Executive Summary - December 2021

Study Group 15 held its eighth meeting of the 2017 study period as a fully virtual meeting from 6-17 December 2021, attended by 320 delegates representing 28 countries. As this is expected to be the final plenary meeting of the study period, SG15 prepared some minor updates to the draft SG15 responsibility and mandates toward update of Resolution 2, and to updates of question texts, for consideration at WTSA-20.
The meeting received 255 contributions and 422 TDs, a decrease in contributions from the virtual meeting held in a similar format in April 2021. The meeting observed the 12-day contribution deadline of Recommendation ITU-T A.1, and all of the contributions to this meeting were submitted using Direct Document Posting (DDP).
 SG15 approved one new Recommendation, consented 42 texts (7 new and 7 revised Recommendations, 22 Amendments, and 6 Corrigenda), and agreed one technical paper, one revised and three new Supplements, and one Appendix.
Given the current COVID-19 situation, all interim activities prior to the next SG15 plenary have been planned as virtual, consisting of 50 single-day or multiple-day virtual meetings. A procedure was defined at the previous plenary for authorizing the conversion of some of these virtual meetings to physical meetings should face-to-face meetings become feasible prior to the next plenary of SG15.
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. No update was needed to the Smart Grid standards overview and work plan, which no longer requires active coordination. SG15 also provided an update to TSAG in respect to WTSA Resolution 73, 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.

​SG15 generated 27 Liaison Statements.

Executive reports from WP Chairmen 

WP1/15 – Transport aspects of access, home and smart grid networks
WP1 Chairman: Tom Starr; WP1 Vice-Chairman: Ian Horsley

Q1/15 met for one day, updating 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 certification and interoperability activities for WP1/15 Recommendations was updated.

Q2/15 met for six days, working on Passive Optical Networks (PON), preparing five texts for consent and three for agreement.   Work started work on two new supplements addressing PON latency and enhanced OLT functions.  Ongoing work is addressing PON slicing.

Q4/15 met for eight days, working on access via metallic conductors.  Six texts were prepared or consent, mostly addressing MGfast.  A new draft Recommendation, G.fastback, addresses bonded G.fast backhaul.

Q18/15 met for five days, working on the Recommendations and Technical Papers related to G.hn, free space optical communication, fibre in the premises, and home networking support of IoT and ultra-high-definition video.  One text was prepared for approval, three for consent, and one Technical Paper for agreement.

WP2/15 – Optical technologies and physical infrastructures
WP2 Chairman: Noriyuki Araki; WP2 Vice-Chairman: Peter Stassar

Q5/15 worked on characteristics and test methods of optical fibres and cables, and installation guidance, and made progress on new Recommendation L.oehc, which deals with optical/electrical hybrid cables for access points, in cooperation with IEC SC86B. Q5/15 also made progress on new Technical Report on optical fibre, cable and components for space division multiplexing transmission. These two documents will be finalized at the next SG15 meeting in 2022.

Q6/15 work on characteristics of optical components, subsystems and systems for optical transport networks. Regarding revision of G.698.2 and its extension for 200 and 400 Gbit/s application, it was agreed to remove this work item from the WP2 work program because no progress has been made over last two and a half years. Q6/15 discussed definition of maximum spectral excursion for 25G NRZ applications in the revision of G.698.1, G.698.2 and G.698.4, proposing to have different requirements for black link channel width and Tx maximum spectral excursion. Also, Q6/15 made progress on the new Recommendation G.owdm (Multichannel WDM applications in the O-band).

Q8/15 worked on optical fibre submarine cable systems and discussed the revision of G suppl.41 to establish guidelines for fibre identification in submarine cable. This document also includes information about OSNR measurement methods and its measurement uncertainties. Q8/15 also discussed on new Recommendations G.dsssc (Dedicated scientific sensing submarine cable system) and G.smart (Scientific monitoring and telecommunication submarine systems) in consideration of the sensing and telecommunication requirements with Joint Task Force on SMART cables. It was also agreed to initiate revision works for relevant Recommendations G.971, G.972, G.976 and G.978 to realize effective and smooth standardization of G.dsssc and G.smart.

Q16/15 work on connectivity, operation and maintenance of optical physical infrastructures and consented the revision of L.400 “Optical fibre splices" and two new Recommendations, L.316 (ex. L.cid) “Cable identification for the construction and maintenance of optical fibre cable networks with optical sensing technique" and L.209 (ex. L.font) “Requirements for fibre optic network terminal box".

WP3/15 – Transport network characteristics
WP3 Chairman: Malcolm Betts; WP3 Vice-Chairman: Glenn Parsons

• Q10/15 consented three Recommendations on Ethernet (G.8012, G.8021 and G.8032 Cor.1) and are continuing to work on the MPLS-TP equipment Recommendation (G.8121).
• Q11/15 consented five Recommendations and agreed two texts related to OTN and is continuing work to evolve and enhance the OTN Recommendations. Discussion is continuing on the support for the beyond 400Gbit/s interfaces being defined in IEEE 802.3.
• Q11/15 is also consented two MTN related Recommendations and continuing to work on MTN Recommendations for equipment.
• Q12/15 has consented new revisions to Recommendations G.7701 on common control aspects and G.7702 on the use of SDN in transport networks.
• Q12/15 and Q14/15 are continuing to discuss how AI/ML capabilities fit into the management and control architecture with a focus on the interfaces to the transport network. They are also considering the evolution of compute and storage technologies impact the architecture of the transport network and the management/control architecture.
• Q13/15 Has continued to enhance the set of Recommendations on frequency synchronization and precision time distribution
• Q13/15 and Q14/15 are continuing to work, in cooperation with IEEE 1588, on the management of the synchronization network and equipment.
• Q14/15 is continuing work on the management of the transport network.
• Q14/15 is continuing to work in cooperation with IEEE 802.1, IEEE 1588, IEEE 802.3, ONF, MEF, BBF, and IETF to provide consistent information models and YANG data models for Ethernet and network synchronization.

Q10/15 consented draft revised G.8012 (Ethernet UNI and NNI, superseding G.8012.1) and G.8021 (Ethernet equipment). These were brought up to date, simplified via direct referencing of relevant mechanisms specified in non-ITU-T standards, and G.8021 is now decoupled from related Q11/15 specification facilitating future updates. Together, the two revisions additionally supersede G.8021.1 and allow G.8001 to be superseded. Q10/15 also consented draft G.8032 Corrigendum 1 in alignment with G.8021 work. Contributions on signal degrade indication and sub-1G transport were discussed without starting new work items. Future work is planned towards July 2023 consent of G.8121 Amd.1 (MPLS-TP equipment) and may include further G.8021-related development.

Q11/15 consented seven and agreed two items during a very full and productive meeting.  The four consented OTN items were G.709 Amendment 2, which includes the addition of an OTU0 interface and other clarifications, some of which were also captured in G.709.4 Corrigendum 1; G.798 Amendment 4, which included updates related to long reach and secure FlexO interfaces; and G.873.1 Amendment 1, which adds ODUCn as a server layer of protected entities.  In addition, the new OTN security supplement G.Sup.otnsec was agreed.  Beyond the consented and agreed OTN items, work continued related to OTN interfaces beyond 400 Gbit/s (B400G).  The two consented MTN items were new G.8331 to specify MTN linear protection and G.8312 Amendment 1.  Additional MTN work continued on draft new G.8321 MTN equipment.  The other two items were the consented G.8023 Amendment 1 and the agreed G.8201 Amendment 1.  The other key topic of discussion was interfaces for carrying sub-1 Gbit/s clients (sub-1G).  Due to the very large number of incoming contributions and recent developments, it was necessary for the sub-1G work at this meeting to focus on high-level topics, with the remainder of the topic deferred to the first Q11 interregnum meeting.  The first interregnum meeting will also cover the remaining B400G and G.8321 contributions that were also deferred due to lack of meeting time.  Q11 plans to hold two additional interregnum meetings to continue work on these and other topics.

Q12/15 consented Revisions to G.7701 and G.7702. A new work item for Amendment 1 to G.7703 was initiated. Common management and control aspects to both SDN and ASON are described in G.7701. Thus, ASON architecture is described using G.7701 and G.7703, and SDN architecture for transport is described using G.7701 and G.7702. The interaction between networking and compute was discussed, particularly with virtual network functions. In a joint meeting with Q2/15, Q11/15, and Q14/15, progress was made on terminology used in WP1 and WP3, and the issue of coordinating slices/VNs across multiple networks was discussed.

Q13/15 consented seven Recommendations related to network synchronization and precision time distribution (G.781.1, G.8271.1 Amd2, G.8273.2 Amd1, G.8275 Amd2, G.8275.1 Amd3, G.8275.2 Amd3 and G.8265.1 Amd1), and 3 Liaisons addressing various topics of interest to Q13.

Among the main updates in the Q13 Recommendations, the PTP over IP profiles (G.8265.1 and G.8275.2), have added mandatory support for transport over IPv6.

G.8275.1 has been enhanced with better alignment with IEEE1588-2019. All PTP profiles have improved the definition of the dataset members also to support the work being done in Q14 on the sync data management.

The G.8275 Amd2 presents new details concerning the IWF between different PTP profiles.

G.8271.1 has finalized the specification of the network limits for sync networks suitable to support also fronthaul applications. 

G.8273.2 has been enhanced with methodology for clock testing.

The G.781.1, new recommendation on Synchronization layer functions for packet-based synchronization, will be an important reference for the IEC/IEEE 60802 project on the TSN profile for industrial automation.

Several new work items have been agreed at this meeting: in addition to items related to progress with the existing Recommendations, Q13 has agreed to develop a new Recommendation, G.8272.2, Timing characteristics of a coherent network Primary Reference Time Clock, that could become an important reference in the area of addressing the GNSS vulnerability issues.

Q13/15 plans to hold one correspondence activity to continue the activity on simulations required for some time sync scenarios; e-meetings are planned to make progress on all various topics in Q13 Work Program.

Q14/15 consented three Recommendations: G.7721.1 (Data models for synchronization management) new; G.7712 (Architecture and specification of data communication network) amendment; G.7711 (Generic protocol-neutral information model for transport resources) Revision; Progress was made on the other active work items. It also initiated two new work items: amendment to G.7721.1 (Data model of Synchronization management) and amendment to G.8051 (Management aspects of the Ethernet transport (ET) capable network element).

Q14/15 plans to hold four tracks of correspondence activities (each of which includes a series of 6 virtual meetings) on modeling coordination (with invited modelling experts from IEEE 1588, IEEE 802.1, IEEE 802.3, ONF, MEF, BBF, IETF, TM Forum), MC management & operation, Transport common information model (TCIM), Ethernet, MPLS-TP, MTN management, and TCIM, OTN & Optical media management.

Decisions (ITU-T SG15, December 2021)
A​AP Approval

WP1/15 – AAP Approval

Con​sent

WP1/15 - Consent:

Note: G.984.5 and G.9805 should be published at the same time.

WP2/15 - Consent:

WP3/15 - Consent:

​Agreement

WP1/15 - Agreement:

​WP2/15 - Agreement

WP3/15 - Agreement

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