Lightweight anonymity protocols provide a well-balanced anonymity and performance by encrypting and decrypting only packet headers under the active and local adversary threat model. Among them, PHI and dPHI are promising in universally providing relationship anonymity. However, when overlaid onto IP, they are susceptible to the router skipping attack, where honest routers are skipped by malicious routers. Although this attack poses a significant threat to anonymity, its prevention is challenging due to the lack of path integrity in these protocols. To address this limitation, this paper integrates path validation into dPHI. This integration is non-trivial, as anonymity and path validation are inherently contradictory requirements. This paper designs and implements pPHI, a novel protocol, and analyzes pPHI in terms of security and performance.

Although secure channels are an essential building block of data plane protocols, their realization on programmable switches remains a significant challenge. Typical approaches offload the computation of authenticated encryption to external devices, compromising either speed or flexibility. Similarly, recent efforts to implement existing constructions of authenticated encryption on the switches face performance limitations due to the numerous recirculations required. This paper presents a novel construction and implementation of authenticated encryption on the switches. It incorporates two instances of Chaskey, a PRF with high compatibility with the switches, to achieve both confid-entiality and integrity with fewer recirculations, integrated using the EtM approach. Multi-block data are handled in CCM mode, implemented through a block rotation mechanism. Furthermore, a divide-and-conquer method realized through packet multi-furcation and rendezvous further reduces recirculations. The construction is verified for security, and its implementation on a Tofino 2 switch exhibits substantial performance improvements.

Programmable switches offer a promising platform for fast and flexible in-network computing. However, a standard mechanism, packet recirculation, degrades throughput due to bandwidth consumption caused by the loopback of not only packet headers but also cumbersome payloads. This paper proposes P4QRS, a mechanism that reduces payload recirculation by retaining payloads within the switch. Specifically, P4QRS bifurcates packets into headers and payloads, which undergo the computation process through pipelines and the buffering process leveraging the switch’s queue behavior, respectively. The headers and payloads then rendezvous for reassembly into complete packets to be sent out. To validate its effectiveness, we evaluated P4QRS through both an analytical model and implementation on state-of-the-art hardware programmable switches. Our results demonstrate that P4QRS operates stably and significantly accelerates complex in-switch computations. Moreover, we address packet reordering, which is a fundamental concern arising because P4QRS performs payload buffering on a per-packet basis rather than per-flow. After identifying the mechanism for developing packet reordering in three stages, we design, implement, and evaluate mitigation strategies targeting each stage. These strategies effectively suppress packet reordering in both flow-aware and flow-unaware cases.

Secure communication relies heavily on authenticated encryption (AE). This poster implements ChaCha20Poly1305, a widely-used AE scheme, on a smartNIC, which is particularly beneficial for high-speed networks. The key design rationale is manually optimizing data layout on hierarchical memory devices on the smartNIC. Our implementation achieves$5.67 \times 10^{6}$and$0.58 \times 10^{6}$packets/s for 64-byte and 1024-byte packets, respectively. As a use case of our AE implementation, we also implement a subset of TLS.

Recent work shows that programmable switches can effectively detect attack traffic, such as denial-of-service attacks in the midst of high-volume network traffic. However, these techniques primarily rely on sampling or sketch-based data structures, which can only be used to approximate the characteristics of dominant flows in the network. As a result, such techniques are unable to effectively detect low-volume attacks that stealthily add only a few packets to the network. Our work explores how the combination of programmable switches, Smart network interface cards, and hosts can enable fine-grained analysis of every flow in a network, even those with only a small number of packets. We focus on analyzing packets at the start of each flow, as those packets often can help indicate whether a flow is benign or suspicious. We propose a unified architecture that spans the full programmable dataplane to take advantage of the strengths of each type of device. We are developing new filter data structures to efficiently track flows on the switch, dataplane-based communication protocols to quickly coordinate between devices, and caching approaches on the SmartNIC that help minimize the traffic load reaching the host. Our preliminary prototype can handle the full pipe bandwidth of 1.4 Tbps of traffic entering the Tofino switch, forward only 20 Gbps to the SmartNIC, and minimize the traffic load to 5 Gbps reaching the host due to our efficient flow filter, packet batching, and SmartNIC-based cache.

Programmable switches are promising platforms for fast and flexible in-network computation; however, a standard mechanism, packet recirculation, degrades throughput due to bandwidth consumption caused by the loopback of not only packet headers but also cumbersome payloads. This paper proposes$\mathrm{P}^{4} \text{QRS}$, a mechanism for retaining payloads within the switch, reducing payload recirculations. Specifically,$\mathrm{P}^{4}$QRS bifurcates packets into headers and payloads, which undergo the computation process through pipelines and the buffering process leveraging the switch's queue behavior, respectively; they then rendezvous for reassembly into complete packets to be sent out. To validate its effectiveness, we evaluated$\mathrm{P}^{4}$QRS using an analytical model and implementation on state-of-the-art hardware programmable switches. Our evaluation shows that$\mathrm{P}^{4}$QRS operates stably and intrinsically boosts complex in-switch computations.

Quantum networks offer the capability of transferring quantum information among remote nodes leveraging the phenomenon of quantum entanglement. A key challenge is entanglement routing, which routes quantum entanglement efficiently in a quantum network to satisfy specific objectives. We focus on an interesting hypothesis that arises from the probabilistic nature of quantum entanglement: There is a tradeoff between accommodating a higher number of quantum entanglements (performance) and serving a broader range of node pairs (fairness). To confirm this hypothesis, we formulate entanglement routing as a multi-objective optimization problem. Our numerical analysis reveals that the solutions of the model form a Pareto frontier, thereby validating the hypothesis. Furthermore, we compare the performance of existing algorithms against this Pareto frontier to understand how the algorithms balance performance and fairness. Our findings contribute to designing entanglement routing algorithms.

A large portion of Internet traffic passes through middleboxes that read or modify messages. However, as more traffic is protected with TLS, middleboxes are becoming unable to provide their functions. To leverage middlebox functionality while preserving communication security, secure middlebox channel protocols have been designed as extensions of TLS. A key idea is that the endpoints explicitly incorporate middleboxes into the TLS handshake and grant each middlebox either the read or the write permission for their messages. Because each middlebox has the least data access privilege, these protocols are resilient against the compromise of a single middlebox. However, the existing studies have not comprehensively analyzed the communication security under the scenarios where multiple middleboxes are compromised. In this paper, we present novel attacks that break the security of the existing protocols under such scenarios and then modify maTLS, the state-of-the-art protocol, so that all the attacks are prevented with marginal overhead.

Consumer privacy leakage from data names poses a serious threat to Content-Centric Networking (CCN) networks. Obfuscating names is a promising countermeasure, and anonymizers with deterministic encryption schemes have been proposed to provide data privacy while enabling CCN features, such as in-network caching. Existing studies assume a weak threat model in which anonymizers are honest, and their obfuscation schemes are not resilient against privacy attacks such as name guessing attacks. This paper designs a name obfuscation framework based on the realistic assumption that anonymizers are semi-honest. The framework strengthens data privacy using multiple keys and separates obfuscation for prefixes and suffixes, and is implemented on a P4 switch to provide Tbps forwarding speed.

The paper presents a Tbps-class anonymity router that supports both an anonymity protocol and IP by leveraging a programmable switch. The key design issue is to place both the compute-intensive header decryption function for anonymity protocol forwarding and the memory-intensive IP forwarding function on the processing pipes of a switch with satisfying its hardware requirements. A prototype router on a programmable switch achieves Tbps-scale forwarding.

Several platforms to efficiently retrieve content from Internet of Things (IoT) devices installed in various locations have been proposed for information-centric networking (ICN). However, location privacy is at stake in such platforms because consumers retrieve content by specifying the plaintext names of the locations of their interest (LOIs). Previous studies on IP have leveraged k-anonymity of location offered by a trusted proxy called an anonymizer to hide LOIs. Specifically, an anonymizer sends content requests to k locations in a location anonymity set, which comprises an LOI and the other dummy locations. This technique can be applied to ICN; however, two problems need to be solved: the adversary models are unrealistic and the requirements for a location anonymity set have been defined in ad-hoc manners. In this study, we assume a semi-honest anonymizer and define the requirements rigorously using the notions of entropy and t-closeness. Next, we design an architecture for location privacy protection and an algorithm for location anonymity set generation. Finally, we evaluate the overhead incurred by our architecture and the quality of generated location anonymity sets through experiments under a realistic scenario. Our results indicate that our architecture and algorithm offer strong location privacy with marginal overhead.

This paper proposes an IP forwarding information base (FIB) encoding leveraging an emerging data structure called a learned index , which uses machine learning to associate key-position pairs in a key-value store. A learned index for FIB lookups is expected to yield a more compact representation and faster lookups compared to existing FIBs based on tries or hash tables, at the cost of efficient FIB updates, which is difficult to support with a learned index. We optimize our implementation for lookup speed, exploiting that for efficient FIB lookups it is enough to approximate the key-position pairs with a piece-wise linear function, instead of having to learn the key-position pairs. The experiments using real BGP routing information snapshots suggest that the size of the proposed FIB is compact and lookup speed is sufficiently fast regardless of the length of matched prefixes.

Federated learning is a privacy-preserving learning system where participants locally update a shared model with their own training data. Despite the advantage that training data are not sent to a server, there is still a risk that a state-of-the-art model inversion attack, which may be conducted by the server, infers training data from the models updated by the participants, referred to as individual models. A solution to prevent such attacks is differential privacy, where each participant adds noise to the individual model before sending it to the server. Differential privacy, however, sacrifices the quality of the shared model in compensation for the fact that participants' training data are not leaked. This paper proposes a federated learning system that is resistant to model inversion attacks without sacrificing the quality of the shared model. The core idea is that each participant divides the individual model into model fragments, shuffles, and aggregates them to prevent adversaries from inferring training data. The other benefit of the proposed system is that the resulting shared model is identical to the shared model generated with the naive federated learning.

Named Data Networking (NDN) is one of promising next generation Internet architectures that aim to realize efficient content distribution. However, in terms of producer anonymity, NDN has a serious problem that adversaries can easily learn who publishes what content due to its feature that content is inherently tied to the producer by the content name and the signature. In this article, we first define producer anonymity rigorously in terms of content-producer unlinkability, and then design a system to achieve it. Our design is based on hidden service, which is an onion routing-based system in IP, however, we improve it to take full advantage of NDN. We demonstrate that our system provides a level of anonymity comparable to hidden service with lower overhead through analysis and experiment.

Verifying remote computing environments, such as computing nodes in fog and edge computing, has gained considerable attention. This poster extends an existing remote attestation method so that it can verify that obtained results are generated by trusted computing nodes as well as remote computing nodes are trusted.

This paper addresses edge computing for location-based service where location data is obtained by Internet of Things devices. A key motivation of the paper is to propose a location-based routing/forwarding framework where a computation request of location data is forwarded to an appropriated edge router. The word “appropriate” means that time of retrieving location data as an argument of the computation is minimized. As the result, computing time is minimized.

Conflict between the two TE (Traffic Engineering) techniques for EE (Energy Efficiency) and LB (Load Balancing) has been paid attention to. This is because the both objectives are difficult to simultaneously achieve due to that the both TE techniques control the routing matrix: power and link cost minimization. The goal of this paper is to show feasibility of achieving a fair tradeoff between these two inherently conflicting objectives by using a game theoretic approach and to develop an algorithm wherein EE and LB objectives are simultaneously achieved in a fair manner.

Crowdsourcing in cellular networks, wherein smartphone users upload sensing data pieces using their smartphones to a service provider, has become popular. However, a shortage of cellular uplink frequency resources prevents a service provider from collecting large data with reasonable costs. Incorporating collaborative upload, wherein representatives upload their sensing data pieces as well as those of others, is a promising solution. A key to make a business based on such crowdsourcing, which we call collaborative crowdsourcing, successful is how to motivate smartphone users to become representatives. In this paper, we propose a novel rewarding scheme for the users to advocate collaborative crowdsourcing.

On the one hand packet-level caching of Information-Centric Networking (ICN) is a key to accommodating Video on Demand (VoD) movies thanks to its fine granularity caching, but on the other hand it would cause degradation in cache hit probability because each of packets constituting a content object is dealt individually. This paper analytically reveals that caching large content objects by using packet-level caching degrades caching hit probability.

It is our great pleasure to welcome you all to the beautiful and exciting city Osaka for the 23rd IEEE International Symposium of Local and Metropolitan Networks (LANMAN 2017 - for the first time held in Japan).

One of key technologies of 5th generation mobile networks is introducing small cells, such as femtocells and picocells, to supplement existing macrocells, and this results in high heterogeneity in mobile networks. Cell association, which selects a base station for each user to connect to, is a fundamental issue to optimize the performance and utilization of heterogeneous networks. This paper develops a heuristic cell association algorithm for heterogeneous networks, which adopts the minimum throughput among users as a criterion to determine user to cell associations. Through simulation experiments, we show that the proposed algorithm increases traffic accommodated in the network as well as it achieves high total and minimum throughput.

Internet of Things (IoT) devices deployed everywhere are expected as potential data sources for various location-based services. This paper designs an anonymous geographical routing/forwarding mechanism to support location-based IoT services, where users collect data pieces from IoT devices by specifying their locations rather than their names/addresses. A key idea of the routing/forwarding mechanism is enabling users to collect location-dependent data without locations of users' interest being leaked.

In the aftermath of natural disasters (e.g., earthquakes and hurricanes), information dissemination to and from citizens and authorities often involves the use of mobile network services. They may do so to seek help, distribute critical information, and possibly to confirm the safety of relatives and friends. The traffic on the cellular network typically increases substantially in the aftermath of such disasters. The situation is further compounded by disruptions caused by damage to the network infrastructure and the non-availability of power. Networks are fragmented, and communication is intermittent and disruption prone. In this paper, we propose a name-based many-to-many communication service for such fragmented networks. The key feature of this service is an integration of several communication methods, such as push-based and pull-based. The service effectively supports a variety of network situations by leveraging the features of information-centric networks.

Named data networking (NDN) has received considerable attention recently, mainly due to its built-in caching, which is expected to enable widespread and transparent operator-controlled caching. One of the important research challenges is to reduce the amount of power consumed by NDN networks as it has been shown that NDN's name prefix matching and caching are power-hungry. As a first step to achieving power-efficient NDN networks, in this paper, we develop a power consumption model of a multicore software NDN router. By applying this model to analyze how caching reduces power, we report that caching can reduce power consumption of an NDN network if the power consumption of routers is in proportion to their load and the computation of caching is as light as that of forwarding.

Virtual machine live migration is a promising solution to provide low end-to-end delay for delay-sensitive applications hosted in data centers. This enables a cloud operator to minimize end-to-end delay by placing virtual machines to the nearest data centers from users. However, a network operator does routing with a different objective, e.g., minimize network resource usages. Since the both operators' objectives are contradictory to each other, we previously proposed to integrate live migration and routing in backbone networks to resolve the contradiction. However, the dominant factor of end-to-end delay for cloud services is a congestion delay at access networks, which was not taken into account in our previous work. In this paper, we apply the integration into wireless access networks prone to suffer from large end-to-end delay and validate its effectiveness in such networks by formulating it as a solvable mixed integer non-liner program. Our new integration model incorporates congestion delays due to wireless links and therefore enables cloud operators to maintain small end-to-end delays for cloud applications. The numerical results indicate that integration of live migration and routing is successful at providing low end-to-end delay to delay-sensitive applications by resolving the contradiction.

This paper proposes an NDN-based message delivery protocol over a cellular network in disasters. Collaborative communication among cellular devices is integrated into the protocol so that power consumed by battery-operated BSs (Base Stations) is reduced when a breakout occurs. A key idea is to reduce consumed radio resources by making cellular devices of which radio propagation quality is better forward messages of neighboring devices. The radio resource reduction contributes to reducing power consumed by a battery-operated BS.

In-network caching in information centric networking (ICN) is considered as a promising approach to reducing energy consumption of an entire network. However, it is also considered as an energy consuming technique. These contradictory claims lead to one research question: Does caching really reduce the energy consumption of the entire network? To answer the question, we formulate an ICN network as an optimization problem with a realistic energy consumption model for an ICN router. By solving the formulation assuming that ICN forwarding software currently under development is used as a forwarding engine of an ICN router, we reveal that in-network caching alone does not reduce much energy but it enhances a currently developed green networking technique even though the forwarding engine is not fully optimized.

How the mobile Internet accommodates a huge number of IoT devices is an important research challenge since their number grows to several billions. An important observation about IoT device communications is that IoT devices have different characteristics in mobility from traditional mobile devices such as cellular phones. Strict mobility management scheme and session mobility provided by handover functions are not required for the IoT device mobility management. In this paper, we focus on IoT communication features, and propose a routing-based mobility architecture for them. Our routing architecture uses the Bloom Filter as a data structure to store routing information. We clarify the effectiveness of our routing architecture in IoT environments.

The market for multiplayer online games is rapidly growing in concert with the growth in broadband Internet connection services. Since such games share a virtual space among many players, it is important to match players to a group so that they share low-latency connections with each other. This is because the latency between them affects the perceived quality of their experience. In this paper, we propose a topology-aware matching algorithm using players' geographical locations. We focus on synchronous multiplayer games that require a latency comparable to a delay of one frame. This paper describes the algorithm and its evaluation by simulations.

Although the virtual collocation of service providers (SPs) on top of infrastructure providers (InPs) via network virtualization brings various benefits, we posit that operational confidentiality has not been considered in this network model. We extend and apply the Secure Multiparty Computation (SMC) protocol to solving Minimum Disclosure Routing (MDR), namely, enabling an SP to route packets without disclosing routing information to InPs. We implement the proposed MDR protocol and evaluate its performance via experiments by comparing it against the prediction based on our analytical performance model. Our study reveals that MDR can be securely achieved with marginal latency overhead with regard to the convergence time in well-engineered nonsecure routing algorithms. Our study sheds light on the path for network virtualization to be used to resolve the challenges for the ISPs of today.

This paper proposes a new type of range-free localization method based on affine transformation. Nodes extract subgraphs with a grid topology from a sensor network and assign x-y coordinates to themselves in a decentralized manner. The nodes estimate their positions using an affine transformation based on the mapping of the physical positions and the x-y coordinates of three anchors in an extracted graph. In contrast with multilateration-based localization methods, the proposed method works well even in a non-convex hull deployment, such as a terrain with big regions without sensors. We provide a theoretical analysis and simulation results. We also present a strategy for minimizing the position estimation error and maximizing the coverage of the proposed method. In the simulation results, the position estimation error is 0.18 (normalized by the radio communication range) and the coverage is almost 100% in a non-convex hull deployment.

In the near future, autonomous and distributed systems consisting of a huge number of sensor nodes are expected to play an important role. Due to their distributed nature, each node should control itself autonomously by means of a local interaction algorithm. Although such local interaction algorithms improve system scalability, how to design a local interaction algorithm has become an issue. In this paper, we describe a local interaction algorithm in a partial differential equation (or PDE) and propose a new design method whereby a PDE is derived from a pattern of control values. A pattern means a distribution of nodes' control values over the network each of which is used to control the node. Nodes behave according to the pattern and as a result they collectively provide network functions such as collision and congestion avoidance. In this paper, we focus on a periodic pattern composed of sinusoidal waves and derive the PDE by exploiting the Fourier method.

Welcome to IEEE ICNP 2010, the Eighteenth International Conference on Network Protocols in Kyoto, Japan! Continuing the tradition of being the premier conferences on network protocols, we have an exciting program with papers, posters and a panel, representing the best of today's research. We are delighted to have two keynote speakers this year: Professor P. R. Kumar (University of Illinois at Urbana-Champaign, USA) and Dr. Shigeyuki Akiba (President and Chief Executive Officer, KDDI R&D Laboratories Inc., Japan).

The current interdomain routing protocol, BGP, is not resilient to a path failure due to its single-path and slowly-converging route calculation. This paper proposes a novel approach to improve the resilience of the interdomain communication by enabling a set of ASes to form an alliance for themselves. The alliance members cooperatively discover a set of disjoint paths using not only the best routes advertised via BGP but also the ones unadvertised. Since such a set of disjoint paths are unlikely to share a link or an AS failure, a member AS can provide a pair of the other members with a transit to circumvent the failure. We evaluate how many disjoint paths we could discover from both advertised and hidden (unadvertised) routes by analyzing publicly available BGP route data. Our feasibility study indicates that an alliance of ASes can establish a set of disjoint paths between arbitrary pair of its alliance members to improve the resilience of interdomain routing among the members.

As the Internet has become a communication infrastructure, inter-domain routing instabilities have become prone to serious problems. Some studies have proposed methods that infer instabilities and their locations by clustering BGP update messages collected at multiple observation points and are based on post-processing using public messages. However, to realize real-time processing, which is vital for network operations, single point observation is a feasible option with costs and today's competitive environments in mind. Therefore, we propose an inference method including a new clustering algorithm that is suitable for messages collected at a single observation point. We also describe the empirical results used to validate our method.

A practical method of locating congested segments on the Internet by periodic end-to-end packet delay measurements along multiple paths is presented. This method is a network tomographic approach based on a clustering technique that effectively tackles the correlation among delay variations. Since the Internet is still highly prone to performance deterioration due to transient delays, locating the segments responsible is vital to ensure that Internet service providers can mitigate or prevent such performance deterioration. Our concern is how to detect and locate such segments promptly in a large network. The proposed method was implemented and evaluated through a real-world experiment by actively measuring packet delays from multiple origins to multiple destinations over the Japanese commercial Internet, and was shown to have considerable potential to precisely locate congested segments.

It is important to monitor routing protocols for stable operation of IP networks. In this paper, we focus on Open Shortest Path First (OSPF), a widely deployed intra-domain routing protocol. Routers running OSPF advertise their link states on Link State Advertisements (LSAs) to the network so the location of OSPF failures on the IP network can be detected by monitoring LSAs. However, in order to identify OSPF failures correctly, it is necessary to consider the association of multiple flooded LSAs when OSPF failures occurred and LSA delay. In this paper, we propose a method of OSPF failure identification based on LSA flooding analysis taking these aspects into account.

This paper addresses the challenge of providing scalable end-to-end differentiated service for group communications. While bandwidth broker (BB) has been proposed for guaranteed services in unicasting, no work has been done to extend it for multicasting. We propose a single-layer BB architecture for intra-domain multicast, and a multi-layer BB for end-to-end services across multiple network domains. Databases in the BB, the join and leave procedures, and their associated control messages are carefully designed. Complexities of the two proposed architectures are formally analyzed. It is shown that, comparing with the single-layer BB architecture, the multi-layer architecture results in much lower join costs and control-message complexity, and is thus highly scalable. Performance is evaluated via simulation of a multi-domain network with heterogeneous receivers. The proposed multi-layer BB architecture successfully provides end-to-end service differentiation in terms of throughput, end-to-end delay, and packet losses. We believe that this work is significant towards offering end-to-end differentiated-service group communications in large-scaled networks.

As a result of widespread of peer-to-peer (P2P) file sharing applications, it is a serious problem that inter-domain traffic between Internet service provider (ISP) networks increases. We present a novel inter-domain traffic flow model focusing on the presence of a passive peer, and proposes a new P2P traffic control method based on the model. This method uses a filter considering P2P flow characteristics and can be applied to the P2P networks whose protocol is closed. We also evaluate both validity and effectiveness of our proposals by performing more than 20 days experiments using real P2P network environment. The results prove that our model is reasonable enough and the proposed method is promising for decreasing inter-domain P2P traffic.

In a large-scale, high-speed mobile IP network, data packets may be dropped on a foreign agent, which manages location information of many mobile nodes, due to an increase in the load of the visitor list search process. In this paper, we propose a fast data transfer method in mobile IP networks by saving the load of the search processes on the foreign agent using cooperation between mobility agents. In our experiment, the foreign agent using our method can forward all the received packets when one hundred thousand entries are recorded in the visitor list. The mobile IP forwarding routine using our method can process all the packets at any packet rate and any packet size on a fast ethernet LAN.

This paper describes a novel mechanism for achieving sufficient TCP performance over some asymmetrical environment without any modification in customer premises. In today's Internet, several types of access media have an asymmetrical bandwidth characteristic, where the downstream link bandwidth is larger than the upstream. However, such asymmetrical environment may cause TCP performance degradation due to upstream link congestion. In order to solve this problem, we propose a PEP (performance enhancement proxy) based approach to improve TCP downloading throughput by reducing upstream traffic using our compulsory IP fragmentation technique. The results of our performance evaluation show that our experimental proxy implementation is capable of accelerating TCP throughput above three times faster comparing to the case without the proxy.

Recently, various mobile networks have been provided for mobile Internet services, and Mobile IP has become a key protocol for location/mobility management for mobile nodes. Although Mobile IP is originally intended to support the mobility of global IP addresses, there are considerable needs for supporting private addresses for mobile nodes due to the rapid growth of mobile terminals and the lack of global addresses. In addition, for global communications, it is also required to realize mobility among several mobile networks operated by different administrative domains. In this paper, we propose an approach to support global roaming among different mobile networks where Mobile IP is used for mobility management of mobile nodes with private addresses in a closed domain. In order to realize global roaming among different mobile IP networks, we have introduced global roaming agent (GRA) for each mobile network. This paper presents detailed roaming procedures using GRA. Implementation and performance evaluation results of our proposed method are also given.

As a result of the spread of Gigabit Ethernet technologies, we need to realize Internet monitoring systems with gigabit-rate capability using commodity hardware. However, it is quite difficult for existing systems just to collect all the packet headers at a gigabit rate even if high-end hardware components are used. In order to support gigabit rate traffic, we propose a novel framework on packet header collection which can be applied to most network interface cards. Our evaluation results show that our first implementation can collect 100% of header information, even in the case that a Gigabit Ethernet link is fully utilized by 384-byte packets, while existing software-based systems can collect less than 50% in spite of using more than twice the CPU resources.

High-speed links such as OC-48c and OC-192c links need to be used as backbone links of the Internet in order to accommodate rapidly increasing Internet traffic. Network experiments over a test bed are important to check new services and new applications perform well over high-speed Internet backbones. In order to obtain the correct experiment results, it is important to use suitable background traffic at the network experiments. The existing traffic testers use MMPP (Markov modulated Poisson process) and MAP (Markov arrival process) as traffic models to generate background traffic. However, MMPP and MAP are so simplistic that the network experiments may produce misleading results. In order to solve the problem, we have developed an OC-48c traffic tester for generating and analyzing long-range dependence traffic because the traffic model is considered one of the most realistic traffic models. The traffic tester achieves the OC-48 rate traffic generation using hardware logic, and enables the long-range dependence traffic generation using time series data of packet numbers or byte numbers.

The growing popularity of IEEE 802.11 has made wireless LAN a potential candidate technology for providing high speed wireless access services. Also, by supporting Mobile IP, wireless LAN can meet demands for expanded wireless access coverage while maintaining continuous connectivity from one wireless LAN to another. In the Mobile IP procedure, mobile node movement can be detected from advertisements of foreign agents that differ from the previously received advertisement and the new "care-of" address is registered with the home agent. However, user packets are not forwarded to the new foreign agent until registration is completed and this interruption may degrade the quality of service especially in real-time applications such as audio and video or may lower the TCP throughput due to retransmission timeout. To tackle these issues, we propose a new low latency handoff method, where access points used in a wireless LAN environment and a dedicated MAC bridge are jointly used to alleviate packet loss without altering the Mobile IP specifications. In this paper, we present the design architecture of the proposed method and evaluate its performance in an actual network environment to verify the effectiveness of our approach.

Satellite-based Internet is one of attractive access media because it can be deployed even in inconvenient locations. However, it is a problem that TCP throughput is degraded by the large propagation delay in the satellite link. We previously proposed to introduce an intermediate gateway only in the carrier side premises to accelerate TCP throughput and confirmed its effectiveness in case of no network congestion. In order to accommodate many subscribers, it is also required to avoid network congestion caused by the extremely asymmetry of the access link. We describe the new TCP gateway taking account of multiple subscribers accommodated by a shared satellite access link. We also confirmed that the new gateway can accelerate TCP throughput more than 8 times avoiding network congestion.

Satellite communication is able to provide wide bandwidth, and satellite-based Internet access is expected to be a high speed Internet access method of the next generation. However, the propagation delay of a satellite link degrades the TCP throughput. The reason for this problem is that TCP performs window based flow control and most communicating hosts use the default window size such as 8 kbytes through 24 kbytes. To deal with this problem, we propose a TCP gateway for satellite-based Internet access. The communication throughput of TCP is improved without any modifications to equipment and terminals of subscribers by introducing this system only at a satellite Earth station. In this paper, we describe the protocol architecture of the TCP gateway and its performance by comparing with conventional methods. The results of a performance evaluation show that the proposed TCP gateway can provide more than 20 times higher throughput than communication without it over a link with 6 Mbps bandwidth and 350 msec round trip time.

Most of current video retrieval systems use video transfer protocols such that servers simply transmit video packets at the same rate as clients play them. If any packets are corrupted during transmission, they will be lost and cannot be recovered by retransmission. In video retrieval systems however the video data are stored in servers and clients can prefetch them prior to playing. So, it might be possible for the video retrieval systems to make corrupted video packets retransmitted before the play-out deadline. However, the application of existing reliable protocols causes problems such that, if a packet does not arrives before the deadline due to retransmission, the packets following it will not be delivered to the upper layer even if they have already arrived. We propose a new video transfer protocol for video retrieval systems over an ATM network which provides video data prefetch, flow control for the video buffer, selective retransmission with a skipping function for video packets that are late for the play-out deadline, and a resynchronization function for the video buffer. We have implemented an experimental system using our protocol and evaluated the performance. The results of the performance evaluation shows that the proposed protocol decreases the number of unplayed video data to less than 1/70 compared with the conventional non-retransmission protocol when random bit errors with a BER of 10/sup -6/ are inserted in an ATM network.