ON2020 Plots Future of ROADMs & T-SDN
Sterling Perrin, Principal Analyst, Heavy Reading
The newly formed ON2020 association held its first public workshop last week at OFC, with about 100 people in attendance and panel participation from Verizon, Facebook, Nokia, Huawei, Fujitsu, Lumentum, Finisar and Heavy Reading. The association describes its vision as driving innovative optical network solutions to better meet the optical networking demands in the cloud era toward year 2020 and beyond.
The OFC workshop focused on two technology areas: future directions for ROADM development and the future of transport SDN and optical networking.
Facebook and Verizon presented perspectives from vastly different market segments -- submarine builds (Facebook) and metro evolution (Verizon) -- and, at times, highlighted the basic differences in requirements that exist between web-scale Internet Companies and traditional telecom operators.
Facebook Global Optical Architect Steve Grubb provided an update on the MAREA submarine cable build connecting Virginia Beach, Virginia, and Bilbao, Spain, a 6,600 km link. The build consists of eight fiber pairs, with a capacity of 20 Tbit/s per pair (using eight QAM modulation) for a total capacity of 160 Tbit/s on the route.
Grubb explained the rationale for web-scale Internet companies like Facebook building their own networks, such as MAREA, versus joining established telecom operator consortia. For Facebook, the decision is based primarily on speed and deployment flexibility, as they are now able to add the amount of capacity they need at the time that they need it. Grubb said traditional telecom consortia were too slow moving, often taking months to negotiate even minimal capacity additions. MAREA owners are Facebook, Microsoft and Telefonica's Telxius.
Fiber is very scarce in subsea routes so maximizing individual fiber capacity and efficiency is always critical. This scarcity is driving Facebook to light both the C and the L band for some submarine routes (which it is doing today on the Pacific Light Cable Network), and to use the most leading edge advances to drive fiber capacity and spectral efficiency. In a post-deadline paper, Facebook and Nokia highlighted a new record achievement of 7.46 bits/second/Hz spectral efficiency on a Facebook submarine link -- transmitting 5,500 km between New York and Ireland and using Nokia's new probabilistic constellation shaping (PCS) technology. (See Nokia & Facebook Push Undersea Fiber to 32 Tbit/s.)
Grubb noted, by contrast, that some of its terrestrial metro DCI links have as many as 20,000 fibers between them.
Verizon's Glenn Wellbrock focused on its metro network evolution where new CDC ROADMs play a key role. Wellbrock said that many of today's individual metro networks are as complex as its entire long haul network. Large Verizon metros have 150 ROADMs today and that number is moving up to 200 ROADMs as traffic grows and as metro regions increase geographically.
On the hardware side, Wellbrock sees continuing increases in the number of degrees beyond today's 16, but he spent most of his presentation time discussing the values of automating the transport network, across layers, to reduce operational costs and to vastly improve network efficiency. Today, two thirds of a typical telecom optical network sit idle due to the combination of 1+1 protection and poor efficiency in active bandwidth, he said. Verizon sees value in automated multi-layer and multi-domain network control in ramping up efficiency.
While 100 percent utilization is not achievable, Wellbrock believes the industry can get well above today's 30-40 percent utilization levels with CDC ROADM hardware and multi-layer SDN control. (See With ROADMs in Place, Next Step Is Software.)
Nokia Director of Transport SDN Solutions Lubo Tancevski presented two possible paths to optical network interoperability:
- SDN-based multi-layer control and management delivered via standardized control/management plane interfaces
- An open optical line system including open ROADM interoperability
Here again, differences in philosophy and approach between the web-scale Internet companies and some traditional telecom operator emerged. Facebook, like other web-scales presenting in other forums, championed the idea of the open line system as a means of simplifying, automating and ensuring interoperability among suppliers. Wellbrock, by contrast, has stated in many forums that the OLS model introduces greater complexity for established networks, like Verizon's, and essentially establishes a lowest common denominator in overall performance. We expect the debate of open hardware, particularly in telecom networks, to continue.
Representing Huawei's optical transmission product line, Principal Scientist Xiang Liu delivered the final presentation. Liu described four key challenges facing the optical networking industry: the new for higher capacity, faster networking, lower costs and power consumption and easier network control and management. Addressing these challenges will require new innovations in the electrical layer, the optical layer and the control and management layer.
Perhaps the strongest area of agreement across suppliers and service providers during the workshop was on the increasing role of telemetry and analytics moving forward. Telemetry is the means of collecting network data in real-time and transmitting it to management systems. Analytics is the sophisticated analysis of that telemetry data with the goal of determining conditions and making recommendations in real time. Ultimately, telemetry and analytics will be tightly tied with SDN control. Suppliers and providers agreed that these are areas of critical investment over the next couple of years that will pay big dividends in improving network efficiency and application performance.
— Sterling Perrin, Principal Analyst, Heavy Reading
This blog is sponsored by ON2020.