Updated on 2022/12/27

写真a

 
FUKUSHIMA Yukinobu
 
Organization
Faculty of Natural Science and Technology Associate Professor
Position
Associate Professor
External link

Degree

  • 博士(情報科学) ( 大阪大学 )

Research Interests

  • Information networks

  • Edge computing

  • Network virtualization

  • Optical networking

Research Areas

  • Informatics / Information network

Education

  • Osaka University   大学院情報科学研究科   情報ネットワーク学専攻

    2003.4 - 2006.3

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    Country: Japan

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  • Osaka University   大学院基礎工学研究科   情報数理系専攻

    2001.4 - 2003.3

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    Country: Japan

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  • Osaka University   基礎工学部   情報科学科

    1997.4 - 2001.3

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    Country: Japan

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Research History

  • Okayama University   大学院自然科学研究科産業創成工学専攻   Associate Professor

    2018.2

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  • Okayama University   大学院自然科学研究科生命医用工学専攻   Assistant Professor

    2015.4 - 2018.1

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  • Okayama University   The Graduate School of Natural Science and Technology   Assistant Professor

    2007.4 - 2015.3

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  • Okayama University   大学院自然科学研究科産業創成工学専攻   Research Assistant

    2006.4 - 2007.3

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Papers

  • An Improvement of an IP Fast Reroute Method Using Multiple Routing Tables Reviewed

    Yuya Tarutani, Masashi Ishigai, Naoto Numata, Yukinobu Fukushima, Tokumi Yokohira

    Journal of Internet Technology   23 ( 6 )   1315 - 1324   2022.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Angle Publishing Co., Ltd.  

    <p>The demand for high Internet availability has increased. As a routing method to recover fast from a single network component (link or node) failure, a method using multiple routing tables has been proposed. In the method, when a component failure occurs, packets which are supposed to pass through the component in the failure free state are rerouted using a backup routing table (backup table: BT) which does not use the component. Thus, it is important to decrease the increased routing cost, and because the method uses multiple BTs, it is also important to decrease the numbers of entries in BTs. In this paper, we propose a new routing method to decrease the increased routing cost. In the conventional method, there are many components that do not fail but are not used for packet forwarding in a BT. In our proposed method, we use such components as much as possible to decrease the increased routing cost. About the decreasing of the numbers of entries in BTs, we simulate packet forwarding for every node-pair and find unnecessary entries which are not used in packet forwarding in any node-pair. Numerical examples show that our proposed method is superior to the conventional method. </p><p> </p>

    DOI: 10.53106/160792642022112306014

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  • Consensus Building using Deep Reinforcement Learning for Energy Management

    Yuya Tarutani, Isato Oishi, Yukinobu Fukushima, Tokumi Yokohira

    IEIE Transactions on Smart Processing & Computing   11 ( 4 )   284 - 291   2022.8

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:The Institute of Electronics Engineers of Korea  

    DOI: 10.5573/ieiespc.2022.11.4.284

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  • VM Migration Considering Downtime for Accuracy Improvement in Multi-stage Information Processing System.

    Kazutoshi Nakane, Takumi Anjiki, Jiquan Xie, Yukinobu Fukushima, Tutomu Murase

    ICCE-TW   335 - 336   2022

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    DOI: 10.1109/ICCE-Taiwan55306.2022.9869040

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    Other Link: https://dblp.uni-trier.de/db/conf/icce-tw/icce-tw2022.html#NakaneAXFM22

  • Minimizing the monetary penalty and energy cost of server migration service

    Yukinobu Fukushima, Tatsuya Suda, Tutomu Murase, Yuya Tarutani, Tokumi Yokohira

    Transactions on Emerging Telecommunications Technologies   2022

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    Current IaaS (infrastructure as a service) cloud service may not satisfy communication QoS (quality of service) requirements of delay-sensitive network applications, if there is a significant physical distance between a server of the network application (NetApp server) at a data center and its network application clients (NetApp clients). In order to improve communication QoS of NetApp clients, we propose server migration service (SMS) in this article. SMS allows NetApp servers to migrate among different locations in the network (1) to optimally locate themselves in relation to NetApp clients and mitigate the QoS degradation caused by location-related factors (ie, propagation delays on network links) and (2) to optimally distribute traffic load over routers and processing load over (physical) computers and decrease the energy consumption. We develop a mixed-integer programming model that determines when and to which locations NetApp servers migrate to minimize the total operating cost of SMS, that is, the sum of the monetary penalty incurred due to QoS violation and energy cost incurred due to energy consumption, while preventing NetApp servers from excessively migrating and adversely impacting QoS of the non-SMS service that share the resource of the substrate network with SMS. Simulation results show that the model developed in this article achieves up to 42% lower total operating cost of SMS compared to the model that only minimizes the monetary penalty of SMS without considering the energy cost of SMS.

    DOI: 10.1002/ett.4511

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  • Throughput Fairness in Congestion Control of Multipath TCP. Reviewed

    Yu Deguchi, Aoshi Kobayashi, Yuya Tarutani, Yukinobu Fukushima, Tokumi Yokohira

    International Conference on Information and Communication Technology Convergence (ICTC)   123 - 126   2022

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    Language:English   Publishing type:Research paper (international conference proceedings)  

    DOI: 10.1109/ICTC55196.2022.9952427

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    Other Link: https://dblp.uni-trier.de/db/conf/ictc/ictc2022.html#DeguchiKTFY22

  • A Secret Sharing Scheme to Reduce the Total Data Size

    Kuniaki Tsuji, Shiden Kishimoto, Yuya Tarutani, Yukinobu Fukushima, Tokumi Yokohira

    2021 International Conference on Information and Communication Technology Convergence (ICTC)   2021.10

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    DOI: 10.1109/ictc52510.2021.9621088

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  • Modification of Enigmail to Use Unique Cryptographic Algorithms in Email Reviewed

    Ryotaro Tani, Yukinobu Fukushima, Yuya Tarutani

    IEIE Transactions on Smart Processing & Computing   10 ( 5 )   2021.10

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

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  • A Server Migration Method Using Q-Learning with Dimension Reduction in Edge Computing

    Ryo Urimoto, Yukinobu Fukushima, Yuya Tarutani, Tutomu Murase, Tokumi Yokohira

    International Conference on Information Networking   2021-January   301 - 304   2021.1

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    Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    Edge computing is a promising computing paradigm that satisfies QoS requirements of delay-sensitive applications. In edge computing, server migration control is indispensable for managing client mobility. As a server migration method for edge computing, the method based on Q-learning has been proposed. However, the method assumes that there is only one application client and the number of destination edge servers is limited to one. In this paper, we propose a server migration method using Q-learning that copes with realistic situations where there are multiple application clients and destination edge servers. The contributions of this paper are as follows: 1) we clarify that, under the situation with multiple application clients and multiple destination edge servers, a straightforward server migration method using Q-learning (RL method) does not scale due to state space explosion, and 2) we propose a server migration method using Q-learning (RL-DR method) that reduces the dimensionality of state space by abstracting the numbers of application clients at all locations into a center of the gravity (COG) of application clients. The simulation results show that 1) RL method shows up to 248% worse performance than conventional server migration methods because of state space explosion and 2) RL-DR method achieves up to 38.3% better performance than the conventional methods.

    DOI: 10.1109/ICOIN50884.2021.9333965

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    Other Link: https://dblp.uni-trier.de/db/conf/icoin/icoin2021.html#UrimotoFTMY21

  • Proposal of device control method based on consensus building using reinforcement learning

    Isato Oishi, Yuya Tarutani, Yukinobu Fukushima, Tokumi Yokohira

    International Conference on Information Networking   2021-January   451 - 456   2021.1

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    Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    Various information is collected from IoT devices through the network. As such device becomes more familiar to the user, services are required to consider the influence of user. However, it is difficult to set the parameters of actuators that build consensus among all users in an environment where people with various preferences coexist. The conventional method minimizes the power consumption under the constraints of the user stress. However, this method has a problem that the calculation overhead is increased as the number of devices and users is increased. In this study, we propose a device control method based on consensus building with reinforcement learning. In the proposed method, the state is reduced by applying reinforcement learning for reducing the calculation overhead. As a result of evaluation, we clarified that our method obtains the device parameters that improve the reward by 1.5 times compared with the conventional method. Moreover, we also clarified that a reward value of 98.6% can be achieved compared to the optimum value.

    DOI: 10.1109/ICOIN50884.2021.9333958

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    Other Link: https://dblp.uni-trier.de/db/conf/icoin/icoin2021.html#OishiTFY21

  • An IP Fast Reroute Method against Multiple Node Failures

    Naoto Numata, Masashi Ishigai, Yuya Tarutani, Yukinobu Fukushima, Tokumi Yokohira

    International Conference on ICT Convergence   2020-October   714 - 719   2020.10

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    Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    Since network failures have a huge negative impact on our daily life, networks should be recovered from the failures as soon as possible. Although a lot of IP fast reroute methods have been proposed, most methods focus on multiple link failures or a single node failure. This paper proposes an IP fast reroute method which can reroute packets against multiple node failures. The paper is the first paper which deals with multiple node failures in the research area on IP fast reroute. The proposed method generates spanning trees to bypass the failures from a given network topology in network design stage, and reroutes a packet using one of the generated spanning trees every time the packet encounters a node failure in network operation stage. Numerical example shows that such spanning trees can be easily generated using our proposed method.

    DOI: 10.1109/ICTC49870.2020.9289623

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    Other Link: https://dblp.uni-trier.de/db/conf/ictc/ictc2020.html#NumataITFY20

  • Performance Evaluation of Feature Encoding Methods in Network Traffic Prediction Using Recurrent Neural Networks

    Yusuke Tokuyama, Ryo Miki, Yukinobu Fukushima, Yuya Tarutani, Tokumi Yokohira

    ACM International Conference Proceeding Series   279 - 283   2020.3

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    Publishing type:Research paper (international conference proceedings)  

    © 2020 ACM. Recurrent neural network method considering traffic volume, timestamp and day of the week (RNN-VTD method) is a promising network traffic prediction method because of its high prediction accuracy. The RNN-VTD method encodes timestamp and day of the week, which are categorical data, to numerical data using label encoding. The label encoding, however, gives magnitude to the encoded values, which may cause misunderstanding of recurrent neural network models, and consequently, the prediction accuracy of the RNN-VTD method may be degraded. In this paper, we investigate the effect of using one-hot encoding instead of label encoding for a feature encoding method in the RNN-VTD method. In the one-hot encoding, each input data is encoded to an k-dimensional 0 - 1 vector where k is the number of category types. Because the encoded data do not have magnitude, it is expected that the prediction accuracy of the RNN-VTD method is improved.

    DOI: 10.1145/3395245.3396441

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  • A TCP Incast Avoidance Method Based on Retransmission Requests from a Client.

    Shiden Kishimoto, Shigeyuki Osada, Yuya Tarutani, Yukinobu Fukushima, Tokumi Yokohira

    2019 International Conference on Information and Communication Technology Convergence(ICTC)   153 - 158   2019

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    Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    DOI: 10.1109/ICTC46691.2019.8939877

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    Other Link: https://dblp.uni-trier.de/db/conf/ictc/ictc2019.html#KishimotoOTFY19

  • Determining Server Locations in Server Migration Service to Minimize Monetary Penalty of Dynamic Server Migration Reviewed

    Yukinobu Fukushima, Tutomu Murase, Gen Motoyoshi, Tokumi Yokohira, Tatsuya Suda

    Journal of Network and Systems Management   26 ( 4 )   1 - 41   2018.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Springer New York LLC  

    In this paper, we propose a new class of service called server migration service (SMS) to augment the existing IaaS (Infrastructure as a Service). SMS allows servers (server-side processes of a network application) to dynamically and automatically migrate as their clients (client-side processes of a network application) change their locations in order to reduce the total monetary penalty that the SMS provider pays to its SMS subscribers when failing to provide them with the guaranteed level of QoS. In this paper, we consider the monetary impact that arises from QoS degradation due to server migration and build an integer programming model to determine when and to which location servers should migrate to minimize the total monetary penalty incurred by the SMS provider. Numerical examples show that SMS achieves up to 96% lower total monetary penalty compared to that without server migration. Numerical examples also show that the integer programming model developed in this paper requires reasonable computation time under realistic parameter settings.

    DOI: 10.1007/s10922-018-9451-6

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  • The Effect of Using Attribute Information in Network Traffic Prediction with Deep Learning. Reviewed

    Yusuke Tokuyama, Yukinobu Fukushima, Tokumi Yokohira

    International Conference on Information and Communication Technology Convergence, ICTC 2018, Jeju Island, Korea (South), October 17-19, 2018   119 ( 297(NS2019 120-133)(Web) )   521 - 525   2018

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  • Workplace Capacity Design Using the Minimum Dominating Set in Server Migration Services. Reviewed

    Yukinobu Fukushima, Itsuho Goda, Tutomu Murase, Tokumi Yokohira

    9th IFIP International Conference on New Technologies, Mobility and Security, NTMS 2018, Paris, France, February 26-28, 2018   1 - 5   2018

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  • Backoff Algorithms to Avoid TCP Incast in Data Center Networks. Reviewed

    Shigeyuki Osada, Daichi Izumi, Shiden Kishimoto, Yukinobu Fukushima, Tokumi Yokohira

    International Conference on Information and Communication Technology Convergence, ICTC 2018, Jeju Island, Korea (South), October 17-19, 2018   515 - 520   2018

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  • Improvement of a TCP incast avoidance method using a fine-grained kernel timer Reviewed

    Shigeyuki Osada, Shogo Wakai, Yukinobu Fukushima, Tokumi Yokohira

    International Conference on Information and Communication Technology Convergence: ICT Convergence Technologies Leading the Fourth Industrial Revolution, ICTC 2017   2017-   147 - 152   2017.12

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:Institute of Electrical and Electronics Engineers Inc.  

    When a standard TCP implementation using the minimum retransmission timeout (RTOmin) of 200 ms is used in distributed file systems in data centers, a well-known throughput degradation called TCP Incast occurs, because 200 ms is too large as an RTOmin in data centers. In order to avoid TCP Incast, a TCP implementation using a much smaller RTOmin attained by a fine-grained kernel timer is proposed. However, throughput still decreases in the implementation when the number of servers in distributed file systems is large. In this paper, we propose an improvement method introducing a new TCP option which enables a client to request servers to retransmit packets in a better timing. Numerical examples obtained by extensive simulation runs show the effectiveness of the improved method.

    DOI: 10.1109/ICTC.2017.8190962

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  • Power-Aware server location decision in server migration service Reviewed

    Yukinobu Fukushima, Tokumi Yokohira, Tutomu Murase, Tatsuya Suda

    2016 International Conference on Information and Communication Technology Convergence, ICTC 2016   150 - 155   2016.11

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:Institute of Electrical and Electronics Engineers Inc.  

    The server migration service (SMS) is an optional service that improves communication QoS of the IaaS cloud service. In the SMS, small-scale data centers (micro data centers) called work places (WPs) are deployed at various locations in the network. In the SMS, a network application (a NW-App) consists of one or more server-side processes of the application (servers) and one or more client-side processes of the application (clients). In the SMS, servers migrate among WPs in order to improve communication QoS between the servers and their clients, unlike in the IaaS cloud service where locations of the servers are always fixed at a data center in the network. In our previous study, we developed an integer programming model and solved it to determine when and to which WPs servers should migrate in the SMS in order to minimize the financial penalty, i.e., SMS provider's financial loss due to degradation of the communication QoS. In this paper, we consider the electricity power cost, an important component of the operational cost of the SMS, in addition to the financial penalty considered in our previous study, in determining when and to which WPs servers should migrate in the SMS. In this paper, we define the operational cost of the SMS as the sum of the financial penalty and electricity power cost and consider a power-Aware server location decision problem in order to minimize the operational cost of the SMS. We formulate the problem as a mixed-integer programming model and solve the model numerically. Numerical examples show that our mixed-integer programming model optimally determines the locations of the servers and decreases the operational cost by up to 15.5% compared to our previous integer programming model, where the power cost was not considered.

    DOI: 10.1109/ICTC.2016.7763457

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  • Performance improvement of an AS-friendly peer selection algorithm for P2P live streaming Reviewed

    Yukinobu Fukushima, Kazuki Kobayashi, Tokumi Yokohira

    International Journal of Computer Networks and Communications   8 ( 1 )   35 - 46   2016

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Academy and Industry Research Collaboration Center (AIRCC)  

    Minimum Physical Hop (MPH) has been proposed as a peer selection algorithm for decreasing inter-AS (Autonomous System) traffic volume in P2P live streaming. In MPH, a newly joining peer selects a peer whose physical hop count (i.e., the number of ASes traversed on the content delivery path) from it is the minimum as its providing peer. However, MPH shows high inter-AS traffic volume when the number of joining peers is large. In this paper, we propose IMPH that tries to further decrease the inter-AS traffic volume by distributing peers with one logical hop count (i.e., the number of peers or origin streaming servers (OSSes) traversed on the content delivery path from an OSS to the peer) to many ASes and encouraging the following peers to find their providing peers within the same AS. Numerical examples show that IMPH achieves at the maximum of 64% lower inter-AS traffic volume than MPH.

    DOI: 10.5121/ijcnc.2016.8103

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  • A trail multi-splitting method for throughput improvement in light trail networks Reviewed

    Yukinobu Fukushima, Wenjie Chen, Tokumi Yokohira

    PHOTONIC NETWORK COMMUNICATIONS   30 ( 2 )   178 - 189   2015.10

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:SPRINGER  

    Light trail networks have been proposed as an extension of lightpath networks in order to enable sub-wavelength bandwidth allocation in WDM networks. The networks need a medium access control (MAC) method to avoid collisions of data transmissions. We have proposed a MAC method which adopts a token-passing mechanism. The method splits one trail into two trails: one upstream trail and one downstream trail and permits independent data transmissions on the trails. However, the method leaves bandwidths of links upstream from the token-holding node idle because the method only splits the original trail into two trails and leaves the upstream trail unsplit. In this paper, we propose a novel token-passing MAC method for further improving trail throughputs. Our proposed method recursively splits the upstream trail, and consequently the original trail can be split into more than two trails. In the proposed method, an appropriate setting of upstream/downstream token-holding times of all nodes is a key factor to successfully accommodate an input traffic. Therefore, we tackle a problem (called a token-holding time decision problem) where we optimize token-holding times of all nodes so that input traffic is successfully accommodated. We formulate the problem as a linear programming model. Numerical examples on maximum effective throughput show that the proposed method is more superior as the ratio of short-hop traffic is higher in input traffic patterns.

    DOI: 10.1007/s11107-015-0509-z

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  • An On-line Algorithm to Determine the Location of the Server in a Server Migration Service Reviewed

    Yuta Hoshino, Yukinobu Fukushima, Tutomu Murase, Tokumi Yokohira, Tatsuya Suda

    2015 12TH ANNUAL IEEE CONSUMER COMMUNICATIONS AND NETWORKING CONFERENCE   740 - 745   2015

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    In IaaS cloud services, QoS of network applications (NW-Apps) may degrade due to location factors such as significant distance between a server-side application (server) of a NW-App at a data center and a client-side application (client) of the NW-App at a client terminal. In order to shorten the distance and to improve the QoS, server migration services (SMSes) have been proposed. In SMSes, servers may migrate between different computers (called work places, WPs) on a network to prevent QoS degradation caused by the changes of client locations. Although server migrations can improve QoS of NW-Apps, they also generate a huge amount of traffic (server migration traffic) in the network. This paper focuses on a server location decision problem where the location of a server is decided in an on-line manner so that QoS of a NW-App is improved under the constraint that the server migration traffic has to be suppressed below an acceptable level. For the problem, we propose a practical on-line algorithm. The key idea behind the proposed algorithm is that the location of the server is decided with consideration of the QoS degradation in the future. The algorithm defines the averagely good location for the server where the QoS is expected to be relatively good for various client locations. Then, it keeps the range of the server's migration within the returnable range where the server can soon come back to the averagely good location. As a result, the QoS can be always kept as good as the one under the averagely good location. Simulation results show that the proposed algorithm improves QoS of the NW-App by up to 30% compared to a greedy algorithm.

    DOI: 10.1109/CCNC.2015.7158070

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  • Optimization of Maximum Timeout Value in TCP with a Fine-grained Timer for Data Center Networks Reviewed

    Ryo Miyayama, Shigeyuki Osada, Yukinobu Fukushima, Tokumi Yokohira

    2014 INTERNATIONAL CONFERENCE ON INFORMATION AND COMMUNICATION TECHNOLOGY CONVERGENCE (ICTC)   433 - 437   2014

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    When the standard TCP implementation is used in distributed. le systems in data center, a well-known throughput degradation called TCP Incast occurs. In order to avoid TCP Incast, a TCP implementation using a specialized. fine-grained timer is proposed. However, the throughput still decreases in the implementation when the number of servers in distributed. le systems is large. In this paper, we clarify that the cause of the decreasing is that maximum timeout value is too large and optimize the value.

    DOI: 10.1109/ICTC.2014.6983174

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  • A Reroute Method to Recover Fast from Network Failure Reviewed

    Yasuhiro Harada, Wang Hui, Yukinobu Fukushima, Tokumi Yokohira

    2014 INTERNATIONAL CONFERENCE ON INFORMATION AND COMMUNICATION TECHNOLOGY CONVERGENCE (ICTC)   903 - 908   2014

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    The demand for high Internet availability has increased. As routing methods to recover fast from a single network component (link or node) failure, methods using multiple routing tables have been proposed. In the methods, when a component failure occurs, packets which are supposed to pass through the component in the failure-free state are rerouted using a routing table (backup table) which does not use the component for packet forwarding. Thus, it is important to decrease the increased routing cost (for example, the number of increased hops of rerouted packets if every link cost is one) due to the reroute as much as possible. In this paper, we propose a new routing method to decrease the increased routing cost. In the conventional methods, there are many components that do not fail but are not used for packet forwarding in a backup table. In our proposed method, we use such components as much as possible, and consequently we try to decrease the increased routing cost. Numerical examples show the effectiveness of our proposed method.

    DOI: 10.1109/ICTC.2014.6983329

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  • Throughput Improvement of TCP Proxies in Network Environment with Wireless LANs Reviewed

    Wang Hui, Yukinobu Fukushima, Tokumi Yokohira

    2014 IEEE REGION 10 SYMPOSIUM   82 - 87   2014

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    Split-connection type proxies have been proposed to improve TCP (Transmission Control Protocol) throughput in network environment with wireless LANs. A proxy is placed at the boundary of a wireless LAN (WLAN) and a wired network and it splits a TCP connection into two virtual TCP connections. We proposed a split-connection type proxy called MDA-Proxy (Modified Decreasing-ACK Proxy), which increases throughput of upflows (flows from wireless hosts to wired hosts) by decreasing the number of ACKs in a WLAN. MDA-Proxy uses two parameters, ack_stock and delay_timer, for each connection. The former controls the number of ACKs sent to a WLAN and the latter is used to recover from losses and delays of ACKs in a wired network. However, it is assumed that MDA-Proxy uses fixed values of the two parameters and their automatic tuning in response to network situation remains to be future work. In this paper, we propose a new type of proxy called ASA-Proxy (Ack_Stock Autotunning Proxy), which automatically tunes the two parameters in MDA-Proxy. Ack_stock is tuned comparing throughputs before and after its changing so that throughput of the connection becomes large, and delay_timer is replaced by the normal TCP retransmission timer because it is better than a fixed value of delay_timer for the inference of losses and delays of ACKs in a wired network. Extensive simulation runs show that ASA-Proxy is superior to MDA-Proxy.

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  • TCP Incast Avoidance Based on Connection Serialization in Data Center Networks Reviewed

    Shigeyuki Osada, Kazutoshi Kajita, Yukinobu Fukushima, Tokumi Yokohira

    2013 19TH ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC): SMART COMMUNICATIONS TO ENHANCE THE QUALITY OF LIFE   142 - 147   2013

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    In distributed file systems, a well-known congestion collapse called TCP Incast occurs because many servers send data to the same client and then many packets overflow the port buffer of the client link. Incast leads to throughput degradation in the network. In this paper, we propose two methods to avoid Incast based on the fact that only one connection can almost fully use the network bandwidth because the bandwidth-delay product is not so large in current data center networks. The first method is a method which completely serializes connection establishments. By the serialization, the number of packets in the port buffer becomes very small, which leads to Incast avoidance. The second method is a method which overlaps the slow start period of the next connection to the current established connection to improve throughput in the first method. Numerical results from extensive simulation runs show the effectiveness of our two proposed methods.

    DOI: 10.1109/APCC.2013.6765931

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  • A Reroute Method Using Multiple Routing Configurations for Fast IP Network Recovery Reviewed

    Daiki Imahama, Yukinobu Fukushima, Tokumi Yokohira

    2013 19TH ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC): SMART COMMUNICATIONS TO ENHANCE THE QUALITY OF LIFE   433 - 438   2013

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    The demands on Internet reliability and availability have increased. As a routing method to recover fast from a single network component (link or node) failure, a method using multiple routing tables has been proposed. In the method, when a component failure occurs, packets which are supposed to pass through the component in no failure state are rerouted using a routing table (backup table) which does not use the component for packet forwarding. Thus, it is important to decrease the increased routing cost (for example, the number of increased hops of rerouted packets if every link cost is one) due to the reroute as much as possible. In this paper, we propose a new routing method to decrease the increased routing cost. In the conventional method, there are such components that do not fail but are not used for packet forwarding in a backup table. In our proposed method, we use such components, and consequently we try to decrease the increased routing cost. Numerical examples show the effectiveness of our proposed method.

    DOI: 10.1109/APCC.2013.6765984

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  • Improvement of a TCP Incast Avoidance Method for Data Center Networks Reviewed

    Kazutoshi Kajita, Shigeyuki Osada, Yukinobu Fukushima, Tokumi Yokohira

    2013 INTERNATIONAL CONFERENCE ON ICT CONVERGENCE (ICTC 2013): FUTURE CREATIVE CONVERGENCE TECHNOLOGIES FOR NEW ICT ECOSYSTEMS   460 - 465   2013

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    In distributed file systems, a well-known congestion collapse called TCP Incast occurs because many servers send data to the same client and then many packets overflow the port buffer of the client link. Incast leads to throughput degradation in the network In our previous work, we have proposed a method to avoid Incast. In the method, we limit the maximum number of simultaneously existing connections to a predetermined constant value. However, we cannot use the method when the data size is small, and because we have not investigated how to optimize the maximum value, Incast may occur if the maximum value is not appropriate. In this paper, we improve the method so that it is applicable regardless of the data size and the maximum value is optimized Numerical results show the effectiveness of our proposed method.

    DOI: 10.1109/ICTC.2013.6675396

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  • Throughput Improvement for TCP with a Performance Enhancing Proxy Using a UDP-Like Packet Sending Policy Reviewed

    Hui Wang, Yuichi Nishida, Yukinobu Fukushima, Tokumi Yokohira, Zhen Wu

    IEICE TRANSACTIONS ON COMMUNICATIONS   E95B ( 7 )   2344 - 2357   2012.7

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    To improve TCP throughput even if the maximum receiving window size is small, a TCP performance enhancing proxy (PEP) using a UDP-like packet sending policy with error control has been proposed. The PEP operates on a router along a TCP connection. When the PEP receives a data packet from the source host, it transmits the packet to the destination host, copies the packet into the local buffer (PEP buffer) in case the packets need to be transmitted and sends a premature ACK acknowledging receipt of the packet to the source host. In the PEP, the number of prematurely acknowledged packets in the PEP buffer is limited to a fixed threshold (watermark) value to avoid network congestion. Although the watermark value should be adjusted to changes in the network conditions, watermark adjusting algorithms have not been investigated. In this paper, we propose a watermark adjusting algorithm the goal of which is to maximize the throughput of each connection as much as possible without excessively suppressing the throughputs of the other connections. In our proposed algorithm, a newly established connection uses the initial watermark value of zero to avoid drastic network congestion and increases the value as long as its throughput increases. In addition, when a new connection is established, every already-established connection halves its watermark value to allow the newly established connection to use some portion of the bandwidth and increases again as long as its throughput increases. We compare the proposed algorithm (CW method) with other methods: the FW method that uses a fixed large watermark value and the NP method that does not use the PER Numerical results with respect to throughput and fairness showed that the CW method is generally superior to the other two methods.

    DOI: 10.1587/transcom.E95.B.2344

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  • An Architecture and a MAC Protocol for Throughput Improvement in Light Trail Networks Reviewed

    Wenjie Chen, Yukinobu Fukushima, Tokumi Yokohira

    IEICE TRANSACTIONS ON COMMUNICATIONS   E95B ( 7 )   2330 - 2343   2012.7

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    Light trail architecture is attracting attention as a new optical wavelength-division multiplexing network architecture that can be built with currently available devices and can achieve bandwidth allocation with granularity finer than a wavelength. Because a light trail is a shared medium, we need a medium access control (MAC) protocol to prevent collisions. Although MAC protocols using token passing can prevent collisions, the bandwidths of links that are located upstream of the token holding node are kept idle. We first propose a dynamic light trail splitting method for increasing throughput of a light trail by using such idle bandwidths. Our method splits a trail into upstream and downstream trails at the token holding node, and independent data transmission on the two trails are permitted. As a result, we expect that the split trail architecture will achieve higher throughput than the original non-split trail architecture. The degree of performance improvement with the split trail architecture depends on how appropriately we determine the upstream and downstream token holding times of every transmission node. Thus, we formulate a problem in which we optimize the token holding times to accommodate requested traffic volume as a linear programming problem. We then derive the throughput of the split trail architecture by solving the problem using the NUOPT solver and investigate the degree of improvement over the original architecture. In addition, we evaluate the end-to-end delay of the split trail architecture by simulation. According to numerical examples, the split trail architecture achieves 1) almost the same throughput as the original one for the worst-case traffic pattern where every transmission node sends data to the terminating node of the trail only, 2) about 1.6 times higher throughput for a uniform traffic pattern where every node pair requests the same traffic volume and an extremely unbalanced traffic pattern where only a few node pairs request huge traffic volume, 3) about 1.9 time higher throughput for the split trail architecture's good-case traffic pattern where every transmission node sends data to its adjacent downstream node only, and 4) the end-to-end delay enough to satisfy any application's QoS requirement according to ITU-T Recommendation Y.1541.

    DOI: 10.1587/transcom.E95.B.2330

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  • Inter-AS Traffic Volume Reduction by Localizing Delivery for P2P Live Streaming Reviewed

    Kazuki Kobayashi, Yukinobu Fukushima, Tokumi Yokohira

    2012 THIRD INTERNATIONAL CONFERENCE ON NETWORKING AND COMPUTING (ICNC 2012)   156 - 161   2012

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    In recent years, there is a big demand for live streaming service over the Internet. As one of the service model, peer-to-peer (P2P) live streaming has been utilized. In the system, it is important to decrease inter-AS (Autonomous System) traffic volume and content delivery delay because the larger volume leads to higher transit cost of ASes and this system treats the live contents, respectively. Therefore, as a conventional peer selection algorithm that tries to decrease them, Minimum Physical Hop (MPH) has been proposed. In MPH, to decrease inter-AS traffic volume, a newly joining peer selects a providing peer with the minimum physical hop count, which is the minimum number of ASes between the providing peer and the newly joining peer. Furthermore, to decrease content delivery delay, if there are several such candidates, it selects a providing peer with the minimum logical hop count, which is the number of Origin Streaming Servers (OSS) or peers passed from an OSS to the peer, from the candidates. However, MPH shows high inter-AS traffic volume when the number of joining peers is large. When we use MPH, candidates for providing peer with large logical hop count tend to swarm in ASes without an OSS while those with small logical hop count do in ASes with an OSS because of the peer selection policy of MPH. As the number of joining peers becomes large, the logical hop counts of the candidates for providing peer in every AS increase. As a result, in the former ASes, the logical hop counts of all the candidates for providing peer reach the upper bound frequently, and the newly joining peer cannot often find its providing peer in the AS, and consequently have to select providing peers in different ASes. In this paper, we improve MPH in order to further decrease the inter-AS traffic volume. In the improved algorithm called Improved Minimum Physical Hop (IMPH), we try to decrease the volume by distributing providing peers with one logical hop count to many ASes. As a result of the evaluation, we show that IMPH achieves to reduce the inter-AS traffic volume by at a maximum of 38% compared to MPH under uniform peer generation distributions.

    DOI: 10.1109/ICNC.2012.31

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  • A Solution to Transmission Halting In a New Flow Control Method TCP-fox Reviewed

    Takumi Shinkai, Wang Hui, Hiroyuki Ishihara, Yuichi Nishida, Yukinobu Fukushima, Tokumi Yokohira

    18TH ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC 2012): GREEN AND SMART COMMUNICATIONS FOR IT INNOVATION   806 - 811   2012

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    TCP-fox is a new flow control method for TCP (Transmission Control Protocol) which allows the sender of a connection to send packets over the receive window advertised by the receiver to obtain higher throughput. However, TCP-fox has the problem that it halts sending packets when the receiver uses a receive buffer auto tuning mechanism. In this paper, we investigate the cause of the halting and present a way to avoid it.

    DOI: 10.1109/APCC.2012.6388193

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  • Destination selection algorithm in a server migration service Reviewed

    Asato Yamanaka, Yukinobu Fukushima, Tokumi Yokohira, Tutomu Murase, Tatsuya Suda

    Proceedings of the 7th International Conference on Future Internet Technologies, CFI'12   15 - 20   2012

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    Using network virtualization technologies for network applications (NW-Apps) consisting of server and clients, we can implement a server migration service where there are many server running environments (working places: WPs) inside a network and servers onWPs can migrate to otherWPs when communication QoSs in some NW-Apps fall off. Because server size is large, the traffic for server migration causes QoS degradation of its background traffic. Thus, it is important to decrease the degree (network impact) of the QoS degradation. In this paper, we propose three destination selection algorithms, MIA (Minimum Impact Algorithm), MRA (Maximum Remaining space Algorithm) and MCA (Maximum Covering Algorithm) that try to decrease the impact while increasing the number of NW-Apps' clients whose SLA (service level agreement) are satisfied. When a server migration is triggered, MIA, MRA and MCA move the server in the WP with the minimum impact, the WP with the maximum remaining space for servers and the WP with the maximum coverage, which is the number of routers under which the corresponding clients can communicate with the server while satisfying the SLA, respectively. Numerical examples show that when the number of accommodatable servers in full-cover WP (a full-cover WP is such WP that communicates with an arbitrary client while satisfying the SLA) is small or there is no full-cover WP, MIA outperforms the others, otherwise MCA outperforms the others. Copyright © 2012 by the Association for Computing Machinery, Inc.

    DOI: 10.1145/2377310.2377315

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    Other Link: http://dblp.uni-trier.de/db/conf/cfi/cfi2012.html#conf/cfi/YamanakaFMYS12

  • Multi-stage change-point detection scheme for large-scale simultaneous events Reviewed

    Yukinobu Fukushima, Tutomu Murase, Masayoshi Kobayashi, Hiroki Fujiwara, Ryohei Fujimaki, Tokumi Yokohira

    COMPUTER COMMUNICATIONS   34 ( 15 )   1810 - 1821   2011.9

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    Change-point detection schemes, which represent one type of anomaly detection schemes, are a promising approach for detecting network anomalies, such as attacks and epidemics by unknown viruses and worms. These events are detected as change-points. However, the schemes generally also detect false-positive change-points caused by other events, such as improper parameter setting of detectors. Therefore there is a requirement for a scheme that detects only true-positive change-points caused by attacks and epidemics by unknown viruses and worms. The true-positive change-points tend to occur simultaneously and intensively in very large numbers, while the false-positive change-points tend to occur independently. Therefore, we expect that the multi-stage change-point detection scheme, which performs change-point detection in a distributed manner and takes account of the correlation among multiple change-points, can exclude false-positive change-points by neglecting those that occur independently. In this paper, we propose the multi-stage change-point detection scheme and introduce a weighting function that gives smaller weight to LDs with higher false-positive rate inferred by GD in order to avoid a set of false-positive alerts generated by the low-accuracy detectors from causing high false-positive rate of the scheme. We evaluate the performance of the scheme by a simulation using the parameter values obtained in an experiment using real random scan worms. In the evaluation, we modify AAWP (Analytical Active Worm Propagation) model so that it can derive the number of infected hosts (i.e., attack hosts) more accurately by considering a failure of infection behavior by random scan worms. The simulation results show that our scheme can achieve an optimal performance (detection rate of 1.0 and false-positive rate of 0) while the stand-alone change-point detection scheme, which does not use the correlation among multiple change-points, cannot attain such optimal performance, and our scheme with alert weighting always shows better detection performance than the scheme without alert weighting. (C) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.comcom.2011.05.001

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  • Optimization of Token Holding Times in Split Light Trail Networks Reviewed

    Wenjie Chen, Yukinobu Fukushima, Tokumi Yokohira

    2011 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE (GLOBECOM 2011)   1 - 5   2011

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    As a new optical WDM network architecture that can be built with currently available devices and can achieve bandwidth allocation with granularity finer than a wavelength, a light trail architecture attracts attention. Because a light trail is a shared medium, we need a medium access control (MAC) protocol to avoid collisions. Although MAC protocols using token passing can avoid collisions, bandwidths of links that locate upstream of the token holding node are kept idle. In this paper, we first propose a dynamic light trail splitting method in order to increase throughput of a light trail by using those idle bandwidths. Our method splits a trail into the upstream trail and the downstream trail at the token holding node and independent data transmissions on the two trails are permitted. As a result, we expect that the split trail architecture achieves higher maximum throughput than the original non-split trail architecture. The degree of throughput improvement by the split trail architecture depends on how appropriately we set upstream and downstream token holding times of every transmission node. Thus, we formulate a problem to decide the token holding times as a nonlinear programming problem, derive the maximum throughput of the split trail architecture by solving the problem using NUOPT solver, and investigate the degree of improvement compared to the original architecture. According to numerical examples, the split trail architecture achieves 1) almost the same maximum throughput as the original one for its unfavorite traffic pattern where every transmission node sends data to the terminating node of the trail only, 2) about 1.6 times as high maximum throughput for a uniform traffic pattern where every node-pair requests the same traffic volume, and 3) about 1.9 time as high maximum throughput for its favorite traffic pattern where every transmission node sends data to its adjacent downstream node only.

    DOI: 10.1109/GLOCOM.2011.6133810

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  • Early Detection of Increasing Traffic with Distributed Traffic Measurement Reviewed

    Yukinobu Fukushima, Mamoru Niboshi, Tutomu Murase, Ryohei Fujimaki, Shunsuke Hirose, Tokumi Yokohira

    TENCON 2010: 2010 IEEE REGION 10 CONFERENCE   809 - 814   2010

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    With the spread of broadband access lines, many bandwidth-consuming services such as video streaming have appeared. The popularity of these services can cause problems such as the shortage of the Internet backbone capacity, so it is important to detect increasing traffic caused by these services early. Conventional detection method called aggregation method tries to detect increasing traffic by predicting its future traffic volume with linear approximation. However, the aggregation method may not cope with increasing traffic whose growth is more rapid than linear growth. In this paper, we propose an early detection method (partial aggregation method) of increasing traffic under per-subnet based distributed traffic measurement. The method predicts 1) future traffic volume for each address in each subnet and 2) the number of subnets having increasing traffic in the future with a linear approximation. Then, the method estimates future traffic volume for each address as a product of the predicted future traffic volume in each subnet and the predicted subnet number. As a result, the method is expected to cope with rapid growth in traffic volume. Simulation results show that the partial aggregation method can detect increasing traffic earlier than the aggregation method by a maximum of 90 days.

    DOI: 10.1109/TENCON.2010.5686580

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  • Performance Evaluation of Multi-stage Change-point Detection Scheme with Alert Weighting Reviewed

    Mari Nakagawa, Yukinobu Fukushima, Tutomu Murase, Ryohei Fujimaki, Shunsuke Hirose, Tokumi Yokohira

    TENCON 2010: 2010 IEEE REGION 10 CONFERENCE   785 - 790   2010

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    As a detection method of large-scale simultaneous events (e.g., DDoS attack), a multi-stage change-point detection scheme with alert weighting was proposed. In the scheme, local detectors (LDs), which are deployed on each monitored subnet, try to detect an event by change-point detection. If they do, they send an alert to global detector (GD). Then GD judges whether an event is occurring by comparing the weight sum of the received alerts with an predetermined threshold value. The weight of an alert is set lower for LDs with higher false-positive rate (FPR). Conventional evaluation results only showed that alert weighting improves the performance for particular combination of two kinds of LDs with different FPRs. In this paper, we investigate the effectiveness of alert weighting for various combinations of two kinds of LDs with different FPRs in detail. We first consider the situation where detection rates (DRs) of all LDs are identical. Then, we consider the situation where high-FPR LDs show higher DR than low-FPR LDs, which is more realistic. Simulation results show that 1) alert weighting does not lead to degradation of detection performance and 2) alert weighting is most effective when event scale is moderate in our numerical examples.

    DOI: 10.1109/TENCON.2010.5686586

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  • Accuracy Improvement of Multi-Stage Change-Point Detection Scheme by Weighting Alerts based on False-Positive Rate Reviewed

    Yukinobu Fukushima, Tutomu Murase, Ryohei Fujimaki, Syunsuke Hirose, Tokumi Yokohira

    CQR: 2009 IEEE INTERNATIONAL WORKSHOP TECHNICAL COMMITTEE AND COMMUNICATIONS QUALITY AND RELIABILITY   29 - +   2009

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    One promising approach for large-scale simultaneous events (e.g., DDoS attacks and worm epidemics) is to use a multi-stage change-point detection scheme. The scheme adopts two-stage detection. In the first stage, local detectors (LDs), which are deployed on each monitored subnet, detects a change point in a monitored metric such as outgoing traffic rate. If an LD detects a change-point, it sends an alert to global detector (GD). In the second stage, GD checks whether the proportion of LDs that send alerts simultaneously is greater than or equal to a threshold value. If so, it judges that large-scale simultaneous events are occurring. In previous studies for the multi-stage change-point detection scheme, it is assumed that weight of each alert is identical. Under this assumption, false-positive rate of the scheme tends to be high when some LDs sends false-positive alerts frequently. In this paper, we weight alerts based on false-positive rate of each LD in order to decrease false-positive rate of the multi-stage change-point detection scheme. In our scheme, GD infers false-positive rate of each LD and gives lower weight to LDs with higher false-positive rate. Simulation results show that our proposed scheme can achieve lower false-positive rate than the scheme without alert weighting under the constraint that detection rate must be 1.0.

    DOI: 10.1109/CQR.2009.5137356

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  • Performance Evaluation of Medium Access Control Methods in Light Trail Networks Reviewed

    Yukinobu Fukushima, Kota Tanaka, Tokumi Yokohira

    11TH INTERNATIONAL CONFERENCE ON ADVANCED COMMUNICATION TECHNOLOGY, VOLS I-III, PROCEEDINGS,   1421 - 1425   2009

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    We evaluate performance of two medium access control methods with token passing, LT-FA MAC and ART MAC, in light trail networks. LT-FA MAC aims at coping with bursty packet arrivals while ART MAC aims at decreasing transmission delay. Simulation evaluation is performed in terms of the number of the maximum transmission nodes accommodated on a light trail and the maximum communication distance under the constraints that the bandwidth utilization rate of 90% and the average transmission delay of 100 ms must be achieved. Simulation results show that ART MAC permits about 500-1500km longer communication distance than LT-FA MAC with the same number of transmission nodes on a light trail and ART MAC accommodates about 15-25 more nodes than LT-FA MAC with the same communication distance.

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  • Retransmission control in TCP with a Performance Enhancing Proxy Reviewed

    Yuichi Nishida, Wang Hui, Hiroaki Matsumoto, Tokumi Yokohira, Yukinobu Fukushima

    10TH INTERNATIONAL CONFERENCE ON ADVANCED COMMUNICATION TECHNOLOGY, VOLS I-III   1881 - +   2008

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    In order to improve TCP performance in networks with large round trip time, a method using a PEP (Performance Enhancing Proxy) is proposed. In the method, the PEP is located on a intermediate router along a TCP connection, and returns acknowledgment packets (premature ACKs) to the source host instead of the destination host. In previous researches, although a congestion control in the PEP which keeps the number of prematurely acknowledged packets below a threshold (watermark) value has been proposed, packet losses are not taken into account, and consequently performance of the PEP under a packet-loss environment has not been investigated. In this paper, we incorporate a retransmission control to deal with packet losses into the congestion control. The proposed retransmission control mainly has two functions. One is to return duplicate premature ACKs or partial premature ACKs to urge the source host to execute the fast retransmission. The other is to retransmit prematurely acknowledged packets to the destination host, when a timeout occurs or three duplicate acknowledgments and a partial acknowledgment from the destination host are received. Simulation results under a packet-loss environment show that the PEP improves throughput larger as the end-to-end propagation delay becomes larger and throughput with PEP is a maximum of four times as much as throughput without PEP.

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  • Performance evaluation of a multi-stage network event detection scheme against DDoS attacks Reviewed

    Tutornu Murase, Yukinobu Fukushima, Masayoshi Kobayashi, Hiroki Fujiwara, Ryohei Fujimaki, Tokunii Yokohira

    2008 7TH ASIA-PACIFIC SYMPOSIUM ON INFORMATION AND TELECOMMUNICATION TECHNOLOGIES   58 - +   2008

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    Change-point detection schemes, which represent one type of anomaly detection schemes, are a promising approach for detecting network anomalies, such as attacks and epidemics by unknown viruses and worms. These events are detected as change-points. However, they generally also detect false-positive change-points caused by other events, such as hardware problems. Therefore there is a requirement for a scheme that detects only true-positive change-points caused by attacks and epidemics by unknown viruses and worms. The true-positive change-points tend to occur simultaneously and intensively in very large numbers, while the false-positive change-points tend to occur independently. We can exclude false-positive change-points by excluding those that occur independently, based on information gathered from the entire network. In this paper, we combine change-point detection schemes with a distributed IDS, and evaluate performance of the combined scheme by a simulation using the parameter values obtained by an experiment using real worms. The simulation results show that the combined scheme detects all the DDoS attacks without any false-positives while we have to tolerate false-positive rate of at least 0.02 to detect all the attacks in a stand-alone IDS scheme.

    DOI: 10.1109/APSITT.2008.4653540

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  • Performance evaluation of a multi-stage network event detection scheme for decreasing the false-positive rate for a large number of simultaneous, unknown events Reviewed

    Tutomu Murase, Hiroki Fujiwara, Yukinobu Fukushima, Masayoshi Kobayashi, Tokumi Yokohira

    Proceedings of the Sixth International Conference on Networking, ICN'07   97   2007

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:IEEE Computer Society  

    Change-point detection schemes are a promising approach for detecting network anomalies, such as attacks and epidemics by unknown viruses and worms. They detect those events as change-points. However, they generally also detect false-positive change-points, those caused by other events such as hardware trouble. A scheme is needed that only detects truepositive change-points, caused by attacks and epidemics. Truepositive change-points tend to occur simultaneously in very large numbers, while false-positive change-points tend to occur sporadically. We can exclude false-positive change-points by excluding change-points that occur sporadically, based on information gathered from the entire network. In this paper, we propose a multi-stage network event detection scheme that aggregates change-point information from distributed IDSs (Intrusion Detection Systems) and detects the true-positive change-points. Simulation results show that, compared to a scheme using only one IDS, our method always yields a smaller false-positive rate under the constraint that the detection rate of the true-positive change-points must exceed 0.99. © 2007 IEEE.

    DOI: 10.1109/ICN.2007.71

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  • Design of logical topology with effective waveband usage in IP-over-WDM networks Reviewed

    Y Fukushima, S Arakawa, M Murata

    PHOTONIC NETWORK COMMUNICATIONS   11 ( 2 )   151 - 161   2006.3

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    We deal with the problem of designing the logical topology in IP-over-WDM networks. Many conventional methods for designing the logical topology assume that a constant number of wavelengths will be available on each fiber. But it is not necessary to utilize all wavelengths on each fiber in building an effective logical topology on a WDM network. Instead, several wave-bands may be considered for introduction while deploying additional wave-bands and their corresponding optical amplifiers when additional wavelengths are actually required. In this case, the number of wavelengths available on the respective fibers depends on the number of optical fiber amplifiers deployed on each fiber. In this paper, we propose a heuristic algorithm for the design of a logical topology with as few optical fiber amplifiers as possible. Our results indicate that our algorithm reduces the number of optical fiber amplifiers with a slight increase of average packet delays.

    DOI: 10.1007/s11107-005-6019-7

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  • A burst assembly method for decreasing end-to-end packet delays in optical burst switching networks Reviewed

    Yukinobu Fukushima, Tokumi Yokohira, Yasuhiro Noine, Kazuteru Nagahara

    2006 10TH INTERNATIONAL CONFERENCE ON COMMUNICATION TECHNOLOGY, VOLS 1 AND 2, PROCEEDINGS   459 - +   2006

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    Although the offset-time-based scheme can differentiate packet/burst loss rate according to their QoS levels in optical burst switching networks, it increases end-to-end packet delays of packets in a burst with higher QoS level. This is because it increases offset time of bursts in proportional to their QoS levels. In this paper, we propose a burst assembly method that decreases end-to-end packet delays. Our proposed method includes packets that arrive during the offset time into the currently assembled bursts while the conventional method includes them into the burst assembled next time. Simulation results show that our method offers more than 21% delay reduction for bursts with the highest QoS level.

    DOI: 10.1109/ICCT.2006.341915

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  • Throughput optimization in TCP with a performance enhancing proxy Reviewed

    Shigeyuki Osada, Wang Hui, Tokumi Yokohira, Yukinobu Fukushima, Kiyohiko Okayama, Nariyoshi Yamai

    2006 10TH INTERNATIONAL CONFERENCE ON COMMUNICATION TECHNOLOGY, VOLS 1 AND 2, PROCEEDINGS   392 - +   2006

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    To improve TCP throughput performance, a method using a PEP (Performance Enhancing Proxy) has been proposed. The PEP operates on a router along a TCP connection. When a data packet arrives at the PEP, it forwards the packet to the destination host, transmits the corresponding ACK (premature ACK) to the source host in behalf of the destination host, and stores a copy of the packet into its own buffer (PEP buffer) in case retransmission of the packet is required. As a congestion control method on the PEP, a method which keeps the number of prematurely acknowledged packets in the PEP buffer below a threshold (watermark) value has been proposed. However, the relation between the watermark value and throughput is not sufficiently investigated, and an optimization method of the watermark value is not proposed. In this paper, we first investigate the relation between the watermark value and the average throughput. Extensive simulations show that the simulation results are roughly classified into two cases. In the first case, the average throughput becomes larger for larger watermark values and becomes a constant value when the watermark is over a certain value. In the second case, although the average throughput becomes larger for larger watermark values in the same way, it decreases when the watermark is over a certain value. Next, based on the results about the relation, we propose an watermark optimization algorithm which can adaptively maximize the average throughput of each connection and also satisfy a fairness condition that the average throughputs of connections are equal to each other.

    DOI: 10.1109/ICCT.2006.341898

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  • A distributed clustering method for hierarchical routing in large-scaled wavelength routed networks Reviewed

    Y Fukushima, H Harai, S Arakawa, M Murata

    IEICE TRANSACTIONS ON COMMUNICATIONS   E88B ( 10 )   3904 - 3913   2005.10

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    The scalability of routing protocol has been considered as a key issue in large-scaled wavelength routed networks. Hierarchical routing scales well by yielding enormous reductions in routing table length, but it also increases path length. This increased path length in wavelength-routed networks leads to increased blocking probability because longer paths tend to have less free wavelength channels. However, if the routes assigned to longer paths have greater wavelength resources, we can expect that the blocking probability will not increase. In this paper, we propose a distributed node-clustering method that maximizes the number of lightpaths between nodes. The key idea behind our method is to construct node-clusters that have much greater wavelength resources from the ingress border nodes to the egress border nodes, which increases the wavelength resources on the routes of lightpaths between nodes. We evaluate the blocking probability for lightpath requests and the maximum table length in simulation experiments. We find that the method we propose significantly reduces the table length, while the blocking probability is almost the same as that without clustering.

    DOI: 10.1093/ietcom/e88-b.10.3904

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  • Planning method of robust WDM networks against traffic changes Reviewed

    Yukinobu Fukushima, Hiroaki Harai, Shin’ichi Arakawa, Masayuki Murata

    Proceedings of The 8th Working Conference on Optical Network Design and Modeling (ONDM 2004)   2004.2

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  • A Design Method for Logical Topologies with Consideration of Wavebands. Reviewed

    Yukinobu Fukushima, Shin'ichi Arakawa, Masayuki Murata, Hideo Miyahara

    Next Generation Optical Network Design and Modelling, IFIP TC6 / WG6.10 Sixth Working Conference on Optical Network Design and Modeling (ONDM 2002), February 4-6, 2002, Torino, Italy   359 - 376   2002

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  • Performance Improvement of a Virtual Network Embedding Algorithm Based on Temporal-Difference Learning

    佐川勇太, 福島行信, 樽谷優弥

    電子情報通信学会大会講演論文集(CD-ROM)   2021   2021

  • Protection method with audio processing against Audio Adversarial Example

    山本泰成, 樽谷優弥, 福島行信, 横平徳美

    電子情報通信学会技術研究報告(Web)   121 ( 66(SP2021 1-23) )   2021

  • A Server Migration Method Using Q learning in Server Migration Service

    瓜本稜, 福島行信, 樽谷優弥, 村瀬勉, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   71st   2020

  • サーバ移動サービスにおける最小支配集合を用いたワークプレース容量設計法の性能改善

    伊藤嵩真, 福島行信, 村瀬勉, 横平徳美

    電子情報通信学会大会講演論文集(CD-ROM)   2019   2019

  • サーバ移動サービスシステムのプロトタイプ開発

    高橋謙太, 福島行信, 村瀬勉, 樽谷優弥, 横平徳美

    情報科学技術フォーラム講演論文集   18th   2019

  • 深層学習を用いたネットワークトラフィック予測

    徳山雄丈, 福島行信, 樽谷優弥, 横平徳美

    情報科学技術フォーラム講演論文集   18th   2019

  • 多重ルーティング形態法における対象外故障の迂回可能性の検討

    石外将史, 樽谷優弥, 福島行信, 横平徳美

    情報科学技術フォーラム講演論文集   18th   2019

  • クライアントからの再送要求に基づくTCPインキャスト回避法

    岸本紫電, 長田繁幸, 長田繁幸, 樽谷優弥, 福島行信, 横平徳美

    情報科学技術フォーラム講演論文集   18th   2019

  • 複数ノード故障に対するIP高速迂回法の検討

    沼田直人, 樽谷優弥, 福島行信, 横平徳美

    情報科学技術フォーラム講演論文集   18th   2019

  • 深層強化学習を用いた経路制御における行動価値関数の変更による性能改善

    大石勲斗, 佐川勇太, 瓜本稜, 福島行信, 樽谷優弥

    情報科学技術フォーラム講演論文集   18th   2019

  • マルチパスTCPのスループット公平性の改善

    泉大地, 樽谷優弥, 福島行信, 横平徳美

    情報科学技術フォーラム講演論文集   18th   2019

  • Link Capacity Provisioning and Server Location Decision in Server Migration Service

    Yukinobu Fukushima, Tokumi Yokohira, Tutomu Murase

    Proceedings of the 2018 IEEE 7th International Conference on Cloud Networking, CloudNet 2018   ???-??? - 3   2018.11

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    © 2018 IEEE. Server migration service (SMS) has been proposed as a new class of service to augment the existing IaaS (Infras-tructure as a Service) cloud service. SMS allows servers (server-side processes of a network application) to dynamically and automatically migrate close to their clients (client-side processes of the network application) in order to reduce the penalty that the SMS provider pays to is SMS subscribers when failing to provide them with the guaranteed level of QoS. In this paper, we tackle a link capacity provisioning and server location decision problem where we consider the sum of link capacity provisioning cost and the penalty as the total expenditure of SMS business, and aim at minimizing the total expenditure. In the problem, we determine how much capacity to add to links, and when and to which location to migrate servers. We formulate the problem as an integer programming model, solve the model, and obtain the optimal link capacities, server locations at each time, and the global optimum value of the total expenditure of SMS business. Numerical examples show that the proposed method decreases the total expenditure of SMS business by up to 49% compared to a conventional method that determines the server locations while fixing the link capacities.

    DOI: 10.1109/CloudNet.2018.8549545

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  • マルチパスTCPのスループット公平性の検討

    廣山航洋, 福島行信, 横平徳美

    電子情報通信学会大会講演論文集(CD-ROM)   2018   ROMBUNNO.B‐6‐71   2018.3

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  • 多重ルーティング形態法における予備テーブルのエントリ数の低減

    豊福成聖, 福島行信, 横平徳美

    電子情報通信学会大会講演論文集(CD-ROM)   2017   ROMBUNNO.B‐6‐79   2017.3

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  • データセンターネットワークにおけるTCPインキャスト回避法の性能改善

    長田繁幸, 若井翔吾, 福島行信, 横平徳美

    電子情報通信学会大会講演論文集(CD-ROM)   2017   ROMBUNNO.B‐6‐64   2017.3

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  • A Design Method of Work Place Capacity Using Minimum Dominating Set in Server Migration Service

    合田一歩, 福島行信, 村瀬勉, 横平徳美

    電子情報通信学会技術研究報告   116 ( 484(NS2016 157-253) )   77‐82   2017.2

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  • Energy-Aware On-line Server Location Decision Algorithm in Server Migration Service

    杉山弘道, 福島行信, 村瀬勉, 横平徳美

    電子情報通信学会技術研究報告   116 ( 484(NS2016 157-253) )   71‐76   2017.2

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  • Energy-Aware Optimal Server Location Decision in Server Migration Service

    福島行信, 村瀬勉, 横平徳美

    電子情報通信学会技術研究報告   116 ( 428(NS2016 141-156) )   53‐58   2017.1

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  • A Prototype Virtual Network Embedding System Using OpenStack,

    Yukinobu Fukushima, Kohei Sato, Itsuo Goda, Heung-Gyoon Ryu, Tokumi Yokohira

    IEIE Transactions on Smart Processing & Computing   6 ( 1 )   60 - 65   2017

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  • サーバ移動サービスにおけるサーバ配置決定アルゴリズムの性能改善

    杉山弘道, 福島行信, 本吉彦, 村瀬勉, 横平徳美

    電子情報通信学会大会講演論文集(CD-ROM)   2016 ( 2 )   ROMBUNNO.B‐6‐63 - 63   2016.3

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  • Performance Improvement of an On-line Server Location Decision Algorithm in Server Migration Service

    杉山弘道, 福島行信, 本吉彦, 村瀬勉, 横平徳美

    電子情報通信学会技術研究報告   115 ( 483(NS2015 168-258) )   493‐498   2016.2

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  • Nonlinearity Sensitivity of FBMC and UFMC Modulation System for the 5G Mobile System

    Changyoung An, Heung-Gyoon Ryu, Yukinobu Fukushima, Tokumi Yokohira

    The 31st International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2016)   1 - 4   2016

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  • Prototype Development of a Virtual Network Embedding System Using OpenStack

    Itsuho Goda, Kohei Sato, Yukinobu Fukushima, Heung-Gyoon Ryu, Tokumi Yokohira

    The 31st International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2016)   21 - 24   2016

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  • Modification of an Energy-Efficient Virtual Network Mapping Method for a Load-Dependent Power Consumption Model

    Shigeyuki Osada, Ryo Miyayama, Yukinobu Fukushima, Tokumi Yokohira

    WSEAS Transactions on Communications   15   240 - 250   2016

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  • Candidate Path Selection Method for TCP Performance Improvement in Fixed Robust Routing

    Yukinobu Fukushima, Takashi Matsumura, Kazutaka Urushibara, Tokumi Yokohira

    IEIE Transactions on Smart Processing & Computing   5 ( 6 )   445 - 453   2016

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  • TCP Incast avoidance based on connection serialization in data center networks

    Shigeyuki Osada, Ryo Miyayama, Yukinobu Fukushima, Tokumi Yokohira

    International Journal of Computer Networks and Communications   8 ( 4 )   83 - 102   2016

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    In distributed file systems, a well-known congestion collapse called TCP incast (Incast briefly) occurs because many servers almost simultaneously send data to the same client and then many packets overflow the port buffer of the link connecting to the client. Incast leads to throughput degradation in the network. In this paper, we propose three methods to avoid Incast based on the fact that the bandwidth-delay product is small in current data center networks. The first method is a method which completely serializes connection establishments. By the serialization, the number of packets in the port buffer becomes very small, which leads to Incast avoidance. The second and third methods are methods which overlap the slow start period of the next connection with the current established connection to improve throughput in the first method. Numerical results from extensive simulation runs show the effectiveness of our three proposed methods.

    DOI: 10.5121/ijcnc.2016.8406

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  • サーバ移動トラヒックの背景トラヒックへの影響に関する実験的評価

    合田一歩, 福島行信, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   66th   ROMBUNNO.20-2   2015.10

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  • 複数アプリケーション存在下におけるマルチパスTCPのスループット評価

    CHEN Chen, 福山諒, 福島行信, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   66th   ROMBUNNO.20-1   2015.10

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  • Performance Evaluation of an Energy Efficient Virtual Network Mapping Method-In the case of load-dependent power consumption model-

    Yuta Hoshino, Yukinobu Fukushima, Tutomu Murase, Tokumi Yokohira, Tatsuya Suda

    The International Conference on Electronics and Software Science 2015 (ICESS 2015)   134 - 144   2015

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  • An On-line Server Location Decision Algorithm in Server Migration Service

    HOSHINO Yuta, FUKUSHIMA Yukinobu, MURASE Tutomu, YOKOHIRA Tokumi, SUDA Tatsuya

    IEICE technical report   114 ( 297 )   59 - 64   2014.11

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    Server migration service (SMS) is proposed as an optional service that can improve QoS of communications by network applications (NW-Apps) in IaaS cloud service. In SMS, computers called work places (WPs) are deployed at various locations in a network, and servers of NW-Apps can migrate to WPs where the servers attain better QoS. When a server migrates, it generates huge traffic, and consequently it causes QoS degradation (NW impact) of the background traffic on the server's migrating route. This paper tackles the server location decision problem where a server's location is decided so that the NW-App's QoS is kept as good as possible under the constraint that the degree of NW impact is suppressed below an acceptable level. For the problem, we propose a server location decision algorithm. The algorithm tries to improve the NW-App's QoS in the present and in the future by restricting the server's migration range within a neighborhood of the WP where the server is assumed to attain good QoS in many situations.

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  • An On-line Server Location Decision Algorithm in Server Migration Service

    星野佑太, 福島行信, 村瀬勉, 横平徳美, 須田達也

    電子情報通信学会技術研究報告   114 ( 297(NS2014 128-146) )   59 - 64   2014.11

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  • メッシュプル型P2Pライブストリーミングにおけるオーバーレイネットワーク構築方式の性能評価

    高塚泰明, 福島行信, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   65th   ROMBUNNO.21-13   2014.10

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  • クラウドコンピューティングにおけるデータセンターネットワークでのTCPインキャストの回避に関する研究

    福島行信

    山陽放送学術文化財団リポート   ( 58 )   24 - 28   2014.9

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  • Power efficient traffic engineering in light trail networks

    FUKUSHIMA Yukinobu, YOKOHIRA Tokumi

    IEICE technical report   113 ( 472 )   337 - 342   2014.3

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    According to rapid increase of the Internet traffic, its total power consumption also increases. Therefore, it is necessary to decrease the total power consumption. Lightpath networks attract attention because they can relief the increase of the total power consumption by bypassing IP routers. Light trail networks have been proposed as an extended network architecture of lightpath networks. Light trail networks can achieve higher throughput than lightpath networks, and it is expected that light trail networks also show higher power efficiency than lightpath networks. In this research, we evaluate the power efficiency of light trail networks. In the evaluation, we reduce a power-efficient routing and wavelength assignment problem to a shortest path problem on an auxiliary graph, and solve it. In order to achieve this, we modify the conventional auxiliary graph for lightpath networks so that it can reflect the communication method of light trail networks. In addition, we calculate link costs of the auxiliary graph so that they corresponds to the increase of the total power consumption caused by the accommodation of traffic demands. Simulation results show that 1) light trail networks show higher power efficiency only when the network load is low and when the bandwidth granularity of communication channels is coarse, and 2) light trail networks show higher blocking probability than lightpath networks when they aim at minimizing the total power consumption.

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  • A Per-burst Traffic Distribution Method in Fixed Robust Routing

    NABETA Takahiro, FUKUSHIMA Yukinobu, YOKOHIRA Tokumi

    IEICE technical report   113 ( 472 )   367 - 372   2014.3

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    Robust routing schemes are attracting attention as a routing scheme to achieve high robustness against changes in traffic patterns without performing both traffic measurement and dynamic change of traffic routes. This scheme, however, causes the performance degradation of TCP because it performs multipath routing and the out-of-order packet arrivals occur frequently. In this paper, we try to improve the performance by modifying a method (traffic distribution method) that determines how traffic should be distributed among the multiple routes for each source-destination (s-d) router pair that performs multipath routing. In the conventional traffic distribution method, the traffic distribution is determined on a per-packet basis. In this case, the number of packet delivery route changing is proportional to the number of the transferred packets, and consequently the out-of-order packet arrivals occur frequently. In this paper, we propose a per-burst distribution method. In this method, the traffic distribution is determined on a per-burst basis, where a burst is defined as a predetermined number of consecutive transferred packets for each s-d router pair. Numerical examples show that the per-burst distribution method can attain much higher throughput than the per-packet distribution method regardless of the burst length and can keep throughput high even when traffic patterns change if we use an appropriate burst length.

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  • 多重ルーティングテーブル法における迂回経路導出法の改良

    今濱宇紀, 原田康弘, 福島行信, 横平徳美

    電子情報通信学会大会講演論文集(CD-ROM)   2014 ( 2 )   ROMBUNNO.B-6-41 - 41   2014.3

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  • Power efficient traffic engineering in light trail networks

    福島行信, 横平徳美

    電子情報通信学会技術研究報告   113 ( 472(NS2013 177-279) )   337 - 342   2014.2

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  • A Per-burst Traffic Distribution Method in Fixed Robust Routing

    鍋田敬寛, 福島行信, 横平徳美

    電子情報通信学会技術研究報告   113 ( 472(NS2013 177-279) )   367 - 372   2014.2

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  • Power Efficiency Evaluation of Medium Access Control Methods in Light Trail Networks

    Ryo Fukuyama, Yukinobu Fukushima, Tokumi Yokohira

    The 29th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2014)   338 - 341   2014

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  • AS-friendly Peer Selection Algorithm for P2P Live Streaming

    Yukinobu Fukushima, Tokumi Yokohira

    International Journal of Multimedia Technology   4 ( 2 )   63 - 73   2014

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  • Power Consumption Evaluation of Light-trail Networks

    Yukinobu Fukushima, Tokumi Yokohira

    The 29th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2014)   289 - 292   2014

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  • Performance Evaluation of Overlay Construction Algorithms in Mesh-pull P2P Live Streaming

    Yukinobu Fukushima, Tokumi Yokohira

    The 29th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2014)   334 - 337   2014

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  • ロバストルーティング方式におけるバースト分配方式

    鍋田敬寛, 瀬崎裕, 福島行信, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   64th   234 - 235   2013.10

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  • TCP Incast Avoidance Based on Connection Serialization

    Osada Shigeyuki, Kajita Kazutoshi, Fukushima Yukinobu, Yokohira Tokumi

    IEICE technical report   112 ( 463 )   249 - 254   2013.3

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    In distributed file systems used in data center, a well-known congestion collapse called TCP Incast occurs because many servers send data to the same client simultaneously and then many packets overflow the port buffer of the client link. It leads to throughput degradation in the network. In this paper, we propose two methods to avoid Incast which called complete serialization and nearly complete serialization. The first method is a method which completely serializes connection establishments. By the serialization, the number of packets in the port buffer becomes very small, which leads to Incast avoidance. The second method is a method which overlaps the next connection to the current established connection to improve throughput in the first method. Numerical results from simulation with NS2 show the effectiveness of our two proposed methods.

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  • Destination Selection Algorithms in Server Migration Service : A Case for Multiple Servers Migration

    YAMANAKA Asato, FUKUSHIMA Yukinobu, MURASE Tutomu, YOKOHIRA Tokumi, SUDA Tatsuya

    IEICE technical report   112 ( 463 )   391 - 396   2013.3

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    Server migration service (SMS)is proposed to improve communication QoS of network applications (NW-Apps)operated in Infrastructure as a Service (IaaS). In SMS, work places (WPs), which refer to computers that run virtual servers of NW-Apps, are deployed at various locations in a network, and the virtual servers may migrate between WPs to achieve better communication QoS. In SMS, it is important to decrease the degree (impact) of negative effect on background traffic caused by migrating servers while keeping NW-Apps' communication QoS good. In this paper, under the assumption that multiple server can migrate at the same time, we propose two destination selection algorithms: EMIA (Extended MIA)and EMCA (Extended MCA)that take account of both NW-Apps' communication QoS and impact. In order to decrease accumulative impact, EMIA migrates servers to WPs with the minimum impact and EMCA migrates servers to WPs with the maximum coverage, which is defined as the range where NW-App can attain good communication QoS so that the number of server migrations needed in the future is decreased. Numerical examples show that the two algorithms can keep NW-Apps' communication QoS the same level and EMCA achieves smaller impact than EMIA.

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  • Optimal Locations of Servers in Server Migration Service

    FUKUSHIMA Yukinobu, MURASE Tutomu, YOKOHIRA Tokumi, SUDA Tatsuya

    IEICE technical report   112 ( 463 )   385 - 390   2013.3

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    In server migration service (SMS), computers called work places (WPs)are deployed at various locations in a network, and virtual servers for network applications (NW-Apps)may migrate between WPs to achieve better QoS. An SMS provider tries to provide an NW-App provider with a certain level of QoS that they agree upon, and if the SMS provider fails, it has to pay penalty (e.g., reimbursement of a part of service charges to users). Thus, the SMS provider is incentivized to migrate servers to satisfy the agreed-upon QoS level. 0n the other hand, an SMS provider also needs to be moderate in performing server migrations to avoid degradation of network QoS (i.e.,QoS of background traffic)caused by server migrations. This paper formulates an integer-programming model for the off-line server location decision (i.e., when and to which WP servers should migrate)where the penalty associated with NW-App's QoS violations is minimized, keeping the number and distance of server migrations below a given level. This paper also compares the minimum penalty obtained through solving the integer-programming model against the penalty obtained with a greedy on-line server locations decision algorithm, which migrates a server to a WP that minimizes the current penalty with no consideration of the penalty that will arise in the future. Numerical examples show that the integer-programming model achieves 36% to 49% lower penalty than the greedy algorithm when the degradation of network QoS is little acceptable.

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  • 多重ルーティングテーブル法における予備テーブル数の低減

    今濱宇紀, 森田健悟, 大谷章太, 福島行信, 横平徳美

    電子情報通信学会大会講演論文集   2013 ( 2 )   82 - 82   2013.3

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  • Destination Selection Algorithms in Server Migration Service-A Case for Multiple Servers Migration-

    山中麻人, 福島行信, 村瀬勉, 横平徳美, 須田達也

    電子情報通信学会技術研究報告   112 ( 463(NS2012 165-289) )   391 - 396   2013.2

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  • TCP Incast Avoidance Based on Connection Serialization

    長田繁幸, 梶田和俊, 福島行信, 横平徳美

    電子情報通信学会技術研究報告   112 ( 463(NS2012 165-289) )   249 - 254   2013.2

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  • Optimal Locations of Servers in Server Migration Service

    福島行信, 村瀬勉, 横平徳美, 須田達也

    電子情報通信学会技術研究報告   112 ( 463(NS2012 165-289) )   385 - 390   2013.2

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  • Decreasing of the Number of Backup Tables in Multiple Routing Table Method for Fast IP Network Recovery

    Daiki Imahama, Yukinobu Fukushima, Tokumi Yokohira

    The 28th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2013)   823 - 826   2013

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  • Optimization of Server Locations in Server Migration Service

    Yukinobu Fukushima, Tutomu Murase, Tokumi Yokohira, Tatsuya Suda

    The Ninth International Conference on Networking and Services (ICNS 2013)   200 - 206   2013

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  • A Wavelength and Converter Assignment Scheme using Converter Usage History in Wavelength-Routed Networks

    Yukinobu Fukushima, Takahiro Ooishi, Tokumi Yokohira

    International Journal of Computer Networks & Communicationsd   5 ( 4 )   63 - 73   2013

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  • A Multi-splitting Method for Light-trail Networks

    Yukinobu Fukushima, Tokumi Yokohira

    The 28th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2013)   803 - 806   2013

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  • A Per-burst Traffic Distribution Method for TCP Performance Improvement in Fixed Robust Routing

    Yu Sezaki, Yukinobu Fukushima, Takahiro Nabeta, Tokumi Yokohira

    The 28th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2013)   819 - 822   2013

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  • 多重ルーティングテーブルを用いたルート迂回法の改良

    森田健悟, 今濱宇紀, 福島行信, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   63rd   384 - 385   2012.10

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  • Hybrid Robust Routing Taking Account of TCP Performance

    鍋田敬寛, 漆原和孝, CHEN Wenjie, 福島行信, 横平徳美

    電子情報通信学会技術研究報告   112 ( 9(CS2012 1-22) )   17 - 22   2012.4

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    Robust routing schemes are attracting attention as a routing scheme to achieve high robustness against changes in traffic patterns without performing both traffic measurement and dynamic change of traffic routes. This scheme, however, causes the performance degradation of TCP because it performs multipath routing and the out-of-order packet arrivals occur frequently. As a routing scheme to improve TCP performance while keeping high robustness against changes in traffic patterns, we proposed a robust routing scheme called MDD (Minimum Delay Difference). For every node-pair, the MDD selects the multiple routes with the minimum propagation delay difference between them as the candidate routes, and then derives the traffic distribution ratio of them so as to minimize the worst case link utilization ratio. According to the numerical example of the conventional research, however, TCP throughput of the MDD is about 70% of its ideal value and there is room for further improvement. In this paper, for the purpose of further improvement of TCP throughput, we propose a hybrid robust routing scheme. The scheme only selects a single candidate route for a predetermined ratio of node-pairs in order to avoid TCP performance degradation cause by packet reordering while it selects multiple candidate routes as well as the conventional scheme for the rest of node-pairs. Numerical examples show that, under the condition that the worst case link utilization ratio must be less than 1.0, our proposed scheme achieves at the maximum of 24% higher throughput than the MDD.

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  • Hybrid Robust Routing Taking Account of TCP Performance

    NABETA Takahiro, URUSHIBARA Kazutaka, CHEN Wenjie, FUKUSHIMA Yukinobu, YOKOHIRA Tokumi

    IEICE technical report. Communication systems   112 ( 9 )   17 - 22   2012.4

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    Robust routing schemes are attracting attention as a routing scheme to achieve high robustness against changes in traffic patterns without performing both traffic measurement and dynamic change of traffic routes. This scheme, however, causes the performance degradation of TCP because it performs multipath routing and the out-of-order packet arrivals occur frequently. As a routing scheme to improve TCP performance while keeping high robustness against changes in traffic patterns, we proposed a robust routing scheme called MDD (Minimum Delay Difference). For every node-pair, the MDD selects the multiple routes with the minimum propagation delay difference between them as the candidate routes, and then derives the traffic distribution ratio of them so as to minimize the worst case link utilization ratio. According to the numerical example of the conventional research, however, TCP throughput of the MDD is about 70% of its ideal value and there is room for further improvement. In this paper, for the purpose of further improvement of TCP throughput, we propose a hybrid robust routing scheme. The scheme only selects a single candidate route for a predetermined ratio of node-pairs in order to avoid TCP performance degradation cause by packet reordering while it selects multiple candidate routes as well as the conventional scheme for the rest of node-pairs. Numerical examples show that, under the condition that the worst case link utilization ratio must be less than 1.0, our proposed scheme achieves at the maximum of 24% higher throughput than the MDD.

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  • TCPスループットを考慮した複合型ロバストルーティング方式

    漆原和孝, 福島行信, 横平徳美

    電子情報通信学会大会講演論文集   2012 ( 2 )   138 - 138   2012.3

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  • B-7-41 Performance Improvement of an AS-friendly Peer Selection Algorithm for P2P Live Streaming

    Kobayashi Kazuki, Fukushima Yukinobu, Henmi Shuhei, Yokohira Tokumi

    Proceedings of the IEICE General Conference   2012 ( 2 )   202 - 202   2012.3

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  • B-6-150 Accuracy Verification and Improvement of Domestic AS Topology Generated Based on CAIDA Dataset

    Henmi Shuhei, Fukushima Yukinobu, Morita Kengo, Yokohira Tokumi

    Proceedings of the IEICE General Conference   2012 ( 2 )   150 - 150   2012.3

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  • B-6-138 Hybrid Robust Routing Taking Account of TCP Throughput

    Urushibara Kazutaka, Fukushima Yukinobu, Yokohira Tokumi

    Proceedings of the IEICE General Conference   2012 ( 2 )   138 - 138   2012.3

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  • P2PライブストリーミングにおけるASフレンドリーなピア選択法の性能改善

    小林和貴, 福島行信, 邉見修平, 横平徳美

    電子情報通信学会大会講演論文集   2012 ( 2 )   202 - 202   2012.3

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  • CAIDA Datasetに基づく国内ASトポロジーの精度検証と改善

    邉見修平, 福島行信, 森田健悟, 横平徳美

    電子情報通信学会大会講演論文集   2012 ( 2 )   150 - 150   2012.3

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  • Light-trail Multi-splitting Method in Light-trail Networks

    福島行信, 菊本大志, CHEN Wenjie, 横平徳美

    電子情報通信学会技術研究報告   111 ( 468(NS2011 179-275) )   463 - 468   2012.3

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    As a new optical network architecture that can be built with currently available devices and can achieve bandwidth allocation with granularity finer than a wavelength, the light-trail architecture attracts attention. For the light-trail architecture using token passing medium access control, the split trail architecture is proposed for improving the throughput. In the architecture, a trail is split into the upstream trail and the downstream trail at the token holding node and independent data transmissions on the two trails are permitted. However, the split trail architecture leaves the bandwidth of links upstream of the upstream-token holding node idle because the split of the trail is driven by the reception of only the downstream-token. In this paper, we propose the multi-split trail architecture for further improving the throughput. Our architecture utilizes the idle bandwidth by splitting the trail driven by the reception of both upstream- and downstream-tokens. We formulate the decision problem of the traffic accommodation where we optimize the token holding times so that the input traffic is successfully accommodated, as a linear programming problem. Then, we derive the maximum effective throughput of the multi-split trail architecture by solving the problem, and investigate the degree of improvement over the split trail architecture. According to numerical examples, the multi-split trail architecture achieves 1) the same maximum effective throughput as the split trail architecture for an uniform traffic pattern where every node pair has the same sending rate, and 2) about 1.93 times as high maximum effective throughput for its favorite traffic pattern where every transmission node sends data to its adjacent downstream node only and their rates are identical.

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  • Light-trail Multi-splitting Method in Light-trail Networks

    FUKUSHIMA Yukinobu, KIKUMOTO Taishi, CHEN Wenjie, YOKOHIRA Tokumi

    IEICE technical report   111 ( 468 )   463 - 468   2012.3

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    As a new optical network architecture that can be built with currently available devices and can achieve bandwidth allocation with granularity finer than a wavelength, the light-trail architecture attracts attention. For the light-trail architecture using token passing medium access control, the split trail architecture is proposed for improving the throughput. In the architecture, a trail is split into the upstream trail and the downstream trail at the token holding node and independent data transmissions on the two trails are permitted. However, the split trail architecture leaves the bandwidth of links upstream of the upstream-token holding node idle because the split of the trail is driven by the reception of only the downstream-token. In this paper, we propose the multi-split trail architecture for further improving the throughput. Our architecture utilizes the idle bandwidth by splitting the trail driven by the reception of both upstream- and downstream-tokens. We formulate the decision problem of the traffic accommodation where we optimize the token holding times so that the input traffic is successfully accommodated, as a linear programming problem. Then, we derive the maximum effective throughput of the multi-split trail architecture by solving the problem, and investigate the degree of improvement over the split trail architecture. According to numerical examples, the multi-split trail architecture achieves 1) the same maximum effective throughput as the split trail architecture for an uniform traffic pattern where every node pair has the same sending rate, and 2) about 1.93 times as high maximum effective throughput for its favorite traffic pattern where every transmission node sends data to its adjacent downstream node only and their rates are identical.

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  • Improvement of an ACK returning method of TCP proxies in network environment with wireless LANs

    Naohiro Honda, Wang Hui, Yuichi Nishida, Yukinobu Fukushima, Tokumi Yokohira

    1st IEEE Global Conference on Consumer Electronics 2012, GCCE 2012   704 - 708   2012

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    In a network environment including a wireless LAN and a wired network, split-connection type proxies have been proposed to improve TCP (Transmission Control Protocol) throughput. A proxy is placed at the boundary between a wireless LAN and a wired network, and it splits a TCP connection which is established between a host (WSTA) in a wireless LAN and a host (STA) in a wired network into two virtual TCP connections. We have proposed a split-connection proxy called DA-Proxy, and simulation results in our previous works show that although the DA-Proxy can increase throughput of downflows (flows from STAs to WSTAs), throughput of upflows (flows from WSTAs to STAs) is not improved and is almost the same as that of upflows without the proxy. In this paper, we propose a new proxy called MDA-Proxy which tries to increase throughput of upflows by decreasing the number of ACKs in a WLAN and show its effectiveness using simulation results. © 2012 IEEE.

    DOI: 10.1109/GCCE.2012.6379960

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  • Optimal TCP Receive Buffer Size under Packet Loss Environment

    Kazutoshi Kajita, Takumi Shinkai, Naohiro Honda, Yukinobu Fukushima, Tokumi Yokohira

    The 27th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2012), CD-ROM (4 pages)   2012

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  • Destination Selection Algorithms in Server Migration Service

    中川真里, 山中麻人, 福島行信, 村瀬勉, 横平徳美, 須田達也

    電子情報通信学会技術研究報告   111 ( 232(NS2011 82-103) )   93 - 98   2011.10

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    Server migration service provides network applications (NW Apps) with server running environment on a computer (WP) and service of server migration to another WP where the NW App can attain better QoS when it is degraded. Because the file size of a server is large, the traffic for server migration causes QoS degradation of its background traffic. Thus, it is important to decrease the degree (impact) of the QoS degradation. In this paper, we propose three destination selection algorithms MIA, MRA and MCA that try to decrease the impact while increasing the number of NW App's clients whose SLA are satisfied. When a server migration is triggered, MIA, MRA and MCA move the server to the WP with the minimum impact, the WP with the maximum remaining space for servers and the WP with the maximum communication range where the SLA is satisfied, respectively. Numerical examples show that when there is no full-cover WP (on which a server can communicate with an arbitrary client while satisfying the SLA) or its space is small, MIA outperforms the others, otherwise MCA outperforms the others.

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  • Destination Selection Algorithms in Server Migration Service

    NAKAGAWA Mari, YAMANAKA Asato, FUKUSHIMA Yukinobu, MURASE Tutomu, YOKOHIRA Tokumi, SUDA Tatsuya

    IEICE technical report   111 ( 232 )   93 - 98   2011.10

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    Server migration service provides network applications (NW Apps) with server running environment on a computer (WP) and service of server migration to another WP where the NW App can attain better QoS when it is degraded. Because the file size of a server is large, the traffic for server migration causes QoS degradation of its background traffic. Thus, it is important to decrease the degree (impact) of the QoS degradation. In this paper, we propose three destination selection algorithms MIA, MRA and MCA that try to decrease the impact while increasing the number of NW App's clients whose SLA are satisfied. When a server migration is triggered, MIA, MRA and MCA move the server to the WP with the minimum impact, the WP with the maximum remaining space for servers and the WP with the maximum communication range where the SLA is satisfied, respectively. Numerical examples show that when there is no full-cover WP (on which a server can communicate with an arbitrary client while satisfying the SLA) or its space is small, MIA outperforms the others, otherwise MCA outperforms the others.

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  • 無線LAN混在環境におけるTCPプロキシのACK返送法の改良

    UHI Gyu, 西田裕一, 福島行信, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   62nd   140 - 141   2011.10

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  • IaaS型クラウドサービスにおけるQoSを考慮したサーバ移動アルゴリズム

    神崎康治, 中川真里, 福島行信, 村瀬勉, 横平徳美, 須田達也

    電子情報通信学会大会講演論文集   2011 ( 2 )   S.119-S.120 - 119"-"S-120"   2011.2

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  • BS-5-13 Server Migration Algorithms Taking Account of Qos in IaaS Cloud Service

    Kanzaki K, Nakagawa M, Fukushima Y, Murase T, Yokohira T, Suda T

    Proceedings of the IEICE General Conference   2011 ( 2 )   "S - 119"-"S-120"   2011.2

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  • Server Push-out Algorithms in Server Migration Service

    神崎康治, 福島行信, 村瀬勉, 横平徳美, 須田達也

    電子情報通信学会技術研究報告   110 ( 449(IN2010 144-210) )   163 - 168   2011.2

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    Server migration service is considered as one of IaaS-typed cloud services. The target of the service is such a application that consists of servers and their clients, and, each server works on a computer called a working place (WP) and can voluntarily migrate to another WP if necessary. However, if the destination WP is full of servers, a server in the WP may be forced to be pushed out of the current WP and migrate to another WP to accept the voluntary immigration server. In this paper, in order to protect some particular servers from experiencing voluntary migration or forced migration much more than the other servers, in the viewpoint of migration fairness, three methods to determine the candidates to be pushed out based on the numbers of voluntary migrations and forced migrations. Next, we propose two methods to determine such one pushed-out server from the candidates that the impact caused by forced migration against the network becomes as small as possible.

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  • Server Push-out Algorithms in Server Migration Service

    KANZAKI Koji, FUKUSHIMA Yukinobu, MURASE Tutomu, YOKOHIRA Tokumi, SUDA Tatsuya

    IEICE technical report   110 ( 449 )   163 - 168   2011.2

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    Server migration service is considered as one of IaaS-typed cloud services. The target of the service is such a application that consists of servers and their clients, and, each server works on a computer called a working place (WP) and can voluntarily migrate to another WP if necessary. However, if the destination WP is full of servers, a server in the WP may be forced to be pushed out of the current WP and migrate to another WP to accept the voluntary immigration server. In this paper, in order to protect some particular servers from experiencing voluntary migration or forced migration much more than the other servers, in the viewpoint of migration fairness, three methods to determine the candidates to be pushed out based on the numbers of voluntary migrations and forced migrations. Next, we propose two methods to determine such one pushed-out server from the candidates that the impact caused by forced migration against the network becomes as small as possible.

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  • Optimization of token holding times in split light trail networks

    Wenjie Chen, Yukinobu Fukushima, Tokumi Yokohira

    GLOBECOM - IEEE Global Telecommunications Conference   110 ( 339 )   197 - 202   2011

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    As a new optical WDM network architecture that can be built with currently available devices and can achieve bandwidth allocation with granularity finer than a wavelength, a light trail architecture attracts attention. Because a light trail is a shared medium, we need a medium access control (MAC) protocol to avoid collisions. Although MAC protocols using token passing can avoid collisions, bandwidths of links that locate upstream of the token holding node are kept idle. In this paper, we first propose a dynamic light trail splitting method in order to increase throughput of a light trail by using those idle bandwidths. Our method splits a trail into the upstream trail and the downstream trail at the token holding node and independent data transmissions on the two trails are permitted. As a result, we expect that the split trail architecture achieves higher maximum throughput than the original non-split trail architecture. The degree of throughput improvement by the split trail architecture depends on how appropriately we set upstream and downstream token holding times of every transmission node. Thus, we formulate a problem to decide the token holding times as a nonlinear programming problem, derive the maximum throughput of the split trail architecture by solving the problem using NUOPT solver, and investigate the degree of improvement compared to the original architecture. According to numerical examples, the split trail architecture achieves 1) almost the same maximum throughput as the original one for its unfavorite traffic pattern where every transmission node sends data to the terminating node of the trail only, 2) about 1.6 times as high maximum throughput for a uniform traffic pattern where every node-pair requests the same traffic volume, and 3) about 1.9 time as high maximum throughput for its favorite traffic pattern where every transmission node sends data to its adjacent downstream node only. © 2011 IEEE.

    DOI: 10.1109/GLOCOM.2011.6133810

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  • Performance evaluation of TCP over multiple paths in fixed robust routing

    Wenjie Chen, Yukinobu Fukushima, Takashi Matsumura, Yuichi Nishida, Tokumi Yokohira

    2011 IEEE International Workshop Technical Committee on Communications Quality and Reliability, CQR 2011   2011

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    Fixed robust routing is a promising approach for ISP networks to accommodate variable traffic patterns with low operational complexity. The routing minimizes the maximum link load by distributing traffic of every source-destination pair to multiple paths (multipath routing). The multipath routing can result in performance degradation of TCP because of frequent out-of-order packet arrivals. In this paper, we first investigate the influences of delay differences among multiple paths and ratio of shorter paths among multiple paths on TCP performance with simulation using ns-2. The simulation results clarify that smaller delay difference and lower ratio of shorter paths among multiple paths lead to higher TCP throughput. Based on the investigation results, we next propose fixed robust routing algorithms that try to improve TCP throughput in addition to decreasing the maximum link load. The first algorithm called MDD (Minimum Delay Difference) selects a set of paths with the minimum delay differences between the shortest and the longest paths as candidate paths for every source-destination pair The second algorithm called MDD-LF (Minimum Delay Difference with Limited Fraction) bounds the fraction of traffic routed on the shortest delay path in addition to selecting the same candidate paths as MDD. Simulations using ns-2 show that, compared to a straightforward fixed robust routing that selects k-shortest hop paths as the candidate paths, MDD and MDD-LF achieve about 22% and 27% higher TCP throughput while MDD and MDD-LF produce about 1.7 and 2.3 times higher maximum link load, respectively. © 2011 IEEE.

    DOI: 10.1109/CQR.2011.5996088

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  • Optimization of Token Holding Times in Split Light-trail Networks

    CHEN Wenjie, 福島行信, 横平徳美

    電子情報通信学会技術研究報告   110 ( 339(NS2010 105-141) )   197 - 202   2010.12

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    As a new optical network architecture that can be built with currently available devices and can achieve bandwidth allocation with granularity finer than a wavelength, the light trail architecture attracts attention. For the light trail architecture using token passing medium access control, the split trail architecture is proposed. In the architecture, a trail is split into the upstream trail and the downstream trail at the token holding node and independent data transmissions on the two trails are permitted. As a result, we expect that the architecture achieves higher maximum throughput than the original unsplit trail architecture. The degree of throughput improvement by the split trail one depends on how appropriately we set upstream and downstream token holding times of each transmission node. In this paper, we formulate decision problem of the token holding times as a non-linear programming problem, derive the maximum throughput of the split trail architecture by solving the problem using NUOPT solver, and investigate the degree of improvement compared to the original one. According to numerical examples, the split trail architecture achieves 1) the same maximum throughput as the original one for its unfavorite traffic pattern where every transmission node sends data to the terminating node of the trail only, 2) about 1.6 times as high maximum throughput for an uniform traffic pattern where every node pair has the same sending rate, and 3) about 1.9 time as high maximum throughput for its favorite traffic pattern where every transmission node sends data to its adjacent downstream node only.

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  • P2Pライブストリーミングにおけるピア選択法の性能評価―部分的なASトポロジーのみが利用可能である場合―

    陶一然, 稲田和也, 辺見修平, 福島行信, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   61st   324 - 325   2010.10

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  • 無線LAN混在環境におけるスプリット型TCPプロキシの性能評価

    何旭明, 西田裕一, 王輝, 福島行信, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   61st   349 - 350   2010.10

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  • AS-friendly peer selection algorithms without AS topology information in P2P live streaming

    Yukinobu Fukushima, Yin Tao, Kazuya Inada, Tokumi Yokohira

    8th Asia-Pacific Symposium on Information and Telecommunication Technologies, APSITT 2010   1 - 6   2010.9

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    In recent years, peer-to-peer (P2P) live streaming systems are emerging because of their high scalability and robustness. In the systems, peer selection algorithms that determine logical topologies of P2P overlay networks have a great influence on important performance metrics such as the maximum number of joining peers and inter-AS (autonomous systems) traffic volume. As conventional algorithms that take account of those metrics, MLH (Minimum Logical Hop) and MPH (Minimum Physical Hop) have been proposed. In MLH, a newly joining peer (say Pnew) selects peers whose logical hop counts are as small as possible, where the logical hop count of a peer is defined as the number of hops from an origin streaming server (OSS) to itself. When there are too many such peers, Pnewselects peers whose physical hop counts are as small as possible, where the physical hop count between two peers is defined as the number of ASs between them. In MPH, Pnewselects peers in the reverse order of MLH. These conventional peer selection algorithms use physical hop count under the assumption that complete AS topology information is available. However, it is hard to obtain the complete information. In this paper, we modify the conventional algorithms so that they use each peer's belonging AS information only instead of AS topology information in order to make them practical. In the modified version of MLH and MPH (MLH' and MPH'), Pnewselects the peers within the same AS as Pnewinstead of peers whose physical hop counts are as small as possible. In addition, in order to distribute top level peers (i.e., peers that directly retrieve video from an OSS) to many ASs, MPH' gives higher priority to selecting peers except OSSs in ASs with OSSs. We evaluate the performance of the modified algorithms by simulation. Simulation results show that 1) MLH' and MPH' achieve almost the same maximum number of joining peers as MLH and MPH, respectively, 2) MLH' shows a maximum of 37% larger inter-AS traffic volume than MLH, 3) MPH' shows larger traffic volume than MPH when the number of joining peers is small, while MPH' shows a maximum of 38% smaller traffic volume than MPH when the number of joining peers is large thanks to the distribution of top level peers to many ASs.

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  • マルチパスルーチングにおけるTCPの性能評価

    松村隆史, 福島行信, 西田裕一, 横平徳美

    電子情報通信学会大会講演論文集   2010   40   2010.8

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  • B-6-40 Performance Evaluation of TCP over Multipath Routing

    Matsumura Takashi, Fukushima Yukinobu, Nishida Yuichi, Yokohira Tokumi

    Proceedings of the Society Conference of IEICE   2010 ( 2 )   40 - 40   2010.8

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  • 分散トラヒック計測に基づく増加トラヒックの早期検出

    二星護, 福島行信, 村瀬勉, 藤巻遼平, 広瀬俊亮, 横平徳美

    電子情報通信学会大会講演論文集   2010 ( 2 )   92 - 92   2010.3

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  • B-6-92 Early Detection of Increasing Traffic with Distributed Traffic Monitoring

    Niboshi M, Fukushima Y, Murase T, Fujimaki R, Hirose S, Yokohira T

    Proceedings of the IEICE General Conference   2010 ( 2 )   92 - 92   2010.3

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  • Early Detection of Increasing Traffic with Distributed Traffic Measuring

    二星護, 福島行信, 村瀬勉, 藤巻遼平, 広瀬俊亮, 横平徳美

    電子情報通信学会技術研究報告   109 ( 449(IN2009 144-215) )   331 - 336   2010.2

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    With the spread of broadband access lines, many services making efficient use of them such as video streaming services have appeared. The popularity of these services can cause problems such as the shortage of the Internet backbone capacity, so it is important to detect increasing traffic which cause these problems early. In this paper, we propose an early detection method (partial aggregation method) of increasing traffic under per-subnet based distributed traffic monitoring. The method estimates future overall traffic volume by taking account of estimated traffic volume in all subnets and the estimated number of subnets generating increasing traffic. We compare the proposed method to a previous method (aggregation method) which takes account of estimated traffic volume in all subnets only. The results show that the partial aggregation method can detect increasing traffic earlier than the aggregation method by a maximum of 90 days.

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  • Early Detection of Increasing Traffic with Distributed Traffic Measuring

    NIBOSHI Mamoru, FUKUSHIMA Yukinobu, MURASE Tutomu, FUJIMAKI Ryohei, HIROSE Shunsuke, YOKOHIRA Tokumi

    IEICE technical report   109 ( 449 )   331 - 336   2010.2

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    With the spread of broadband access lines, many services making efficient use of them such as video streaming services have appeared. The popularity of these services can cause problems such as the shortage of the Internet backbone capacity, so it is important to detect increasing traffic which cause these problems early. In this paper, we propose an early detection method (partial aggregation method) of increasing traffic under per-subnet based distributed traffic monitoring. The method estimates future overall traffic volume by taking account of estimated traffic volume in all subnets and the estimated number of subnets generating increasing traffic. We compare the proposed method to a previous method (aggregation method) which takes account of estimated traffic volume in all subnets only. The results show that the partial aggregation method can detect increasing traffic earlier than the aggregation method by a maximum of 90 days.

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  • Throughput Improvement based on Dynamic Trail Partitioning in Light-Trail Networks

    TANAKA Kota, CHEN Wenjie, FUKUSHIMA Yukinobu, YOKOHIRA Tokumi

    IEICE technical report   109 ( 448 )   479 - 484   2010.2

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    As a new optical network architecture that can be built with currently available devices, light trail networks attract attention. A trail is an unidirectional communication channel which is set up by reserving a specific wavelength along a route between a source node and a destination node, and packet communication from an arbitrary node to its downstream nodes is possible. Because a trail is a shared medium, we need medium access control (MAC) to avoid collisions of packets. Token passing type MAC methods such as light-trail fair access MAC (LT-FA MAC) and adaptive round time MAC (ART MAC) have been proposed. In those methods, however, downstream bandwidth of the token holding node is only used, and upstream bandwidth becomes idle. In this paper, we try to improve throughput of a trail by using those idle bandwidth effectively in a token passing type MAC method. In order to achieve this, we propose a dynamic trail partitioning method that dynamically partitions a trail into upstream trail and downstream one at the token holding node, and permits parallel transfer of data using two trails. Numerical calculations and simulations show that the dynamic trail partitioning method can improve throughput by a maximum of more than 80%.

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  • Throughput Improvement based on Dynamic Trail Partitioning in Light-Trail Networks

    田中康太, CHEN Wenjie, 福島行信, 横平徳美

    電子情報通信学会技術研究報告   109 ( 448(NS2009 162-260) )   479 - 484   2010.2

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    As a new optical network architecture that can be built with currently available devices, light trail networks attract attention. A trail is an unidirectional communication channel which is set up by reserving a specific wavelength along a route between a source node and a destination node, and packet communication from an arbitrary node to its downstream nodes is possible. Because a trail is a shared medium, we need medium access control (MAC) to avoid collisions of packets. Token passing type MAC methods such as light-trail fair access MAC (LT-FA MAC) and adaptive round time MAC (ART MAC) have been proposed. In those methods, however, downstream bandwidth of the token holding node is only used, and upstream bandwidth becomes idle. In this paper, we try to improve throughput of a trail by using those idle bandwidth effectively in a token passing type MAC method. In order to achieve this, we propose a dynamic trail partitioning method that dynamically partitions a trail into upstream trail and downstream one at the token holding node, and permits parallel transfer of data using two trails. Numerical calculations and simulations show that the dynamic trail partitioning method can improve throughput by a maximum of more than 80%.

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  • TCP-fox: A New Flow Control Method for Improving TCP Throughput in Large Bandwidth-Delay Product Networks

    Yuichi Nishida, Hiroyuki Ishihara, Wang Hui, Yukinobu Fukushima, Tokumi Yokohira

    International Symposium on Broadband Communication (ISBC) 2010   2010

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  • Performance Evaluation of TCP Proxies in Network Environment Including Wireless LANs

    Yuichi Nishida, Wang Hui, Yukinobu Fukushima, Tokumi Yokohira

    The 25th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2010)   1231 - 1234   2010

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  • A burst assembly method to reduce end-to-end delay in optical burst switching networks

    Fukushima Yukinobu, Wenjie Chen, Fujiwara Yasuyuki, Tokumi Yokohira

    WSEAS Transactions on Communications   8   894 - 903   2009.11

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    Although the offset-time-based scheme can differentiate loss rates of packets according to their QoS levels in optical burst switching networks, it also increases end-to-end delay of packets with higher QoS level. This is because it increases offset time of bursts in proportional to QoS levels of packets which are included in the bursts. In this paper, we propose a burst assembly method that reduces end-to-end delay. Our proposed method includes packets that arrive during the offset time into the currently assembled bursts while the conventional method includes them into the burst assembled next time. Simulation results show that our method offers 12-23% delay reduction for packets with the highest QoS level.

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  • P2PライブストリーミングにおけるAS間トラヒックの低減を目指したピア選択法

    銀桃, 福島行信, 稲田和也, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   60th   ROMBUNNO.21-17   2009.10

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  • 光トレイル網におけるメディアアクセス制御方式の性能評価

    田中康太, 福島行信, 横平徳美

    電子情報通信学会大会講演論文集   2009 ( 2 )   174 - 174   2009.3

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  • B-6-13 Accuracy Improvement of Multi-Stage Change-Point Detection Scheme Based on Alert Weighting

    Wang En, Fukushima Yukinobu, Murase Tutomu, Fujimaki Ryohei, Hirose Syunsuke, Yokohira Tokumi

    Proceedings of the IEICE General Conference   2009 ( 2 )   13 - 13   2009.3

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  • B-7-32 Performance Evaluation of Light-Trail Networks with Cut-Through Function

    Chen Wenjie, Fukushima Yukinobu, Yokohira Tokumi

    Proceedings of the IEICE General Conference   2009 ( 2 )   176 - 176   2009.3

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  • カットスルー機能を備えた光トレイル網の性能評価

    CHEN Wenjie, 福島行信, 横平徳美

    電子情報通信学会大会講演論文集   2009 ( 2 )   176 - 176   2009.3

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  • アラートの重み付けによる階層型変化点検出方式の精度改善

    WANG En, 福島行信, 村瀬勉, 藤巻遼平, 広瀬俊亮, 横平徳美

    電子情報通信学会大会講演論文集   2009 ( 2 )   13 - 13   2009.3

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  • Performance Evaluation of Peer Selection Algorithms for P2P Live Streaming

    FUJIWARA Yasuyuki, FUKUSHIMA Yukinobu, YIN Tao, INADA Kazuya, YOKOHIRA Tokumi

    IEICE technical report   108 ( 458 )   423 - 428   2009.2

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    In this paper, we propose two peer selection algorithms to increase the number of joining peers and decrease the traffic amount between ASs in P2P live streaming, where we assume that the number (logical hop count) of relaying peers is limited by a predetermined value in order to keep real-time property of live streaming. In the first method, a newly joining peer selects such providing peers that the logical hop count is minimum to increase the number of joining peers. And then if there are several such providing peers, the newly joining peer selects such providing peers that the number (physical hop count) of ASs between the newly joining peer and each of the providing peers is minimum to decrease the traffic amount between ASs. In the second peer selection method, a newly joining peer selects providing peers in the reverse order of the first selection method. Simulation results show that the former increases the number of joining peers compared to the latter. Moreover, when the number of joining peers is small (large), the traffic amount between ASs in the latter (the former) is smaller.

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  • Performance evaluation of AS-friendly peer selection algorithms for P2P live streaming

    Yukinobu Fukushima, Kazuya Inada, Yin Tao, Yasuyuki Fujiwara, Tokumi Yokohira

    2009 15th Asia-Pacific Conference on Communications, APCC 2009   866 - 870   2009

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    In this paper, we evaluate the performance of peer selection algorithms: MLH (Minimum Logical Hop) and MPH (Minimum Physical Hop) to increase the number of joining peers and to decrease inter-AS traffic volume in P2P live streaming, where we assume that every peer's logical hop count (the number of providing peers between an origin streaming server and the peer) is limited by a predetermined value in order to keep real-time property of live streaming. In MLH, a newly joining peer selects such providing peers that the logical hop count is minimum to increase the number of joining peers. And then if there are several such providing peers, the newly joining peer selects such providing peers that the number (physical hop count) of ASs between the newly joining peer and each of the providing peers is minimum to decrease the inter-AS traffic volume. In MPH, a newly joining peer selects providing peers in the reverse order of MLH. Simulation results show that MLH achieves about from 20% to 60% more maximum joining peers than MPH, and MPH shows smaller inter-AS traffic volume than MLH when the number of joining peers is small while MLH shows smaller inter-AS traffic volume when the number of joining peers is large. ©2009 IEEE.

    DOI: 10.1109/APCC.2009.5375467

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  • Throughput Improvement of TCP using Split-Connection Type Proxies in Network Environment including Wireless LANs

    Yuichi Nishida, Wang Hui, Hiroaki Matsumoto, Hiroyuki Ishihara, Tokumi Yokohira, Yukinobu Fukushima

    The 24th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2009   1360 - 1363   2009

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  • Dynamic splitting of light trails for increasing throughput in light trail networks

    FUKUSHIMA Y.

    Proceedings of ITC-CSCC, July 2009   1370 - 1373   2009

  • Performance Evaluation of Medium Access Control Methods in Light Trail Networks

    Yukinobu Fukushima, Kota Tanaka, Tokumi Yokohira

    11TH INTERNATIONAL CONFERENCE ON ADVANCED COMMUNICATION TECHNOLOGY, VOLS I-III, PROCEEDINGS,   2009 ( 2 )   1421 - 1425   2009

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    We evaluate performance of two medium access control methods with token passing, LT-FA MAC and ART MAC, in light trail networks. LT-FA MAC aims at coping with bursty packet arrivals while ART MAC aims at decreasing transmission delay. Simulation evaluation is performed in terms of the number of the maximum transmission nodes accommodated on a light trail and the maximum communication distance under the constraints that the bandwidth utilization rate of 90% and the average transmission delay of 100 ms must be achieved. Simulation results show that ART MAC permits about 500-1500km longer communication distance than LT-FA MAC with the same number of transmission nodes on a light trail and ART MAC accommodates about 15-25 more nodes than LT-FA MAC with the same communication distance.

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  • Performance evaluation of AS-friendly peer selection algorithms for P2P live streaming

    Yukinobu Fukushima, Kazuya Inada, Yin Tao, Yasuyuki Fujiwara, Tokumi Yokohira

    2009 15th Asia-Pacific Conference on Communications, APCC 2009   108 ( 458(IN2008 132-221) )   866 - 870   2009

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    In this paper, we evaluate the performance of peer selection algorithms: MLH (Minimum Logical Hop) and MPH (Minimum Physical Hop) to increase the number of joining peers and to decrease inter-AS traffic volume in P2P live streaming, where we assume that every peer's logical hop count (the number of providing peers between an origin streaming server and the peer) is limited by a predetermined value in order to keep real-time property of live streaming. In MLH, a newly joining peer selects such providing peers that the logical hop count is minimum to increase the number of joining peers. And then if there are several such providing peers, the newly joining peer selects such providing peers that the number (physical hop count) of ASs between the newly joining peer and each of the providing peers is minimum to decrease the inter-AS traffic volume. In MPH, a newly joining peer selects providing peers in the reverse order of MLH. Simulation results show that MLH achieves about from 20% to 60% more maximum joining peers than MPH, and MPH shows smaller inter-AS traffic volume than MLH when the number of joining peers is small while MLH shows smaller inter-AS traffic volume when the number of joining peers is large. ©2009 IEEE.

    DOI: 10.1109/APCC.2009.5375467

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  • 光バースト交換網におけるオフセット期間中の到着パケットもバースト化するバースト生成法の性能比較

    野稲泰寛, 福島行信, 横平徳美

    電子情報通信学会大会講演論文集   2008 ( 2 )   150 - 150   2008.3

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  • BS-5-2 Detection of Worm Epidemics Based on a Change in the Number of Destination IP Addresses in Multi-Stage Change-Point Detection Scheme

    Niboshi Mamoru, Murase Tutomu, Kobayashi Masayoshi, Fujimaki Ryohei, Fukushima Yukinobu, Yokohira Tokumi

    Proceedings of the IEICE General Conference   2008 ( 2 )   "S - 60"-"S-61"   2008.3

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  • B-7-73 Performance Comparison of Burst Assembly Methods Assembling Packets Arriving during an Offset Period into a Burst in Optical Burst Switching Networks

    Noine Yasuhiro, Fukushima Yukinobu, Yokohira Tokumi

    Proceedings of the IEICE General Conference   2008 ( 2 )   150 - 150   2008.3

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  • 階層型変化点検出機構における宛先IPアドレス数の変化に基づくワーム拡散の検出

    二星護, 村瀬勉, 小林正好, 藤巻遼平, 福島行信, 横平徳美

    電子情報通信学会大会講演論文集   2008 ( 2 )   S.60-S.61 - 60"-"S-61"   2008.3

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  • Performance Evaluation of Multi-Stage Change-Point Detection Scheme against DDoS Attacks by Random Scan Worms

    Tutomu Murase, Yukinobu Fukushima, Masayoshi Kobayashi, Sakiko Nishimoto, Ryohei Fujimaki, Tokumi Yokohira

    IEEE Communications Society Communications Quality and Reliability Workshop 2008 (CQR 2008)   2008

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  • A throughput optimization algorithm for TCP connections with different routes in long-delay satellite environments

    Wang Hui, Nobuto Watanabe, Shigeyuki Osada, Tokumi Yokohira, Yukinobu Fukushima

    25th AIAA International Communications Satellite Systems Conference   2007.12

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    Although Transmission Control Protocol (TCP) is widely used in the Internet, its performance is poor in networks with long delays. To improve TCP performance in such networks as long-delay satellite environments, the use of a PEP (Performance Enhancing Proxy) has been proposed. The PEP operates on a router that connects a terrestrial link and a satellite link along a TCP connection. When a data packet arrives at the PEP, it forwards the packet to the destination host, transmits the corresponding ACK (premature ACK) to the source host on behalf of the destination host, and stores a copy of the packet in a local buffer (PEP buffer) in case retransmission of the packet is required. As a congestion control method on the PEP, a method that keeps the number of prematurely acknowledged packets in the PEP buffer below a threshold (watermark) value has been proposed, and a watermark value optimization algorithm has been also proposed under the assumption that all connections have the same route. In this paper, we propose a watermark value optimization algorithm under a more realistic assumption that connections have different routes. We define the upper bound of the average throughput of a connection as the maximum average throughput in the case that the connection only exists in network. For a given set of connections, the proposed algorithm tries to attain that the average throughputs of connections with smaller upper bounds are equal to their respective upper bounds, and the number of such connections (maximized-connections) is maximized, and the average throughputs of connections with larger upper bounds are maximized under the condition that they are equal to each other and are larger than or equal to any upper bound of the maximized-connections. Numerical examples show that the proposed algorithm attains such goal. © 2007 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

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  • 同時多発イベント検出を目的とした階層型変化点検出機構の性能評価

    王遠, 村瀬勉, 小林正好, 藤巻遼平, 福島行信, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   58th   ROMBUNNO.21-11   2007.10

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  • Retransmission Control in TCP with a Performance Enhancing Proxy

    西田裕一, 横平徳美, 福島行信

    電子情報通信学会技術研究報告   107 ( 221(NS2007 53-79) )   77 - 82   2007.9

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    In order to improve TCP performance in networks with large round trip time, a method using a PEP (Performance Enhancing Proxy) is a proposed. In the method, the PEP is located on a intermediate router along a TCP connection, and returns acknowlegdment packets (premture ACKs) to the source host instead of the destination host. In previous researches, although a congestion control in the PEP which keeps the number of prematurely acknowledged packets below a threshold (watermark) value has been proposed, packet losses are not taken into account. In this paper, we incorporate a retransmission control to deal with packet losses into the congestion control. the proposed retransmission control mainly has two functions. One is to return duplicate premature ACKs to solicit the fast retransmission in the source host, and the other is to retransmit packets by timeouts and receive of duplicate acknowledgments from the destination host. In addition, TCP selective acknowledgment (SACK) option is supported in the PEP. If the source host can treat the option, the PEP returns premature ACKs with the option.

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  • Retransmission Control in TCP with a Performance Enhancing Proxy

    NISHIDA Yuichi, YOKOHIRA Tokumi, FUKUSHIMA Yukinobu

    IEICE technical report   107 ( 221 )   77 - 82   2007.9

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    In order to improve TCP performance in networks with large round trip time, a method using a PEP (Performance Enhancing Proxy) is a proposed. In the method, the PEP is located on a intermediate router along a TCP connection, and returns acknowlegdment packets (premture ACKs) to the source host instead of the destination host. In previous researches, although a congestion control in the PEP which keeps the number of prematurely acknowledged packets below a threshold (watermark) value has been proposed, packet losses are not taken into account. In this paper, we incorporate a retransmission control to deal with packet losses into the congestion control. the proposed retransmission control mainly has two functions. One is to return duplicate premature ACKs to solicit the fast retransmission in the source host, and the other is to retransmit packets by timeouts and receive of duplicate acknowledgments from the destination host. In addition, TCP selective acknowledgment (SACK) option is supported in the PEP. If the source host can treat the option, the PEP returns premature ACKs with the option.

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  • A Wavelength and Converter Assignment Scheme for Decreasing Blocking Probability in Wavelength-Routed Networks

    Yukinobu Fukushima, Takahiro Ooishi, Tokumi Yokohira

    The 12th OptoElectronics and Communication Conference and The 16th International Conference on Integrated Optics and Optical Fiber Communication (OECC/IOCC 2007)   454 - 455   2007

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  • Performance Evaluation of a Multi-Stage Network Anomaly Detection Scheme for Decreasing the False-Positive Rate against a Large Number of Simultaneous, Unknown Events

    村瀬勉, 福島行信, 小林正好, 藤原弘輝, 横平徳美

    電子情報通信学会技術研究報告   106 ( 358(IN2006 89-113) )   25 - 30   2006.11

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    Change-point detection schemes are a promising approach for detecting network anomalies such as attacks and infections by unknown viruses and worms. They detect those behaviors as change-points. In general, however, because they also detect false-positive change-points, those caused by other factors such as hardware troubles, we need a scheme that only detects true-positive change-points caused by attacks and infections. True-positive change-points tend to occur simultaneously, and the number of true-positive change-points is very large, while false-positive change-points tend to occur sporadically. We exclude false-positive change-points by neglecting change-points that occur sporadically, based on information gathered from the whole network. In this paper, we propose a multi-stage network anomaly detection scheme that aggregates change-point information from distributed IDSs (Intrusion Detection Systems) and detects the true-positive change-points. Simulation results illustrate that, compared to a scheme using only one IDS, our method always yields a smaller false-positive rate, a reduction of up to 98%, under a constraint that the detection rate of the true-positive change-points must exceed 0.99.

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  • Performance Evaluation of a Multi-Stage Network Anomaly Detection Scheme for Decreasing the False-Positive Rate against a Large Number of Simultaneous, Unknown Events

    MURASE Tutomu, FUKUSHIMA Yukinobu, KOBAYASHI Masayoshi, FUJIWARA Hiroki, YOKOHIRA Tokumi

    IEICE technical report   106 ( 358 )   25 - 30   2006.11

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    Change-point detection schemes are a promising approach for detecting network anomalies such as attacks and infections by unknown viruses and worms. They detect those behaviors as change-points. In general, however, because they also detect false-positive change-points, those caused by other factors such as hardware troubles, we need a scheme that only detects true-positive change-points caused by attacks and infections. True-positive change-points tend to occur simultaneously, and the number of true-positive change-points is very large, while false-positive change-points tend to occur sporadically. We exclude false-positive change-points by neglecting change-points that occur sporadically, based on information gathered from the whole network. In this paper, we propose a multi-stage network anomaly detection scheme that aggregates change-point information from distributed IDSs (Intrusion Detection Systems) and detects the true-positive change-points. Simulation results illustrate that, compared to a scheme using only one IDS, our method always yields a smaller false-positive rate, a reduction of up to 98%, under a constraint that the detection rate of the true-positive change-points must exceed 0.99.

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  • 性能改善プロキシを用いたTCPにおける公平性の検討

    渡辺暢人, 長田繁幸, 福島行信, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   57th   532 - 533   2006.10

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  • 光バースト交換網におけるエンド間遅延の低減を目指したバースト生成法

    福島行信, 永原一輝, 野稲泰寛, 横平徳美

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   57th   530 - 531   2006.10

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  • Design of wavelength-convertible edge nodes in wavelength-routed networks

    Yukinobu Fukushima, Hiroaki Harai, Shin'ichi Arakawa, Masayuki Murata

    Journal of Optical Networking   5 ( 3 )   196 - 209   2006

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    Wavelength converters reduce the connection blocking probability in wavelength-routed networks by eliminating the wavelength continuity constraint. We develop a method for deployment of wavelength converters in wavelength-routed networks with an overlay model. In these networks, most wavelength converters are deployed on edge nodes to cover the difference in the numbers of wavelengths multiplexed on access and core links. Therefore reduction of wavelength converter cost on edge nodes leads to minimizing the wavelength converter cost in the whole network. We propose an ingress edge node architecture with fixed wavelength converters that have limited wavelength convertibility but are more economical than full wavelength converters. In our architecture, each input access link of ingress edge nodes is equipped with fixed wavelength converters, and input wavelengths from the access links are evenly distributed on the output core link. As a result, competition for a free wavelength on an output core link is avoided. Simulation results show that our edge node architecture offers about 20% cost reduction compared with a node architecture that uses only full wavelength converters where networks are actually under operation and a full wavelength converter cost to fixed wavelength converter cost ratio is 3:1. © 2006 Optical Society of America.

    DOI: 10.1364/JON.5.000196

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  • Throughput Optimization for TCP with an Active Proxy in Long-Delay Satellite Environments

    Wang Hui, Shigeyuki Osada, Tokumi Yokohira, Yukinobu Fukushima, Deng Chaolong, Kiyohiko Okayama, Nariyoshi Yamai

    2006 Joint Conference on Satellite Communications (JC-SAT 2006)   2006

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  • Throughput optimization in TCP with a performance enhancing proxy

    Shigeyuki Osada, Wang Hui, Tokumi Yokohira, Yukinobu Fukushima, Kiyohiko Okayama, Nariyoshi Yamai

    2006 10TH INTERNATIONAL CONFERENCE ON COMMUNICATION TECHNOLOGY, VOLS 1 AND 2, PROCEEDINGS   106 ( 236(NS2006 70-98) )   392 - +   2006

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    To improve TCP throughput performance, a method using a PEP (Performance Enhancing Proxy) has been proposed. The PEP operates on a router along a TCP connection. When a data packet arrives at the PEP, it forwards the packet to the destination host, transmits the corresponding ACK (premature ACK) to the source host in behalf of the destination host, and stores a copy of the packet into its own buffer (PEP buffer) in case retransmission of the packet is required. As a congestion control method on the PEP, a method which keeps the number of prematurely acknowledged packets in the PEP buffer below a threshold (watermark) value has been proposed. However, the relation between the watermark value and throughput is not sufficiently investigated, and an optimization method of the watermark value is not proposed. In this paper, we first investigate the relation between the watermark value and the average throughput. Extensive simulations show that the simulation results are roughly classified into two cases. In the first case, the average throughput becomes larger for larger watermark values and becomes a constant value when the watermark is over a certain value. In the second case, although the average throughput becomes larger for larger watermark values in the same way, it decreases when the watermark is over a certain value. Next, based on the results about the relation, we propose an watermark optimization algorithm which can adaptively maximize the average throughput of each connection and also satisfy a fairness condition that the average throughputs of connections are equal to each other.

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  • Deployment of Wavelength Converters in Wavelength-Routed Overlay Networks

    FUKUSHIMA Yukinobu, HARAI Hiroaki, ARAKAWA Shinichi, MURATA Masayuki

    IEICE technical report. Information networks   105 ( 323 )   13 - 18   2005.10

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    Wavelength converters reduce connection blocking probability in wavelength-routed networks by eliminating the wavelength continuity constraint. We develop a method for deployment of wavelength converters in wavelength-routed overlay networks. In these networks, most wavelength converters are deployed on edge nodes to cover the difference in the numbers of wavelengths multiplexed on access and core links. Therefore reduction of wavelength converter cost on edge nodes leads to minimizing the wavelength converter cost in the whole network. We propose an ingress edge node architecture with fixed wavelength converters that are more economical than full wavelength converters. In our architecture, each input access link of ingress edge nodes is equipped with fixed wavelength converters and input wavelengths from the access links are evenly distributed on the output core link. As a result, competition for a free wavelength on an output core link is avoided. Simulation results show that our edge node architecture offers more than 46% cost reduction.

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  • Deployment of Wavelength Converters in Wavelength-Routed Overlay Networks

    FUKUSHIMA Yukinobu, HARAI Hiroaki, ARAKAWA Shinichi, MURATA Masayuki

    IEICE technical report. Information networks   105 ( 323 )   13 - 18   2005.10

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    Wavelength converters reduce connection blocking probability in wavelength-routed networks by eliminating the wavelength continuity constraint. We develop a method for deployment of wavelength converters in wavelength-routed overlay networks. In these networks, most wavelength converters are deployed on edge nodes to cover the difference in the numbers of wavelengths multiplexed on access and core links. Therefore reduction of wavelength converter cost on edge nodes leads to minimizing the wavelength converter cost in the whole network. We propose an ingress edge node architecture with fixed wavelength converters that are more economical than full wavelength converters. In our architecture, each input access link of ingress edge nodes is equipped with fixed wavelength converters and input wavelengths from the access links are evenly distributed on the output core link. As a result, competition for a free wavelength on an output core link is avoided. Simulation results show that our edge node architecture offers more than 46% cost reduction.

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  • On the robustness of planning methods for traffic changes in WDM networks

    Y Fukushima, H Harai, S Arakawa, M Murata

    JOURNAL OF OPTICAL NETWORKING   4 ( 1 )   11 - 25   2005.1

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    Language:English   Publisher:OPTICAL SOC AMER  

    Many conventional WDM network planning and/or designing schemes assume that future traffic demand is known beforehand. However, it is difficult to predict future traffic demand accurately. We develop a scheme to design a WDM network that accommodates as much traffic as possible against a variety of traffic patterns, that is, a WDM network robust against traffic uncertainties. Our basic idea is to select a node pair that is expected to be a bottleneck in the future and then to deploy network equipment so that the volume of traffic accommodated by the node pair increases. Our simulation results show that the WDM network designed with our method can accommodate more traffic demand than those designed with the existing methods at the same cost. (c) 2004 Optical Society of America.

    DOI: 10.1364/JON.4.000011

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  • Distributed clustering method for large-scaled wavelength routed networks

    Y Fukushima, H Harai, S Arakawa, M Murata

    2005 Workshop on High Performance Switching and Routing   416 - 420   2005

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    The scalability of routing protocol has been considered as a key issue in large-scaled wavelength routed networks. Hierarchical routing scales well by yielding enormous reductions in routing table length, but it also increases path length. This increased path length in wavelength-routed networks leads to increased blocking probability because longer paths tend to have less free wavelength channels. However, if the routes assigned to longer paths have greater wavelength resources, we can expect that the blocking probability will not increase. In this paper, we propose a distributed node-clustering method that maximizes the number of lightpaths between nodes. The key idea behind our method is to construct node-clusters that have much greater wavelength resources from the ingress border nodes to the egress border nodes. which increases the wavelength resources on the routes of lightpaths between nodes. We evaluate the blocking probability for lightpath requests and the maximum table length in simulation experiments. We find that the method we propose significantly reduces the table length, while the blocking probability is almost the same as that without clustering.

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  • Distributed Clustering Method for Large-Scaled Wavelength Routed Networks

    FUKUSHIMA Yukinobu, HARAI Hiroaki, ARAKAWA Shin'ichi, MURATA Masayuki

    電子情報通信学会技術研究報告. PN, フォトニックネットワーク   104 ( 518 )   1 - 6   2004.12

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    Language:Japanese   Publisher:The Institute of Electronics, Information and Communication Engineers  

    The scalability of routing table length is indispensable for constructing large-scaled WDM network. Hierarchical routing yields enormous reduction in routing table length, but it also yields increase in path length. In wavelength-routed networks, the increase in path length leads to increase in blocking probability because of less probability to find idle wavelengths on the longer paths. However, if the longer paths have more wavelength resources, we expect that the blocking probability does not get worse. In this paper, we propose a new node-clustering method that maximizes the number of lightpaths between nodes. The key idea of our method is to construct the node-clusters that have much wavelength resources from the ingress border nodes to the egress border nodes, which increases the wavelength resources on routes of lightpaths between nodes. We evaluate blocking probability of lightpath requests and table length by simulation experiments. The results show that our proposed method greatly reduces the table length, while the blocking probability is almost the same as the results with no clustering.

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  • Distributed Clustering Method for Large-Scaled Wavelength Routed Networks

    福島行信, 原井洋明, 荒川伸一, 村田正幸

    電子情報通信学会技術研究報告   104 ( 518(PN2004 68-75) )   1 - 6   2004.12

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  • Planning and Design Methods for WDM Networks Robust against Traffic Changes

    FUKUSHIMA Yukinobu, HARAI Hiroaki, ARAKAWA Shin'ichi, MURATA Masayuki, MIYAHARA Hideo

    Technical report of IEICE. PS   103 ( 1 )   11 - 16   2003.4

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    Language:English   Publisher:The Institute of Electronics, Information and Communication Engineers  

    Many researches have been investigated on planning or designing WDM networks assuming that the future traffic demand is known beforehand. Practically, it is difficult to predict the future traffic demand accurately since there are various types of data traffic with different traffic characteristics. In this paper, we propose a scheme to design a WDM network that will accommodate as much traffic as possible against a variety of traffic patterns, that is, robust WDM network. The straightforward way to meet this objective is to design a network to maximize the volume of traffic accommodated in the future. To achieve this simply, we divide the WDM network design problem into two subproblems, the OXC-deployment problem and the fiber-deployment problem. In both problems, we propose schemes to maximize the volume of traffic demand that can be accommodated in the future by taking into account the maximum flow value of each node-pair. We handle those problems by incrementally extending network resources based on the ADD algorithm. By deploying network resources until they reach a condition that a robust WDM network needs to fulfill, we can design a robust WDM network. We compare our proposed scheme with the existing method using various traffic matrices. The results show that the WDM network designed by our method can accommodate more traffic demand than the one, designed by the existing method with the same cost.

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  • A design method for logical topologies with consideration of wavebands

    Yukinobu Fukushima, Shin'ichi Arakawa, Masayuki Murata, Hideo Miyahara

    IFIP Advances in Information and Communication Technology   114   360 - 376   2003

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    Among the several architectures for IP (Internet Protocol) over WDM networks, one promising approach is to overlay a logical topology that consists of lightpaths on the physical WDM network, such that each lightpath carries IP traffic between edge nodes. Many of the conventional methods for designing the logical topology deal with the case of a constant number of wavelengths being available on each fiber. While the number of wavelengths offered by current optical technology is now of the order of thousands, it is not necessary to utilize all wavelengths on each fiber in building an effective logical topology on a WDM network. Instead,.several wavebands may be considered for introduction by deploying. optical fiber amplifiers when additional wavelengths are actually required. In this case, the number of available wavelengths on the respective fibers depends on the number of optical fiber amplifiers deployed on each fiber. In this paper, we propose a new heuristic algorithm for the design of a logical topology with as few optical fiber amplifiers as possible, so that the approach is cost-effective. We then compare our proposal with conventional methods in terms of average packet delays and throughput, and show that our algorithm reduces the number of optical fiber amplifiers required. We also investigate the effect of increasing the number of wavelengths multiplexed on each fiber, by assuming that the product of the number of available wavelengths and the bandwidth of each wavelength is constant. The results show that such a logical topology is able to accommodate a greater volume of traffic by multiplexing more wavelengths on each fiber. The approach thus conforms to Cao's Law. © 2003 by Springer Science+Business Media Dordrecht.

    DOI: 10.1007/978-0-387-35670-9

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  • An Enhanced Minimum Interference Routing Algorithm for Multi-Period Planning of WDM Lightpath Networks without Traffic Prediction

    FUKUSHIMA Y., HARAI H., ARAKAWA S., MURATA M., MIYAHARA H.

    IEICE technical report. Information networks   102 ( 213 )   7 - 12   2002.7

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    Language:Japanese   Publisher:The Institute of Electronics, Information and Communication Engineers  

    It is difficult to predict future traffic precisely although it is assumed that the amount of future traffic is predictable in many researches on a multi-period planning for WDM networks. In this paper, we propose a wave-length-routing algorithm that maximizes the number of accommodated lightpaths without precise prediction of future traffic demand. Since our algorithm reduces the number of leased fibers, it can be effectively applied to a multi-period planning for WDM networks. We show that the proposed algorithm reduces the number of leased fibers more than the existing algorithm does while it accommodates lightpaths more.

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  • A minimum interference routing algorithm for multi-period planning of wdm lightpath networks without traffic prediction

    Yukinobu Fukushima, Hiroaki Harai, Shin'iehi Arakawa, Masayuki Murata, Hideo Miyahara

    European Conference on Optical Communication, ECOC   3   2002

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    © 2002 DTU. We propose a new routing algorithm for accommodating lightpaths in WDM networks. Our algorithm is integrated into multi-period planning of WDM networks without traffic prediction. We show that it achieves higher efficiency than existing algorithms.

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  • A minimum interference routing algorithm for multi-period planning of wdm lightpath networks without traffic prediction

    Yukinobu Fukushima, Hiroaki Harai, Shin'iehi Arakawa, Masayuki Murata, Hideo Miyahara

    European Conference on Optical Communication, ECOC   3 ( 213(IN2002 33-41) )   7 - 12   2002

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    Language:Japanese  

    © 2002 DTU. We propose a new routing algorithm for accommodating lightpaths in WDM networks. Our algorithm is integrated into multi-period planning of WDM networks without traffic prediction. We show that it achieves higher efficiency than existing algorithms.

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  • A Design Method of Logical Topology with Considering Available Wave-bands on Each Fiber.

    福島行信, 荒川伸一, 村田正幸, 宮原秀夫

    電子情報通信学会技術研究報告   101 ( 196(RCS2001 62-78) )   33 - 38   2001.7

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  • A Design Method of Logical Topology with Considering Available Wave-bands on Each Fiber

    FUKUSHIMA Yukinobu, ARAKAWA Shin'ishi, MURATA Masayuki, MIYAHARA Hideo

    IEICE technical report   101 ( 194 )   33 - 38   2001.7

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    Language:Japanese   Publisher:The Institute of Electronics, Information and Communication Engineers  

    Among several architectures for IP(Internet Protocol)over WDM networks, one promising way is to overlay a logical topology consisting of lightpaths over the physical WDM network such that each lightpath carries IP traffic between edge nodes. The conventional design methods of the logical topology consider the case that the constant number of wavelengths are available on each fiber. However, a current optical technology provides several wave-bands and the order of thousands wavelengths, by deploying additional optical fiber amplifiers, and hence the number of available wavelengths depends on the number of optical fiber amplifiers deployed on a fiber. In this paper, we propose a new heuristic algorithm to design a logical topology with a least number of optical fiber amplifiers. We then compare our proposal with conventional methods in terms of the average packet delays, throughput, and show that our algorithm reduces the number of optical fiber amplifiers. We also investigate the effect of increasing the number of wavelengths multiplexed on fiber, by asssuming the product of the number of available wavelengh and the bandwidth of a wavelength to be constant. The results show that the logical topology can accommodate more traffic volume by the large number of wavelengths multiplexed on the fiber, which confirms that the results yield a Cao's Law.

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  • A Design Method of Logical Topology with Considering Available Wave-bands on Each Fiber

    FUKUSHIMA Yukinobu, ARAKAWA Shin'ichi, MURATA Masayuki, MIYAHARA Hideo

    Technical report of IEICE. RCS   101 ( 196 )   33 - 38   2001.7

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    Language:Japanese   Publisher:The Institute of Electronics, Information and Communication Engineers  

    Among several architectures for IP(Internet Protocol)over WDM networks, one promising way is to overlay a logical topology consisting of lightpaths over the physical WDM network such that each lightpath carries IP traffic between edge nodes. The conventional design methods of the logical topology consider the case that the constant number of wavelengths are available on each fiber. However, a current optical technology provides several wave-bands and the order of thousands wavelengths, by deploying additional optical fiber amplifiers, and hence the number of available wavelengths depends on the number of optical fiber amplifiers deployed on a fiber. In this paper, we propose a new heuristic algorithm to design a logical topology with a least number of optical fiber amplifiers. We then compare our proposal with conventional methods in terms of the average packet delays, throughput, and show that our algorithm reduces the number of optical fiber amplifiers. We also investigate the effect of increasing the number of wavelengths multiplexed on fiber, by assuming the product of the number of available wavelength and the bandwidth of a wavelength to be constant. The results show that the logical topology can accommodate more traffic volume by the large number of wavelengths multiplexed on the fiber, which confirms that the results yield a Cao's Law.

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Research Projects

  • Construction of a medical information secure management system using ICT and encryption technology

    Grant number:20K20484  2019.06 - 2023.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Pioneering)  Grant-in-Aid for Challenging Research (Pioneering)

    野上 保之, 日下 卓也, 福島 行信, 横平 徳美, 山内 利宏

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    Grant amount:\25350000 ( Direct expense: \19500000 、 Indirect expense:\5850000 )

    効率のよい秘密鍵暗号実装のための乱数生成法の提案,ブロック暗号ベースの検索可能暗号の実装について研究を進めた.ペアリング暗号を活用した公開鍵暗号ベースの検索可能暗号の実装,個人情報保護のための可変長セキュリティ公開鍵暗号について着手した.データベース・秘密分散について,TCPインキャストの対策研究を行った.メールシステムについて,本研究で開発する拡散暗号法をプロトコルスタック内のどのプロトコルレイヤに対して適用することが望ましいかを検討した.その結果,メールの送信者から受信者までのエンドツーエンドでの暗号化通信を可能とするPGPやS/MIMEに対して拡散暗号法を適用するのが最も望ましいとの結論に至った.このようにエンドツーエンドでの暗号化通信を担うプロトコルレイヤに対して拡散暗号法を適用することにより,拡散暗号法を利用できるユーザは送信者と受信者のみに限定されるものの,その一方で,送信者から受信者までの通信路上のすべての通信区間および中継ホスト(メールサーバ)において,メールが拡散暗号法により暗号化された状態を保つことが可能となる.メールシステムで,メールサーバを運用するサーバ計算機のセキュリティを向上させるために,Linuxにおいて標準で採用されているSELinuxに着目し,SELinuxのセキュリティポリシを細粒度に削減する手法を提案し,その実現方式を示した.この手法によって,SELinuxで標準で配布しているセキュリティポリシから不要なポリシ記述を削減でき,メールサーバで必要となる操作のみを許可するセキュリティポリシを生成できる.これにより,メールサーバプログラムや他のプログラムに脆弱性があったとしても,必要最小限の操作しか許可されず,被害を抑制することが期待できる.また,仮想計算機モニタを利用して,ゲストOSでのプログラム実行の証拠を保
    全するシステムの検討を行った.

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  • データセンターネットワークにおけるスループット急落の回避に関する研究

    Grant number:19K11926  2019.04 - 2022.03

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    横平 徳美, 福島 行信

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    Grant amount:\4290000 ( Direct expense: \3300000 、 Indirect expense:\990000 )

    分散ファイルシステムを採用している最近のデータセンターのネットワークにおいては、多数のサーバが、ほぼ同時に(並列に)、1台のコンピュータ(クライアント)に向けてデータを送信しようとすることがしばしば起こる。このとき、イーサネットスイッチのポートにおいてバッファーオーバーフローが起こり、スループットが0に近い値に急落するという最悪の状況(インキャスト)が起こってしまうことがある。本研究の目的は、分散ファイルシステムにおいて、各サーバのデータ送信終了時間の公平性を気にする必要はなく、全サーバがデータ送信を終了するための時間が重要であることに着目して、サーバからのデータ送信を直列化することにより、インキャストを回避しつつスループットを最大にする方法を考案し、実際に実験ネットワークでその有効性を実証することである。
    2019年度は、データセンターネットワークにおける各リンクの伝送速度、イーサネットスイッチのポートバッファサイズ、サーバから送信されるデータ量(ユニットサイズ)等が与えられた時、インキャストを回避し、かつ、スループットを最大化できる同時設定(同時に並列化できる)コネクション数を求めることができるように、従来筆者らが提案しているコネクション直列化法を拡張した方法(拡張コネクション直列化法)を考案した。
    また、高精度のカーネルタイマーを使用して、最小タイムアウト値を従来の200ミリ秒から数100マイクロ秒にすることにより、インキャストを回避しようとする従来の方法において、クライアントからサーバに再送要求を出すことで、インキャスト回避の可能性を高くできる方法を提案した。
    さらに、上述した方法を統合して、実際のデータセンターネット上で動作できるようにするための基礎的検討を行った。

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  • Development of energy-efficient virtual network mapping technologies

    Grant number:15K00129  2015.04 - 2018.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)  Grant-in-Aid for Scientific Research (C)

    Fukushima Yukinobu

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    Grant amount:\4940000 ( Direct expense: \3800000 、 Indirect expense:\1140000 )

    It is indispensable to decrease the Internet's power consumption. In this research, we tackle an energy-efficient virtual network mapping problem where we map requested virtual networks on the physical network so that the power consumption associated with the mapping is minimized. We first obtain the theoretical lower bound on the power consumption with mathematical programming. Then, we develop a heuristic that achieves the near-optimal power consumption in polynomial time.

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  • Power efficient traffic engineering technologies in all-optical networks

    Grant number:24500081  2012.04 - 2015.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)  Grant-in-Aid for Scientific Research (C)

    FUKUSHIMA Yukinobu

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    Grant amount:\4810000 ( Direct expense: \3700000 、 Indirect expense:\1110000 )

    In this research, I try to develop power-efficient traffic engineering technologies that reduce power consumptions of all-optical networks with spatial and temporal traffic aggregations. Computer simulations clarify that (1) our routing and wavelength assignment method that makes use of spatial traffic aggregation achieves at most 9% lower power consumption than a conventional method, and (2) our medium access control method that makes use of temporal traffic aggregation achieves at most 60% lower power consumption for the network load of 0.1 compared with when the network load is 0.9.

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  • Routing and medium access control technologies in new generation all-optical networks

    Grant number:22700073  2010 - 2011

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)  Grant-in-Aid for Young Scientists (B)

    FUKUSHIMA Yukinobu

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    Grant amount:\2600000 ( Direct expense: \2000000 、 Indirect expense:\600000 )

    In this research, I try to develop(1) a routing technology that is equipped with high robustness against traffic changes and high friendliness with an upper layer protocol, and(2) a medium access control technology that maximizes communication capacity. Numerical calculations and computer simulations clarify that(1) our proposed routing method achieves at a maximum of 27% higher TCP throughput than a conventional method while keeping the robustness against traffic changes, and(2) our proposed medium access control method achieves at a maximum of 1. 94 times higher throughput than a conventional method.

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  • Scalable lightpath establishment method for realizing high throughput in next-generation backbone networks

    Grant number:19760257  2007 - 2008

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)  Grant-in-Aid for Young Scientists (B)

    FUKUSHIMA Yukinobu

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    Grant amount:\2500000 ( Direct expense: \2200000 、 Indirect expense:\300000 )

    本研究の目的は、スケーラブル(拡張性がある)かつ高いスループットを実現する(より多くのトラヒックを収容可能である)次世代基幹網を実現することである。これを達成するために、通信チャネルである光パスを設定する際に経路上の資源利用情報および各ノードペアの過去の波長変換器使用履歴に基づいて適切に波長変換箇所を決定することによりスケーラビリティおよびスループットの向上を実現する光パス設定方式を考案した。シミュレーション評価により、考案方式はスループットを向上させること、および、大規模網へも適用可能であることを明らかにした。

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