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ITU-T Study Group 15 executive summary

15-26 February 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 fifth meeting of the 2013-2016 study period in Geneva from 15-26 February 2015, attended by 258 delegates representing 27 countries.
The meeting received 362 contributions and 488 TDs, a slight increase 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 one new Recommendation, one revised Recommendation and three amendments, determined two new amendments, re-initiated the approval process on two new amendments, and consented 44 texts (three new Recommendations, fifteen revised Recommendations, 18 amendments, and eight corrigenda). Agreement was reached on one new and three revised supplements, and re-publication of an in-force Recommendation with amendments incorporated.
Several particularly noteworthy accomplishments include:
-   ITU-T experts boost Optical Transport Network beyond 100G
-   ITU-T achieves industry first with new standards for 40 Gbit/s fibre to the home
-   New ITU-T standard for 10 Gbit/s symmetric fibre to the home
SG15 authorized 14 interim Rapporteur group meetings to be held prior to the next SG15 plenary, 15 virtual meetings, and generated 43 liaison statements.
The next plenary meeting of SG15 will be held 19-30 September 2016 in Geneva.
In fulfilling its lead study group responsibilities, SG15 revised the Access Network Transport (ANT) standards overview and work plan, revised the Optical Transport Networks and Technologies (OTNT) standardization work plan, and revised the Home Network Transport (HNT) Standards Overview and Work Plan. The Smart Grid standards overview and work plan remained unchanged in this meeting
During this meeting, SG15 continued the process of preparing for WTSA-2016, developing draft updates of question texts and updates to the responsibilities and mandates of SG15 as specified in WTSA Resolution 2 to forward to the final meeting of TSAG for this study period. SG15 also responded concerning the TSB director’s “food for thought” study group structure proposal.

Executive reports from WP Chairmen

WP1/15 – Transport aspects of access, home and smart grid networks
WP1/15 Chairman: Tom Starr
Proposed updates to the text describing the Questions WP1/15 were prepared.
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 and providing G.9807.1 (XGS-PON) for Consent. Work also progressed on G.RoF, G.989.2 Amd.2, and G.989.3 Amd.1. Future work is planned for 25 Gbit/s PON.
Q4/15 focused on G.fast, VDSL2 and the related PLOAM Recommendations, producing amendments and corrigenda for consent. In joint work with Q18/15, G.9977 was prepared for approval.
Q15/15 work on Smart Grid recommendations focused on G.shp6, G.9903, and G.primex. Q15/15 requested the appointment of a new Associate Rapporteur - Paolo Treffiletti (ST Microelectronics), replacing Mr Thierry Lys.
Q18/15 worked on the G.hn family of recommendations, G.9977, G.9979 Amd.1, and Visible Light Communication (VLC) systems.

WP2/15 – Optical technologies and physical infrastructures
WP2/15 Chairman: Francesco Montalti
Q5/15: The activity addressed the revision of the single-mode fibre Recommendations G.652, G.654 and G.657 that are expected to go to consent at the September 2016 SG15 meeting.
The revision of G.652 and G.657 addressed the items of spectral attenuation over a wider range, launching conditions for measurements on G.657 fibres, new chromatic dispersion values and statistical specifications approach. It was agreed to continue discussion on statistical treatment of chromatic dispersion and attenuation.
Regarding the new fibre category G.654.E for terrestrial applications, there was an agreement on geometric and transmission characteristics. It was decided not to introduce a maximum attenuation at 1625 nm in this version, and continue discussion including the applicability of link design attenuation.
Q5/15 agreed to maintain G.651.1 on multimode fibres and requested additional information on the current deployment condition of this kind of fibres.
The Recommendations on measurement methods – G.651.1, G.650.1 and G.650.3 – were discussed and are expected to be consented at the first meeting in the next study period, as well as a revised G.Suppl-40.
The latest draft of new G.Suppl-fcr, “Optical Fibre and Cable Reliability Guidelines”, was discussed and agreed to continue a correspondence activity in order to reach agreement at the September 2016 SG15 meeting.
Q5/15 prepared a base for discussion for the joint meeting with Q6/15 about chromatic dispersion characteristics of G.652 fibre, G.654.E fibre for terrestrial use, and a new work item of Space Division Multiplexing (SDM). Regarding this last topic it was found difficult to consider a conceptual document under responsibility of Q5/15 and Q6/15 at this time, however, the meeting welcomed further contributions for information.
Q6/15 finalized revised G.959.1, “Optical transport network physical layer interface”, for consent and G.Suppl.39, “Optical system design and engineering considerations”, for agreement at this meeting.
Progress on the revision of G.697, “Optical monitoring for dense wavelength division multiplexing systems”, was made for a possible consent at the September 2016 SG15 meeting, taking also into account the progress in Q7/15 regarding the revision of G.663.
Regarding the new Recommendation G.metro, “Multichannel bi-directional DWDM applications with port agnostic single-channel optical interfaces”, the activity was focussed on the establishment of sets of parameters and associated values to enable multi-vendor interoperability for low-cost metro applications on the basis of port-agnostic endpoints.
Activities on the revision of G.698.2, G.959.1 and G.Suppl.39 will continue.
Q7/15 made progress in the preparation of the new L.fmc, “Field mountable single-mode optical fibre connectors”, and in the revision of the Appendix 2 of G.663, “Application related aspects of optical amplifier devices and subsystems”, toward a consent at the September 2016 SG15 meeting.
Q8/15 progressed in the discussion on the revision of G.973, “Characteristics of repeaterless optical fibre submarine cable systems”, considering 100 G applications for submarine systems, which is expected to be consented at the September 2016 SG15 meeting.
Also revised 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”, are expected to be consented at the September 2016 SG15 meeting.
A possible new work item of using submarine cable network for climate monitoring and disaster prediction was presented by ITU/WMO/UNESCO IOC JTF. After discussion, it was concluded that it seems premature from both technological and commercial points of view to create a new Recommendation at this moment. At the same time, it was agreed to keep attention on this technology for future standardization work.
Q16/15 finalized the revision L.59, “optical fibre cables for indoor applications”, for consent with the new Recommendation number L.103.
Progress was made on the new Recommendations L.91, "Microducts technology and its application in the access network"; L.cci, “Installation with minimal infrastructures”; L.dsa, “Cables for direct surface applications”; L.oxcon, “Requirements for passive optical nodes: outdoor optical cross connect cabinet”; L.pneid, “Passive node elements with automated ID tag detection”.
Progress was made also on the revision of L.57, “Air assisted installation of optical fibre cables”; L.60, “Construction of optical/metallic hybrid cables”; and L.79, “Optical fibre cable elements for microduct blowing-installation application”.
L.83 Amd.1, “Low impact trenching technique for FTTx networks”, dealing with the “Effect of micro-trenches on road pavements” is expected to be prepared for Agreement at the September 2016 SG15 meeting.
In Q17/15, revised L.53, “Optical fibre maintenance depending on topologies of access networks” (now renumbered L.310), and the draft new Recommendation L.392 (formerly L.dm-nrr-mdru), “Disaster management for improving network resilience and recovery with movable and deployable ICT resource units”, were consented.
The new Recommendation L.nrr-frm, “Framework of disaster management for network resilience and recovery”, could not proceed to consent because of lack of contributions and will be considered for further improvement at the next meeting.
The proposal of the new classification of the L-series Recommendations by technical area and not chronologically was endorsed. Starting from this meeting the new/revised Recommendations will be published with the new numbering and a procedure for implementing the new numbering on the old recommendations has been agreed with the ITU-T secretariat.

WP3/15 – Transport network characteristics
WP3/15 Chairman: Ghani Abbas
In its fifth meeting in the current study period WP3/15 had a very busy meeting. It successfully progressed the work on a number of Recommendations and produced 22 documents for approval or consent and two supplements for agreement. WP3/15 produced 19 liaisons and reviewed, provided revised text of the Question texts for the next study period and agreed two new work items addressing “n x 100 Gbit/s FlexO Group Interfaces for the Optical Transport Network” and “OTN Module Framer Interfaces (MFI)”. WP3/15 scheduled six interim meetings and a number of correspondence activities to progress its 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, revised G.8001, “Terms and definitions for Ethernet frames over transport”, was consented.
WP3/15 made considerable progress on a number of transport network technology fronts, including OTN beyond 100G, FlexEthernet, nx100Gb/s FlexO Group Interfaces for the OTN, SDN in Transport networks, OTN and Ethernet protection, Ethernet OAM and Equipment specifications for Packet based Transport Networks, transport network architecture, time and frequency transport, generic and technology-specific transport equipment management requirements and information models.
In the area of network restoration and protection, WP3/15 consented an amendment to MPLS-TP linear protection which provides “Format of APC specific information”, “Descriptions about management information (MI) signals” and “Descriptions on trail protection architecture”. WP3/15 also agreed to work on MPLS-TP ring protection based on MPLS-TP shared ring protection work being done by the IETF MPLS WG . Additionally WP3/15 progressed the work on ODU shared mesh protection (ODU SMP) and agreed to develop a supplement for Multi-domain Segmented Protection (MDSP) Ethernet Dual Node Interconnection where solutions for multiple failures cases are described.
In the area of interfaces, OAM and packet equipment, WP3/15 consented a revised Recommendation G.8113.1 specifying OAM mechanisms for MPLS-TP in packet transport networks, and revised all Recommendations in the G.8121 series specifying the characteristics of MPLS-TP equipment functional blocks supporting protocol neutral constructs (G.8121), the tools defined in G.8113.1 (G.8121.1) and the tools defined in G.8113.2 (G.8121.2). WP3/15 also progressed the work on G.8021, “Ethernet Equipment”, in particular regarding functional modelling of the Ethernet PHY, and agreed to prepare a revision of G.8011, “Ethernet service characteristics”.
In the area of Optical Transport Network (OTN), WP3/15 has consented a revised Recommendation G.709 which includes the addition of beyond 100 Gbit/s OTU, ODU and OPU frame formats support for frequency and time synchronisation; additional client mappings; and optical layer terminology updates.
G.suppl-56, “OTN Transport of CPRI signals”, was revised to add CPRI Option 10 and agreed. A corrigendum to Recommendation G.806, “Characteristics of transport equipment - Description methodology and generic functionality”, updating SDL diagrams was also consented. Revised G.703, “Physical/electrical characteristics of hierarchical digital interfaces”, adding a synchronization interface was consented. Revised G.7041, “Generic Framing Procedure”, adding support for extended synchronization messaging was consented. New G.Suppl-58 for “OTN Module Framer Interfaces” was agreed.
Considerable progress was made on G.872, “Architecture of optical transport networks”, particularly with the G.709 revision, transport SDN, and common control aspects. A revised G.800, “Unified functional architecture of transport networks”, was consented.
Significant progress was also made on synchronization, in particular concerning PTP over OTN, SyncO, transport of frequency, time and phase over packet networks. In this area it was agreed to Consent the following:
-   G.8260 Amd.1, “Definitions and terminology for synchronization in packet networks”
-   G.8261 Cor.1, “Timing and synchronization aspects in packet networks”
-   G.8271 (revised), “Time and phase synchronization aspects of Packet Networks”
-   G.8264 Amd.2, “Distribution of timing information through packet networks”
-   G.8265.1 Cor.1, “ Precision time protocol telecom profile for frequency synchronization”
-   G.8275 Amd.2 “Architecture and requirements for packet-based time and phase delivery”
-   G.8275.1 (revised) “Precision time protocol telecom profile for phase/time synchronization with full timing support from the network”
-   G.8275.2, “Precision time Protocol Telecom Profile for time/phase synchronization with partial timing support from the network”
-   G.811 Amd.1, ” Timing characteristics of primary reference clocks”
-   G.8272 Amd.1, “Timing characteristics of primary reference time clocks”
In the area of Management and control of transport systems and equipment, WP3/15 produced the following:
-   Approval G.7712 Amd.2, “Architecture and specification of data communication network”
-   Consent of G.8151 Amd.1, “Management aspects of the MPLS-TP network element”
-   The work on the following topics was further progressed:
     -   Transport aspects of SDN and its control and management
     -   Enhancement to G.7710, “Common Equipment Management Requirements”
     -   Enhancement to G.7711, “Generic protocol-neutral information model for transport resources”
     -   Management of synchronization
     -   Management requirement and information/data models for OTN, Carrier Ethernet, and MPLS-TP, in particular to progress
     -   Draft new Recommendation G.8152/Y.1375, “Protocol-neutral management information model for the MPLS-TP transport NE