BRANDON COLLINGS ROADM
F or communications networks, accommodating persistent traffic and topology growth in a cost-and operationally- effective manner has been both an industry challenge and imperative for decades. To the benefit of consumers globally, this is a challenge that the industry has consistently overcome through new architectures and technology innovations such as dense wavelength division multiplexing (DWDM), traffic management and aggregation using OTN and Ethernet, and reconfigurable optical add/drop multiplexing (ROADM) network technology. Each has allowed network operators to scale and evolve their networks as traffic and customer demands developed over time, maximising the utilisation of previously deployed infrastructure while allowing newly deployed resources to be optimally aligned to new demand, all without requiring the operational expense of significant manual intervention and reconfiguration of previously deployed equipment. The deployment of ROADM networks began over 15 years ago as operators recognised that this technology enabled the deployment of new capacity with optical mesh topologies. Capacity could now be deployed more rapidly, with less operational complexity allowing for new revenue streams and lower operating costs. ROADM deployment has allowed operators to extend the lifetime of their networks, extracting more service value and delaying the capital expense of deploying new infrastructure. For these reasons, ROADMs have been deployed widely around the globe, predominantly in the long-haul and metro segments, where minimal manual intervention and improved network efficiency using
There Are Many Reasons Why GLOBAL ROADM DEPLOYMENTS ARE EXPANDING
ROADM networks are now widespread, but deployments are still increasing. Lumentum’s CTO Brandon Collings , looks at the reasons why
based motives, global in nature, largely uncoupled, and expected to be long lasting.
network traffic is generally greater. Global optical network capacity continues to grow at an average of
26% CAGR, according to Cisco’s Visual Networking Index: Forecast and Trends, 2017-2022, and is driving increased optical network deployments. In 2019, sales of wavelength selective switches (WSSs), the core element of ROADM networks, are poised to be twice that of only four years ago and 2023 sales are predicted to be 150% that of 2019 (see Fig1). While the optical industry has notoriously experienced cyclical behaviour driven by specific operator(s) activities, the current impressive increase of ROADM deployment is being driven by broadly
The underlying reasons for this growth can be characterised by three general trends: l ROADM networks are now being deployed by operators in geographical regions and network segments where they have historically not been deployed l Operators who have deployed ROADM networks are evolving to next-generation infrastructures utilising relatively larger quantities of more advanced WSSs l More WSS units are being deployed per network node relative to the historical average as multiple fibres are being used per route to support network capacity growth DEPLOYMENTS INTO HISTORICALLY NEW SPACES In any network, traffic management flexibility and routing are required so the network can adapt to traffic growth while being resilient to physical layer faults
Fig 1: Annual WSS unit sales/ year. Source: LightCounting Optical Components Market Forecast, Oct 2018
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| ISSUE 17 | Q2 2019
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