研究者詳細 - 山中　直明

論文 - 山中　直明

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Delay-sensitive slot allocation method minimizing switching idle time in PLZT optical switch for active optical access network

Kunitaka Ashizawa, Takehiro Sato, Hidetoshi Takeshita, Satoru Okamoto, Naoaki Yamanaka, Eiji Oki, Andrea Fumagalli, Malathi Veeraraghavan

IEICE Communications Express (ComEX) 4 （ 6 ） 217 - 222 2015年07月

研究論文（学術雑誌）, 共著

Active Optical Network (ActiON) using a conventional slot allocation method in Plumbum Lanthanum Zirconate Titanate (PLZT) optical switches was proposed. The conventional slot allocation method shortens the switching idle time, which is a product of the switching guard time and the number of switching times. However, the transmission waiting time could exceed a user’s allowable delay. This paper proposes a delay-sensitive slot allocation method, which minimizes the switching idle time while considering the user’s allowable delay. Numerical results show that the proposed method reduces the number of switching times by up to 88 percent when compared to the conventional method.

Application Centric Energy Efficient Ethernet with Quality of Service Support

Ion Popescu, Takahiro Miyazaki, Mirai Chino, Xiaoyu Wang, Satoru Okamoto, Annie Gravey, Philippe Gravey, Malathi Veeraraghavan, Maite Brandt-Pearce, Naoaki Yamanaka

IEE Electronics Letters 51 （ 15 ） 1165 - 1167 2015年07月

研究論文（学術雑誌）, 共著

Energy Efficient and Enhanced-type Data-centric Network Architecture

Shanming Zhang, Hidetoshi Takeshita, Satoru Okamoto, Naoaki Yamanaka

International Journal of Computer & Information Science (IJCIS) 16 （ 1 ） 60 - 70 2015年03月

研究論文（学術雑誌）, 共著

Information-centric networking (ICN) as an alternative has been researched for future Internet architecture. In this paper, a novel network architecture called Energy Efficient and Enhanced-type Data-centric Network (E3-DCN) is proposed for ICN. E3-DCN not only realizes ICN but also has the ability of data generation by organizing and combining relevant resource such as original data and kinds of processing services. In addition, in order to improve energy efficiency of data transmission, E3-DCN chooses optimal transmission path to transmit data based on packet switching and optical switching. Moreover, based on current traffic situation, E3-DCN reconfigures network topology such as unused nodes and links to operate in sleep mode for energy saving dynamically. And meanwhile, data caching strategies are applied into E3-DCN for data distribution based on the distribution of users. Data caching shortens transmission distance, so data transmission energy, latency and network load is decreased. Based on these approaches, E3-DCN achieves an energy efficient network.

Overview of the 10th International Conference on IP+Optical Network (iPOP2014)

NAOAKI YAMANAKA, Satoru Okamoto, Atsushi Hiramatsu

NewBreeze 27 （ 1 ） 4-5 2015年01月

研究論文（学術雑誌）, 共著

Span Power Management Scheme for Rapid Lightpath Provisioning in Multi-Core Fiber Networks

Bijoy Chand Chatterjee, Yamini Jayabal,NAOAKI YAMANAKA, Satoru Okamoto, Andrea Fumagalli, Eiji Oki

IEE Electronics Letters 51 （ 1 ） 76 - 78 2015年01月

研究論文（学術雑誌）, 共著

The activation time when creating lightpaths is adversely affected by the time optical amplifiers, which are required to adjust the newly added signal power. This shortcoming is particularly true with multicore erbium-doped amplifiers. A fibre span power management scheme is proposed based on the use of dummy wavelength signals, whose function is to alleviate this shortcoming and shorten the required lightpath activation time. An analytical model is developed to estimate the effectiveness of the proposed scheme in achieving this goal.

Photonic Network Vision 2020 - Toward Smart Photonic Cloud

Ken-ichi Kitayama, Atsushi Hiramatsu, Masaki Fukui, Takehiro Tsuritani, YAMANAKA NAOAKI, Satoru Okamoto, Masahiko Jinno, Masafumi Koga

IEEE Journal of Lightwave Technology (JLT) 32 （ 16 ） 2760-2770 2014年08月

研究論文（学術雑誌）, 共著

A smart photonic cloud is defined as a universal network platform without any physical or logical constraint that provides flexible connectivity for machine-to-machine communication such as networked high-performance computing or intra- and inter-data center networks. The key requirements for the network in the Big Data era include an ultralarge capacity with low power consumption, low latency, as well as flexibility on demand to the changes in the configuration and bandwidth of the optical path. To cope with the growing demand for network virtualization, novel photonic layer virtualization will be proposed,which differs fromthe conventional approach in terms of the number of slices and the dynamic range of the bandwidth of each slice. First, the objectives and the guiding principle of the vision will be addressed. Next, three “Ss” will be presented that represent the key enabling technologies, namely scale-free photonics, smart photonic networking, and a synthetic transport platform.

Using Optical-Approaches to Raise Energy Efficiency of Future Central and/or Linked Distributed Data Center Network Services

Naoaki Yamanaka, Hidetoshi Takeshita, Satoru Okamoto, Takehiro Sato

International Journal of Networking and Computing 4 （ 2 ） 209 - 222 2014年07月

研究論文（学術雑誌）, 共著

Novel optical network architectures are proposed for creating future network services. The first architecture is a centralized approach for higher energy efficiency; it yields a data center-centric metro/access optical aggregation network based on wavelength/time-slot multiplexing. Not only higher application layer functions but also all layer-3 or upper traffic are transferred through the simple metro/access optical aggregation network and switched in a huge centralized giant router at the data center. Its simple optical switching is 200 times more energy efficient and only one electrical router is needed, so power consumption of the network can be reduced ten or twenty fold compared to the existing Internet. The second is service mash-up by linked data through a network that uses broadband optical wire for the IoT era. All service contents, hardware, and software programs are defined as service parts. Optical wire interconnects some service parts and creates new mash-up services in the network. That creates deep network functionality in combination with network and processing functions.

エラスティック光アグリゲーションネットワークにおける論理OLTのマイグレーション手法

佐藤丈博, 樋口雄紀, 竹下秀俊, 岡本聡, 山中直明, 大木英司

電子情報通信学会和文論文誌B J97-B （ 7 ） 474-485 2014年07月

研究論文（学術雑誌）, 共著

複数のネットワークサービスを単一物理網上で提供し, トラヒック収容効率の向上および省電力化を実現する次世代光メトロ・アクセス融合型ネットワーク「エラスティック光アグリゲーションネットワーク（EλAN）」が提案されている. EλANでは局側装置であるOLTがプログラマビリティを持ち, 論理OLTを異なる物理OLT間や局舎間で自由にマイグレーションすることが可能になる. 本稿では, EλANの省電力化を目的とした論理OLTのマイグレーション手法を提案する. 具体的には, 稼働する物理OLT数が最小となる論理OLTの配置, およびその配置に至るマイグレーション手順を得ることを目的とした最適化問題を線形計画問題としてモデル化し, 物理OLTのスリープ率およびマイグレーションの実行回数について性能評価を行った結果を述べる. また, EλANのプロトタイプシステム上で行った論理OLTのマイグレーションの基本動作の確認について報告する

省電力ネットワークMiDORi におけるPoint to Multi-point 対応ルーチング高速計算手法

平尾明子, 竹下秀俊, 岡本聡, 大木英司, 山中直明

電子情報通信学会和文論文誌B J97-B （ 2 ） 99-109 2014年02月

研究論文（学術雑誌）, 共著

本論文では, ネットワーク中のトラヒックを特定リンクに集約することで, 空となった未使用リンクをスリープ状態にし, ネットワーク全体の消費電力を削減するMiDORiネットワーク技術における多対多対応ルーチング手法としてSuperPosed Minimum Spanning Tree (SPMST)アルゴリズムを提案する. 提案アルゴリズムは, 多対多接続MiDORiネットワークにおける要求条件である, 高い省電力性実現, 20秒以内での100ノード以上かつ, 1000マルチキャストグループ以上対応の計算実行を満たす. 計算機シミュレーションにより, 提案するアルゴリズムの省電力性・計算時間・マルチキャストグループ収容数の有効性を示すとともに, MiDORiネットワークのプロトタイプシステムにおける提案アルゴリズムの有効性を検証した.

Proposal of Data-centric Network for Mobile and Dynamic Machine-to-Machine Communication

松原大典, 藪崎仁史, 岡本聡, 山中直明, 高橋達郎

電子情報通信学会英文論文誌B E96-B （ 11 ） 2795-2806 2013年11月

研究論文（学術雑誌）, 共著

Machine-to-Machine (M2M) communication is expected to grow in networks of the future, where massive numbers of low cost, low function M2M terminals communicate in many-to-many manner in an extremely mobile and dynamic environment. We propose a network architecture called Data-centric Network (DCN) where communication is done using a data identifier (ID) and the dynamic data registered by mobile terminals can be retrieved by specifying the data ID. DCN mitigates the problems of prior arts, which are large size of routing table and transaction load of name resolution service. DCN introduces concept of route attraction and aggregation in which the related routes are attracted to an aggregation point and aggregated to reduce routing table size, and route optimization in which optimized routes are established routes to reduce access transaction load to the aggregation points. These allow the proposed architecture to deal with ever increasing number of data and terminals with frequent mobility and changes in data.

サービス品質保証型の大規模省電力クラウドシステム－3都県に跨る大規模システムによる実証実験－

鈴木敏明, 垂井俊明, 馬場智宏, 高瀬晶彦, 山田亜紀子, 清水翔, 宗宮利夫, 竹下秀俊, 堀江光, 山中直明

情報処理学会デジタルプラクティス 4 （ 4 ） 342-351 2013年10月

研究論文（研究会，シンポジウム資料等）, 共著

近年、サーバ、ストレージ、端末、ネットワーク等の技術進展により、クラウドサービスが急激に普及し始めている。また、サービスの多様化やユーザの増加により、サービス提供システムの拡大とともに消費電力が急増しており、システムの省電力化が重要な課題の1つとなっている。本論文では、複数のデータセンタとそれらを接続するネットワークより構成される大規模なクラウドシステムおよび提供するサービスに対して、サービスの品質を維持したシステムの省電力化手法について提案する。また、3都県に跨る大規模システムによる実証実験により、サービス品質を維持したクラウドシステムの省電力化について有効性を検証した。

A Parallelized OSPF Weight Setting Scheme based on a Genetic Algorithm for Multi-Core CPUs

菊田洸, 岡本聡, 大木英司, 山中直明

Cyber Journals: Multidisciplinary Journals in Science and Technlogy, Journal of Selected Areas in Telecommunications Vol.3 （ Issue 9, No.3 ） 1-8 2013年09月

研究論文（研究会，シンポジウム資料等）, 共著

Open Shortest Path First (OSPF) is one of the most widespread routing protocols in the world. In OSPF networks, routers calculate the paths for every traffic demand, based on weight values that are configured in advance. OSPF Weight Setting (OSPF-WS) is an NP-hard search problem; find the set of weights that maximizes network utilization. Internet Service Providers (ISPs) are facing the challenge of solving OSPF- WS within practical time and find the best weight set for the efficient use of the network. One heuristic approach, a scheme based on the Genetic Algorithm (GA), has been reported to offer fast solution of OSPF-WS. This scheme identifies good solutions comparable with the output of the conventional Integer Linear Programming (ILP) scheme. However, its calculation cost is still excessive for larger networks, thus higher processing performance is required. Unfortunately, the processing speed of single processing cores has become saturated, and the recent trend is a shift to multi-core processors. To best utilize the performance offered by these processors, the algorithm should be redesigned and suitably parallelized for multi-core CPUs. This paper redesigns the scheme of OSPF-WS with GA to create a parallelized algorithm with much lower computation overhead. Its performance is evaluated on a 16-core Intel Xeon processor and the result is a roughly 13 fold faster calculation speed than the original algorithm on a single-core CPU. This result shows the potential of further speedups with larger scale parallel processing units such as the GPGPU.

Next Generation Green Metro/Access Network Architecture using Time-slot-based Optical Aggregation Network for Multi-service Access

山中直明, 竹下秀俊, 徳橋和将, 佐藤丈博

Cyber Journals: Multidisciplinary Journals in Science and Technology JSAT Vol.3 （ 2 ） 7-12 2013年03月

研究論文（研究会，シンポジウム資料等）, 共著

An extremely energy efficient layer-3 network architecture based on optical slot-type aggregation is proposed for the future Internet. Huge numbers of user traffic streams are multiplexed by optical wavelength/time-slots at the central data center router. Each time-slot is transparent, so all types of service can be integrated on any slot. In other words, user IP packets are aggregated and transferred through the Optical Aggregation Network to the centralized router, transparently. The proposed network architecture realizes a network structure well suited to traffic centralization, and reduces the power consumption to 1/10-1/20 compared to the existing Internet.

Experiment of Point-to-Multipoint VLAN Path Establishment on the Overlay-Model-Based GMPLS-Controlled Wide Area Ethernet

菊田洸, 石井大介, 岡本聡, 山中直明

電子情報通信学会英文論文誌 E95-B （ 10 ） 3302-3306 2012年10月

研究論文（研究会，シンポジウム資料等）, 共著

A High-Speed Routing Engine for Software Defined Network

高山, 清水翔, 岡本聡, 山中直明

電子情報通信学会英文論文誌（ August 2012 Edition ） 1-7 2012年08月

研究論文（研究会，シンポジウム資料等）, 共著

Recently, attention is particularly focused on the research of Software defined network (SDN) for reducing network management complexity. The one of a key technology of SDN is OpenFlow. OpenFlow provide a centralized controller for network and the scalability of controller is main issue. In this paper, we propose a high-speed routing engine for improve the scalability of OpenFlow controller. Unlike conventional architectures of routing engine, the proposal is a hardware routing engine that using on-chip diorama network. We define the Diorama Network as a virtual emulated network in a chip. We implement a prototype of the routing engine on an actual dynamically reconfigurable processor (DRP), and test results show that the prototype can execute the shortest path calculation 19 times faster than the current approach.

多様化メトリックネットワークでのフラッディング経路探索シグナリングによるコネクション確立

菊田洸, 石井大介, 岡本聡, 大木英司, 山中直明

電子情報通信学会英文論文誌 E95-B （ 8 ） 2600-2609 2012年08月

研究論文（研究会，シンポジウム資料等）, 共著

GMPLSは様々なネットワーク上のコネクション制御を実現するネットワーク制御プロトコルである. GMPLSネットワークにおける経路計算はソースノードによって行われ, その際にネットワーク全体のメトリック情報を必要とする. しかし, メトリック計算が多様化するにつれ, ソースノードが所持すべき情報は多くなり, これらを最新状態に保つことは, 交換される制御メッセージ数が膨大となることから困難となる. そこで, 本稿ではフラッディングにより, ソースノードでの計算を不要とした経路計算方式を提案した. この方式ではフラッディングされたメッセージがメトリック情報を集めながら計算され, 各ホップで最短距離となる経路を通過しながら転送される. 提案方式が制御メッセージ数を低減するということは, コンピュータシミュレーションを用いて評価された.

Energy efficient network design tool for green IP/Ethernet networks

竹下秀俊, 山中直明, 岡本聡, 清水翔, 高山

Elsevier Journal Optical Switching and Networking 9 （ Issue 3 ） 264-270 2012年07月

研究論文（研究会，シンポジウム資料等）, 共著

An innovative energy-efficient network design algorithm and a tool to lower the network power consumption are proposed. The goal is an energy efficient network that carries its rated communication load while meeting the QoS requirements by using the minimum set of nodes and links. QoS metrics include hop limit, bandwidth limit reliability and stability. The proposed algorithm addresses the set-covered problem. To discover the optimum network configuration efficiently, we propose a network configuration generation algorithm that utilizes DAPDNA-2, a parallel data flow type reconfigurable processer. The processor automatically produces the node/link set in n-digit binary form where links are modeled as ‘‘1’’ for power on and ‘‘0’’ for power off; it also confirms that the QoS requirements are satisfied. Evaluation results show that DAPDNA-2 is 2-orders faster than the conventional sequential method running on a Pentium-4 processor. Prototype Gigabit Layer-2 switches having remote link power on/off and traffic monitoring functions are developed. Using these switches, we successfully demonstrate an energy efficient IP/Ethernet network. The evaluation results show that network power savings of up to 30% can be realized under the NFSNET topology model. The proposed algorithm and power efficient network architecture can be applied to realize the future green network.

Hybrid Passive/Active Optical Access Network Architecture that Reduces OLT Power Consumption

徳橋和将, 石井大介, 岡本聡, 山中直明

Cyber Journals: Multidisciplinary Journals in Science and Technology, Journal of Selected Areas in Telecommunications(JSAT) （ June Edition ） 2012年06月

研究論文（研究会，シンポジウム資料等）, 共著

省電力な光ネットワーク研究の最前線

山中直明, 徳橋和将, 竹下秀俊

レーザー学会誌レーザー研究 40 （ 5 ） 351-355 2012年05月

研究論文（研究会，シンポジウム資料等）, 共著

MPCP based Active Optical Access Network with PLZT High-speed Optical Switch

徳橋和将, 芦沢國, 徳橋和将, 石井大介, 岡本聡, 山中直明, 若山浩二, 梨本恵一

Elsevier Journal Optical Switching and Networking 9 （ Issue 2 ） 118-129 2012年04月

研究論文（研究会，シンポジウム資料等）, 共著

An active optical access network architecture with our newly developed PLZT ((Pb, La) (Zr, Ti)O3) high-speed optical switch is introduced, with a view to realizing the nextgeneration high capacity scalable access network. This system is developed based on the latest IEEE standard of PON (10G-EPON; IEEE802.3av) in consideration of the coordination with future high capacity PON. PLZT high-speed optical switches are able to switch an optical signal at nano-second speed (<5–10 ns). Generally, the merits of using optical switches are increasing the number of subscribers and transmission distance easily, preventing malicious ONUs from interfacing with the communication between OLT and the other ONUs, realizing fast fiber and OLT protection/restoration and providing various services by controlling optical switches dynamically. This paper focuses on two key technologies; a PLZT optical switch and a new discovery process for active optical access network based on MPCP defined at IEEE802.3. A major challenge in designing active optical access network is supporting the discovery process of MPCP because it does not offer broadcast transmission unlike the regular PON. We propose here a new discovery process; it has been tested successfully in an implementation of our proposed system.

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