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.989.1 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 1 (08/2015) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Optical line systems for local an
2、d access networks 40-Gigabit-capable passive optical networks (NG-PON2): General requirements Amendment 1 Recommendation ITU-T G.989.1 (2013) Amendment 1 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100
3、G.199 GENERAL CHARACTERISTICS COMMON 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 INT
4、ERCONNECTION 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 TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 General G.
5、900G.909 Parameters for optical fibre 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
6、.949 Digital line systems G.950G.959 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.989 Metallic access networks G.990G.999 MULTIMEDIA QUALITY OF SERVIC
7、E AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS 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 Recommendati
8、ons. Rec. ITU-T G.989.1 (2013)/Amd.1 (08/2015) i Recommendation ITU-T G.989.1 40-Gigabit-capable passive optical networks (NG-PON2): General requirements Amendment 1 Summary Amendment 1 to Recommendation ITU-T G.989.1 (2013) provides additional information on protection and/or restoration in NG-PON2
9、 networks using flexible wavelength scheduling, which is not covered in clause 9.4, as well as other new requirements of the ITU-T G.989-series systems not captured in ITU-T G.989.1 (2013). Requirements identified for inclusion in this amendment are: Network protection in the case of a multi-wavelen
10、gth access system. In particular, the possibility of ODN topologies that appear to be type B (shared splitter), but that provide additional capabilities. Also, the potential for 1:n protection in addition to the 1:1 protection previously described. Transport of wireless fronthaul links over the acce
11、ss system. Such links have exceptional service requirements and these are evolving as the application develops in the industry. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.989.1 2013-03-09 15 11.1002/1000/11810 1.1 ITU-T G.989.1 (2013) Amd. 1 2015-08-13 15 11.1002/1000
12、/12557 _ * 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.989.1 (2013)/Amd.1 (08/2015) FOREWORD The International Telecommun
13、ication 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 technical, operating and tariff
14、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 which, in turn, produce Recommenda
15、tions 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 Recommendati
16、on, 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
17、 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 does not suggest that complian
18、ce 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 concerning the evidence, validity or
19、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, which may be required to impl
20、ement 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 publication may be reproduced, by any m
21、eans whatsoever, without the prior written permission of ITU. Rec. ITU-T G.989.1 (2013)/Amd.1 (08/2015) iii Table of Contents Page 1) Clause 2, References . 1 2) Clause 3, Definitions 1 3) Clause 4, Abbreviations and acronyms 1 4) Clause 7.6, High data rate services . 1 5) Clause 9.4, Resilience and
22、 redundancy requirements 1 6) Clause 9.6, Power reduction . 9 7) Clause 9.12, Transport of wireless fronthaul links over the access system 11 8) Appendix I, OLT resilience configuration 12 9) Appendix II, Transmission technique for mobile fronthaul . 13 10) Bibliography . 13 Rec. ITU-T G.989.1 (2013
23、)/Amd.1 (08/2015) 1 Recommendation ITU-T G.989.1 40-Gigabit-capable passive optical networks (NG-PON2): General requirements Amendment 1 1) Clause 2, References Add the following new reference to clause 2: ITU-T G.989 Recommendation ITU-T G.989 (2015), 40-Gigabit-capable passive optical network (NG-
24、PON2): Definitions, abbreviations and acronyms. 2) Clause 3, Definitions Replace clause 3 with the following text: See ITU-T G.989 for the definitions used in this Recommendation. 3) Clause 4, Abbreviations and acronyms Replace clause 4 with the following text: See ITU-T G.989 for the abbreviations
25、and acronyms used in this Recommendation. 4) Clause 7.6, High data rate services Add new clause 7.6 with the following text: 7.6 High data rate services To accommodate the prospective increase in customer bandwidth demand, NG-PON2 systems may support an optional extension for services in excess of 1
26、0 Gbit/s upstream and/or downstream towards one PON client. 5) Clause 9.4, Resilience and redundancy requirements Replace clause 9.4 with the following text: 9.4 Resilience and redundancy requirements PON resilience will become more important in supporting business applications and high value consum
27、er applications, such as IPTV, especially in the node consolidation scenario. Node consolidation/bypass creates a high number of subscriber lines on the highly centralized access node. A redundancy mechanism is required to avoid service disruption to potentially thousands of users in the event of fi
28、bre cable or equipment failure. Besides the usual hardware redundancy requirements at the OLT and in the backhaul transmission equipment (towards the metro/core), networks require feeder and/or OTL line redundancy options to avoid large scale customer outages as well as full redundancy for business
29、services requiring end-to-end type C protection. NG-PON2 systems must support the resilience options defined in clause 14 of ITU-T G.984.1 including duplex and dual parenting duplex system configuration as well as the extensions described in Appendices II and III of ITU-T G.984.1. For PON redundancy
30、, use cases and guidelines are defined in b-ITU-T G-Sup.51. 2 Rec. ITU-T G.989.1 (2013)/Amd.1 (08/2015) Figure 9-1 shows an example of fibre path diversity ensuring resilience against cuts in the most vulnerable part of the access network. The redundant feeder fibre could terminate at a diverse CO l
31、ocation, or at the same CO location as the primary OLT. G . 9 8 9 . 1 ( 1 3 ) _ F 9 - 1N G - P O N 2O L TS pl i t t e rN G - P O N 2ONUN G - P O N 2O L TS e c on da r y O L T ( O pt i on a l )P r i m a r y O L TFigure 9-1 NG-PON2 resilience scenario Redundant splitters, especially in the highest lev
32、el of hierarchy, may also be deployed and should be supported. Typically, redundancy requirements become less stringent for the customer premises, unless the end customer is, for example, a large scale enterprise or premium user. In the redundant architecture, rapid restoration may be required. For
33、instance, service interruption time must be less than 50 ms for enterprise or premium users. The following subclauses show examples of network protection in the case of multi-wavelength access systems. 9.4.1 Type B protection Transceiver faults occur frequently in some scenarios and feeder fibre fau
34、lts may occur in other scenarios. In type B protection, OLTs or OLT channel terminations (CTs) and feeder fibres are protected. Figure 9-2 Type B protection 1:1 model with dual homing Figure 9-2 shows the 1:1 model of type B protection with dual parenting. The recovery procedure is the same as for t
35、ype B protection of GPON/XG-PON. The backup OLT is a copy of the working OLT. All backup OLT CTs must be turned off until the protection switchover occurs. Rec. ITU-T G.989.1 (2013)/Amd.1 (08/2015) 3 Figure 9-3 Type B protection 1:1 model with single backup CT As shown in Figure 9-3, the backup OLT
36、includes a designated OLT CT to protect the working OLT CTs. When a protection switchover is triggered, the ONUs tune to the wavelength pair supported by the backup OLT CT. The backup OLT CT must be turned off until the protection switchover occurs. 4 Rec. ITU-T G.989.1 (2013)/Amd.1 (08/2015) Figure
37、 9-4 Type B protection 1:n model (a) CT failure, (b) feeder fibre failure Figure 9-4 shows the architecture of 1:n type B protection. The backup OLT consists of an OLT CT with a tunable transceiver to protect all working OLT CTs. When a working OLT CT fails, the backup OLT CT tunes its wavelength ch
38、annels to protect the failed OLT CT, as shown in Figure 9-4(a). The ONUs associated with the failed working OLT CT can remain unchanged. When the feeder fibre from a working OLT CT fails as shown in Figure 9-4(b), all ONUs must tune to the wavelength channels supported by the backup OLT CT. Rec. ITU
39、-T G.989.1 (2013)/Amd.1 (08/2015) 5 Figure 9-5 Type B protection 1:n model with dual parenting Figure 9-5 shows the 1:n type B protection with dual parenting. The backup OLT supports the same wavelength channels as the working OLTs. When any failure occurs in a working OLT or a feeder fibre, the bac
40、kup OLT continues the PON operation with the associated ONUs. 9.4.2 Type C protection For Type C protection, which is a full duplex system (1+1 model), the ONU has two tunable transceivers as shown in Figure 9-6. Accordingly, recovery from failure at any point is possible by switching to the standby
41、 facilities. In order to simplify protection management and for fast service configuration, the same wavelength configuration of the working TWDM channel and the backup TWDM channel is recommended. In Figure 9-7, the ONU chooses one tuneable wavelength transceiver plus one fixed wavelength transceiv
42、er for backup. In this case, a dedicated wavelength of the tuning range for the backup PON port is allocated to protect the working PON. In addition, if the ONU adopts a two MAC chipsets architecture in type C protection, the ONU can simultaneously activate to both the working OLT PON and the backup
43、 OLT PON via two PON MACs and two transceivers. The service recovery time could be less than 50 ms. 6 Rec. ITU-T G.989.1 (2013)/Amd.1 (08/2015) Figure 9-6 Type C protection 1+1 model with two tunable transceivers in ONUs Figure 9-7 Type C protection 1+1 model with one tunable transceiver and one fix
44、ed transceiver in ONUs 9.4.3 Type W protection In type W protection, which is the newly defined category in this Recommendation, only the OLT (or OLT CT) is protected. In some cases, type W protection is achieved by using wavelength tuning in ONUs. Rec. ITU-T G.989.1 (2013)/Amd.1 (08/2015) 7 Figure
45、9-8 Type W protection - 1:n model with backup OLT CT Figure 9-9 Type W protection 1:n model with all active OLT CTs The 1:n model of type W protection is shown in Figure 9-8. In the TWDM system, one of the OLT CTs is configured to be the backup OLT CT for other working OLT CTs. CT4 in Figure 9-8 is
46、set to be the backup OLT CT. When any failure occurs in a working OLT CT, the affected ONU tunes to the associated backup TWDM channel based on the pre-configuration information stored in the ONU. Figure 9-9 shows another 1:n model of type W protection. This protection feature is inherent in the nat
47、ure of NG-PON2 ONU wavelength tunability. All OLT CTs are active during operation. Each OLT CT can protect the other OLT CTs. If an OLT CT fails, its ONUs tune to wavelengths associated with other OLT CTs. In Figure 9-9, OLT CT3 fails and it is protected by OLT CT4. In another approach with a shorte
48、r protection time, the backup channels can be pre-configured in the ONUs. When a failure occurs, the affected ONUs can tune to the backup channels without waiting for the OLT instructions. 8 Rec. ITU-T G.989.1 (2013)/Amd.1 (08/2015) Figure 9-10 Type W protection (n+1):n model The (n+1):n model of ty
49、pe W protection is shown in Figure 9-10. A dedicated OLT CT with a tunable transceiver is configured to be the backup OLT CT. When a working OLT CT fails, the backup OLT CT (tunable transceiver) tunes to the same wavelength channel as the working OLT CT. In order to avoid rogue OLT behaviors, the backup OLT CT tunes its wavelengths only after recognizing the working OLT CT failure. The model does not require any ONU operation in protection switchover. Figure 9-11 Type W protec
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