ATLANTA, GA--Mindful that social-networking sites like Facebook and YouTube, along with financial institutions such as the New York Stock Exchange (NYSE) are demanding more communications bandwidth and higher-speed transmissions, the folks at the Georgia Institute of Technology, through the Georgia Tech 100G Networking Consortium (www.100g.gatech.edu), have just completed a test bed that will put 100 gigabit per second (100 Gbps or simply 100G) systems to the test.
Facebook (Palo Alto, CA) network architect Donn Lee says that his company needs 100 Gbps core switching just to keep up with the millions of new Facebook users being added each week to the current 300 million active users. And NYSE Euronext, who traditionally used 10 Gbps service-provider connections, was driven by its increased network traffic to look at new alternatives. Andy Bach, Sr. VP and global head of communications for NYSE Euronext, said, “He who connects the order faster gets the order, so anything we can do to speed that up is a good thing.” In response, NYSE Euronext is completing two network data centers this month that will support 100 Gbps.
The test bed
There is perhaps no better way to ensure the rapid deployment of 100G networks than to learn from an actual installed test bed. Consortium director Stephen E. Ralph says, “The GaTech 100G Optical Networking Consortium is an industry-led effort. Industry partners benefit from the knowledge and experience in more fundamental research with an extended time horizon for applications, which is typical of research conducted in academic environment; Universities are generally more free to explore a wider variety of possibilities and therefore generate original solutions to practical problems. In turn, our companies, including ADVA Optical Networking, OFS, Ciena, and Verizon, provide the real-world view of the telecommunications field, balancing the technological advancements with other equally important aspects of a successful business such as component and equipment cost, reliability, and ease of use in existing and new network environments.”
Ralph credits the joint academic and industry structure of the Georgia Tech 100G Consortium as the reason for the successful creation of the test bed. “Having this research conducted at a reputable and business-neutral institution like Georgia Tech has allowed us to develop a test bed for transmission at 100 Gbps per wavelength with minimum cost. This is due to multiple donations in equipment and components from the participants, which would not have been possible if we were to conduct this experimental research at any of the member companies. Having to purchase all the components (fiber, optical amplifiers, wavelength-selective switches, laser sources, modulators, balanced receivers) required for the 100G test bed would have increased the cost of this research significantly.”
The Consortium is exploring a variety of modulation formats, network environments, and fiber types using simulation tools and the experimental test bed hardware. Recently, the performance of 112 Gbps differential quadrature phase shift keying (DQPSK) has been quantified on a range of network configurations representing different dispersion compensation per span. Modulation techniques such as DQPSK improve resilience to impairments encountered in older fiber. “Optimum and robust dispersion maps have been identified and these results have been supported by accurate simulations,” says Ralph. “Also in simulation we have quantified the robustness of alternative formats that may enable us to demonstrate 448 Gbps per wavelength.” Facebook would like that!
--Gail Overton