Charting the path forward for 400G+ coherent optics

Heavy Reading’s Sterling Perrin highlights more key findings from the 2022 Coherent Optics Survey, focusing on operator preferences for coherent pluggable optics and integration challenges.

Sterling Perrin, Senior Principal Analyst, Heavy Reading

December 1, 2022

5 Min Read
Charting the path forward for 400G+ coherent optics

The move to 400G requires a number of big decisions. Do you standardize on pluggable optics or opt for a mix of embedded and pluggable options? If so, what goes where? Do you migrate to IPoDWDM, retain traditional DWDM systems or opt for a mix of both? If maintaining traditional DWDM systems, what role (if any) should 400G coherent pluggables serve?

To understand the future of high speed coherent optics, Heavy Reading launched the Coherent Optics Market Leadership Program with industry partners Ciena, Effect Photonics, Infinera and Ribbon. The 2022 project was based on a global network operator survey, conducted in August, that attracted 87 qualified responses.

This is the final installment of four blogs highlighting the key findings from the 2022 Coherent Optics Survey. It focuses on operator preferences for embedded versus coherent pluggable optics and the challenges in integrating coherent optics in routers, or IP over DWDM (IPoDWDM).

Decision time

Heavy Reading asked network operators about their coherent optical network evolution strategies. The survey data shows that network operators are evenly split. 35% intend to use whatever technology provides the lowest total cost of ownership (TCO) for each network segment, and 36% plan to standardize on pluggable optics in the aggregation/metro and 600G/800G for the long-haul/backbone network.

The split makes sense. Compared to pluggables, embedded optics may cost more, but they also deliver higher performance (as measured in reach and spectral efficiency). These attributes are most prized in long-haul and subsea networks, where the longest reach translates directly to lowest cost/bit by eliminating regeneration sites, maximizing fiber capacity and enabling the delivery of 400GbE services over any distance. Presumably, the 35% of operators that want the best technology for each network segment will largely favor embedded optics for their long-haul networks, as this approach addresses maximum cost/bit savings with best spectral efficiency.

Given the breadth of different types of network architectures, fiber plant characteristics and geographic coverage around the world, there is no one-size-fits-all solution for network operators.

Figure 1: Which statement best describes your coherent optical network evolution strategy? n=87 (Source: Heavy Reading, 2022) n=87
(Source: Heavy Reading, 2022)

Requirements for the metro

In metro networks, the choice of pluggable versus embedded optics is more complex but will, again, be dictated by network characteristics. Interoperable coherent pluggable optics can address a subset of metro architectures. 400G coherent pluggables with enhanced capabilities will address a greater range of reach and line system requirements for many operators. Where bandwidth demands, service type and ROADM configuration require greater spectral efficiency, embedded optics will be needed.

For the near term, at least, the majority of operators expect a hybrid environment of coexistence between pluggable and embedded optics, with 57% of respondents expecting a mix of embedded 600/800G and pluggable optics in their metro networks. Thanks to continued innovation in coherent optical technology to enable a wide breadth of pluggable coherent capabilities, along with broad-based industry collaboration in standards bodies, the growing momentum of pluggables is clear. Nearly one-third (28%) of operators expect to utilize 100–400G pluggable optics exclusively in their metro networks. 15% still expect to standardize on high performance embedded optics only.

Figure 3: What are the top barriers to coherent DWDM pluggables adoption in routing/switching products (IPoDWDM)? n=87 (Source: Heavy Reading, 2022) n=87
(Source: Heavy Reading, 2022)

Barriers to IPoDWDM

The adoption of coherent pluggable optics opens the door to new metro architectures based on integrating those optics directly in routers (i.e., IPoDWDM). The promise of coherent IPoDWDM is great, and Heavy Reading and other research companies are covering the emerging trend extensively, including in earlier blogs in this series.

But like any new technology, there are still significant challenges that must be addressed. The top IPoDWDM barriers selected by operator respondents are lack of converged organizations (selected by 34% of respondents), insufficient number of third-party pluggable optics (selected by 31%), lack of router ports supporting 15+ watts (30%), and lack of APIs to manage the optical layer through routers (also 30%). Significantly, of the 10 barriers listed, 7 of them were selected by at least 25% — meaning that many barriers are top of mind for many operators.

Figure 2: What are your requirements for your metro network deployments? n=87 (Source: Heavy Reading, 2022) n=87
(Source: Heavy Reading, 2022)

Lack of convergence between IP and optics groups is commonly cited as a top barrier — both in past Heavy Reading surveys on IPoDWDM architectures and in individual discussions with operators and suppliers. But a large number of operators claim varying degrees of organizational convergence today. Heavy Reading wanted to understand how respondents with converged roles view top barriers to IPoDWDM adoption. We filtered results by those whose roles include both IP and optics (e.g., converged functions).

For this subset of operators, the lack of APIs to manage the optical layer rises to the top (selected by 38% of the group). The data suggests that as operators successfully tackle organizational convergence, the lack of APIs will become the next big issue to resolve. It is also interesting that, even for respondents in converged roles, the lack of convergence between IP and optical groups remains a primary IPoDWDM challenge, possibly indicating disparate operational processes that need to be consolidated. Ranking second, and tied with the lack of third-party pluggables options, lack of converged organization was selected by 31% of this subset.

Results indicate that, despite the promise of IPoDWDM and operators' moves toward network convergence, there is still much organizational work to be done.

Looking for more information?

This blog is sponsored by Ciena.

— Sterling Perrin, Senior Principal Analyst — Optical Networking & Transport, Heavy Reading

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About the Author(s)

Sterling Perrin

Senior Principal Analyst, Heavy Reading

Sterling has more than 20 years of experience in telecommunications as an industry analyst and journalist. His coverage area at Heavy Reading is optical networking, including packet-optical transport and 5G transport.

Sterling joined Heavy Reading after five years at IDC, where he served as lead optical networks analyst, responsible for the firm’s optical networking subscription research and custom consulting activities. In addition to chairing and moderating many Light Reading events, Sterling is a NGON & DCI World Advisory Board member and past member of OFC’s N5 Market Watch Committee. Sterling is a highly sought-after source among the business and trade press.

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