1、 International Telecommunication Union ITU-T G.984.1TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 2(04/2012) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Optical line systems for local and access networks Gigabit-capable
2、passive optical networks (GPON): General characteristics Amendment 2 Recommendation ITU-T G.984.1 (2008) Amendment 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
3、TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER 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.40
4、0G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 General G.900G.909 Parameters for optical fibre
5、 cable systems G.910G.919 Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s G.920G.929 Digital line transmission systems on cable at non-hierarchical bit rates G.930G.939 Digital line systems provided by FDM transmission bearers G.940G.949 Digital line systems G.950G.959
6、Digital section and digital transmission systems for customer access to ISDN G.960G.969 Optical fibre submarine cable systems G.970G.979 Optical line systems for local and access networks G.980G.989Access networks G.990G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPE
7、CTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.984.1 (2008)/Amd.2 (04/2012)
8、i Recommendation ITU-T G.984.1 Gigabit-capable passive optical networks (GPON): General characteristics Amendment 2 Summary Amendment 2 to Recommendation ITU-T G.984.1 (2008) includes: 1) text describing operation of GPON with IEEE 1588; 2) use cases for GPON frequency and time of day synchronizatio
9、n; and 3) Transport of ESMC SSM over PON. History Edition Recommendation Approval Study Group 1.0 ITU-T G.984.1 2003-03-16 15 2.0 ITU-T G.984.1 2008-03-29 15 2.1 ITU-T G.984.1 (2008) Amd.1 2009-10-09 15 2.2 ITU-T G.984.1 (2008) Amd.2 2012-04-22 15 ii Rec. ITU-T G.984.1 (2008)/Amd.2 (04/2012) FOREWOR
10、D 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 studying te
11、chnical, 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 whic
12、h, 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 and
13、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 (to
14、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 words
15、does not suggest that compliance 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 concer
16、ning 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 received notice of intellectual property, protected by patents
17、, 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 2012 All rights reserved. No part of this publicat
18、ion may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.984.1 (2008)/Amd.2 (04/2012) iii Table of Contents Page 1 Scope 1 2 Changes to clause 4 “Abbreviations and acronyms“ 1 3 Appendices IV, V and VI . 1 Appendix IV Operation with IEEE 1588 1 Append
19、ix V Use cases for frequency and time of day synchronization . 2 Appendix VI Transport of ESMC messages over PON 6 4 Add the following to the bibliography 7 Rec. ITU-T G.984.1 (2008)/Amd.2 (04/2012) 1 Recommendation ITU-T G.984.1 Gigabit-capable passive optical networks (GPON): General characteristi
20、cs Amendment 2 1 Scope This amendment to Recommendation ITU-T G.984.1 includes text describing the operation of GPON with IEEE 1588; use cases for GPON frequency and time of day synchronization; and the transport of ESMC messages over PON. 2 Changes to clause 4 “Abbreviations and acronyms“ Add the f
21、ollowing abbreviations to the list in clause 4: ESMC Ethernet Synchronization Messaging Channel OSSP Organizational Specific Slow Protocol PRC Primary Reference Clock PTP Precision Timing Protocol RNC Radio Network Controller ToD Time of Day 3 Appendices IV, V and VI Add Appendices IV, V and VI as f
22、ollows: Appendix IV Operation with IEEE 1588 (This appendix does not form an integral part of this Recommendation.) IEEE 1588 describes a protocol for transferring time and/or frequency through a packet network. The protocol is explained in b-1588 Tutorial. G-PON distributes the IEEE 1588 master and
23、 slave functionality between the OLT and the ONU. The OLT will perform the slave port function (or in the case of a shelf, the OLT will receive the frequency and time from the function in the shelf which performs the slave port function). The OLT synchronizes the PON line rate to the network clock f
24、requency and transfers the time of day information to the ONU using the method in Amendment 2 to ITU-T G.984.3, clause 10.4.6. The ONU uses the methods specified in ITU-T G.984.2 to recover frequency and ITU-T G.984.3 to recover time. The ONU will then either function as a master port to subsequent
25、nodes or output the time and frequency through another interface. 2 Rec. ITU-T G.984.1 (2008)/Amd.2 (04/2012) Appendix V Use cases for frequency and time of day synchronization (This appendix does not form an integral part of this Recommendation.) There are many applications where precise time and/o
26、r frequency must be transferred through a packet network from a source to a destination. In this appendix several use cases are described in terms of the methods used to deliver frequency and/or time. Since most of the use cases mentioned are related to mobile backhauling applications, examples will
27、 use the RNC and NodeB network elements, though these use cases are not intended to be exhaustive. Frequency and/or time of day synchronization is provided to the OLT via either: 1) a physical timing interface (e.g., synchronous Ethernet) (frequency only) 2) IEEE 1588 + synchronous Ethernet 3) IEEE
28、1588 + non-synchronous Ethernet 4) Physical ToD interface + synchronous Ethernet. Frequency and/or time of day (ToD) synchronization is supplied from the ONU via either: 1) a physical timing interface (e.g., synchronous Ethernet) (frequency only) 2) IEEE 1588 + synchronous Ethernet 3) IEEE 1588 + no
29、n-synchronous Ethernet 4) a physical ToD interface + synchronous Ethernet. The use cases are described in terms of various combinations of these synchronization inputs and outputs as shown in Table V.1. Table V.1 G-PON synchronization use Use case Network synchronization to OLT UNI synchronization f
30、rom ONU 1 SyncE (frequency only) SyncE (frequency only) 2 IEEE 1588 and SyncE IEEE 1588 and SyncE 3 IEEE 1588 IEEE 1588 4 IEEE 1588 IEEE 1588 and SyncE 5 IEEE 1588 and SyncE ToD interface and SyncE 6 IEEE 1588 ToD interface and SyncE 7 ToD interface and SyncE ToD interface and SyncE Figure V.1 depic
31、ts use case 1 where frequency only is transferred through the G-PON network. The clock interface at the OLT input and the ONU output is a physical timing interface such as synchronous Ethernet (SyncE), defined in b-ITU-T G.8262. The OLT synchronizes the PON line rate to this physical interface. The
32、ONU outputs a physical timing interface such as synchronous Ethernet which is synchronous to the PON line rate. Rec. ITU-T G.984.1 (2008)/Amd.2 (04/2012) 3 Figure V.1 Using synchronous Ethernet in G-PON (use case 1) There are several use cases of interest which use IEEE 1588 (use cases 2 to 6), with
33、 the following assumptions. The PRC provides a frequency reference. The OLT network interface is Ethernet, with the Ethernet line rate either synchronous to a network frequency reference (synchronous Ethernet) or not synchronous to a network frequency reference. The OLT obtains time of day using IEE
34、E 1588, usually through intervening nodes between the OLT and the PRC. The OLT synchronizes to the network frequency reference either using synchronous Ethernet, IEEE 1588, or some other physical layer synchronous interface. The OLT transfers the time of day to the ONU using the method specified in
35、clause 10.4.6 of Amendment 2 to ITU-T G.984.3. The OLT transfers the network frequency reference to the ONU via its downstream line rate, which is synchronous to the network frequency reference. The ONU user interface is Ethernet, with the Ethernet line rate either synchronous to a network frequency
36、 reference (synchronous Ethernet) or not synchronous to a network frequency reference. The ONU may also have a physical time interface (e.g., 1 pps). G.984.1(08)-Amd.2(12)_FV.2aRNCITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ONUONUONUONUNode BNode BNode BNode BSyncESyncESyncESyncE1588158815881588
37、ETHETHETHETH1588 andSyncE1588 andSyncEMasterETHETHPacketnetworkOLTSlaveSlaveSlaveSlaveMasterMasterMasterMasterITU-TG.984.3SlaveITU-T G.984.3GrandmasterclockFigure V.2a PTP use case 2: ONU as IEEE 1588 master, OLT as IEEE 1588 slave, with SyncE at both SNI and UNI 4 Rec. ITU-T G.984.1 (2008)/Amd.2 (0
38、4/2012) G.984.1(08)-Amd.2(12)_FV.2bRNCITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ONUONUONUONUNode BNode BNode BNode B1588158815881588ETHETHETHETH15881588MasterETHETHPacketnetworkOLTSlaveSlaveSlaveSlaveMasterMasterMasterMasterITU-TG.984.3SlaveITU-T G.984.3GrandmasterclockFigure V.2b PTP use case
39、 3: ONU as IEEE 1588 master, OLT as IEEE 1588 slave, without SyncE G.984.1(08)-Amd.2(12)_FV.2cRNCITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ONUONUONUONUNode BNode BNode BNode BSyncESyncESyncESyncE1588158815881588ETHETHETHETH15881588MasterETHETHPacketnetworkOLTSlaveSlaveSlaveSlaveMasterMasterMas
40、terMasterITU-TG.984.3SlaveITU-T G.984.3GrandmasterclockFigure V.2c PTP use case 4: ONU as IEEE 1588 master, OLT as IEEE 1588 slave, with SyncE at UNI Figures V.2a and V.2b show use cases 2 and 3 for wireless backhaul, respectively. The OLT has an IEEE 1588 slave port at the SNI, which obtains the ti
41、me of day from the network. This time of day is passed to the ONU as described above, and the ONU passes the time of day from an IEEE 1588 master port to node B. If the OLT network feed is synchronous Ethernet (use case 2), then the OLT will synchronize its downstream PON line rate to the synchronou
42、s Ethernet line rate; otherwise the OLT will synchronize its downstream PON line rate to the IEEE 1588 time of day (use cases 3). If the link between the ONU and node B is synchronous Ethernet (use cases 2), then the synchronous Ethernet line rate will be synchronized to the downstream PON line rate
43、. Synchronous Ethernet ESMC messages would be used in conjunction with the synchronous Ethernet to indicate clock quality. Figure V.2c illustrates use case 4 where the OLT does not receive synchronous Ethernet and derives the downstream PON line rate from 1588. In this case the ESMC messages would c
44、orrespond to the 1588 clock quality and not a clock quality received via ESMC at the OLT. Rec. ITU-T G.984.1 (2008)/Amd.2 (04/2012) 5 Figures V.3a and V.3b show use cases 5 and 6 for wireless backhaul, respectively. The only difference between Figure V.2 and Figure V.3 is that the ONU has a physical
45、 interface for transferring time to node B, such as a ToD interface. If the OLT network feed is synchronous Ethernet (use case 5), then the OLT will synchronize its downstream PON line rate to the synchronous Ethernet line rate; otherwise the OLT will synchronize its downstream PON line rate to the
46、IEEE 1588 time of day (use cases 6). NOTE The details of the physical ToD interface are FFS. Figure V.4 shows use case 7, where a physical ToD interface is provided as an input to the OLT. The OLT processes the ToD information and sends timing information to the ONU according to the description prov
47、ided in clause 10.4.6 of Amendment 2 to ITU-T G.984.3. The ONU processes the received timing information and outputs the timing information using a physical ToD interface. G.984.1(08)-Amd.2(12)_FV.3aRNCITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ONUONUONUONUToD and SyncEETHETHETHETH1588 andSyncE
48、1588 andSyncEMasterETHETHPacketnetworkOLTITU-TG.984.3SlaveITU-T G.984.3GrandmasterclockToD and SyncEToD and SyncEToD and SyncENode BNode BNode BNode BFigure V.3a PTP use case 5: ONU with a physical time interface, OLT as IEEE 1588 slave, with SyncE at both SNI and UNI G.984.1(08)-Amd.2(12)_FV.3bRNCI
49、TU-TG.984.3ITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ONUONUONUONUToD and SyncEETHETHETHETH1588 1588MasterETHETHPacketnetworkOLTITU-TG.984.3SlaveITU-T G.984.3GrandmasterclockToD and SyncEToD and SyncEToD and SyncENode BNode BNode BNode BFigure V.3b PTP use case 6: ONU with a physical time interface, OLT as IEEE 1588 slave, with SyncE at UNI 6 Rec. ITU-T G.984.1 (2008)/Amd.2 (04/2012) G.984.1(08)-Amd.2(12)_FV.4RNCITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ITU-TG.984.3ONUONUONUONUToD and SyncEETHETHETHETHMasterETHETHPacketnetworkOLTIT
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