Introduction to the JOCN special issue on low-margin optical networks

Yvan Pointurier; Jean-Luc Augé; Martin Birk; Emmanouel Varvarigos

doi:10.1364/JOCN.11.00LMO1

It is our pleasure to guest-edit this special issue of the Journal of Optical Communications and Networking (JOCN) on low-margin optical networks! Please be aware that this special issue spans two months: four articles (including two invited papers) are published in the September issue, and another six articles (including another two invited papers) are published in the October issue.

The various areas surrounding low-margin optical networks have progressed incredibly since the publication of a seminal paper [1] more than six years ago (!), which introduced a taxonomy of margins in optical networks and focused on the impact on margins by flexible transponders, which were then a novelty. Today, flexible transponders are routinely deployed; quality of transmission (QoT) estimators have improved by accounting for more physical-layer effects and reducing their inaccuracy; open elements (physical or software) have improved interoperability between layers and between data and control planes, making hardware monitoring information better suited for exploitation by the control plane; and control planes are now SDN-based, rendering networks more dynamic and therefore suited to near-real-time adaptation to the changes of the underlying physical layer, which is additionally more widely monitored. All of these factors combined greatly contribute to the possibility of margin reduction.

The ten papers selected for this special issue cover a broad area surrounding low-margin optical networks. All papers underwent the standard rigorous IEEE/OSA peer-review process. All key stakeholders in the field of optical networking are represented: traditional operators, webscales, equipment vendors, and academia.

Topic-wise, we are glad to see that the key aspects of low-margin optical network design and operation are covered:

• Optimization of QoT tools accounting for novel effects is tackled in no less than five papers by such leading teams as the University of Cambridge (“Design considerations for low-margin elastic optical networks in the nonlinear regime [Invited]”), the University of Arizona/NEC (“Model transfer of QoT prediction in optical networks based on artificial neural networks”), Chalmers University (“Channel allocation in elastic optical networks using traveling salesman problem algorithms”), IIIT Delhi/UCL/BT (“Effect of reduced link margins on C+L band elastic optical networks”), and Nokia Bell Labs (“Revisiting the calculation of performance margins in monitoring-enabled optical networks”).
• A key enabling component, a transponder akin to an optical modem that has been field-trialed, is presented and evaluated in a paper from Infinera, Telia, RISE, and TU Munich (“Autonomous intelligent transponder enabling adaptive network optimization in a live network field trial”); the Ciena paper (“Practical considerations for near-zero margin network design and deployment [Invited]”) also tackles the optical modem.
• A more global, holistic, systems-oriented vision is presented in the ORCHESTRA consortium paper (“Toward efficient, reliable, and autonomous optical networks: the ORCHESTRA solution [Invited]”) and in the aforementioned Ciena paper, both of which include QoT/margin estimation, planning, and operational aspects.
• The key trade-off between saving CAPEX and availability downgrading by running an optical network at low margins is tackled in the ORCHESTRA and Ciena papers, along with the Microsoft paper (“Low-margin optical networking at cloud scale [Invited]”), which gives many insights on the real-life, at-scale operation of a large low-margin optical network; many Microsoft network details are reported for the first time.

With such a wealth of great work, there is no longer any good reason to operate optical networks with a lot of extra dBs of margin! We hope that readers will find inspiration in these papers to further decrease margins in the networks that they design or operate.

With that, we would like to thank the authors of the papers who sometimes made heroic efforts to meet the publication deadlines; the many reviewers, thanks to whom the quality of the papers dramatically improved; and our Editor-in-Chief Jane Simmons who proposed and steered the special issue to what you can read today and whose availability for advising is unparalleled.

Guest Editors

Yvan Pointurier

Nokia Bell Labs, France

Lead Guest Editor

Jean-Luc Augé

Orange Labs, France

Martin Birk

AT&T, USA

Emmanouel (Manos) Varvarigos

NTUA, Greece

Jane M. Simmons

Editor-in-Chief

REFERENCE

1. J.-L. Augé, “Can we use flexible transponders to reduce margins?” in Optical Fiber Communication Conference (OFC), Mar. 2013, paper OTu2A.1.

Introduction to the JOCN special issue on low-margin optical networks

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Journal of Optical Communications and Networking