420 research outputs found
Optical Switching for Scalable Data Centre Networks
This thesis explores the use of wavelength tuneable transmitters and control systems within the context of scalable, optically switched data centre networks. Modern data centres require innovative networking solutions to meet their growing power, bandwidth, and scalability requirements. Wavelength routed optical burst switching (WROBS) can meet these demands by applying agile wavelength tuneable transmitters at the edge of a passive network fabric. Through experimental investigation of an example WROBS network, the transmitter is shown to determine system performance, and must support ultra-fast switching as well as power efficient transmission. This thesis describes an intelligent optical transmitter capable of wideband sub-nanosecond wavelength switching and low-loss modulation. A regression optimiser is introduced that applies frequency-domain feedback to automatically enable fast tuneable laser reconfiguration. Through simulation and experiment, the optimised laser is shown to support 122×50 GHz channels, switching in less than 10 ns. The laser is deployed as a component within a new wavelength tuneable source (WTS) composed of two time-interleaved tuneable lasers and two semiconductor optical amplifiers. Switching over 6.05 THz is demonstrated, with stable switch times of 547 ps, a record result. The WTS scales well in terms of chip-space and bandwidth, constituting the first demonstration of scalable, sub-nanosecond optical switching. The power efficiency of the intelligent optical transmitter is further improved by introduction of a novel low-loss split-carrier modulator. The design is evaluated using 112 Gb/s/λ intensity modulated, direct-detection signals and a single-ended photodiode receiver. The split-carrier transmitter is shown to achieve hard decision forward error correction ready performance after 2 km of transmission using a laser output power of just 0 dBm; a 5.2 dB improvement over the conventional transmitter. The results achieved in the course of this research allow for ultra-fast, wideband, intelligent optical transmitters that can be applied in the design of all-optical data centres for power efficient, scalable networking
SDT: A Low-cost and Topology-reconfigurable Testbed for Network Research
Network experiments are essential to network-related scientific research
(e.g., congestion control, QoS, network topology design, and traffic
engineering). However, (re)configuring various topologies on a real testbed is
expensive, time-consuming, and error-prone. In this paper, we propose
\emph{Software Defined Topology Testbed (SDT)}, a method for constructing a
user-defined network topology using a few commodity switches. SDT is low-cost,
deployment-friendly, and reconfigurable, which can run multiple sets of
experiments under different topologies by simply using different topology
configuration files at the controller we designed. We implement a prototype of
SDT and conduct numerous experiments. Evaluations show that SDT only introduces
at most 2\% extra overhead than full testbeds on multi-hop latency and is far
more efficient than software simulators (reducing the evaluation time by up to
2899x). SDT is more cost-effective and scalable than existing Topology
Projection (TP) solutions. Further experiments show that SDT can support
various network research experiments at a low cost on topics including but not
limited to topology design, congestion control, and traffic engineering.Comment: This paper will be published in IEEE CLUSTER 2023. Preview version
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