Automation Journey in Core and Metro Networks: an Operator View

Network automation is the current challenge that operators face to accelerate end-to-end service delivery and improve network operations in the context of rapidly growing capacity needs. Optical networks have long been built using vendors’ turn-key solutions, resulting in complexity for the operator to automate its multi-vendor networks in a consistent way. Questioning the vendors’ lock-in in disaggregating the optical transmission systems (i.e., splitting the system into parts, where each part can be provided by a different vendor) provides advantages (e.g., cost) but also additional complexity. Openness and standardization appear as key for these multi-vendor scenarios. The path is not easy, but it is not a matter of choice: opening and interoperability are obligations that we face because of the need for automation. The journey that we detail in this paper is the one that we think will be sustainable from our side. The opposite, i.e., continue building vendors’ silos and staking per-vendor specialized applications, is not sustainable. We propose a step-by-step approach, starting with the non-disaggregated situation, followed by partial and full disaggregation architectures to the last evolution towards data centric networking. We present and discuss implementations that Orange has been contributing to and identify some gaps the industry should address. We show that current works in the communities of open source, open initiatives, and standardization bodies are addressing all these steps, and in this respect can accelerate the deployment of automation solutions in current and future optical transport networks.

Operator view on optical transport network automation in a multi-vendor context [Invited]

Rouzic

Renais

Meuric

et al. 2022

GNPy model of the physical layer for open and disaggregated optical networking [Invited]

Curri¹

2022

Networking technologies are fast evolving to support the request for ubiquitous Internet access that is becoming a fundamental need for the modern and inclusive society, with a dramatic speed-up caused by the COVID-19 emergency. Such evolution needs the development of networks into disaggregated and programmable systems according to the software-defined networking (SDN) paradigm. Wavelength-division multiplexed (WDM) optical transmission and networking is expanding as physical layer technology from core and metro networks to 5G x -hauling and inter- and intra-data-center connections requiring the application of the SDN paradigm at the optical layer based on the WDM optical data transport virtualization. We present the fundamental principles of the open-source project Gaussian Noise in Python (GNPy) for the optical transport virtualization in modeling the WDM optical transmission for open and disaggregated networking. GNPy approximates transparent lightpaths as additive white and Gaussian noise channels and can be used as a vendor-agnostic digital twin for open network planning and management. The quality-of-transmission degradation of each network element is independently modeled to allow disaggregated network management. We describe the GNPy models for fiber propagation, optical amplifiers, and reconfigurable add/drop multiplexers together with modeling of coherent transceivers from the back-to-back characterization. We address the use of GNPy as a vendor-agnostic design and planning tool and as physical layer virtualization in software-defined optical networking.

Spatially disaggregated model for self-channel interference in mixed fiber optical network segments

Virgillito

Castoldi

Amico

et al. 2023

Coherent transmission technology is widely diffused in backbone optical uncompensated transmission (UT) network segments. In metro and access network segments instead, intensity-modulated direct detected channels at 10 Gbps requiring inline dispersion compensation units (DCUs) are still largely used. While the transition to coherent technology is foreseen in the dispersion managed (DM) network segment, in the meantime, it would be handy to route coherent channels through DM network segments to fully exploit deployed hardware and available spectrum and improve network flexibility. In this scenario, self-channel interference (SCI) exhibits strongly coherent accumulation due to the presence of DCUs, which is not well modeled by traditional analytical models for non-linear interference estimation used for path feasibility assessment. In this paper, we propose a semi-analytical model able to fill this gap. We show that our proposed model is able to provide a quick, conservative estimation of the SCI noise on both UT and DM systems, including optical line system configurations with mixed fiber types.