Thanks to broadband and video services, the demand for capacity on fiber networks will continue unabated for years to come, and with that in mind, service providers are currently mulling how to ramp up their core optical networks.

Bright House Networks and Fujitsu Network Communications recently completed a field trial of 400 Gbps and 800 Gbps on a ring between Tampa Bay and Orlando. The trial, which started six months ago, used “super channels” on the cable operator’s live production network to hit the 400G and 800G speeds. Bright House Networks characterized the trial as its future path for terabit speeds.

The trials used Fujitsu’s 400G optical networking transceivers over its Flashwave 9500 Packet Optical Networking Platforms.  

John Dickinson, Bright House Networks“One of the cruxes of the trial was to put these super channels, the 200-, 400-, 800 gig, over the existing production network,” said John Dickinson, senior director of network strategy and architecture, Bright House Networks. “This gear was obviously prototype and not shipping in the Fujitsu 9500 platform today, so it was kind of put onto the network in conjunction with the existing 9500. The cards obviously don’t fit in the 9500 chassis so they had to be set beside them, but it was put on to the exact same network as the existing platform.

“We’re getting more densities out of the existing fiber by going to 16 QAM,” Dickinson continued. “It’s more going to gridless optics in terms of the DWDM lineup, but we are getting more out of each wavelength. These super channels are twice as dense as 100 gig. We’re getting 200 gig out of the same optical spacing as we currently get out of our 100 gig today.”

By using a gridless system, Dickinson said that Bright House Networks was able to dynamically add the super channels to its existing lambdas.

“If it was a completely new gridded system, you have to set up new dark fiber to actually deploy it,” Dickinson said. “I think the fact that it integrates with the existing, deployed wavelengths is really key for operators and engineers. To be able to deploy this on an existing system where you have existing lambdas already, you can literally overlay this on the same fiber without having to either provision new fiber or stand up a whole new optical platform.”

The 800G trial was just a matter of doubling up on super channels with additional lasers and receivers.

“They were basically running 200 gig super channels, and they had enough equipment to add two more super channels to the existing production network,” Dickinson said. “That added another 400, so we had literally 800 gig running between Tampa and Orlando on this ring.

“They had twice equipment so they went ahead and activated all of the equipment that they had. They even mentioned if they had more, they could have gone to a terabit because it’s basically adding 200 gig increments at a time.”

While the technology exists, albeit in the very early stages, for 400G and 800G speeds, it could be up to five years before service providers hit full throttle.

Dell’Oro Group vice president Jimmy Yu said that 100 gigabit is building momentum, thanks to DP-QPSK and 16 QAM modulation schemes, as well as work around the 100G client side OTN, or Ethernet-based interfaces. Yu said that about 30 percent of the capacity shipping today was coming from 100 gigabit wavelength speeds.

“I would say that 100G is kind of the new 10G speed, where it’s sort of at that number where you’re not only getting the right line speed on the optics for long haul distances, but you’re also getting IEEE standards on 100 gigabit on the client side as well,” he said. “There are a lot of positive standards that were developed around 100 gigabit. The component companies have started to develop the piece parts around 100 gigabit so there’s been a lot of good movement there.

“Even though 400G is probably available today, I think the adoption is going to take a while because I think 100 gig has so much runway to go,” Yu continued. “I’m projecting that 100 gigabit will probably continue to grow through 2018.”

Yu said that while 100G can reach the range of 3,000 kilometers unregenerated, 400G is currently limited to around 700 kilometers, which makes the latter useful for metro spans in the short term.

Another factor for the adoption of 400G is price point. Service providers won’t bite on 400G unless it has a better dollar per bit rate than 100 gigabit, Yu said.

Dickinson said Bright House Networks is seeing the typical 40 percent CAGR year-over-year in bandwidth growth, but the move to 400G or 1 terabit will be also be dictated by the cost balance.

“It comes down to: are four 100 gigs more effective, or one 400 gig? You have to cross the boundaries just as we did with 10 gig,” he said. “When 100 gig became less than ten 10 gigs, then economically it was a wiser choice to go with 100 gig.

“I think the same thing will be true for when you move to the 400 gig, 800-, or even 1 terabit. It’s always kind of a cost balance of whether it’s cheaper to buy less efficient spectrum in multiple hundreds or is it more cost effective to go to one 400?”

For 400G to take flight, Yu said that new line cards, which might be out next year, and additional standards, such as the IEEE’s 400G Ethernet standards, need to be in place, and that price points and capacity demands need to further drive the demand for the faster speeds.

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