RETN sets coherent pluggable future with 400GbE build
RETN, an independent global network provider, completed the deployment of Juniper’s 400GbE coherent pluggable optics across its entire Pan-Eurasian IP network, reflecting the growing momentum around IP-over-DWDM (IPoDWDM).
This build marks one of the largest IP-over-DWDM (IPoDWDM) deployments currently in production. RETN’s deployment spans backbone links ranging from 300 to 950 kilometres and involves hundreds of 400G pluggables—all of which are fully operational, stable, and live in production.
Besides offering greater speeds and efficiency, RETN said the deployment highlights its sustainability efforts.
In tandem with achieving 40% power savings, RETN was also able to reduce its carbon footprint by 55% and reduce space requirements by 15%.
RETN's network spans multiple continents, including Africa, the Americas, Asia, and Europe.
Today, RETN’s network delivers over 75 terabits of connectivity to its partners and customers. The deployment of 400G pluggables will enable RETN to exceed 100 terabits soon.
By leveraging Juniper's equipment to create a standardised, homogeneous infrastructure that simplifies operations and accelerates deployments, RETN can reduce complexity and expand its Eurasian footprint with a scalable, repeatable model.
Tony O’Sullivan, CEO of RETN, said the 400G rollout sets a foundation for future technology shifts, including 800 G.
“Our widespread rollout of 400G services, powered by Juniper’s latest routing platforms, positions us at the forefront of ultra-high-capacity, sustainable networking,” he said. “We're also actively evaluating 800G technology to ensure our network remains future-ready.”
What is IP-over-DWDM?
IP over DWDM (IPoDWDM) integrates IP routers and switches directly into Optical Transport Networks (OTN) using pluggable DWDM transceivers, eliminating the need for separate transponders or grey interfaces. This approach simplifies network architecture and reduces costs by directly connecting IP devices to the DWDM line system.
New service drivers
Having started as a data logistics business provider that provides IP transport, RETN has continued to evolve its service set.
It then started selling Layer 3 MPLS capacity around 2013. This drove RETN to build a DWDM network to scale the bandwidth for the IP/MPLS network.
“At that time, the thought was we should be using IP/MPLS network to sell services to customers as well,” O’Sullivan said. “
RETN had been running Infinera optical systems as well as a mix of Ciena and other vendor equipment.
“When we completed our network upgrade in 2022, we were able to take advantage of 400 GE pluggable optics,” O’Sullivan said. “This allows us to slice the optical spectrum efficiently in such a way that we can implement 400GigE optics.”
RETN sees two key benefits from the pluggable optics approach: economics and environmental sustainability.
"The first driver is money--it is much cheaper to use pluggable optics than transponders,” O’Sullivan said. “The other part is the environment because these devices are more powerful and space-efficient.”
He added that pluggable optics also allow it to be more responsive to its customers’ bandwidth needs. “In terms of configurability, it’s much easier to use pluggable optics than a traditional transponder to spin up resources more quickly,” O’Sullivan said.
Ongoing network evolution
Today, RETN’s network evolution is centered on 400G Ethernet.
RETN uses 400G in various applications, including cloud storage, AI, machine learning, and large-scale data centers.
The service provider is also investigating 800 GigE pluggable optics, but O’Sullivan said, “that’s a bit further down the line of about two to three years from now.”
Moving to 400 GbE didn’t come easily. RETN did a thorough evaluation of multiple vendors.
“We saw this 18 months ago, where we started testing across 20 different vendors to understand whether there was any difference between the major brands and the third-party ones,” O’Sullivan said. “In many cases, we found that many of the third-party ones were equal to or outperformed the branded ones.”
Regarding 800G, RETN is waiting for a time when the platforms are ready to meet its business case requirements.
“800 GigE is the next step,” O’Sullivan said. “We’re ready for it on the line system. It’s just a case of when the optics are cost-efficient and energy efficient enough to warrant it and making sure the routers are ready for the 800 GigE optics as well.”
IPoDWDM creates new benefits
Adopting IP over DWDM technology was a simple decision for RETN. When it examined the core network hops in its European fiber network, the majority are in the 600 km range.
This made sense to go to 400 GbE pluggable technology.
As a provider serving multiple geographies, the use of IP over DWDM will depend on market dynamics.
“It worked on the European side,” O’Sullivan said. "Obviously, for different geographies, it has different applicability between those core hubs.”
RETN’s application for 400GigE optics could also benefit the provider’s customer base, which consists of three main elements: wholesale carriers, content providers, and business enterprises.
“Enterprises are moving towards higher bandwidth Layer 1 services, but aren’t quite there yet,” O’Sullivan said. “Customers wishing to use 400 GigE optics on our network are mainly wholesale and content, but wholesale more so because content providers build their own DWDM networks.”
The next question for RETN is, where will its wholesale customers go with 400 GbE optics? It could mean selling these customers a slice of spectrum instead of capacity.
“It is an interesting question about how you productize spectrum because spectrum is either on or off on a specific range of frequencies,” O’Sullivan said. “It brings into question how you deal with SLAs and product definitions, but we’ll cross that bridge when we see the requirement from customers.”
Service evolution
RETN sells three core products, with Layer 1 service consisting of 30% of its revenues.
It was one of the first European providers to adopt 100 GbE. However, it bypassed the 40G wavelength service evolution.
“So far, 100 GigE has been successful,” O’Sullivan said. “What we have seen in terms of the transition to 400 GigE is just as the price points are starting to become appealing to customers, where that multiple of 100G and 400G is changing, that’s where 400G pluggable optics start to come in.”
He added that the question “is how far on those medium haul wavelengths between 400 and 800 km, how 400G will go traditional transponders and how much will be a spectrum sale and customers using their pluggable optics.”
What made the upgrade to 400 GigE pluggable optics for RETN was that it made a wholesale change to its entire network backbone. It only must change a small segment of its network in Western Europe from G.655.
G.655 fiber, also known as non-zero dispersion-shifted fiber (NZDSF), is a type of single-mode optical fiber designed to minimize dispersion effects at the wavelength of 1550 nm, which is crucial for long-haul, high-capacity telecommunications systems.
Switching from G.655 to another fiber type requires careful consideration of application requirements, cost, performance needs, and system compatibility.
“The reason we were able to achieve this across the vast majority of our network was that we invested in a wholesale upgrade of the line across the entire backbone,” O’Sullivan said. “This is a prerequisite to moving onto this 400 GigE pluggable network, and it will be interesting to see what other networks are prepared to go down that route quickly enough to justify it.”
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Cignal AI: IP-over-DWDM port deployments to surpass 700k in 2027
Driven by cloud operator Datacenter Interconnect (DCI), Cignal AI, in its 2024 IP-over-DWDM Pluggables Forecast, notes that the standardization, development, and maturation of 400G pluggable coherent optics (400ZR) have coincided with the ongoing AI spending boom, with volumes increasing faster than any previous DWDM technology. The deployments will come in phases.
Once 800G and 1600G are adopted, the cloud operator's 400G purchases peak in 2026. Looking forward, the research firm notes that the performance gap between embedded and pluggable optics will further shrink with 1600G, making IP-over-DWDM even more attractive from a network design perspective. Cignal AI cautions that the adoption rate of IP-over-DWDM will be “slow and steady,” but “the technology’s space, power, and cost benefits will justify the change in architecture for many operators.”
About the Author
Sean BuckleySean Buckley
Sean is the Editor-in-Chief of Lightwave. He establishes and executes Lightwave's editorial strategy across its website, email newsletters, events, and other information products. Before coming to Lightwave in July 2023, he served as editor of Broadband Communities. Earlier, he served as senior editor of FierceTelecom and the editor of the former Telecommunications Magazine. He got his start in the optical industry in 1998 when he became the editor of enterprise and optical networks at Information Gatekeepers. He has a BA in English from the University of Massachusetts, Boston, and lives in Dracut, Mass, with his wife, two sons, and his cat, Dove.
