Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：English   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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

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Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)   Publisher：NTT  

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Language：English   Publishing type：Research paper (bulletin of university, research institution)   Publisher：NTT  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

Network function virtualization is regarded as a promising candidate for future networks. Although many advantages are expected, there is still a lack of services that directly link to increased revenue for telecom operators. Therefore, we propose a new NFV-based service, virtual network integration as a service (VNIaaS). The service allows enterprise network administrators to construct and monitor virtual enterprise networks as necessary. As a key enabler, we further propose vConductor, an innovative technology due to its automatic network provisioning, multi-objective resource scheduling, and NFV-oriented inventory management characteristics. Finally, we show the feasibility through implementation of a prototype system. We believe that this contribution will be a catalyst to accelerate the industrialization of NFV.

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

In this study, we have studied on placement of management data based on NFV reference model for the use case of the NFV orchestrating across the data center and the wide area network (WAN).

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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

NFV, being discussed and standardized in ETSI, is regarded as a promising candidate technology for Future Networks. Although many advantages are expected, the introduction of NFV will greatly challenge current management systems. In this paper, we summarize some of the carrier's requirements for the management of NFV, based on which we propose vConductor as an NFV management solution. We say vConductor is innovative due to its characteristics of automatic service provisioning, end-to-end inventory management, and generic system design. To achieve these goals, we design a completely modular-based system structure and refine the process of provisioning a virtual network service. Furthermore, we propose a general data model, specifically for NFV, starting from the TM Forum SID. We believe that vConductor will be a catalyst for accelerating the industrialization of NFV.

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

Capital expenditure (CAPEX) and operating expenses (OPEX) have been practical concerns for telecommunication companies, and Network Function Virtualization (NFV) has attracted significant attention in recent years. However, the NFV Infrastructure (NFVI) includes a wide variety of resource types and stakeholders. Hence, there is still a need for the existing resource scheduling approaches, but they are no longer sufficient. In this paper, we propose a Multi-objective Resource Scheduling Algorithm (MORSA) to optimize the NFVI resources. In the development of the MORSA, we designed a plug-in architecture to satisfy various requirements related to NFVI resources and stakeholder policies. The MORSA allows the NFVI Resource Scheduler to optimize simultaneously the combination of possibly conflicting objectives with multifaceted constraints in complex real world situations. Evaluation results show that the MORSA obtains approximate solutions among conflicting objectives in a reasonable computation time.

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

BitTorrent is one of the most popular P2P file sharing applications worldwide. Each BitTorrent network is called a swarm, and millions of peers may join multiple swarms. However, there are many unreachable peers (NATed (network address translated), firewalled, or inactive at the time of measurement) in each swarm; hence, existing techniques can only measure a part of all the peers in a swarm. In this paper, we propose an improved measurement method for BitTorrent swarms that include many unreachable peers. In essence, NATed peers and those behind firewalls are found by allowing them to connect to our crawlers by actively advertising our crawlers' addresses. Evaluation results show that the proposed method increases the number of unique contacted peers by 112% compared to the conventional method. Moreover, the proposed method increases the total volume of downloaded pieces by 66%. We investigate the sampling bias among the proposed and conventional methods, and we find that different measurement methods yield significantly different results.

DOI： 10.1587/transinf.E96.D.249

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Language：English   Publishing type：Doctoral thesis   Publisher：Applied Computer Science Course, The Graduate School of Interdisciplinary Information Studies, The University of Tokyo  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Despite its great success, Bit Torrent suffers from the content unavailability problem where peers cannot complete their content downloads due to some missing chunks, which is caused by a shortage of seeders who hold the content in its entirety. The multi-swarm collaboration approach is a natural choice for improving content availability, since content unavailability cannot be overcome by one swarm easily. Most existing multi-swarm collaboration approaches, however, suffer from content-related limitations, which limit their application scopes. In this paper, we introduce a new kind of multi-swarm collaboration utilizing a swarm as temporal storage. In a nutshell, the collaborating swarms cache some chunks of each other that are likely to be unavailable before the content unavailability happens and share the cached chunks when the content unavailability happens. Our approach enables any swarms to collaborate with each other without the content-related limitations. Simulation results show that our approach increases the number of download completions by over 50% (26%) compared to normal Bit Torrent (existing bundling approach) with low overhead. In addition, our approach shows around 30% improved download completion time compared to the existing bundling approach. The results also show that our approach enables the peers participating in our approach to enjoy better performance than other peers, which can be a peer incentive.

DOI： 10.1587/transinf.E95.D.1446

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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

Although Bit Torrent scales well to support large peer populations, the non-uniform seeder distribution over swarms leads to suboptimal content distribution. In this paper, we propose Seeder Trading enabling the over-seeded swarms to trade the seeder bandwidth with the under-seeded swarms to examine the potential improvement through trading seeder bandwidth across swarms. Simulation results show that the under-seeded swarms can improve the content download performance while retaining the performance of over-seeded swarms, which means the content distribution performance and efficiency are improved. We also show that the trading seeder bandwidth across swarms can be done within short time (i.e., 60 seconds in our simulation).

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

In this paper, we propose a new kind of P2P traffic control technique, called Netpherd exploiting the peer selection adaptation (i.e., preferring peers who are likely to provide better performance). Netpherd tries to enable the peers to communicate with the peers of the local domain by manipulating network performance (i.e., adding an artificial delay to the inter-domain traffic) at network device like router. Simulation results show that Netpherd can increases (decreases) the intra-domain (inter-domain) traffic by affecting the peer selection adaptation. Netpherd also improves the content download performance.

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

In recent years, BitTorrent traffic accounts for a substantial percentage of Internet traffic in the world. However, the current BitTorrent protocols disregards traffic cost at the underlying network and generate a large amount of inter-AS traffic. As a result, BitTorrent peers may suffer from slow download of files due to long delays. Moreover, ISPs may limit BitTorrent traffic to reduce inter-AS traffic. In this paper, we propose a new approach localizing BitTorrent traffic within neighboring ASes, gBPEXh, in which a controller and peers directly exchange lists of peer in the vicinity through BitTorrent's PEX protocol. Conducting experiments on Planet Lab, we show that BPEX significantly reduces inter-AS traffic and peers' download completion time. © 2012 IEEE.

DOI： 10.1109/3PGCIC.2012.15

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：電子情報通信学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In the network operator-friendly P2P traffic control technique such as P4P, peers are supposed to select their communication partners by following a guidance issued by the network operator. Thus, the guidance has significant impact on the traffic control. However, detailed performance study of available guidances is missing. Most existing approaches do not show how they affect intra-domain traffic control in detail while mostly focusing on inter-domain traffic control. In this paper, we try to understand how the guidances affect the intra and inter-domain traffic control for better guidance improving the traffic control. Through simulations, we reveal the following. The performance-based guidance reflecting the networking status shows attractive results in distributing the traffic over intra-domain links and in reducing the cross-domain traffic and the charging volume of inter-domain link compared to the distance-based guidance enforcing simple localization. However, the performance-based guidance shows one limitation that can cause unstable traffic control. To overcome the identified limitation, we propose peer-assisted measurement and traffic estimation approach. Then, we verify our approach through simulations.

DOI： 10.1587/transinf.E94.D.2460

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

Despite its great success, BitTorrent suffers from a content unavailability problem where peers can not complete their content downloads due to some missing chunks, which is caused by an absence of seeders. Multi-swarm collaboration approach is a natural choice for improving the content availability, since the content unavailability can not be managed by one swarm easily. Most existing multi-swarm collaboration approaches, however, show content-related limitations, which limit their application scopes. In this paper, we introduce a new kind of multi-swarm collaboration utilizing a swarm as a temporal storage. In a nutshell, the collaborating swarms cache some chunks of each other that are likely to be unavailable when the seeders are online and share the cached chunks when the content unavailability happens. Our approach enables any swarms to collaborate with each other without the content-related limitations. Simulation results show that our approach improves the number of download completions by over 50% compared to vanilla BitTorrent with low caching overhead. The results also show that our approach enables the peers participating in our approach to enjoy better performance than other peers, which can be an peer incentive.

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

BitTorrent is one of the most popular P2P file sharing applications in the world. Each BitTorrent network is called a swarm and millions of peers may join multiple swarms. However, there are many unreachable peers (NATed, Fire-Walled, or inactive at the time of the measurement) in each swarm. Due to this unreachable peers problem, the existing work can measure only a part of the entire peers in a swarm. In this paper, we propose an improved measurement method for BitTorrent swarms that many unreachable peers. In a nutshell, our crawler obtains peers behind NAT and firewalls by letting them connect to our crawlers through actively advertising our crawlers addresses to them. The evaluation result shows that our proposed method increases the number of unique contacted peers by 112 % compared to the conventional method. The proposed method also increases the total volume of downloaded pieces by 66 %. We then investigate the sampling bias among our proposed method and conventional methods, and find that different measurement methods can lead to significantly different measurement results.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

BitTorrent is one of the most popular P2P file sharing applications in the world. Each BitTorrent network is called a swarm and millions of peers may join multiple swarms. However, there are many unreachable peers (NATed, FireWalled, or inactive at the time of the measurement) in each swarm. Due to this unreachable peers problem, the existing work can measure only a part of the entire peers in a swarm. In this paper, we propose an improved measurement method for BitTorrent swarms that include many unreachable peers. In a nutshell, our crawler obtains peers behind NAT and firewalls by letting them connect to our crawlers through actively advertising our crawlers addresses to them. The evaluation result shows that our proposed method increases the number of unique contacted peers by 112 % compared to the conventional method. The proposed method also increases the total volume of downloaded pieces by 66 %.

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

A surplus seeding capacity is often observed in large swarms with many seeders while small swarms with few seeders suffer from low download performance. In this paper, we propose a multi-swarm collaboration approach, called Seed-erTrading to improve overall content distribution performance by exploiting non-uniform distribution of seeders over swarms. In a nutshell, we enable the over-seeded swarms to share their surplus seeding capacity with the under-seeded swarms. To realize the SeederTrading, we resolve several issues including estimation of swarm capacity, selection of swarms to be matched, and seeder trading across the selected swarms. Our extensive measurement shows that 12.9% of under-seeded swarms can achieve their maximum download throughput by utilizing the surplus seeding capacity. Simulation results show that the under-seeded swarms can improve the download performance by over 20% while retaining the content distribution performance of over-seeded swarms. We also show that the trading seeding capacity across swarms can be done within 60 seconds. © 2011 IEEE.

DOI： 10.1109/IPDPS.2011.313

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

BitTorrent is one of the most popular P2P file sharing applications in the world. Each BitTorrent network is called a swarm and millions of peers may join multiple swarms. Due to swarm's large network size and complexity, many resources (PC servers, the Internet connection, etc.) are required for measuring all the swarms in the world. For this reason, the existing work is forced to measure only a part of the entire set of swarms, thus, ends up understanding only a part of it. In this paper, we propose a resource-efficient method for crawling multiple BitTorrent swarms by only a limited amount of resources such as a single PC server. In the proposed method, our crawler avoids collecting redundant information of swarms without pressing WAN access links nor expending much processing resources. We also use a number of techniques to efficiently crawl all the participating peers of multiple swarms. We crawl over 4.3 million unique. torrent files, small files that store metadata used in BitTorrent, and 48,000 tracker addresses. We can crawl 4.3 million swarms within an hour. We obtain 24 swarm snapshots and 10 million unique peers in a day.

DOI： 10.1109/ISADS.2011.72

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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

Peer-to-Peer (P2P) file sharing applications have dramatically increased in popularity for the past few years. Although a P2P file sharing network shares many files, it does not usually have a management and control mechanism for the files exchanged. Consequently, copyright infringement and malware propagation in P2P file sharing networks have become prevalent. In order to prevent these file distribution, content poisoning has attracted much attention recently. Although content poisoning aims to obfuscate users by diffusing a lot of poisoned chunks in P2P networks, its effect to the networks have not been well studied yet. In this paper, we apply content poisoning to "Share", one of the most popular P2P file sharing applications in Japan, to control its file distribution. Our evaluation includes how effective our proposed content poisoning method to a live Share network composed of over 100,000 active peers. The evaluation result shows that our content poisoning method decreases the number of peers that complete file download to less than 5% compared to the case without our control. Our content poisoning method also reduces additional traffic required for poisoning to 4%.

DOI： 10.1109/AINA.2010.68

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：情報処理学会  

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

Peer-to-peer (P2P) file-sharing applications are now widely used. The traffic generated by the P2P applications occupies a significant proportion of Internet traffic, and has an enormous impact on the backbone networks. Since these peers communicate by constructing virtual overlay routes, which are constructed independently from the IP networks topology, the characteristics of P2P traffic between regional networks such as those in prefectures and Autonomous Systems (ASs) have become an important issue. Consequently, it is necessary to understand the actual status of the characteristics of traffic matrices in order to construct and manage future networks. In this paper, we measured and analyzed the file transfer characteristics, such as traffic matrices, between prefectures and between ASs, by identifying file transfers between peers in Winny network, one of the most popular P2P applications in Japan. The results reveal that Winny increases traffic between prefectures and ASs, because file transfers in Winny network does not take account of locality.

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

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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

Peer-to-Peer (P2P) file sharing networks have witnessed dramatic increase in popularity for the past few years. In order to meet the demand of users, most P2P file sharing networks have been primarily focusing on improving transmission efficiency and network scalability. However, these networks do not usually have management mechanisms for distributing files in general. Consequently, copyright infringements in P2P file sharing networks have become prevalent. In order to prevent illegal file distribution, several anti-P2P companies have controlled the file distribution by index poisoning. Although index poisoning aims to obfuscate uses by diffusing a lot of dummy metadata in P2P networks, its effects have not been well studied yet. In this paper, we apply index poisoning to a Winny network, one of the most popular P2P file sharing networks in Japan, to control the file distribution. Our evaluation includes index poisoning in a live Winny network composed of over 100,000 active peers. The result shows that our proposed method can decrease the number of query hits to less than 0.004% compared to the case without our control, and that index poisoning is effective to control a small number of files. However, the result also shows that the index poisoning could cause a serious damage on a Winny network, when many files are under our control simultaneously.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：情報処理学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：情報処理学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：情報処理学会  

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Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：電子情報通信学会  

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

This report presents a method for visualizing scale-free networks. Scale-free networks are said to be difficult to analyze and visualize, because distribution of the vertex degrees follow the power-law nature. Sasaki et al proposed scale-free network visualization technique that creates the hierarchical representation, referring to their vertex degrees. By using the AS relations data, we improve the method of Sasaki et al, and visualize the scale-free networks more clearly. We also applied the proposed method to overlay traffic data of BitTorrent in order to demonstrate the effective visualization of communication paths between a pair of peers over the scale-free network.

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