Executive Summary July 2024

​​​Montreal, Canada 1-12 July 2024
ITU-T Study Group 15
Networks, Technologies and Infrastructures for Transport, Access and Home
Study Group 15 Chair: Glenn Parsons

​Study Group 15 held its fourth meeting of the 2022-2024 study period in-person in Montreal, Canada 1-12 July 2024 at the kind invitation by ISED (Innovation, Science and Economic Development Canada / Government of Canada) with Ericsson Canada as the lead sponsor. It had more than 400 registrations and was attended by 326 delegates representing 35 countries. The in-person meeting was welcomed as a rapid means to build consensus.
The meeting received 343 contributions and 422 TDs. The meeting observed the 12-day contribution deadline of Recommendation ITU-T A.1, and almost all of the contributions to this meeting were submitted using Direct Document Posting (DDP).
SG15 approved three new Recommendations, consented 47 texts (3 new and 13 revised Recommendations, 28 Amendments, and 3 Corrigenda), and agreed 7 supplements, one technical report and one technical paper.
Interim activities prior to the next SG15 plenary have been planned as virtual or in-person, consisting of 35 single-day or multiple-day meetings.
In fulfilling its lead study group responsibilities, SG15 revised the Access Network Transport (ANT) standards overview and work plan, the Home Network Transport (HNT) Standards Overview and Work Plan, and the Optical Transport Networks and Technologies (OTNT) standardization work plan.
SG15 generated 39 Liaison Statements. These included an update to the JCA IMT-2020 concerning the IMT-2020 roadmap, and an update to ITU-T SG2 regarding the Telecommunication Management and OAM project plan.

WP1/15 – Transport aspects of access, home and smart grid networks
WP1/15 Chair: Tom Starr, Vice Chair: Ian Horsley
Q1/15 met for one day, updating the web-based Access Network Transport (ANT) Standards Overview and Work Plan documents. The web-based Home Network Transport (HNT) Standards Overview and Work Plan document was revised. The list of certification and interoperability activities for WP1/15 Recommendations was updated.

​Q2/15 met for four days, working on Passive Optical Networks (PON).  Three texts for consent and two Supplements for agreement were prepared. Q2/15 plans to hold four interim meetings.  One A.1 and two A.13 statements were prepared for new projects addressing PON security and fine grain service flows.  Q2/15 prepared a liaison to TSAG proposing that Q4/9 be merged into Q2/15 for the next study period.

Q3/15 met for four days, working on fibre indoor networks (G.fin) and other aspects of home networking.  Three Recommendations were prepared for approval and one Recommendation was prepared for consent. One Supplement was prepared for agreement. Q3/15 plans to hold three interim meetings. Two A.13 statements were prepared for new projects addressing premises networking for small and medium enterprise and integrated sensing in the premises.

Q4/15 met for one day addressing five contributions on broadband access over metallic conductors. Q4/15 updated its terms of reference in preparation of WTSA2024.  Q4/15 plans to hold one interim virtual meeting.

All the WP1/15 questions met jointly to progress a new technical paper summarizing the work and products of WP1/15.  An A.13 justification for this activity was produced and a joint virtual meeting is planned for December 2024.

WP2/15 – Optical technologies and physical infrastructures
WP2/15 Chair: Paul Doolan;  Vice-Chair: Sudipta Bhaumik

WP2/15 consented two new Recommendations, seven revisions , one amendment  and agreed four revised texts.
The two new Recommendations both come under the responsibility of Q8/15 :
G.9730.1 (ex. G.dsssc) : Dedicated scientific sensing submarine cable system.
G.9730.2 (ex. G.smart) : Scientific monitoring and reliable telecommunication submarine systems.
One of the agreed texts was the first revision of the technical report on Optical fibres, cables and systems (TR-OFCS) since 2015. The revision work was led by Vice Chair Sudipta Bhaumik and included contributions from all Questions in the Working Party. The WP2/15 work programme was updated, we agreed to begin development of a new Recommendation (Lnis) on “Practical considerations on network infrastructure sharing" and to new revisions of six other Recommendations.

Q5/15 consented revisions to L.101, L.103, G.652. G.654, G.657, and G.Suppl.40. The revision to G.652 is particularly noteworthy; the Recommendation itself is 40 years old, this latest revision provides new information on statistical O-band chromatic dispersion properties of links consisting of concatenated cables that is important for emerging high performance IM-DD applications. It is worth noting that the work done on this revision to G.652 benefitted from collaborative work between questions in WP1/15 and experts in IEEE. Q5/15 prepared three technical flyers on the revisions of G.652, G.654 and G.657.

Interim E-meeting and correspondence activities are planned to progress revision work on multiple Recommendations and on new G.Sup.G.65x which will be the 'Roadmap for SDM optical fibres concerning the development of G.65x series Recommendations'.

Q6/15 consented an amendment  of G.959.1 and made significant progress on many work items including distributed fibre optic sensing, free space optics and transmitter quality metrics for 800G applications. Q6/15 has agreed to a virtual RGM to progress the free space optics work (G.fso) and to an Interregnum meeting hosted by Huawei, that will take place in Hong Kong (China) from 18 to 22 November 2024. Five correspondence activities will take place in preparation for that meeting.

Q7/15 agreed a revision to LSTP-GLSR and progressed work on revisions of L.341, L.360 and L.pcc. As mentioned above Q7/15 decided to initiate a new Recommendation L.nis,  “Practical considerations for network infrastructures sharing".  The focus of this work will be to discuss technical considerations in a non-regulatory context and to identify what would be additional considerations for shared infrastructure versus infrastructure occupied by a single operator.

Correspondence activities are planned to progress revisions of L.341, L.360 and L.391 and to progress the new L.pcc and L.nis draft Recommendations.

Q8/15 consented revisions to G.971, G.972 and agreed a revision of G.Sup.41 in addition to the two new Recommendations mentioned earlier.
A revision of ITU-T G.979 “Characteristics of monitoring systems for optical submarine cable systems" was initiated and, along with revisions to G.976 and G.978 will be the subject of correspondence activities before the next plenary meeting of SG15.​

WP3/15 – Transport network characteristics
WP3 Chair: Malcolm Betts; WP3 Vice-Chair: Tom Huber
 
Q10/15 has initiated work on a new Recommendation that will simplify referencing of the IEEE 802.3 LAN/MAN Standards from other ITU Recommendations.

Q11/15 has continued to refine and enhance the suite of OTN Recommendations and has initiated a new work item on the definition of beyond 1 Tbit/s. (B 1T)

Q12/15 is continuing to work on the application of SDN to the transport network and the interfaces to AI/ML and Digital Twin applications.
Q12/15 updated the OTNT SWP

Q13/15 continued its work to enhance the accuracy and robustness of time and frequency distribution.
Q13/15 are starting to work on extending the ITU defined synchronization frameworks and profiles to apply to synchronization in data centres. This work is being undertaken in cooperation with IEEE P1588, IEEE P1952, IEEE P3335, IEEE IC Timing in Datacentre and OCP.

Q14/15 is continuing to extend the suite of management Recommendations to allow management of the new functions recently defined by Q10, Q11 and Q13./15
Q14/15 is continuing to work in cooperation with IEEE 802.1, IEEE 1588, IEEE 802.3, Linux Foundation ONMI, MEF, BBF, and IETF to provide consistent information models and YANG data models for transport networks, the current focus of this work is on the management of network synchronization and Ethernet.

Per Question highlights:

Q10/15 consented draft corrigenda to ITU-T G.8121 and ITU-T G.8121.1 (MPLS-TP equipment) and updated its Question text in alignment with preparation, towards consent in March 2025, of a new draft ITU-T G.eth (Ethernet) to make the IEEE 802.3 Ethernet standard available as an ITU-T Recommendation through referencing and avoid the need for A.5 qualification. Q10/15 also proposed three additional new work items that were agreed at this meeting towards consent in March 2025. A new draft amendment to ITU-T G.8121 was prepared adding support for reporting the state of linear and ring protection processes to equipment management functionality in support of related Q14/15 YANG work. New amendments to ITU-T G.8013/Y.1731 (OAM for Ethernet-based networks) and ITU-T G.8021 (Ethernet equipment) will be prepared the amendments will provide additional cross-referencing to facilitate interpretation of the specifications.

Q11/15 made significant progress on all of its agenda topics, with seven consented Recommendations and an agreed Supplement in addition to approving a total of ten new work items. Q11 continued its work associated with OTN for rates beyond 1 Tbit/s (B1T). B1T discussions were a significant focus of this meeting, resulting in one new work item on FlexO interfaces for B1T (e.g., 1.6 Tbit/s) long reach interfaces.  Additional B 1T work items are expected to be agreed at the next SG15 meeting.
Work on other topics included fine grain MTN (fgMTN), fine grain OTN (fgOTN), and FlexO.
The consented Recommendations include; a major amendment to G.798 that added new functional blocks to describe fgOTN and FlexO equipment; new G.808.4 on linear protection for fgOTN and fgMTN networks; an amendment to G.8312 on MTN interfaces that adds support for carrying fgMTN constant bit rate clients and hitless resizing for fgMTN packet clients; an update to the G.8312.20 MTN overview; updates to G.709.1 and G.709.5 on FlexO. In addition, revised G.Sup58 (Optical transport network module framer interfaces) adding FOIC1.2-RS interfaces was agreed.
Other new work items include; amendments to OTN interface Rec. G.709 associated with fgOTN; updates to FlexO Recommendations G.709.3, G.709.5 and G.709.6; amending Rec. G.8321 to include functional block information associated with the G.8312 amendment consented at this meeting; an update amendment to Rec. G.8023 related to clarification on fault propagation and references to IEEE 802.3 processes; updates to the Rec. G.709.20 and G.8312.20 the overviews of fgOTN and fgMTN, respectively.
In addition, a work item was approved to develop a new technical report GSTR.MTN to describe MTN.
Q11/15 plans to hold a face-to-face Interregnum meeting in November 2024 in Hong Kong.

Q12/15 consented a revision to G.807, this revision used an updated definition of OTSi that was developed in collaboration with Q6/15. This revision enhanced the description of signals over point to multipoint (PtMP) optical topologies. The functional architecture defined in G.800/G.807 was used to provided clarity of the issues of fgOTN over PtMP optical topologies and fibre sensing that were discussed with in other SG15 Questions.
Amendments were consented to management and control Recommendations G.7701, G.7702, and G.7703. Discussions on AI/ML/DT topics focussed on the importance of interfaces and data to/from applications using those technologies. This was joint work with Q14/15.
A new work item on an Amendment to G.8310 was initiated.
The OTNT Standardization Work Plan was updated and Issue 34 will be liaised to other SDOs.
Several liaisons were sent to SG11 on multiple issues and informed them of our work on SDN, slicing, and call/connection control as applied to transport networks.
A joint face-to-face interregnum meeting is planned with Q14 for 2-6 December 2024 in Geneva.

Q13/15 continued the work on requirements and solutions for time and frequency synchronization. Updates to several Recommendations have been consented at this meeting. Among these, the PTP profiles in G.8275 Amd1, G.8275.1 Amd2, G.8275.2 Amd2, G.8265.1 Amd1 including new parameters that can be used to enhance the management and monitoring of the sync network.

The use of Enhanced Accuracy metrics TLV is introduced in new Supplement Suppl.FTS. This is an important tool that can be used to report detailed PTP network performance characteristics.
The G.781 (synchronization layer functions for synchronization over the physical layer) was amended with further enhancements to the sync PHY dataset.
Time sync clocks (G.8262 Rev, G.8273.2 Amd1 and G.8273.3 Amd1, G.8273.4) have been updated, to include new interfaces that can be used to carry timing.
The consented G.8271 Amd1 includes new requirements for the transport of timing over 5G.
G.8251 Amd1 was consented including fgOTN requirements.
Work was progressed on other Recommendations planned for consent next year. Among these, the G.8271.1 (network limits for time synchronization over full timing support) with further analysis of network scenarios integrating sync over 5G.
Work continued on the new work item on Enhanced partial timing support (“ePTS") with solutions that can be used to control the asymmetries in the network.
Two new work items were approved: Sync in Data centres to enhance the solutions developed by Q13 over the last decades for use in Data centres applications. A liaison was sent to the relevant groups in IEEE and OCP to coordinate the work. Emeetings will be arranged to coordinate the work. The first Emeeting is planned for September 2024.
A new Technical Report will be developed to address the latest technology on optical clocks.
Liaison statements were sent to O-RAN to communicate the updates on the synchronization recommendations currently used in O-RAN, and to IEEE P1952 on the ongoing study on synchronization resiliency.
Joint meetings were held with Q14 on synchronization management and with Q11 on CBR over fgMTN.
Q13/15 plans to hold a face-to-face Interregnum meeting in November 2024 in Hong Kong.

Q14/15 consented 9 Recommendations including work on OTN, Ethernet, MPLS-TP, and Sync management.  Work continues to progress efforts on common equipment management, architecture and information modelling for the management-control components and functions.  Nine new work items were started to continue the work to enhance the information and data modelling to remain in lockstep with the protocol work on-going in Q10, Q11, and Q13. Work on a new supplement was started to capture the modelling considerations for optical media networks.
Several liaisons were sent, including to all our partners announcing the continuation of the coordination on information and data modelling.  A liaison was sent to O-RAN to provide information related to synchronization modelling, including the Recommendations consented at the July plenary and those planed for the March 2025 plenary.
Q14 will continue to coordinate with Q13 progress the work on SyncPhy modelling and YANG development.

Q14 has planned 4 sets of 2-hour interregnum e-Meetings for each of 4 topics. The meetings will progress
1) IM/DM model coordination with industry partners,
2) management-control requirements and modelling,
3) ETH, MPLS-TP, MTN and common modelling, and
4) OTN and Media modelling.
A joint face-to-face interregnum meeting is planned with Q12 for 2-6 December 2024 in Geneva.

Decisions (ITU-T SG15, July 2024)

WP1/15 - AAP Approval

WP1/15 - Consent

WP2/15 - Consent

WP3/15 - Consent

WP1/15 - Agreement

WP2/15 - Agreement

WP3/15 - Agreement

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