Feature Topic: Optical Technologies for Data Center Networks

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Natasha Simonovski

Feature Topic: Optical Technologies for Data Center Networks

Tue, 08/27/2013 - 12:19 — Natasha Simonovski

In recent years, large-scale data centers have continued to be built out as the global Internet traffic has grown exponentially. These include both multi-tenant carrier-neutral ones and private data centers, and host many Internet application servers. Increasingly intelligent, low-latency, high-bandwidth networks are required among data centers and within them due to emerging applications such as cloud computing and “big data” processing. Inside the data center rack, multiple processing cores are being integrated into a single chip to achieve higher processing power. This means that the communication requirements between racks in the data centers will continue to increase significantly, as these cores require a fast and low-latency interconnection scheme to communicate with the storage system and the other servers inside or outside of the racks. Another major challenge to the data center network is the energy consumption, as the conventional data center networks are based on electrical switching fabric whose energy consumption increases with the processing speed and capacity. As a result, data center networks account for an increasingly high percentage of the overall IT power consumption, and contribute to growing percentage of the total ICT greenhouse gases emissions. Optical technologies could overcome these limitations and meet the needs for next generation data center networks, due to the large bandwidth capacity of the optical fiber and the low power consumption rate in optical switching. Therefore, a significant amount of research has been carried out in the past few years to develop optical interconnects and networking technologies for data center applications. This Feature Topic aims to capture the latest progress and results in optical technologies for data center network applications, ranging from optical interconnect components and architecture to network management and optimization to application in large-scale computing. The first article, “Technologies and Protocols for Data Center and Cloud Networking” by N. Bitar et al., opens this issue from the cloud networking prospective. It discusses the demands for large-scale multi-tenant data centers and clouds, reviews various switching, routing, and optical transport technologies, and analyzes their applicability in addressing the networking needs of large-scale multi-tenant data centers. In the second article, “The Prospect of Inter-Data-Center Optical Networks” by X. Zhao et al., the authors discuss the traffic growth trends and capacity demands of Google’s inter-data-center network, and how they drive the network architectures and technologies to scale capacities and operational ease on existing fiber plants. Recent research findings and emerging technologies are reviewed, and some critical areas to improve efficiency and flexibility of inter-data-center optical networks are pointed out. The third article, “Optical Interconnection Networks in Data Centers: Recent Trends and Future Challenges” by C. Kachris et al., addresses the intra-data-center networking aspect. It provides an update on recent developments in the field of ultra-high-capacity optical interconnects for intra-data-center communication, examines and compares recently proposed architectures and technologies, and outlines future trends and research challenges. The fourth article, “Large-Scale Wavelength Routing Optical Switch for Data Center Networks” by K. Sato et al., focuses on one important subsystem in intra-data-center interconnect: the wavelength routing optical switch. It addresses the scalability issue in particular, and proposes a promising technology for the development of 1000 × 1000 scale large port count optical switches. 

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