DENVER -- Cable Next-Gen Technologies and Strategies -- The explosion in bandwidth demand is not merely requiring network operators to add capacity to their networks but also to make fundamental changes in technology deployments that will ultimately deliver operational, cost and service improvements, two Infinera executives explained here today.
By 2019, dense wave division multiplexed fiber is expected to deliver more than 19,000 terabits of capacity, which would require 380,000 of today's 100Gbit/s transponders, said Gaylord Hart, director, MSO market segment, Infinera Corp. (Nasdaq: INFN).
"We need a solution that deploys more bandwidth in larger chunks to reduce the operational cycles," he said. At the same time, cable operators need to lower the cost per bit, maximize the use of existing fiber resources and reduce both power/space/heat required for equipment and the operational cycles and turn-up times, Hart noted. On the transport side, they also need to increase spectral capacity, optimize reach and increase network flexibility and efficiency.
Hart and his colleague, Anuj Malik, manager of product marketing, laid out the case for key optical technologies to address these and other issues: 1.2 TB Multi-Carrier Super-Channel using newer flex-grid channels, multi-layer switching that combines digital switching and optical switching, and a new generation of ROADMs (reconfigurable optical add-drop multiplexers).
The flex-grid channels move away from the channel scheme initially developed by the ITU which used fixed 50GHz channels with guard bands in between in favor of flexible channels based on combining chunks of 12.5GHz of spectrum with less space reserved for guard bands.
"With fewer guard bands and flexible channel wide, you can get a 23% increase in usable amplifier spectrum," Hart explained. "And you can mix and match flex-grid and fixed-grid system and re-use the spectrum as the network evolves."
Migrating to multi-carrier super-channels using flex-grid is the fastest way to get to the necessary bandwidth, he said, because other options require silicon that is years away in development.
"There is a huge increase in component account to accomplish this," Hart conceded. "Nevertheless multi-carrier super channels offer the fastest time to market, and we anticipate within 18-24 months to see some of these implemented."
Infinera is addressing the large component count for multi-carrier super channels with its photonic integrated circuits which use two monolith integrated circuits to replace dozens of discrete components.
"There are 500G super channels commercially available since 2012 serving five by 100 gig waves, and these can be implemented with today's photonically integrated circuits," he said. "The component complexity and count goes away, which means a savings in power, space and component count. PIC provides the only scalable super-channel solution."
The flexibility to tune wavelengths to any combination of 12.5GHz channels enables operators to support coming new services such as the next Carrier Ethernet interfaces at 400 Gbit/s, Hart noted. There are also multiple modulation options that can be used, depending on the specific requirements for capacity and reach.
Multi-layer switching, which combines digital switching and optical switching, allows network operators to switch lower rate services in the digital domain, and higher capacity "express" type services in the optical domain, giving each the most efficient treatment and avoiding stranded bandwidth, noted Malik. By using the appropriate switching method based on the traffic type and capacity, service providers can realize both capex and opex savings.
Services below 100G that require adding and dropping of traffic at lower speeds on highly meshed networks -- Malik called it "meshiness" -- and need 50 millisecond restoration are more efficiently switched in the digital domain, which the high-speed fully filled super-channels on high-capacity express routes between major cities are better switched optically.
Without multi-layer switching, traffic is only groomed at the source, which can lead to multiple channels that are only partially filled, he said. With multi-layer switching, bandwidth can be seen as an available resource pool, and wavelengths can be fully filled to save capex.
Malik also made a strong case for newer colorless, directionless, contentionless ROADMs to "provide truly flexible optical transport infrastructure." And while he didn't directly address the role of SDN, Malik said the flex-grid and CDC-ROADMs are required elements of a programmable network that can be controlled via SDN. In fact, Infinera recently announced its first commercial SDN deployment with Pacnet in Asia, Hart said. (See Pacnet Offers Transport SDN Services.)
— Carol Wilson, Editor-at-Large, Light Reading