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 2 (04/2016) 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 OF THINGS AND SMART CITIES Internet protocol aspects Transport Distribution of timing information through packet networks Amendment 2 Recommendation ITU-T G.8264/Y.1364 (2014) Am
3、endment 2 ITU-T G-SERIES RECOMMENDATIONS 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
4、 TELEPHONE SYSTEMS ON METALLIC LINES 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
5、CHARACTERISTICS G.600G.699 DIGITAL TERMINAL 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 TRAN
6、SPORT GENERIC ASPECTS G.7000G.7999 PACKET 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
7、details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.8264/Y.1364 (2014)/Amd.2 (04/2016) i Recommendation ITU-T G.8264/Y.1364 Distribution of timing information through packet networks Amendment 2 Summary Amendment 2 to Recommendation ITU-T G.8264/Y.1364 (2014) adds additional tex
8、t to cover extended ESMC messages. History Edition 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
9、ITU-T G.8264/Y.1364 (2008) Cor. 2 2012-02-13 15 11.1002/1000/11526 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 2.2 ITU-T G.8264/Y.1364 (2014) Amd
10、. 2 2016-04-13 15 11.1002/1000/12810 * To access 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 G.8264/Y.1364 (2014)/Amd.2 (04/2016) FOR
11、EWORD 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 Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studyin
12、g 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 every four years, establishes the topics for study by the ITU-T study groups
13、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 purview, the necessary standards are prepared on a collaborative basis with ISO
14、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 voluntary. However, the Recommendation may contain certain mandatory provisions
15、(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 the negative equivalents are used to express requirements. The use of such wo
16、rds does not suggest that compliance with the Recommendation is required 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 con
17、cerning 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 Recommendation, ITU had not received notice of intellectual property, protected by
18、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 http:/www.itu.int/ITU-T/ipr/. ITU 2016 All rights reserved. No part of this p
19、ublication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.8264/Y.1364 (2014)/Amd.2 (04/2016) 1 Recommendation ITU-T G.8264/Y.1364 Distribution of timing information through packet networks Amendment 2 1) Additions to clause 4, Abbreviations and
20、acronyms Add the following acronyms to the existing list: eEEC Enhanced Ethernet Equipment Clock ePRTC Enhanced Primary Reference Time Clock PRTC Primary Reference Time Clock SyncE Synchronous Ethernet 2) Changes to clause 11.3.1, ESMC Format Add the following text to the end of clause 11.3.1: An NE
21、 must discard and not forward upon reception any TLV within the ESMC PDU that it does not recognize. 3) Insertion of new clauses 11.3.1.3 and 11.3.1.4 Insert the following new clauses after clause 11.3.1.2: 11.3.1.3 Extended QL TLV format In order to support new clocks and added functionality, an ex
22、tended QL TLV is defined in Table 11-4.1. This TLV is twenty bytes in length and supports the information contained in the specified fields. The related format is in Table 11-4.2, and the new clock quality levels are defined in Table 11-4.3. This supports new clock types as well as carrying new info
23、rmation. Table 11-4.1 Extended QL TLV Octet number Size/bits Field 1 8 bits Type: 0x02 2-3 16 bits Length: 0x0014 4-20 136 bits Extended SSM (see Table 11-4.2) 2 Rec. ITU-T G.8264/Y.1364 (2014)/Amd.2 (04/2016) Table 11-4.2 Extended SSM format Octet number Size/bits Field 1 8 bits Enhanced SSM code (
24、see Table 11-4.3) 2-9 64 bits SyncE Master ID, Note 1 10 8 bits Flag; Note 2 11 8 bits Number of cascaded eEECs from the nearest SSU/PRC 12 8 bits Number of cascaded EECs from the nearest SSU/PRC 13-17 40 bits Reserved for future use NOTE 1 The SyncE Master ID is for further study. NOTE 2 bit 0 mean
25、s mixed EEC/eEEC (i.e., 1 if at least one of the clocks is not an eEEC; 0 if all clocks are eEEC); bit 1 means partial chain (i.e., 1, if the TLV has been generated in the middle of the chain and the count of the EEC/eEEC is incomplete); bits 2-7 reserved for future use. See also clause 11.3.1.4. Ta
26、ble 11-4.3 Enhanced SSM codes for SyncE Clock Message SSM code As per ITU-T G.781/ ITU-T G.8264 QL as per ITU-T G.781/ ITU-T G.8264 (refer to the QL TLV) 0xFF PRTC QL-PRTC 0x20 ePRTC QL-ePRTC 0x21 eEEC QL-eEEC 0x22 11.3.1.4 Interworking between different SyncE generations While the Extended QL TLV i
27、s developed for use with the eEEC, the basic mechanism could be applied in future to the older EEC. This results in three possible combinations of clocks that need to be considered; eEEC with Extended QL TLV support, EEC with no Extended QL TLV support, and the EEC with Extended QL TLV support. In c
28、ase of already deployed nodes not supporting the Extended QL TLV, interworking between different generations of synchronous Ethernet is achieved by the fact that a network element must discard and not forward upon reception any TLV within the ESMC PDU that it does not recognize. The Extended QL TLV
29、allows the count of the number of cascaded eEEC and EEC clocks. If a clock not supporting the Extended QL TLV is present within a chain of clocks, discarding the TLV, as noted above, will result in incomplete counts. The Extended QL TLV specifies a flag to allow clocks supporting enhanced ESMC messa
30、ges to have the ability to report the presence of clocks that may have discarded TLVs. As an example, in case of a chain of eEECs, Bit 0 and Bit 1 will both be “0“ at the output of the chain indicating that the syncE chain is fully based on eEECs, and the count of clocks is complete. In case of an i
31、ntermediate EEC, not able to process the Extended QL TLV, the EEC shall drop the TLV. At the next eEEC in the SyncE chain, the TLV will be added with both Bit 0 and Bit 1 set to “1“ to indicate that the SyncE chain is not fully based on eEEC, and the count of clocks is not complete. However, in case
32、 of an intermediate EEC that is able to process the Extended QL TLV, at the output of that EEC bit 0 is set to 1 to indicate that the SyncE chain includes a mix of EEC and eEEC, and Bit 1 is set to 0 to indicate that the count of the clocks in the chain is complete. ITU-T Y-SERIES RECOMMENDATIONS GL
33、OBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS, INTERNET OF 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,
34、 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 management Y.1200Y.1299 Tra
35、nsport 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 Frameworks and functional architecture models
36、 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 Enhancements to NGN Y.2300Y.2399 Network management Y.2400Y.2499 Network control ar
37、chitectures and protocols Y.2500Y.2599 Packet-based Networks Y.2600Y.2699 Security Y.2700Y.2799 Generalized 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.
38、4049 Definitions and terminologies Y.4050Y.4099 Requirements and use cases Y.4100Y.4249 Infrastructure, 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
39、 Y.4700Y.4799 Identification and security Y.4800Y.4899 For further details, please refer to the list of ITU-T Recommendations. Printed in Switzerland Geneva, 2016 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D General tariff principles Series E Overall network op
40、eration, 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 multimedia systems Series I Integrated services digital network Series J Cable networks and
41、 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, installation and protection of cables and other elements of outside plant Series M Telecommunica
42、tion 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 subjective and objective assessment methods Series Q Switching and signalling Series R
43、 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, Internet of Things and smart cities Series Z Languages and general software aspects for telecommunication systems
