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The future is 400Gbps: How Europe is testing 17Tbps links to cope with data explosion

France Telecom is dipping its toe in the water of 400Gbps optical networking links to support our growing thirst for cloud and multimedia - but it won't be rushed.
Written by Anne Morris, Contributor

As consumers' and businesses' data consumption continues to grow, telcos are looking to retool their networks to keep on top of our increasing demand for bandwidth. One European telco is now looking ahead to a future where links carrying terabits of data could be the norm.

France Telecom reached a networking landmark earlier this month with the deployment of what it says is the world's first optical link with a capacity of 400Gpbs per wavelength in a live network. With 44 wavelengths, the fibre link can carry 17.6Tbps of traffic, with capacity four times the maximum found elsewhere.

Following a field trial, the 400Gbps link — deployed by Alcatel-Lucent — is now being trialled as part of France Telecom's live network between Paris and the city of Lyon.

For France Telecom, which owns mobile operator Orange, the three-month pilot of the 400Gbps link will enable it to fully investigate the ramifications of the high-speed optical networking technology and inform its decision on how and when to "generalise" 400Gbps across its entire network, according to Olivier Gombert, director of the transmission factory at France Telecom. "We can learn things from the pilot," he said.

A move to 400Gbps may seem a bit premature given that 100Gbps is only now ramping up in earnest: according to Infonetics Research, 100Gbps will rise from just five percent of deployed wavelengths in 2012 to 37 percent in 2015 as carriers move from 10Gbps and 40Gbps.

For France Telecom, any wider rollout of 400Gbps technology will depend not only on the outcome of the pilot but also on customers' interest.

"It's a kind of race. We always want to be one step ahead of our customers" — Olivier Gombert, France Telecom

According to Gombert, there is still strong demand for 10Gbps and increasingly 100Gbps. However, international network operators such as France Telecom should anticipate what customers will want further down the line, he added.

"It's a kind of race," he said. "We always want to be one step ahead of our customers."

Renater, the public interest group that manages the telecommunications network for technology, teaching and research institutions in France, will be France Telecom's first customer to test the functionality of the technology in a real-world situation.

"[The Paris-Lyon] link transports the bulk of France's scientific data that passes through our network," said Patrick Donath, managing director of Renater, in a statement. "This pilot phase also aims to test the latest switching equipment supplied by major OEMs on a network running at this capacity and will enable us to anticipate the architecture of Renater's network in the coming years. A 400Gbps network is an important step forward for the networks and research projects of tomorrow."


Developments with 400Gbps optical networking have widened the debate about client-side standards, not least because the battle over whether to standardise on 40Gbps or 100Gbps was only recently settled when the Optical Internetworking Forum (OIF) chose a modulation format for 100Gbps.

The OIF said in January it has set up a committee to look into the requirements for 400Gbps modules, although that does not mean it is about to standardise on the technology. Some industry watchers believe 400Gbps will be a stepping stone on the way to 1Tbps, and suggest 400Gbps should even be leapfrogged in favour of the faster technology — as 40Gbps was for 100Gbps. For others, 1Tb Ethernet would be a step too far at present.

Gombert naturally keeps an eye on the client-side standardisation work. His primary focus is to support France Telecom-Orange's continuing investment in the development of super-fast infrastructure to support the growing use of cloud computing and multimedia content, and to guarantee transmission quality while keeping costs down. At the same time, the operator says it isn't about to take any risks by launching new technology before it is mature enough.

"We need to be cautious with our customers," Gombert added, noting that the Paris-Lyon route was chosen for the 400Gbps pilot "to keep it closer to home".

"When we announced the migration to 100Gbps we used the international Paris-London route as the technology was much more mature," he added.

Outside of France, 100Gbps remains a key focus for carriers globally: Infonetics Research noted in December that there has been "a flurry of prototyping, sampling and trial activity all around the world, including China, where plans for 100Gbps have been bumped up by 12 months since we spoke to operators there last spring."

The research company said worldwide shipments of 100Gbps-coherent transceivers more than tripled in 2012, and will at least double in 2013. 

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