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ITU-T Study Group 15 (Study Period 2005 – 2008)
Summary of Last Meeting

Meeting Executive Summary

11 - 22 February 2008
SG15 Chairman; Yoichi Maeda

Overview of the sixth SG 15 meeting of the study period 2005 - 2008

Geneva, 22 February 2008, the plenary meeting of Study Group 15 drew to a close with agreement on a total of 40 new and revised texts including 1 approved Recommendation, 36 consented Recommendations and 3 agreed documents. 336 delegates represented 30 countries with 281 Contributions and 364 Temporary Documents. This was the biggest meeting of any Study Group in this study period.

The meeting progressed work on Questions related to three key areas of optical and metallic access networks, optical transport network technology and structure, and progressed Lead Study Group activities on ANT and Optical technologies. The meeting reviewed and updated the SG15 work programme and discussed Liaison Statements from/to other groups including IEC, IETF, OIF and IEEE to harmonize works with relevant bodies.

The meeting prepared SG15 reports to the TSAG correspondence group on study group restructuring, ICTs and Climate Change issues, Promotion, DC-CET, Coordination and Electronic Working Method (EWM) issues.

Key progress made in this SG15 meeting includes the first discussion among SG15 members on power saving and the SG’s approval of its restructuring proposal and new question texts for the next study period.

The first early morning tutorial sessions on power saving were held over three days, and each attracted more than 100 participants as described in the WP1 report. The Chairman of SG15 expressed his thanks to Dave Faulkner and Andrew Nunn for their contribution to the tutorial arrangement.

The meeting agreed the following mandate and work area and objectives for SG15 in the next study period:

The mandate of SG15 is to both continue and evolve studies on optical transport networks and access network infrastructures, systems, equipment, optical fibres, and the corresponding control plane technologies including metallic, optical and packet-based technologies with a clear focus on market requirements and drivers, technology innovation to enable the evolution towards future transport solutions. This encompasses the development of related standards for the in-premises such as home networking, access, metropolitan and long-haul sections of telecommunication networks. It was agreed to send SG15’s proposal on restructuring and new question texts for the next study period to TSAG for WTSA-08.

Another key achievement in this meeting was the SG15 agreement to establish an Ad Hoc group on T-MPLS which resulted from an agreement for a collaborative approach for T-MPLS standardization. The meeting agreed to initiate the creation of a joint working team (JWT) involving appropriate experts from ITU-T and IETF to best leverage ITU-T and IETF design expertise and authority. The Chairman of SG15 expressed his thanks to Malcolm Betts and David Ward for their strong leadership and collaboration. Further details concerning this group can be found at:

In the closing plenary, a special event for the presentation of Certificates for Vice-chairmen and Rapporteurs was organized to express thanks for their great contribution to ITU-T SG15 activities.

The fourth networking event in SG15 was successfully organized with a support of Wuhan Research Institute of Post and Telecommunications and attracted a lot of participation on Thursday 7 June 2007. It was agreed that the networking event would be held in the next SG15 meeting to facilitate communication and networking amongst participants of the different Questions.

Changes of Rapporteurs, Editors and SG15 representatives

The updated list of Rapporteurs can be found at:
The updated list of Editors of the Recommendations can be found at:
The updated list of SG15 representatives and other roles can be found at:

Executive reports from WP chairmen and SG15 public relations coordinator
Working Party 1/15 - Optical and metallic access network

WP1 Chairman: Andrew Nunn

WP1/15 prepared one new Recommendation, two revised Recommendations, seven Amendments and one Corrigendum for consent. In addition, one revised Recommendation was submitted for approval following the resolution of Additional Review comments.

In fulfilling its Access Network Transport (ANT) co-ordination role, WP1/15 also updated the ANT Standards Overview (Issue 15) and the ANT Work Plan (Issue 14).

Draft new Recommendation G.984.6 on reach extension for Gigabit capable Passive Optical Access Networks was completed by Q2/15. This Recommendation is the latest edition to the G-PON series of optical access system specifications. This document outlines the architecture and interface parameters for GPON systems with extended reach using a physical layer reach extension device, including regenerators or optical amplifiers. The maximum physical reach is up to 60km, with loss budgets in excess of 27.5 dB being achievable in both spans. This new capability will allow operators to provide optical access service to areas that were previously out of reach, and also explore new network designs for greater central office consolidation.

Work continued within Q4/15 on draft new Recommendation - Next generation home networking transceivers, with over 30% of the Contributions to Q4/15 being addressed to this topic. Work also continued in Q1/15 on draft new Recommendation G.hnta on Home Network transport architecture. It is anticipated that both and G.hnta will be completed in December 2008.

The Additional Review comments addressed to draft revised Recommendation G.984.4 - Gigabit-capable Passive Optical Networks (GPON): ONT Management and Control Interface specification, were resolved by Q2/15 thus allowing it to be approved in the closing SG15 plenary.

Revisions of the following Recommendations were completed:
  • G.984.1 - Gigabit-capable Passive Optical Networks (GPON): General characteristic
  • G.984.3 - Gigabit-capable Passive Optical Networks (G-PON): Transmission Convergence Layer Specification
Amendments to the following Recommendations were also completed:
  • G.984.2 - Gigabit-capable Passive Optical Networks (GPON): Physical Media Dependent (PMD) layer specification
  • G.984.4 - Gigabit-capable Passive Optical Networks (GPON): ONT Management and Control Interface specification
  • G.992.3 - Asymmetric digital subscriber line transceivers 2 (ADSL2)
  • G.992.5 - Asymmetric Digital Subscriber Line (ADSL) transceivers – Extended bandwidth ADSL2 (ADSL2plus)
  • G.993.2 - Very high speed Digital Subscriber Line Transceivers 2
  • G.994.1 - Handshake procedures for Digital Subscriber Line (DSL) transceivers
  • G.997.1 - Physical layer management for digital subscriber line (DSL) transceivers
Key work for 2008 includes:
  • Progression of draft new Recommendation G.hnta – Generic Home Network transport architecture
  • Progression of draft new Recommendation G.gbe - Requirements for a 1Gbit/s point-to-point Ethernet-based fibre access system
  • Progression of draft new Recommendation - Next generation home networking transceivers
  • Progression of draft new Recommendation - Line Testing for Digital Subscriber Lines (DSL)
  • Progression of draft new Recommendation G.inp - Impulse Noise Protection
  • Progression of draft new Recommendation G.vector - Self FEXT cancellation
Under the auspices of WP1/15, SG15 held three power saving tutorial sessions. In order not to reduce meeting time these were held between 0830 – 0930 on 13, 14 & 15 February. The sessions were attended by more than 100 participants on each day and were judged a success in terms of raising awareness of the issues. The programme for these sessions and presentations can be found at:

Working Party 2/15 - Optical transport network technology

WP2 Chairman: Gastone Bonaventura

WP2 prepared four revised Recommendations and one Amendment for consent as well as one Supplement for Agreement. A Recommendation was proposed for deletion.

In the area of the optical fibres the revised version of Recommendation G.650.3 contains significant and technical changes aimed to give for each test a more consistent structure, a guidance on typical wavelengths to test at and whether the tests are carried out in one direction only or in both directions. Moreover it has been proposed to delete G.651 mainly because with the approval of Rec. G.651.1 the rather old and poorly maintained Rec. G.651 can be considered as being superfluous.

As for the optical systems, the revised version of Recommendation G.959.1 contains many new inter-domain application codes for intra-office, short haul and long haul systems, as well as for single-channel (up to 40 Gbit/s) and multi-channels (at 2.5 Gbit/s and 10 Gbit/s up to 32 channels) systems.

As for the optical components and subsystems the new version of Recommendation G.666 has been updated in particular with a new text related to the measurements of parameters of the polarization mode dispersion compensators. The Amendment to the Recommendation G.671 is mainly devoted to the modifications of the parameter tables for the passive chromatic dispersion compensators and the single optical channel passive chromatic dispersion compensators.

In the optical fibre submarine cable area the revised Recommendations G.972 has been made in order to insert the new definitions of the terms used in the Recommendation G.978 on the submarine cables.

In the framework of WP2, the new Supplement G.Sup42 (Guide on the use of the ITU-T SG15 Recommendations related to Optical Technology) has been submitted for Agreement at this Plenary. This Supplement contains a Guide with an introduction to each category of Recommendations on the optical technology and for each Recommendation is given a short description of the purpose, of the content and, in many cases, also of the evolution of the content in the subsequent versions.

Key ongoing work includes:
  • the preparation of a new Supplement on general aspects of optical fibre and cable;
  • a revision of G.698.2 with respect to the inclusion of 10 Git/s application codes at 50 GHz channel spacing and of 40 Gbit/s application codes;
  • a revision of G.Sup39 with a description of the characteristics of the advanced modulation formats which are at present under consideration for the new optical systems at 40 Gbit/s and beyond 100 Gbit/s;
  • a work on the choice of the OTU4 bit rate, especially in relation to the choice of suitable modulation formats;
  • the revision of G.671, in particular with respect PON splitter issues;
  • the preparation of a new Recommendation on longitudinal compatible DWDM applications for repeaterless optical fibre submarine cables.
Moreover during this meeting a new interesting proposal for study has been made. It has been proposed to start looking at physical implementations of short-reach OTU4 interfaces and at associated sets of parameter values having in mind that these short-reach OTU4 interfaces could be implemented as parallel lanes (CWDM or DWDM) over a single fibre.

Working Party 3/15 – Optical transport network structure

WP3 Chairman: Stephen J. Trowbridge

WP3 prepared two new and ten revised Recommendations for consent, together with five amendments and three corrigenda. A revised supplement and an amendment were prepared for agreement.

WP3 continued its progress in developing specifications for carrier grade packet transport technologies.
  • For T-MPLS, a new joint working team of experts has been formed across ITU-T and IETF to best leverage the expertise of both groups. The ITU-T participation in this team is provided through the T-MPLS ad hoc group, which was created and held its first two days of meetings during the time of the SG15 plenary meeting.
  • Carrier grade Ethernet is enhanced with a new Recommendation G.8032 for Ethernet ring protection switching.
  • Carrier grade timing and synchronization in packet networks is improved with a revision of G.8261 providing jitter and wander limits, equipment tolerance for timing at the boundary between TDM and packet networks and defining the architecture of Synchronous Ethernet networks. An amendment was developed for G.8262 regarding synchronous Ethernet equipment slave clocks, including the restrictions that this can only be applied for full-duplex constant bit-rate Ethernet interfaces. A new Recommendation G.8264 was completed regarding timing distribution through packet networks, together with an enhancement to G.781 to extend Synchronous Status Messaging (SSM) to networks based on Synchronous Ethernet as well as SDH and PDH.
  • An amendment to the ASON architecture Recommendation G.8080 provides for application of the ASON control plane to packet networks.
Work was completed on jitter limits and equipment tolerance for STM-256 interfaces (SDH 40 Gbit/s), resulting in amendments to G.783 and G.825 and a corrigendum to G.8251.

Work continues on network element management. In this meeting, revisions were completed to the SDH and OTN network element management Recommendations G.784 and G.874. In addition, a revision to the Data Communication Network Recommendation G.7712 was completed to add data-link layer requirements of management and signaling communications channels.

In fulfilling its Optical Technology co-ordination role, WP3/15 updated the Optical Transport Networks & Technologies Standardization Workplan (Issue 10). In addition, updates were completed to the terminology Recommendations for SDH, OTN, ASON, and Ethernet transport (G.780, G.870, G.8081, and G.8001).

Important ongoing and emerging work for WP3/15 into the next study period includes:
  • Work on evolution of the Optical Transport Network, including higher speed interfaces to support 40 Gbit/s and 100 Gbit/s Ethernet currently being standardized in the IEEE P802.3ba task force.
  • New work to provide mechanisms for Time and Phase distribution over packet networks.
  • The Ethernet Services Recommendations (G.8011 series) are being revised to better align with the specifications of the Metro Ethernet Forum (MEF). The service architectures include Ethernet private line, Ethernet virtual private line, Ethernet virtual private LAN, Ethernet virtual private rooted multipoint, and Ethernet private LAN service.
  • Work continues in Ethernet network architecture definition as part of the overall packet transport network specification.

SG15 public relations coordination

SG15 public relations coordinator: Shaohua Yu

SG15 received 17 other role and representative’s reports reflecting the highlights of other SDO’ activities and proposed the following hot topics for promotion from consented texts or important activity on Power saving tutorial sessions, Gigabit-capable Passive Optical Networks (G-PON): Reach extension, Guide on the use of the ITU-T SG15 Recommendations related to optical technology and Creation of T-MPLS Joint Working Team. You will see the news stories in ITU-T E-flash news, which have resulted in some media interest and coverage. The meeting agreed update seven Flyers: DSL, GPON, CWDM, Optical fibres and cables, Optical transport systems (OTS), ASON and OTN, and create three new Flyers: DWDM, Ethernet and packet timing.

The 20 reply’s LSs for the outgoing LSs from the June 2007 SG15 plenary meeting, the 82 new incoming LSs from SDO’s reply and the 26 relevant responses, as well as 43 new outgoing LSs contained at the 11 – 22 Feb. 2008 SG15 meeting to reflect collaboration and coordination relations with other SDO.

The second joint ITU-T/IEEE Workshop (19-20 June 2008, Geneva) is preparing based on the work of Steering committee meeting. The SG15 provides preliminary information on the workshop titled “Joint ITU-T/IEEE Workshop on Next Generation Optical Access Systems”. ITU-T and the IEEE will hold a joint workshop on Next Generation Optical Access Systems.

NEXTComm, 16-19 June, 2008, Las Vegas will see ITU-T members, and guests stage an interoperability showcase for both traditional FTTP-focused G-PON technology, as well as emerging applications such as G-PON fed xDSL services, Enhancement band operation (G.984.5), and G-PON Reach Extender demonstrations ( ITU, together with Telcordia, have collaborated to organize a multi-company interoperability demonstration. Any optical access system, customer premises equipment, or G-PON device vendor with commercial products compliant with G.984 series recommendations are eligible to participate in the Pavilion. TD 283/GEN provides a status report on the planned ITU G-PON (G.984) Pavilion at NETXcomm 2008 ( in Las Vegas, USA, 16-19 June, 2008.

It is agreed the text of the G.sup42 on "Guide on the use of the ITU-T Recommendations related to Optical Technology", update “Access Network Transport overview and work plan” and “OTNT standardization work plan”. These guiding documents could be used by developing countries as part of type approval of services and systems and in developing national specific requirements for deploying new networks and services.

Promotion, coordination and requirements for developing countries and countries with economies in transition (DC-CET) were updated well, including the responses of “ITU-T activities on bridging the standardization gap”, “Improve the Geographic Distribution of Workshops” and “Assessment of ITU-T Recommendations in the light of Climate Change” from TSAG.

SG15 at a Glance

General areas of study on “Optical and other transport network infrastructures”

SG 15 is the focal point in ITU T for the development of standards on optical and other transport network infrastructures, systems, equipment, optical fibres, and the corresponding control plane technologies to enable the evolution toward intelligent transport networks. This encompasses the development of related standards for the customer premises, access, metropolitan and long haul sections of communication networks.

Lead study groups in specific areas of study to SG 15

In fulfilling its Access Network Transport (ANT) co-ordination role, WP1/15 also updated the ANT Standards Overview (Issue 15) and the ANT Work Plan (Issue 14).
Lead study group on access network transport

In fulfilling its Optical Technology co-ordination role, WP3/15 updated the Optical Transport Networks & Technologies Standardization Workplan (Issue 10).
Lead study group on optical technology

Key objectives and results of this SG 15 meeting

Review the interim activities since June 2007
Progress the work of the Questions
Progress work on Lead Study Group issues on ANT and Optical technologies
Prepare texts of Recommendations for ‘Consent’ at the closing plenary
Prepare texts for ‘Agreement’ at the closing plenary
Deal with the approval of draft Recommendations, texts for Agreement and deletion of existing Recommendations
Process Liaison Statements from/to other groups
Plan interim activities
Review and update the Study Group 15 work programme
Review and update the SG15 representatives and other role’s activities
Prepare SG15’s comments on Study restructuring for the next study period to TSAG Correspondence Group
Prepare SG15’s comments on Coordination, Promotion and DC-CET issues to TSAG
Prepare SG15’s involvement in future workshops and external events
Prepare SG15’s material for promotion activities

SG15 meeting schedule for 2008
    Next SG15 meeting (tentative); 1 – 12 December 2008, Geneva


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