72 research outputs found

    SDN-controlled and Orchestrated OPSquare DCN Enabling Automatic Network Slicing with Differentiated QoS Provisioning

    Get PDF
    In this work, we propose and experimentally assess the automatic and flexible NSs configurations of optical OPSquare DCN controlled and orchestrated by an extended SDN control plane for multi-tenant applications with differentiated QoS provisioning. Optical Flow Control (OFC) protocol has been developed to prevent packet losses at switch sides caused by packet contentions.Based on the collected resource topology of data plane, the optical network slices can be dynamically provisioned and automatically reconfigured by the SDN control plane. Meanwhile, experimental results validate that the priority assignment of application flows supplies dynamic QoS performance to various slices running applications with specific requirements in terms of packet loss and transmission latency. In addition, the capability of exposing traffic statistics information of data plane to SDN control plane enables the implementation of load balancing algorithms further improving the network performance with high QoS. No packet loss and less than 4.8 us server-to-server latency can be guaranteed for the sliced network with highest priority at a load of 0.5

    Screening of Lignocellulose-Degrading Superior Mushroom Strains and Determination of Their CMCase and Laccase Activity

    Get PDF
    In order to screen lignocellulose-degrading superior mushroom strains ten strains of mushrooms (Lentinus edodes939, Pholiota nameko, Lentinus edodes868, Coprinus comatus, Macrolepiota procera, Auricularia auricula, Hericium erinaceus, Grifola frondosa, Pleurotus nebrodensis, and Shiraia bambusicola) were inoculated onto carboxymethylcellulose agar-Congo red plates to evaluate their ability to produce carbomethyl cellulase (CMCase). The results showed that the ratio of transparent circle to mycelium circle of Hericium erinaceus was 8.16 (P<0.01) higher than other strains. The filter paper culture screening test showed that Hericium erinaceus and Macrolepiota procera grew well and showed extreme decomposition of the filter paper. When cultivated in guaiacol culture medium to detect their abilities to secrete laccase, Hericium erinaceus showed the highest ability with the largest reddish brown circles of 4.330 cm. CMCase activity determination indicated that Coprinus comatus and Hericium erinaceus had the ability to produce CMCase with 33.92 U/L on the 9th day and 22.58 U/L on the 10th day, respectively, while Coprinus comatus and Pleurotus nebrodensis had the ability to produce laccase with 496.67 U/L and 489.17 U/L on the 16th day and 18th day. Based on the results, Coprinus comatus might be the most promising lignocellulose-degrading strain to produce both CMCase and laccase at high levels

    Taburan, kepelbagaian dan sepsis kelawar di tiga kawasan habitat vegetasi di hutan Sukau, Sandakan , Sabah

    Get PDF
    This research was carried out with the aim to record and compare information on the diversity, distribution and abundance of bat species at three different habitats of Sukau Rainforest. These were the primary forest, oil palm plantation and village area. Sampling was conducted for six days at each habitat using three mist net and a sweep net. A total of248 individuals of 15 species were caught in this study. Results showed that the village area has the highest bat diversity (H'=1.9) followed by primary forest (H'=I.4). The oil palm plantation area recorded the lowest diversity (H'=O.9). The presence of Sungai Kinabatangan nearby, the close proximity of Gua Keruak, the presence of human settlements and the mixed vegetation were identified to contribute to the high diversity at the village area. It was expected that the primary forest area has higher bat diversity as compared to the oil palm plantation area due to the abundance of food available for bats at this forest and the presence of undisturbed roosting sites. In contrast, the lower diversity recorded at the oil palm plantation was probably because of the less abundance of food available for bats particularly nocturnal insects which is the main diet of Microchiropterans. However, the occurrence of Megachiropterans was high at the oil palm plantation area which is probably because of the presence of oil palm fruits. It can be concluded from this study that there is a difference in terms of bat diversity and this maybe correlated with variation of the vegetations whereby suitability and availability of food and roosting sites play an important role

    Nanoseconds-controlled and SDN-enabled Optical Switching System for Fast and Flexible Data Center Networks

    Get PDF

    Synergistic Switch Control Enabled Optical Data Center Networks

    Get PDF
    Optical switching, which benefits from high bandwidth and low latency, promises to revolutionize data center networks that suffer from a bandwidth bottleneck and hierarchical structure. However, the lack of adaptable and fast optical switch control schemes, the lack of optical buffers for contention resolution, and the high cost of clock and data recovery (CDR) impede the practical deployment of optical switches in data centers. Networking communities have tried to address these challenges from different perspectives. However, the proposed solutions may be interdependent and thus introduce unexpected issues. In this article, a synergistic optical switch control mechanism is proposed to simultaneously solve the aforementioned challenges. The developed label control technique allows for controlling and configuring packet switching within 43.4 ns. The implementation of clock distribution achieves a fast CDR of 3.1 ns at low cost, and the design of an optical flow control protocol prevents packet loss caused by packet contention

    Nanosecond optical switching and control system for data center networks

    Get PDF
    Electrical switching based data center networks have an intrinsic bandwidth bottleneck and, require inefficient and power-consuming multi-tier switching layers to cope with the rapid growing traffic in data centers. With the benefits of ultra-large bandwidth, high-efficient cost and power consumption, switching traffic in the optical domain has been investigated to replace the electrical switches inside data center networks. However, the deployment of nanosecond optical switches remains a challenge due to the lack of corresponding nanosecond switch control, the lack of optical buffers for packet contention, and the requirement of nanosecond clock and data recovery. In this work, a nanosecond optical switching and control system has been experimentally demonstrated to enable an optically switched data center network with 43.4 nanosecond switching and control capability and with packet contention resolution as well as 3.1 nanosecond clock and data recovery

    HiFOST: A scalable and low-latency hybrid data center network architecture based on flow-controlled fast optical switches

    No full text
    To solve the bandwidth and latency issues in current hierarchical data center network (DCN) architectures based on electrical switches, we propose a novel hybridDCNarchitecture based on distributed flow-controlled fast optical switches (FOS) and modified top-of-the-rack (TOR) switches (HiFOST). The intra-cluster interconnection of HiFOST is built by FOS with wavelength switching in nanoseconds' time for an efficient statistical multiplexing operation, while the inter-cluster interconnection is connected by the TOR interfaces directly. Due to the lack of practical optical buffers, optical flow control is implemented to retransmit packets in case of contention. We investigate the performance of HiFOST DCN with different TOR buffer sizes, optical link capacities, elastic allocation of transceivers, and network scales under realistic data center (DC) traffic. The results show an average serverto- server latency of less than 2.8 μs, a packet loss <5.6 × 10-6 at load of 0.5 for a DC size of 94,080 servers with limited 50 KB TOR buffer. In addition, for scaling out the servers' number and scaling up the data rate of connected servers, the cost and power consumption of the HiFOST DCN have been investigated and compared with the electrical Fat-Tree and Leaf-Spine DCN architectures, as well as with the optical H-LION and OPSquare DCN architectures. Results indicate that, for 94,080 servers operating at 10 Gb/s, HiFOST has a 48.2% and 34.1% savings of the cost and 46.3% and 32.5% savings of the power consumption with respect to the Fat-Tree and Leaf-Spine, respectively. For a HiFOST DCN supporting a 10880 server, scaling up the operating data rate of the server to 100 Gb/s, the HiFOST solution has a cost savings of 35.6% and 34.1% and power consumption of 56.5% and 59.2% as compared to the Fat-Tree and Leaf-Spine, respectively

    Performance assessment of OPSquare data center network with elastic allocation of WDM transceivers

    No full text
    Under realistic OPSquare data center traffic model, the impact of the packet loss ratio and sever end-to-end latency of elastic allocation of WDM transmitters at top of rack (ToR) is numerically investigated. Results show that with limited 50 KB buffer, a sever end-to-end latency lower than 2 μs and packet loss ratio below 10-6 could be guaranteed for different traffic patterns and loads when the WDM transmitters at ToRs are adaptively allocated. An analyses on costs and power consumption indicate that the elastic allocation of WDM transmitters will not cause dramatic fluctuation in power consumption, while cost will increase with more usage of transmitters

    Low-Latency Optical Wireless Data-Center Networks Using Nanoseconds Semiconductor-Based Wavelength Selectors and Arrayed Waveguide Grating Router

    Get PDF
    In order to meet the massively increasing requirements of big-data applications, data centers (DCs) are key infrastructures to cope with the associated demands, such as high performance, easy scalability, low cabling complexity and low power consumption. Many research efforts have been dedicated to traditional wired data center networks (DCNs). However, DCNs’ static and rigid topology based on optical cables significantly limits their flexibility, scalability, and even reconfigurability. The limitations of this wired connection can be addressed with optical wireless technology, which avoids cable complexity problems while allowing dynamic adaption and fast reconfiguration. Here, we propose and investigate a novel optical wireless data-center network (OW-DCN) architecture based on nanoseconds semiconductor optical amplifier (SOA)-based wavelength selectors and arrayed waveguide grating router (AWGR) controlled by fast field-programmable gate array (FPGA)-based switch schedulers. The full architecture, including the design, packet-switching strategy, contention solving methodology, and reconfiguration capability, is presented and demonstrated. Dynamic switch scheduling with a FPGA-based switch scheduler processing optical label and software-defined network (SDN)-based reconfiguration were experimentally confirmed. The proposed OW-DCN was also achieved with a power penalty of less than 2 dB power penalty at BER < 1 × 10−9 for a 50 Gb/s OOK transmission and packet-switching transmission
    • …
    corecore