SAN FRANCISCO -- Software-defined networking (SDN) will be the future of optical networking, according to speakers at the OFC Conference, held March 11 to 13 in San Francisco. SDN will help curb ongoing issues bandwidth capacity.
“We’re getting to where there isn't a heck of a lot of capacity left... and bandwidth seems to be an insatiable demand,” Robert Tkach, director of advanced photonics research at Alcatel-Lucent Bell Labs, told conference attendees. “The rate of capacity has fallen down and isn’t as efficient.”
Robert Tkach speaks at OFC 2014.
(Photo by Jessica Lipsky.)
SDN aims to make building and running large networks more efficient by moving network tasks from complex ASICs and APIs to standard interfaces, merchant chips, and open-source software. Currently, the best commercial systems operate at about 4 Bits/Hz spectral efficiency, which Tkach said “isn’t that much room.”
“We’re going through a massive transition now in which we are replacing all our copper pairs with fiber. We’ve burned through the dot com exuberance and will need some capacity, but at some point, do we top out or does it keep going forever?” speaker David Clark, a MIT senior research scientist for advanced network architecture, questioned.
While spectral efficiency has increased 10 times over as many years, Tkach said this trend isn’t likely to continue. Increased data usage, inter-computer communication, and processor speeds have slowed the efficiency evolution; increasing signal processing alone would create distortion from fiber linearity eventually limiting system performance.
“SDN is the next step for high capacity, fancy media, but it’s expensive and difficult to deploy. SDN continues optical communication area, and uses those same techniques, but doesn’t necessarily require new fiber,” Tkach said.
Capital expenditures are necessary to get the ball rolling on SDN and cost integration will help drive the cost down, Clark and Tkach said.
David Clark at OFC 2014.
(Photo by Martin Rowe.)
“I think what’s going on now has a very strong societal imperative and we are getting communications everywhere. The question is how fast, and it's gated by capex,” Clark said. “If the cost of optical stuff comes down deployment is going to be quicker.”
Network and optical engineers can further employ SDN by using spatial multiplexing, a transmission technique using separately encoded data signals from multiple transmit antennas, to save fibers. These multicore fibers can operate at 10 times the capacity as single fiber strands, Tkach notes.
The expanding Internet of Things and mobile sector won’t have any particular influence in the rollout of SDN, Tkach said. He could not speculate on a timeline of transition to SDN.
“My take on it is sort of application agnostic, as technology makes it possible to do more things and that has been a good thing. I don t really see it as being driven by applications,” he said. “For the most part the network can support all activity. I don’t see [mobile or wearables] affecting what we do in optical communications.”
Clark had a slightly different take on mobile’s place in often expensive optical networking. Curating the capacity and experience of mobile users is key to making a profit and managing bandwidth.
“If you are a smart wireline ISP you want to make sure to your customer is not mobile and dependent only on a mobile device,” Clark said. “Making sure that the fixed experience cannot be replicated in mobile space -- making sure that you have so much capacity that you can do things there that you can’t do on mobile.”
“Right now we don’t have any other option beside SDN,” Tkach said. “There probably ought to be other options out there; we should be on the lookout for that.”
— Jessica Lipsky, Associate Editor, EE Times