.1 to a newly created clause 11.1.1, and modify the text as shown below: 11.1 Packet-level SSM Figure 11-1
20、 makes no reference to the specific type of channel that is used. In the case of SDH, dedicated overhead is present in the transport overhead. In the case of Ethernet, this does not exist, but a mechanism is required in order to provide this communication ability. For the case of synchronous Etherne
21、t SSM, the message channel is based on IEEE 802.3 Link OAM and uses an IEEE organizational specific slow protocol (OSSP) to convey the QL of the respective Ethernet Physical signal. Note, IEEE 802.3 defines multiple slow protocols and allows different slow protocols to be used within a single system
22、 over a single link segment. With respect to the ESMC, implementations must respect that the QL applies to the physical layer clock and process the ESMC appropriately. For example, link aggregation (LAG) IEEE 802.1AX is another function that utilizes slow protocols and provides a mechanism for carry
23、ing MAC frames over a group of links. As noted in IEEE 802.3 clause 57.2.2, LAG operates above OAM and hence above the ESMC. Since the ESMC is modelled on Link OAM, processing of ESMC messages is therefore required on each synchronous Ethernet enabled link in the LAG group. It is also important to n
24、ote that the use of parallel links, such as the case with LAG, needs to be carefully considered due to the potential for creation of timing loops (see clauses 5.13.2 and 5.13.3.1 of ITU-T G.781. 11.1.1 ESMC operation with link aggregation (LAG) IEEE 802.3 defines multiple slow protocols and allows d
25、ifferent slow protocols to be used within a single system over a single link segment. With respect to the ESMC, implementations must respect that the QL applies to the physical layer clock and process the ESMC appropriately. For example, link aggregation (LAG) IEEE 802.1AX is another function that u
26、tilizes slow protocols and provides a mechanism for carrying MAC frames over a group of links. As noted in IEEE 802.3 clause 57.2.2, LAG operates above OAM and hence above the ESMC. Since the ESMC is modelled on Link OAM, processing of ESMC messages is therefore required on each synchronous Ethernet
27、 enabled link in the LAG group. It is also important to note that the use of parallel links, such as the case with LAG, needs to be carefully considered due to the potential for creation of timing loops (see clauses 5.13.2 and 5.13.3.1 of ITU-T G.781. As noted in clause 5.13.2 of ITU-T G.781, the co
28、ncept of a “bundle“ is introduced in cases where multiple timing links share the same synchronization source (i.e., the same EEC in the case of synchronous Ethernet). In this situation, which also applies to LAG, when a network element selects one port of a bundle as its synchronization input, it ha
29、s to return DNU/DUS on all timing capable ports of the bundle. It is left to the operators either to configure several synchronous Ethernet enabled ports or only one synchronous Ethernet enabled port of the LAG. ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPE
30、CTS 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.499 Numbering, addressing and naming Y.500Y.599 Operation, administration and maintenance Y.600Y.699 Secur
31、ity 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.1200Y.1299 Transport Y.1300Y.1399 Interworking Y.1400Y.1499 Quality of service and network performance Y.1
32、500Y.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 Frameworks and functional architecture models Y.2000Y.2099 Quality of Service and performance Y.2100Y.2199 Service aspects: Service capab
33、ilities 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.2
34、799 Generalized mobility Y.2800Y.2899 Carrier grade open environment 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. Printed in Switzerland Geneva, 2015 SERIES OF ITU-T RECOMMENDATIONS Series A Organizatio
35、n of the work of ITU-T Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multim
36、edia systems Series I Integrated services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Environment and ICTs, climate change, e-waste, energy efficiency; construction, installatio
37、n and protection of cables and other elements of outside plant Series M Telecommunication management, including TMN and network maintenance Series N Maintenance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Terminals and s
38、ubjective and objective assessment methods Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks, open system communications and security Series Y Global information infrastructure, Internet protocol aspects and next-generation networks Series Z Languages and general software aspects for telecommunication systems
