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ITU-T Study Group 15 executive summary

​19-30 September 2016
ITU-T Study Group 15
Networks, Technologies and Infrastructures for Transport, Access and Home
Study Group 15 Chairman: Stephen Trowbridge

Study Group 15 held its sixth and final meeting of the 2013-2016 study period in Geneva from 19-30 September 2016, attended by 267 delegates representing 34 countries.

The meeting received 341 contributions and 438 TDs, a slight decrease from the previous meeting. The meeting observed the 12-day contribution deadline of revised Recommendation ITU-T A.1, and nearly all of the contributions to this meeting were submitted using Direct Document Posting (DDP).

SG15 approved two new Amendments, determined two texts (one new Amendment and one revised Recommendation), consented 52 texts (7 new Recommendations, 18 revised Recommendations, 12 Amendments, and 15 Corrigenda). Agreement was reached on one Amendment and two new Supplements, and on the proposed deletion of one Recommendation.

Several noteworthy accomplishments include:

  • application extension over coax wires
  • Dynamic Time Assignment (DTA) specification
  • Update of optical fibre Recommendations G.652, G.654 and G.657, as well as the new supplement G. Suppl.59 related to optical fibre reliability.
  • New enhanced primary reference time clock (PRTC) specification enhanced PRTC, G.8272.1 /Y.1367.1.
  • New Recommendation G.7701 on Common Control Aspects.
  • New "Flexible OTN" short-reach specification to provide OTN client interfaces beyond 100G.

SG15 authorized 16 interregnum face-to-face Rapporteur group meetings to be held prior to the first SG15 plenary of the 2017-2020 study period, 17 virtual meetings, and generated 39 liaison statements. The first plenary meeting of SG15 in the 2017-2020 study period is provisionally scheduled 19-30 June 2017 in Geneva.

In fulfilling its lead study group responsibilities, SG15 revised the Access Network Transport (ANT) standards overview and work plan, the Optical Transport Networks and Technologies (OTNT) standardization work plan, the Home Network Transport (HNT) Standards Overview and Work Plan, and the Smart Grid standards overview and work plan.

As this meeting followed the final meeting of TSAG for this study period, most of the SG15 preparation for WTSA-2016, including developing draft updates of question texts and updates to the responsibilities and mandates of SG15 as specified in WTSA Resolution 2 had been completed in the February 2016 meeting.

Executive reports from WP Chairmen

WP1/15 – Transport aspects of access, home and smart grid networks
WP1/15 Chairman: Tom Starr

Q1/15 updated the Access Network Transport (ANT) Standards Overview and Work Plan documents. The Home Network Transport (HNT) Standards Overview and Work Plan document was revised. The list of CIT activities in other organizations related to technologies based on recommendations from WP1/15 was updated.

Q2/15 worked on Passive Optical Networks (PON), producing amendments and revisions for G.98x series Recommendations.  Work also progressed on G.RoF, G.989.2 Am2, and G.989.3 Am1.  Future work is planned for XGS-PON reach extenders, and PON transmission faster than 10 Gbps.

Q4/15 focused on, VDSL2 and the related PLOAM Recommendations, providing many improvements including the operation of over coax wires and DTA (dynamic time assignment). 

Q15/15 work on Smart Grid recommendations focused on G.9901, G.9903, G.9904.1, and the Smart Grid Standardization Work Plan.  

Q18/15 worked on the family of recommendations and Visible Light Communication (VLC) systems.

WP2/15 – Optical technologies and physical infrastructures
WP2/15 Chairman: Francesco Montalti

Q 5/15 worked on the revision of G.652 and G.657 addressing the items of spectral attenuation over a wider range, new chromatic dispersion values and statistical specifications approach. In the revised G.654 a new fiber G.654.E for terrestrial links has been standardized. The revision of Recommendations G.650.1 and G.650.3 on measurement methods will be carried out in the next study period.

Q6/15 finalized the revision of Recommendation G.697 "Optical monitoring for dense wavelength division multiplexing systems", taking also into account the progress in Q7/15 regarding the revision of Recommendation G.663. The current highest priority of Q6/15 is to establish sets of parameters and associated values to enable multi-vendor interoperability for the various modulation formats for 40G and 100G application codes in a revision of G.698.2. This activity requires contributions from vendors and Telecom operators. In the next study period the activity on G.metro will continue, and revisions of G.695 and G.959.1, adding interface specifications reusing 200G and 400G components developed for IEEE P802.3bs has been planned.

Q7/15 made progress in the preparation of the new Recommendation L.fmc "Field mountable single-mode optical fibre connectors", towards consent at the next SG15 meeting. A draft Amendment to G.663 containing a new Clause II.3.4 in the Appendix II was produced for agreement at this meeting. The current priority of Q7/15 is to progress towards the revision of G.671 and G.672, to enhance the text and parameter definitions to allow for flexible grid applications.
Q8/15 finalized the revisions of G.973 "Characteristics of repeaterless optical fibre submarine cable systems" considering 100 G applications for submarine systems, G.979 "Monitoring system for optical fibre submarine cable systems", G.971 "General features of optical submarine cable systems", G.972 "Definition of terms relevant to optical fibre submarine cable systems" for consent at this meeting. It was decided to start the study on the standardization of longitudinal compatibility for repeatered submarine cable systems and create a new Recommendation as G.977.1  "Longitudinally compatible DWDM applications for repeatered optical fibre submarine cable systems", referring to G.973.1.

Q16/15 finalized the development of new Recommendation L.162/L.coi "Microduct technology and its applications" and a revision of the Recommendation L.155/L.83 "Low-impact trenching technique for FTTx networks." Progress was made on the new Recommendations, L.cci "Criteria for optical cable installation with minimal existing infrastructure", L.dsa "Optical fibre cables for direct surface application", L.oxcon "Requirements for passive optical nodes: Outdoor optical cross connect cabinet" and L.pneid "Passive node elements with automated ID tag detection". Correspondence activities have been planned for developing each document toward consent at SG15 meetings to be held in 2017 and 2018. Progress was made also on the revision of other L. series Recommendations. Three new work item proposals were reviewed, and the proposal to create a new Recommendation "Requirements for Passive Optical Nodes: Fiber Distribution Box" was endorsed. 

Q.17/ 15 addressed the discussion about the draft new Recommendations L.nrr-frm and L.wdc. Regarding L.nrr-frm "Framework of disaster management for network resilience and recovery", it became clear the impossibility to improve the technical substance of L.nrr-frm because of the first-level objective of this document. According to some proposal the Recommendation was transformed into a Supplement with appropriate refinement for the agreement to the June 2017 meeting. The provisional name was changed as "L-300series.sup.nrr-frm". The draft new Recommendation L.wdc "Water detection in underground closures for the maintenance of optical fibre cable networks" was also discussed, proposed modification and new appendix were agreed. Q.17/15 also agreed to continue to discussion toward future new work items concerning Live fibre detection in PONs and Maintenance, inspection and repair of supporting infrastructures.

WP3/15 – Transport network characteristics
WP3/15 Chairman: Ghani Abbas

In its sixth and final meeting in the current study period WP3 had a very busy and productive meeting. It has successfully progressed the work on a number of Recommendations and produced twenty-one documents for consent and one supplement for agreement. WP3 produced 17 liaisons and agreed four new work items addressing "Flexible OTN (FlexO) frame formats for long-reach interface", "Frame format and HD FEC for OTU4 Long Reach metro applications", "Enhanced Primary Reference Clock" and " Synchronization OAM requirements". We have scheduled five interregnum meetings and a number of correspondence activities to progress our work.

In fulfilling its Optical Technology and Optical Transport Network coordination role, WP3/15 updated the Optical and other Transport Networks & Technologies Standardization Work Plan. Additionally, a revised Recommendation G.870 "Terms and definitions for OTN" and G.8101 "Terms and definitions for MPLS transport profile" were consented. We have also consented a new Recommendation G.808 "Terminology for protection and restoration".

In the area of network restoration and protection we have consented an amendment to G.8131 "MPLS-TP linear protection", which provides support for pseudowire (PW) protection and modifications to the references of terms. We have also consented an amendment to G.8032 "Ethernet Ring Protection", which provides support for management information. We have also agreed a G. Supplement 60 ""Ethernet Linear Protection Switching with Dual Node Interconnection". Additionally, we progressed the work on ODU shared mesh protection (ODU SMP).

In the area of interfaces, OAM and packet equipment, we consented a revised Recommendation G.8011 "Ethernet Service Characteristics", a revised G.8021 "Characteristics of Ethernet transport network equipment functional blocks "and an amendment to G.8012 "Ethernet UNI and Ethernet NNI". We have also consented corrigendum to MPLS series of recommendations (G.8113.1, G.8121, G.8121.1 and G.8121.2).

In the area of Interfaces for Optical Transport Network (OTN), we have consented an amendment to Recommendation G.709 which provides extension to the current recommendation G.709. Additionally, an amendment to Recommendation G.798 "Characteristics of optical transport network hierarchy equipment functional blocks" was consented.

In the area of transport network architecture, a revised Recommendation G.872 "Architecture of optical transport networks" was consented. We also consented a new Recommendation G.7701 "Common Control Aspects".

Significant progresses was also made on time and frequency synchronization with the consent of 2 new Recommendations, G.8266, (telecom grandmaster clocks for frequency synchronization), and G.8272.1 (Enhanced Primary Reference Time Clock) and the revision of G.8273.2  (telecom boundary clocks and telecom time slave clocks). Corrigendum to G.8262 and G.813 were also consented.

Progress was also made on studies of future synchronization requirements and on topics of common interest with other questions such as synchronization management where an Appendix dealing with Management view of the synchronization network included in the revised G.7711, PTP transport over OTN and the distribution of time synchronization over the access network.

In the area of Management and control of transport systems and equipment, we have consented a revised G.874.1 "Optical transport network (OTN): Protocol-neutral management information model for the network element view",  a revised recommendation G.7711 "Generic protocol-neutral information model for transport resources" and G.8052 "Protocol-neutral management information model for the Ethernet Transport capable network element" , a new recommendation G.8152 "Protocol-neutral management information model for the MPLS-TP network element" and an amendment to  G.7710 " Common equipment management function requirements".