Beyond 100G, Optical Vendors Push for 400G

With 100Gbit/s optical networking coming into its own starting in 2013, several vendors and some carriers have already begun work on making a 400Gbit/s generation happen.
December's announcement from Japan involving Fujitsu Ltd., NEC Corp. and NTT Communications Corp. is just the latest in a series of 400Gbit/s technology developments in the lab.
It follows 400Gbit/s chip announcements made earlier this year by Ciena Corp., Alcatel-Lucent and Huawei Technologies Co. Ltd., making it seem certain that 400Gbit/s is the next generation for optical, just as it's going to be for Ethernet. (See Ciena Pushes Ahead to 400Gbit/s, and Huawei Shows 400Gbit/s DWDM Prototype.)
Whether 400Gbit/s will be like 40Gbit/s, in terms of being a brief stop for the optical freight train on the way to a bigger destination (1Tbit/s), remains to be seen.
However, Kevin Drury, director of product marketing for Alcatel-Lucent's optical portfolio, says many of the 400Gbit/s advancements in recent months are strongly rooted in finding ways to do 100Gbit/s better, more efficiently and at less cost.
"For us, 400Gbit/s is all about 100Gbit/s," he says. "We used a 200Gbit/s multiplexer strategy to take in two 100Gbit/s interfaces and have them come out as 200Gbit/s, and could do the same thing with a 400Gbit/s mux. Because you could achieve 400Gbit/s with that approach, that's what got the most notice and interest from carriers. Honestly, we were surprised at the level demand and interest it has been getting with 100Gbit/s deployments just beginning to happen."
Drury adds, "When you hear about carriers doing terabits between data centers, you can see where things are going, but the economic realities are that 40Gbit/s shipments are still growing and will continue to [do so] for the next 12 months, and that 100Gbit/s hardware costs are still in some cases more than 10x10G. If you can create a 400Gbit/s interface, that can help the 100Gbit/s upgrade make more sense for some carriers."
The budding 400Gbit/s evolution has fired up some debate about 400Gbit/s standards. The timing of the standards talk may seem surprising to some, given that 100Gbit/s deployment commitments did not begin to flow in earnest until this year, but as Heavy Reading analyst Sterling Perrin pointed out in a Light Reading webinar, "100Gbit/s & Beyond: Preparing for the Terabit Era," more than 170 carrier commitments to 100Gbit/s have been made thus far, up from a single-digit handful in 2010. That makes 400Gbit/s, and even 1Tbit/s, seem not so far away.
Separately, Infinera Corp. has been making its own case for 500Gbit/s for more than a year, and for now is the loudest voice on 1Tbit/s. "The next generation for us will be a terabit on a chip," says Vinay Rathore, senior director of solutions marketing at Infinera. "We have trialed that, but haven't announced an availability date, and it could be a couple years before it's a factor in the market."
Regarding standards, the Institute of Electrical and Electronics Engineers Inc. (IEEE) is still expected to have a 400Gbit/s client-side Ethernet standard call-for-interest at its plenary meeting this coming March. Meanwhile, the International Telecommunication Union (ITU) Study Group 15 started looking at 400Gbit/s in September. That group potentially could discuss a fixed-rate 400Gbit/s standard, but also will consider a flexible-rate transport container along the lines of Nx100Gbit/s or Nx200Gbit/s. Infinera, along with Verizon Communications Inc. and Finisar, was behind the OTU Adapt proposal for line-side flexibility.
Both standards efforts will culminate around 2016. Around that time, most vendors should be well on their way to whatever lies beyond 400Gbit/s.
"It takes two to three years between each chip generation," Drury says. "Our 100Gbit/s Photonic Service Engine was in 2010; our 400Gbit/s was in March of 2012. It remains to be seen what the next stop will be, but we should get to that next point by 2015."
Whatever the timing and content of these standards, they will not affect the willingness of carriers to move to 400Gbit/s and beyond, says Mike Adams, vice president product and technical marketing at Ciena.
"The issue presenting itself now is the client-side standard, and it doesn't so much matter what the rate is on the other side," he says. "The bottom line is that carriers are interested now in what lies beyond 100Gbit/s because they want to future-proof their networks. We are building the next generation on what we already have in the 100Gbit/s ecosystem, leveraging parts that are already in the network, and that is the important thing in getting it to market when they're ready."
— Dan O'Shea, Communications Writer, Innovation Generation