Search

A type of Bitcoin node called "Full Node" has to hold the entire of historical transaction data called "Blockchain" to verify that new transactions are correct or not. To operate nodes as Full Nodes, the required storage size will be too large for resource-constrained devices. In this paper, to mitigate storage size, we propose a storage load balancing scheme by distributed storage based on Distributed Hash Table (DHT). By our scheme, nodes in a DHT cluster can behave like Full Nodes without holding the entire of the blockchain.

Motivated by the deployment of wide-area high-speed networks, we propose GENEVA, the streaming control algorithm using generalized multiplicative-increase/additive-decrease (GMIAD). Because current typical con- gestion controllers such as a TCP-friendly rate control prevent occurrences of network congestion reacting susceptibly to packet loss, it causes a significant degradation of streaming quality due to low-achieving throughput (i.e., lower throughput than the maximum throughput that a streaming flow requires in maximum audio/video quality) and data packet losses. GENEVA avoids this problem by allowing a streaming flow to maintain moderate network congestion while trying to recover lost data packets that other competing flows cause during the process of probing for available bandwidth. Using the GMIAD mechanism, the FEC window size (the degree of FEC redundancy per unit time) is adjusted to suppress occurrences of bursty packet loss, while trying to effectively utilize network resources that other competing flows cannot consume due to reductions in the transmission rate in response to packet loss. We describe the GENEVA algorithm and evaluate its effectiveness using an NS-2 simulator. The results show that GENEVA enables high-performance streaming flows to retain higher streaming quality under stable conditions while minimizing the adverse impact on competing TCP performance.

The tussle in IP multicast, where different enablers have interests that are adverse to each other, has led to a halt in inter-provider multicast deployment and created a situation in which enabling inter-domain multicast routing is considered a deterrent for network providers. This paper presents ODMT (On-demand Inter-domain Multicast Tun- neling), an on-demand inter-provider multicast tunneling that is autonomous in operation and manageable through its definable policy control. In the architectural design, we propose a new approach of enabling inter-provider multicast by decoupling the control-plane and forwarding-plane. Focusing on the control-plane without changing the forwarding- plane, our solution changes the traditional open multicast service model into a more manageable service model in inter-domain multicast operation, hence it eases the Internet-wide multicast deployment.

MANET for NEMO (MANEMO) is a new type of network that integrates multi-hop mobile wireless networks with global connectivity provided by Network Mobility (NEMO). Two factors limit the scalability of MANEMO: the volatility of topologically correct global addresses, and excessive traffic load caused by inefficient use of nested tunnels and the consequent redundant routing of packets. We propose NAT-MANEMO, which solves both problems by applying NAT for some mobile router addresses, bypassing tunnel nesting. This approach retains global addresses for mobile end nodes, preserving application transparency, and requires only minimal modification to existing specifications. Our ideas are evaluated using simulation and a proof of concept implementation. The simulation shows the additional signaling overhead for the route optimization introduced by our proposal is negligible compare to the bandwidth of an IEEE 802.11 link. The implementation confirms that route optimization reduces latency and improves throughput.

Effective bandwidth utilization and scalability are vital issues for IP networking over a large-scale uni-directional link (UDL), such as a wide-area wireless broadcast over satellite or terrestrial digital broadcasting. On a large-scale UDL, the current network architecture is not scalable to cover an extraordinary number of receivers that communicate using a Link-layer Tunneling Mechanism (LLTM). This paper proposes a network architecture for a large-scale UDL that: (1) decreases the traffic load of LLTM at the upstream network of the UDL, (2) coordinates the data link layer and network layer of receivers without communications via UDL, and (3) enables neighbor discovery for direct communication between receivers via a bi-directional link that is used as a return path for LLTM. Simulation results showed that our approach reduces by more than 90% the control messages to be sent via UDL compared with IPv6 stateless address autoconfiguration on the existing network architecture. Our proposal improves the UDL bandwidth consumption from O(N) to O(1), so that the bulk of the bandwidth can be utilized for delivering services, not for network configuration of receivers.

International audience; Motivated by the deployment of post-disaster MANEMO (MANET for NEMO) composed of mobile routers and stations, we evaluate two candidate routing protocols through network simulation, theoretical performance analysis, and field experiments. The first protocol is the widely adopted Optimized Link State Routing protocol (OLSR) and the second is the combination of the Tree Discovery Protocol (TDP) with Network In Node Advertisement (NINA). To the best of our knowledge, this is the first time that these two protocols are compared in both theoretical and practical terms. We focus on the control overhead generated when mobile routers perform a handover. Our results confirm the correctness and operational robustness of both protocols. More interestingly, although in the general case OLSR leads to better results, TDP/NINA outperforms OLSR both in the case of sparse networks and in highly mobile networks, which correspond to the operation point of a large set of post-disaster scenarios.

Mobile IPv6 and Network Mobility (NEMO) have been standardized as IP extensions. While these technologies are planned to be adopted by several communities, such as the vehicle, aviation, and cellular industries, Mobile IPv6 has serious deployment issues such as scalability, protocol resilience, and redundancy. In these technologies, a special router called a home agent is introduced to support the movement of mobile nodes. This home agent introduces overlapping, inefficient routes, and becomes a single point of failure and a performance bottleneck. In this paper, a new concept for scalable and dependable mobility management scheme is proposed. Multiple home agents serve the same set of mobile nodes. The Home Agent Reliability protocol and Home Agent migration are introduced to achieve this concept. We also propose an overlay network named a Global Mobile eXchange (GMX) that efficiently handles data traffic from and to mobile nodes, and operates home agents as would an Internet eXchange Point (IXP).

Failure avoidance capability is a desired feature for telecommunication networks, such as the Internet. However, not all failures can be promptly bypassed on the Internet because routing systems that are responsible for detecting and avoiding failures cannot detect all failures. Consequently, failures can interrupt internet communications for a long time, such as a few hours. This paper proposes a novel routing architecture called Drouting that enables flexible failure avoidance. In Drouting, routers calculate multipaths from a source to a destination by constructing Directed Acyclic Graphs (DAGs) that include all links in the intra-domain network graph. IP packets carry packet tags that are set by the end host. The packet tags are used to select a network path from the multipath routes. In this paper, the failure avoidance property of Drouting architecture is evaluated through comparison with another proposal, Deflection, using simulations. Simulations were performed on inferred and synthetic topologies. Drouting exhibits similar performance with Deflection in terms of the number of nexthops, the number of paths and the length of paths, while Drouting outperforms Deflection in the probability of success of failure avoidance.

For satellite communication links to be used comprehensively and in a manner consistent with their features as a basis for Internet communications, it has become necessary to add a framework based on the features of satellite communications to the protocol architecture of the Internet. For this purpose, the authors' group has been engaged in the development of the new UDLR (unidirectional link routing) protocol mechanism. This paper discusses UDLR from the following viewpoints. (1) The method of actual network construction should be established effectively so as to make use of the features and advantages of satellite communications. (2) Conditions other than protocol definitions should be stated clearly for the purpose. (3) A feasibility network should be constructed to explore the optimal application area. The principles in their current form are summarized for each of the above points. UDLR has been implemented on the feasibility testbed over the whole Asian area. The transparent coexistence of a multicast video distribution system utilizing the concurrency feature of satellite communications and other Internet application systems has been achieved. It is demonstrated that UDLR functions effectively in the use of satellite communications in the Internet. The possibility of using satellite communications to support new modes of Internet application, such as broadcast stream distribution, is shown. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(5): 60– 69, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20319

This paper considers a connectionless (CL) packet switching network, such as IP, and proposes a method in which unused addresses are used as labels for packet flows with various granularities, which are transferred along explicitly specified routes. Generally, in CL packet-switched networks, the next packet is selected and relayed to arrive at the destination host on the basis of the destination address attached to the packet. Consequently, it is impossible to transfer packets which have the same destination address but different requirements along separate routes. One technique for performing such a transfer is multi-protocol label switching (MPLS) and is based on a different transfer paradigm. The cost of this method is high because the transfer schemes of each participating router must be modified. To address this problem, this paper proposes a method for flow-based explicit route transfer. In the proposed method, a particular packet flow is allocated to an unused address so that an explicit route is composed from the unused address and the destination address of the packet is translated. In this method, the transfer scheme is kept essentially the same and explicit route transfer is realized only through a simple extension to the router. Depending on the mode of application, it is unnecessary to modify internal routers; the method can easily be applied to existing networks. In this paper, an application of the method to IP, as a typical CL packet switching network, is described, and the features of the proposed method are discussed. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(9): 78–89, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20308

Network Mobility (NEMO) Basic Support is the standard protocol to provide continuous network connectivity and movement transparency to a group of nodes moving together, as in a vehicle. However, the protocol suffers from sub-optimal routing and packet overhead caused by a bi-directional tunnel between the Mobile Router (MR) connecting the mobile network to the Internet and its Home Agent (HA). When a nested NEMO is formed, these inefficiencies become intolerable for real-time multimedia applications. To optimize the delivery of these packets, this study proposes Optimized NEMO (ONEMO) that is capable of providing an optimal path with minimum packet overhead in various scenarios with nested mobility. The protocol is designed to offer the path with minimum signaling overhead and functional requirements are limited to its MRs. Evaluation through measurements against NEMO Basic Support and comparison among other solutions showed effectiveness of the protocol.

SUMMARY IP multicast technology is highly advantageous for various applications and future needs in the Internet. Yet, it is generally recognized that the IP multicast routing protocol is fairly complex and nonscalable and requires additional maintenance and operational cost to network administrators. Although there has been much research related to IP multicast and most router vendors already support basic IP multicast routing protocols, there is still a big gap between what is reported as the stateof-the-art in the literature from what is implemented in practice. In this paper, we clarify the complexities of traditional multicast communication and describe possible solutions using the one-to-many multicast communication model called Source-Specific Multicast (SSM). We explain this communication model and the corresponding routing architecture and examine the statistics obtained for the number of multicast routing entries in our backbone router, which is connected to the international backbone. We also introduce our international collaboration activities that are contributing to the deployment and promotion of IP multicast services in the Internet.

DNS is the baseline for the Internet. However, no method has yet been established for measurement of the service situation of DNS. In the present research, a method is established for measurement and evaluation of the performance of DNS as the name resolving system of the Internet. The method proposed in this paper can easily be adopted at any location in the world and can be applied to any DNS server or DNS server set. In this method, measurement is easily performed with a tool called dnsprobe and dialup. By using the reference DNS server, the measured results can be corrected. In this way, measured results obtained throughout the world can be uniformly compared. Using this method, the reachability of a root DNS was measured from 27 locations. The results make it possible to understand the reachability of present root DNS servers from various locations in the world and to reveal its tendencies. This research methodology allows judgment of the fairness of DNS service and provides assistance in choosing installation locations when new DNS servers are installed. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 89(10): 66–75, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20211

On the Internet, two different IP protocols are deployed such as IPv4 [7] and IPv6 [1]. The Mobile Router uses the basic NEMO protocol [2] which is IPv6 protocol specific. During the early period of time that IPv6 transition is occurring it is very likely that a Mobile Router will move to an IPv4 only access network. When this occurs the Mobile Router will no longer be able to operate using the basic NEMO protocol. There has already been some earlier work to provide IPv6 capability over an IPv4 access network for a Mobile Router [9], [10]. This paper provides a capability by to maintain IPv6 connectivity for the Mobile Router via its Home Agent with IPv4-in-IPv6 encapsulation with no special boxes to be deployed elsewhere in the network.

IP Multicast network deployment is still lagging far behind the Internet. Meanwhile, satellite links have been considered as the links that can deliver multicast traffic efficiently because of their broadcast nature. This paper analyzes the deployment of global multicast networks using satellite unidirectional links assuming that the Internet's backbone networks become the UDL feeds, and regional and stub networks become the receivers. The main objective is to understand how and how much satellite unidirectional links benefit the deployment of global multicast networks. We simulate deployment scenarios on several instances of the Internet topology taken from the RouteViews BGP routing table snapshots, where each scenario consists of UDL feeds and receivers placement strategies. The performance of each deployment scenario is measured using the multicast link count, cumulative multicast out-degree, and the expected number of downstreams per UDL receiver. Our simulations demonstrate that such a deployment gives an advantage over deployment using the existing links on the Internet.

With cloud service becoming more popular, low-latency communication is required between servers in a data center. Low-latency node-to-node or application-to-application notification can be achieved in a NUMA [1] (Non-Uniform Memory Access) system, but requires dedicated, special-purpose network infrastructure. However, IP networks are commonly used in data centers. Using a custom FPGA-based NIC, we create NUMA-like behavior using hardware-generated IP packets which can be transmitted over commodity Ethernet switches and IP routers. We demonstrate ping-pong acknowledgments between two PCs equipped with our IP-NUMA boards. Our IP-NUMA implementation exhibits latency as much as ten times lower than software using Berkeley sockets over a consumer-grade Ethernet switch. iSCSI initiator-target communications and transaction-based distributed software systems will benefit from the reduced latency.

In this paper, we present a network architecture using satellite communications (a wide-area unidirectional communication medium) and a ground network (a two-way communication medium) that is effective in an environment exhibiting a trend toward nonsymmetrical traffic, as well as the implementation of such an architecture. Unidirectional data transmission channels have poor compatibility with the existing Internet routing control architecture, and they do not make the best use of wide-band unidirectional links offered by existing routing control techniques used in the satellite communications. In this study, we propose an architecture based on unidirectional links integrated into existing Internet routes that enables the party requesting the data transmission to send, using an address translation mechanism, a query to the sending party using multiple network addresses of satellite and ground links. Effectiveness of the network address translation mechanism was demonstrated by experiments using actual satellite communication links and simulation based on a LAN environment. At the present time, the increasing use of the Internet in residences and small offices leads to increasing traffic, especially in the direction of information acquisition from outside sources rather than from the users to outside networks. The proposed architecture makes it possible to build satellite communication channels representing a wide-area broadcast-type communication medium that can be used as communication routes suited to this increasing traffic trend. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(12): 93–103, 2000

We propose the Floating Ground Architecture (FGA) for network mobility and ad hoc network convergence. Various factors, including excessive dependence on intelligence in the fixed network, result in the Internet having a de facto logical boundary one hop from the fixed network. To reduce these dependencies, FGA introduces a new logical layer, called Floating Ground, between the fixed network infrastructure and the mobile network, aiming to bridge these different types of network systems. Thanks to the effect of this buffer layer, the architecture: 1) optimizes routes in a deeply nested mobile router arrangement, 2) simplifies mobility event handling under frequent movement of the nodes, and 3) transparently introduces additional functionality with no additional intelligence on the infrastructure side. Through evaluation of our proposed architecture using an actual software implementation running via Direct Code Execution simulation, optimized routes are confirmed with three possible mobility scenarios, demonstrating the handoff duration is dramatically reduced in the short-distance movement scenario, which happens in 78.4%, at maximum, of the handoff events under actual taxi cabs movement in real world. Qualitative analysis of FGA shows it minimizes modification of the network components and existing standardized protocols, and is therefore more suitable for self-organized, distributed network extension than competitive approaches.

In this paper, iDANS, which is a location based information dissemination platform for smartphones composing a vehicular ad-hoc network, is proposed and evaluated. The primary objective of iDANS is to disseminate and share information swiftly between vehicles within a designated area. In order to meet the demands, iDANS disseminates the information which is most relevant to the current location on a priority basis. It also makes use of devices that cannot acquire the current location accurately as relay nodes. The technical feasibility of iDANS was verified on iPhones, and simulations were done in order to verify the effectiveness of the platform. As a result of the simulations, it was verified that iDANS was up to 5.5 times more effective compared to random dissemination, in terms of disseminating more information among vehicles within a designated area.

International audience; Despite years of research in ad hoc routing protocols, only a few have been investigated in the context of MANEMO (MANET for NEMO), which provides a hierarchical structured network and global connectivity. Motivated by the deployment of post-disaster MANEMOs composed of mobile routers and stations, we evaluate two candidate routing protocols through analytical models, simulation, and field experiments. The first protocol is the widely adopted Optimized Link State Routing protocol (OLSR) and the second is the combination of the Tree Discovery Protocol (TDP) with Network In Node Advertisement (NINA). To the best of our knowledge, this is the first time that these two protocols are compared in both theoretical and practical terms. We focus on the control overhead generated when nodes perform a handover. Our results confirm the correctness and operational robustness of both protocols. More interestingly, although in the general case OLSR leads to better results, TDP/NINA outperforms OLSR in the case of sparse networks, which corresponds to the operation point of our target scenario.

We have implemented Multi-Session based Network Security Event Detector: ROOK to detect botnet activity and P2P file sharing traffic and our results show that our method is less false positives than existing network security event detectors (e.g. IDS). We proposed a network security event detection method by analyzing correlation among multiple sessions. Our method can recognize hosts behaviors by rules that describe multi-session correlations: a rule includes the order of starting sessions and information exchange between sessions. By this method, ROOK detected DNS and IRC activities of bots in the experiment.

“Content Cruising System (CCS)” is developed as a decentralized and autonomous distribution system for location-based contents. The content put into CCS carries itself to the destination location and tries to remain there by continual wireless ad-hoc communications among mobile nodes. Focusing on the density of nodes, to tackle the Broadcast Storm problem is imperative. CCS has an avoidance mechanism of redundant transmissions constructed by cooperation of its pre- loaded algorithms, therefore CCS can avert the Broadcast Storm problem regardless of the increase in the number of nodes. Through the experiments with a network simulator, it was confirmed that the mechanism functioned as planed, packet loss on the air was kept lower, the time taken to acquire flowed contents was shortened considerably when the mechanism was applied. In this paper we describe the basic operation of the mechanism and examine the effectiveness of it from various angles.

In this paper, we present a new computer architecture called All-IP computer architecture, which realize a flexible computer re-configuration environment via IP networks. Our new IP-based protocols connect devices to the host computer that were previously limited to a physical attachment. To construct All-IP computer environment, we designed a protocol to manage and discover device resources on IP networks. We also evaluated a protocol called USB/IP, which is expected to be one of the device interconnection protocols in the All-IP computer architecture.

Due to the dissemination of high speed DSL and FTTH, real-time streaming applications transmitting high quality audio and video data have been commonly used on the Internet. These applications usually have strict requirements on delay and packet loss. However, it is difficult to fully satisfy the requirements in general, since the end users cannot guarantee the streaming quality on the best-effort Internet. In this paper, we investigate an FEC (Forward Error Correction) function on DV streaming. We study the relation between network bandwidth and FEC recovery rate upon data transmission, and the receiver's play quality and FEC calculation cost. Our experimental results given on top of our testbed network show that the FEC function can provide the best possible streaming quality, without leading the further disruption of video and audio irrespective of the available network bandwidth.

This paper describes the network architecture of an Asia-wide satellite Internet that considers the situations in developing regions. The design considerations for the architecture are costs, effective use of satellite bandwidth, scalability, and routing strategy when combined with terrestrial links. The architecture includes using one-way shared satellite links to reduce costs, IP multicast to leverage the broadcast nature of satellite links, QoS, audio-video application gateway to adapt to the limited bandwidth of satellite links. This architecture is implemented in an operational network testbed connecting 13 countries and supporting a distance learning project.

A multihomed node has several paths with its correspondent, maintained by several multihoming protocols. The decision to route a packet over a specific path relies on filter rules, which result from the comparison between the path's characteristics and the user policy. Multihoming protocols or their implementations provide various user interfaces to configure the filter rules. However, there is currently no method to describe user policy in terms of cost, bandwidth, delay and other network characteristics, and to compare this policy with the path characteristics. We thus propose in this paper a new framework for policy management for flow distribution, which offers a user interface to define policies and generates filter rules for each multihoming protocol. We first sort out the requirements for users in the multihomed environment. By reviewing some of the most important multihoming protocols and implementations, we show that they do not match all those requirements. We then propose a new policy management framework that fits those very requirements.

This paper proposes an adaptive Overlay Multicast protocol for real-time group communication in a heterogeneous environment. Overlay multicast technology relies on end nodes by delegating the multicast functionality from routers in IP Multicast. Overlay multicast research has two major issues to consider: heterogeneous resource environment and instability of end nodes. In our protocol, data is divided into multiple layers using abstract layered data structure. The number of layers is used for the main metric to construct the multicast tree to satisfy the demand for end nodes resource environment. Furthermore, multi-path layer distribution method for fast recovery from multicast tree partition and congestion avoidance method are proposed to deal with the unstableness at end node.

SOI Asia project aims at Asia-wide distance education development with its design emphasizing on new model of network technologies that provides wide-coverage high-quality network to support high-quality distance education instead of relying on the available Internet connectivity with inadequate quality. A 13-Mbps unidirectional broadcast satellite covers Asia region enabling lecture sharing among student sites. IPv6 multicast overlay network is established by UDLR and IPv6 tunnel technologies to create a virtual network connecting lecturer-site and student-sites on top of network heterogeneity. Bandwidth optimization and scalability are achieved by IPv6 multicast. QoS using policy routing and ALTQ utilizes and manages bandwidth to ensure high quality lectures. Experiment results show that SOI Asia environment delivers better quality streams with stable rate, high correlation, low data loss and jitter compared to the available Internet connectivity. These design aspects, technology model and experimental results can be the considerations of future region-wide distance education development

In the near future, mobile communication will become majority on the Internet according to quick progress of wireless technology and mobility protocols. Mobile IPv6 has been standardized at IETF and almost ready to deploy on the Internet. However, handover technology of Mobile IPv6 is still under development. Since Mobile IPv6 does not specify optimized handover mechanism, it takes certain period to complete handover. In this paper, we investigate a mechanism to minimize handover latency without any modification to Mobile IPv6. We take position that a mobile node will utilize multiple interfaces to achieve smooth handover. With multiple interfaces, the Internet access can be continued even while Mobile IPv6's movement is proceeded. SCTP is a transport protocol capable of handling multiple addresses for each session. A mobile node uses a home address as a primary address and another available address as a secondary address. The SCTP fails over to the secondary address while the primary address (i.e. home address) is inactive during handover. The advantage of this proposal is that it required modification to neither Mobile IPv6 and SCTP.

Network Mobility (NEMO) Basic Support protocol is the standard to provide continuous network connectivity and movement transparency to a group of nodes moving together, as in a vehicle. However, the protocol suffers from suboptimal routing and packet overhead caused by a bi-directional tunnel between the Mobile Router (MR) connecting the mobile network to the Internet and its Home Agent (HA). When nested mobile networks are formed, these issues are critical for real-time appli- cations. This study proposes a mechanism which provides suffi- cient optimal path applicable to the various configuration known in nested mobility. The proposed Optimized NEMO (ONEMO) protocol decreases packet overhead, uses minimum signaling overhead, and modification is limited to MRs. Evaluation through comparison among other solutions showed effectiveness of the scheme.

In the near future, we expect many mobile networks (ex. vehicle in-side network, personal area network) are connected to the Internet and to the other mobile network to support rich applications for user's daliy life. There are several technology to connect these mobile networks to network and the Internet such as Mobile IP, Network Mobility (NEMO) and Mobile Ad-hoc Network (MANET). We specially investigate the use of both NEMO and MANET for efficient communication for an in-vehicle network. This paper proposes Mobile Gateway supporting policy based routing. It manages both NEMO connectivity and MANET connectivity and switches path to a destination according to application requirements and network environment. Our results shows this approach is efficient for vehicle network.

This paper looks at the message implosion problem that may happen on large-scale reliable multicast communications. We propose that receivers track the senders of recent feedback messages and store them in a list to determine the back-off interval to send a feedback message. We call our proposal tracked sender list (TSL). The issues regarding this proposal are how many receivers to be stored in a receiver's list, back-off timer intervals, p.d.f selection, and how a receiver stores itself in its list. We analyzed and simulated our proposal using various parameters values in both networks with equal delay and with heterogeneous delays to show the message suppression performance. The results demonstrate that TSL gives a low number of messages over a wide range of receivers even with a short back-off interval and it is not susceptible to packet losses. Our results also show that TSL performs better than other p.d.fs that is used in message suppression.

This paper proposes a novel technique to enable flow-level multi-path forwarding on IPv6 networks. Generally on such networks, any packet from a node is forwarded toward a destination along the same path, even if some of the packets belong to a different flow with different characteristics. In accordance with packet characteristics and to fulfil demands such as traffic engineering and QoS routing, flow-level multi-path forwarding allows explicit selection of the paths on which to send packets. Multi protocol label switching (MPLS) technology has been used to perform this function so far. However, to apply MPLS on an existing IPv6 network, all non-MPLS-enabled routers in the network must be replaced with MPLS-enabled routers. Therefore, the migration cost is generally expensive. Our previous work has proposed a technique called flow-mapping explicit host routing (FMEHR,), that renders similar results to MPLS using unused address spaces such as IP private addresses. This paper describes the FMEHR concept and its realization on an IPv6 network and discusses its characteristics.

In this paper, virtual mobility control domain (VMCD) is proposed to enhance mobility protocols such as mobile IP and network mobility (NEMO). These mobility protocols rely on a single agent called the home agent. This leads to protocol weakness in terms of system robustness and redundant routes. In VMCD, multiple anchor points serving the same home network are placed as home agents at different networks on the Internet backbone. These anchor points advertise the route of the same home network to the backbone from different networks. It is similar to anycast routing approach of root DNS. By genuine routing, packets meant for mobile nodes are always drawn into the closest anchor point and are delivered to the mobile node by the anchor point on behalf of home agent. In addition, even if one of the anchor points fails, another anchor point immediately takes over for the failed anchor point. VMCD provides better routes for mobile nodes and protocol robustness with minimal involvement of end nodes. This paper discusses the VMCD solutions and shows the efficiency and effectiveness of VMCD.

Providing “always-on” Internet connectivity is crucial for mobile networks in automobiles and personal area networks. The Network Mobility (NEMO) protocol provides such a support involving a bi-directional tunnel between a gateway for the mobile network and a Home Agent. However, the routing path between them is hardly optimal. In this paper, we investigate the use of ad-hoc routing protocols for route-optimized communication between mobile networks. We describe enhancements to a mobile gateway to choose the optimal route for a destination. The route can be provided by the ad-hoc routing protocol or by the basic nemo routing approach itself whenever it is desirable. Our results indicate that this approach provides better routes than the basic nemo routing approach. It also provides detour route(s) when a mobile network is disconnected from Internet access.

Recent years, trend of researches in ad-hoc networks are routing, multicasting and optimized flooding. Focusing on data flooding in ad-hoc networks, proposed scenarios of common researches are limited due to lack of scalability. If there are lots of communication originators, it is obvious that wireless resources are inapplicable. In this study, our typical scenario is that a mobile ad-hoc network is deployed in a city area and many shops, such as shopping malls and restaurants, disseminate their commercial advertisements to the network. This paper points out the lack of scalability issues considering existing IP flooding schemes and proposes a novel application flooding scheme supporting automatic data size adaptation. In this scheme, size of flooded data is dynamically sampled depending on network congestion level so that data can be delivered in a scalable manner to all nodes using MANET.

Internet technology assumes all links are bidirectional, hence it does not take advantage of the broadcast nature of radio frequency communications. RFC3077 based on E. Duros et al. (2001) emulates broadcast connectivity in UDL (UniDirestional Link) and it provides generic solution for all network layer mechanisms. However, this method doesn t support some OSPF based on J. Moy (1998) network topology. We extended the definition of UDL. Our extention enables a node does not have to be reachable from another node. With our extention, we can use every connectivities over UDL as routes then we extended OSPF to handle unidirectional links. Our extension enables all OSPF routers to construct the routing table including UDL, and it is compatible with general OSPF implementation.

RFID attracts attention as a useful device in location-aware application. SPEARS WG of WIDE Project had already developed a system (2003), which uses RFID devices as a sensor of human's location. Purpose for this system is to provide the service based on a user's location in a conference. In this system, the model in which location of user is gathered and provided for each user was adopted. This paper describes several areas of problems and improvements in our latest implementation. The following functions were implemented by the addition of a system called "Area-d": 1) provide a service tied with a location, and 2) provides users' communication rendezvous service. These functions are able to add to the existing system without altering the existing model. This paper describes a location-oriented data processing model and applications.

In this paper, we describe the Optimized Route Cache Management Protocol (ORC) as a network mobility protocol and evaluated it through experiments on a prototype implementation. ORC provides mobility transparency to a network regardless of network movements. Mobile network is a network that moves entirely. Typical examples for a mobile network are personal area networks (PAN) and networks inside vehicles. ORC is based on mobile IPv6 and is combined with the Internet routing mechanisms for network mobility management. ORC assigns a unique unchanging subnet prefix to a mobile network and notifies and maintains a mobile network's route called binding route (BR). A BR is an association between the prefix of the mobile network and a current available address known as care-of address in mobile IPv6. ORC allows interior gateway protocol (IGP) routers named ORC routers to cache a BR. ORC routers intercept packets destined to the mobile network and route them to the mobile network according to the BR. The BR must be updated as soon as the mobile network changes the care-of address by its topological position, employing constant BR exchange to ORC routers and temporary BR exchange to dynamically discovered ORC routers. Based on the experimental results, ORC is confirmed to provide network mobility and optimal communication in terms of route optimization. The evaluation shows that route optimization is required for network mobility to improve communication performance.

This paper describes the design and implementation of a data dissemination application for the satellite Internet using uni-directional links. The satellite network is suitable for multicasting, and uni-directional link routing (UDLR) technology allows ease of construction. However the conventional data sharing method is uncongenial to a UDLR network because this network has many receivers on a flat satellite segment, and the return terrestrial link is narrow and cannot be shared. In order to solve these problems, we proposed an application for multicast data dissemination. It is based on NACK and receiver-initiative. All required parameters and requested data are sent out by a sender and a receiver receives data according only to a set of specific parameters sent by the sender. NACKs received by the sender within a time period which is configured by the receiver are distributed. We applied and evaluated this system on a satellite network.

On the current Internet, the routing architecture consists of intra-domain routing and inter-domain routing. For inter-domain routing an autonomous system (AS), represents the administrative network domain, which is managed by a single institution with its operational policy. ASs exchange AS reachability information with each other. Without inter-domain routing, all nodes on the Internet cannot communicate across multiple ASs. Therefore, inter-domain routing is an essential element in global Internet operation. However, due to several reasons such as miss-configuration on the routers, it often happens that one AS (say AS1) propagates the prefix that has been already assigned to another AS (say AS2) and other peers receive its routing prefix update from AS2 and inject the misconfigured AS information to their peering routers. Since the routing information associated with AS1 is overwritten by AS2, AS1 loses network reachability. This problem is known as the conflict origin AS prefix or the multiple origin AS (MOAS). We recognize that this is a severe problem which degrades the quality of Internet backbone infrastructure. We focus on this problem and propose a mechanism that can detect the conflict origin AS prefix automatically using the policy database.

Satellite links are very sensitive to their environments, and often become unstable. Operators have to monitor satellite links continuously in order to effectively determine their status. However, monitoring satellite links over a widely spread network demands great expenditures of time, finance, and human resources. The difference in skill levels among operators is also problematic. This paper describes a system for monitoring the status of satellite links on the Internet: Modem Watch Dog (MWD). MWD collects the status information of satellite links continuously, and visualizes the information on its Web. MWD provides easy access and understanding of the continuous state of satellite links for operators, even if they are not familiar with the operation of satellite links. MWD has been operating in the AB network. MWD visualizes the continuous status of a satellite link, and indicates the link's normal status and predicted problems caused by equinox Sun interference in Southeast Asia. Through the use of MWD, monitoring the status of satellite links can be easily accepted as part of the layered network operation of the Internet.

The vehicle environment is a good testbed to investigate Internet mobility technologies. Based on testing of buildings, protocol implementation details and problems to deploy it are clarified. This paper describes them. The InternetCAR Project had already done testing to connect vehicles to the IPv6 Internet. Some applications including vehicle diagnosis and teleconference, are implemented on the test system. The test system has the following functions: 1) several communication media with a media switching technology, 2) MobileIPv6 function for continuous connectivity, and 3) network mobility (NEMO) function to provide continuous Internet connectivity for an in-vehicle network. This paper introduces the problems of developing the InternetCAR testing system. The design and solutions are also described.

Route flap is an undesirable phenomenon in the Internet and needs to be eliminated for more stable and robust networks. We present our observations of such persistent route flaps on OSPF in some detail. We show how flaps adversely affect OSPF routing and communication environment in general through our experiments. The current OSPF's implicit timer damping function is found inefficient as each flap may lead to a few seconds of lost connectivity. We implemented a scheme for damping the route flaps and show as to how this methodology can solve such problems in OSPE. Our implementation shows considerable improvement over the ones where none of such techniques were applied.

Denial of Service attacks are divided into two types, one is logic attack and the another one is flooding attack. Logic attack exploits security hole of the software such as operating system and web server bugs, then causes system crash or degrade in the performance. Logic attack can be defended by upgrading software and/or filtering particular packet sequences. In this paper, characteristics of the flooding attacks is described. For the monitoring tools, AGURI, that we have developed, is used. Using the traffic pattern aggregation method, AGURI can monitor the flooding attacks in real network traffic for a long term.

This paper proposes a communication system which ensures Internet connectivity and network transparency to a group of nodes with several network interface devices. We also implement this system as In-vehicle Router System. A vehicle consists of a group of nodes such as sensor nodes and devices held by passengers, is connected to the Internet through several network interface devices. It is typical for buses, trains, and airplanes to have such Mobile Internet environment, and the nodes in such vehicles have to change the attachment point of the Internet frequently. But the nodes would then not be able to maintain transport and higher-layer connections if it changes the attachment point. Thus, it is important to provide mobility support like Mobile IP. These nodes include low cost network appliances with only limited space for extra functions. It is preferred that a solution has no impact on these low cost nodes. Therefore, existing Host Mobility Protocol is not suitable for this situation. In this article, we propose the In-vehicle Router System as a solution to this situation by combining network mobility protocol with Interface switching system. We also implement and evaluate our system on the InternetITS testbed. We have confirmed that our system provides enough functionality to satisfy the requirements of Mobile Internet vehicles.

A system architecture for continuous mobility of Internet-connected computers is designed and proposed. The architecture considers network transparency, geographical location transparency, and performance transparency, with strong support for mapping between an identifier space of the Internet and geographical location information. The architecture is defined by 1) identifier space support functions, 2) continuous Internet connectivity functions, and 3) performance transparency functions. Two experimental systems are implemented based on the architecture and are tested. The systems achieve continuous mobility in practical environments for automobiles connecting to the Internet, and in classrooms with about 40 roaming students.