This paper presents a target view of network research toward Beyond 5G. We conduct R&D on the field of "Innovative Networks" which enable networks to respond to the rapid growth in communication traffic, dynamic changes in communication quality, and various network services to realize the digital transformation of advanced social systems in Society5.0, which is cyber-physical integrated society in the Beyond 5G era. Our research target is fundamental and system technologies for optical and wireless communications and for networking. Those enable to fulfill essential functions of the broadband, resilient, ultra-reliable, and ultra-low latency communications desired in the Beyond 5G era.

Bridge inspection using drones has become considerably more attractive owing to the ability of drones to gather information safely in lesser time and at a lower cost than traditional inspection methods. However, one of the critical issues in drone-based bridge inspection is ensuring stable communication between the operation base and inspection drones. The inspection drone easily loses sight of the operation base because bridges have intricate structures. Therefore, this study developed a radio map-based flight planning method of autonomous repeater drones for bridge inspection in order to ensure stable communication. Based on the inspection scenario, the repeater drone needs to ensure the communication with a minimum movement even under position deviations caused by winds. First, we generated a three-dimensional radio map of the bridge. Then, under the assumption that the inspection drone adopted a predetermined path, we developed a path planning method for a repeater drone based on the radio map. Some path planning examples demonstrated that the generated path reduces the moving distance and is also robust against the position error, in addition to ensuring stable communication.

This paper proposes a concept of large-scale emulation and evaluation environment of wireless communication systems. The environment can build radio nodes called virtual node by software in cyberspace and provide interaction among the virtual nodes and the reconfigurable physical radio devices that are connected to the environment from the outside. The environment therefore enables preliminary investigations and evaluations for the highly advanced and complicated wireless systems in the future. Moreover, in the radio interactive emulation, the radio propagation parameters based on the preliminary obtained models are suitably referred. The proposed wireless emulation environment enables wireless emulations required in the six typical wireless systems that are further developed and promoted in B5G/6G society. The paper shows evaluation and consideration of the fundamental performances for the proposed wireless emulation environment that includes numerical investigation for the interconnection performances between the virtual nodes and the reconfigurable physical radio devices, as well as fundamental operation for the wireless emulation with suitable visualization functions.

Many technologies are implemented on the assumption that they will use a wireless environment. When evaluating these technologies, it is necessary to consider wireless links in various situations because the status of the wireless environment is affected by many physical phenomena and obstacles. Thus, it is not easy to evaluate these technologies. We have been studying and developing technology that enables us to evaluate software and hardware implementations for wireless technologies without transmitting radio waves by reproducing wireless sections on a wired network testbed. In this paper, we explain a detailed implementation of testbed middleware to easily introduce newly proposed technologies to the testbed. The architecture also enables us to introduce functions for wireless emulation to our testbed. Taking a small radio experiment as an example, we introduce a detailed implementation that enables wireless emulation in cooperation with the entire testbed.

In recent years, the importance of pre-verifying the status of wireless communications has increased for designing offices. Because wireless communication is used for various purposes in offices, this technology has become a basic infrastructure for business. Therefore, when building a new office or renovating an office, verifying the impact on radio waves while designing the workspace is paramount. However, no highly accurate simulation tools for radio waves are available that can be easily used by office planners, who do not possess expert knowledge of radio waves. To address this challenge, we propose smart office planning system that can be linked to a radio wave emulation system that can verify radio wave propagation and communication behavior with high accuracy and can be easily used by office planners. This paper presents the results of a usability evaluation of a smart office planning system. As a result, users could easily set simulation scenario by preparing a general-purpose template option and could evaluate the state of wireless communication by using 2 visualization strategies: a three-dimensional visualization that simultaneously presents the three-dimensional structure of the office space, radio propagation, and communication behavior, and a two-dimensional visualization that visualizes problems affecting the quality of work. Moreover, in the future, by integrating the smart office planning system with the radio wave emulation system, office planners will presumably be able to verify the effects of workspace design on radio waves in advance, thereby reducing the man-hours required for office construction and ensuring adequate communication quality in the workspace.

In this paper, we propose a spatio-temporal data aggregation protocol in Vehicular Delay Tolerant Network (VDTN). We focus on Asynchronous Vehicular Crowdsensing Service (AVCS) to collect volume sensor data (e.g., images captured by on-board cameras) from VDTN-enabled vehicles. In AVCS, it is critical to cope with the huge redundant traffic generated by a large number of vehicles. We propose a novel protocol to aggregate volume spatio-temporal sensor data in Hybrid DTN data collection architecture. By assigning spatio-temporal identifiers (STI) to the aggregation targets in AVCS and extending the message exchange protocol to treat STI in VDTN, the redundant traffic can be significantly improved. Simulation results using a real taxi trace dataset showed the effectiveness of the proposed data aggregation protocol. The coverage of the crowdsensing was improved around 20-35% with 80% traffic reduction compared with the baseline aggregation protocol.

In this paper, we propose a new centralized Vehicle Delay/Disruption Tolerant Network (VDTN) architecture for vehicle volume data collections in the rural areas called "Hybrid DTN". Hybrid DTN applies Software Defined Network (SDN) into VDTN. A centralized controller controls data deliveries by the wide-area cellular network as a control-plane network and collects large volume sensor data from the vehicles to the cloud using VDTN as a data-plane network. We defined an oracle model called Delivery Status Oracle (DSO) for Hybrid DTN, in which the controller manages the delivery status of the distinct messages. By using DSO, Hybrid DTN can achieve the high data delivery success rate even for large volume sensor data collection in the rural cellular network. Simulation results using a real taxi trace dataset showed the practicalness of the Hybrid DTN with DSO; a combination with Epidemic routing algorithm hugely improved delivery completion rate with smaller delivery latency and smaller traffic.

We present the LASK protocol and its platform implementation that supports distributed k-Nearest Service Discovery. LASK achieves scalable and locality-aware name-based service discovery and routing for the target nodes avoiding redundant lookup message exchanges across the edge networks.

Edge computing enables application services to leverage low-latency responses. This paper describes the design of infrastructure-as-a-service for edge computing (EC-IaaS) to realize multiple application services on the same edge servers. In the provision of application services, it is important for application service providers (ASPs) to satisfy proximity constraints regarding the edge servers hosting virtual machines (VMs). State-of-the-art methods to provide VMs satisfying these proximity constraints require ASPs to have a large amount of information from an EC-IaaS provider, which incurs large computational and communication overheads. Otherwise, the edge servers will incur the large power draw. In this paper, we propose a virtual region model. The virtual region model abstracts the details of an edge computing infrastructure. We extend the VM request and placement processes based on the virtual region model, to support dynamics of end-user devices. We confirm that the amount of information, which ASPs receive from an EC-IaaS provider, is the same level of the least amount required by the state-of-the-art methods. Additionally, the power draw of edge servers is the same as the minimum in the state-of-the-art methods, and this level is even sustained when the number of end-user devices changes in a city.

Software defined networking (SDN) and network function virtualization (NFV) technologies enable us to create, manage and operate network services more flexibly. Distributed placement of controllers reduces the response time of control operations and distributes load of controllers. Many prior studies have investigated several algorithms of controller placement in networks. However, those algorithms take longer computation time and require a lot of information. Thus, they are difficult to use, especially in large networks. To simplify the controller placement problem, we propose a salience-based approach, where the salience value of a link is defined as the number of shortest path trees that traverse the link. We found that by placing controller functions on the nodes having many high-salient links, the controller placement approach shortens the length of control paths and keeps controllers' load low even in large networks.

Recent progress of computer networks realizes advanced network services such as high-resolution video streaming and Internet of things (IoT) but it requires further huge amount of traffic. To expand transmission capacity, various studies develop time division multiplexing (TDM), wavelength division multiplexing (WDM), and spatial division multiplexing (SDM) technologies. Time-division packet spatial super-channel (pSSC) is expected as one of promising solutions to realize high throughput with low cost. We have developed a switching node system for the pSSC transmissions. The pSSC is suitable for large data transmission. On the other hand, overhead of pSSC is not negligible in the case of small size data transmissions. This paper proposes a fractional pSSC switching system design for both large and small data transmissions. We introduce the spatial super-channel slicing concept and ILP solution for effective data transmission having bimodal distribution of data size. Effect on slice spatial channel was validated through simulation where it is 50% better than no slicing system.

This paper presents an overlay network protocol called “LASK: Locality-Aware Service discovery protocol for K-nearest search”, for supporting scalable and locality-aware distributed k-Nearest Service Discovery (kNSD). The kNSD provides a lookup function to find k service nodes located close to the requester. Importance of such function increases under the situation of growth in size and the diversity of the resources in the so-called edge computing environments. In LASK, efficient cooperative routing algorithm is implemented utilizing the two-dimensional structure of key-order preserving structured overlay networks that are constructed according to the network topology and the name of the service. This structure achieves scalable and locality-aware routing of the lookup messages to the matched nodes avoiding redundant data transmissions across the edge networks. Extensive simulation evaluations show that LASK could achieve small discovery latency in the large-scale edge computing environments; a typical kNSD took less than 5 ms in a data center network model and less than 100 ms in the Internet model even when there are 100,000 nodes in the entire network.

The Autonomic Resource Control Architecture (ARCA) we have designed in previous work is intended to provide elastic resource adaptation in virtual computer and network systems by automating management tasks in edge/branch virtual networks. Our objective is to reduce the time required to continuously estimate or anticipate the amount of resources that a system requires by considering its workload together with event data notified by external detectors. However, analyzing such amount of data can take a long time and thus delay management decisions and system adaptation. Moreover, too frequent changes in the amount of allocated resources can hassle the underlying controllers. In this paper we propose a method to resolve these problems by filtering input data items to reduce their rate while smoothing non-persistent spikes to reduce the volatility of resource allocations. We evaluate it by running an algorithmic model with a set of input data following a Pareto distribution, analyzing the accuracy of different variations of the proposed method. We found that the accuracy of the resulting allocations is improved by 13% to 30%, depending on the specific configuration of the proposed method.

Service function (SF) chaining enables network operators and infrastructure providers to flexibly orchestrate virtualized network functions (NFs) at various places on software defined virtual networks. Meanwhile, with the rapid prevalence of Internet-of-Things (IoT) applications and mobile network services, quality-of-service (QoS) requirements are getting increasingly diverse and network traffic volume and pattern are varying rapidly. The time-varying network traffic requires the infrastructure provider to dynamically adjust the appropriate amount of computational resources (e.g. CPU) assigned to an NF to efficiently process the traffic in the SF chaining infrastructure. In this paper, to adequately allocate CPU resources (available in limited amount) to virtual networks (VNs) requiring to satisfy diverse QoS levels in response to traffic variation without manual operations, we propose autonomic arbitration of CPU resources along SF chains which combines two CPU resource adjustment methods: The first method performs resource arbitration among VNs within a node, and the second method migrates NFs among nodes within a VN. These methods autonomically adjust the amount of CPU resource allocated to each NF so that over utilization of CPU can be avoided as much as possible. Moreover, during the autonomic resource adjustments in SF chains, the proposed methods are able to maintain communication paths on the substrate network so that the service is not interrupted at all. We also propose differentiated resource allocation for QoS differentiation and transferable resource searching. Through computer simulation, we verify that our autonomic resource adjustment methods can reduce the occurrence of CPU-saturation by more than 90%.

Vehicles are considered to constitute a large portion of new devices getting connected to 5G or beyond networks. Connected vehicles should be enabled to communicate with each other and roadside infrastructure securely, reliably, and in ultra-low latency. Vehicles should be able to discover and identify other vehicles in their surrounding very quickly. For this purpose, we propose a directory service that can store a huge number of vehicle's records and provide the records to querying vehicles in a very short latency (mostly less than 10 milliseconds). Similarly, it can dynamically update the records within a few seconds, while fully complying with record owner-centric privacy policy. The preliminary experiment results obtained from a simple testbed implementation with computers demonstrate the feasibility of the proposed system to meet the target lookup and update performance of connected vehicles.

Current network service requirements are increasing the pressure on the level of flexibility and reliability that must be provided by the virtual computer and network systems that host them while enforcing close-to-optimum resource allocations to minimize both monetary and operational costs. A key requirement is the fast detection and adaptation to workload changes, which is beyond human abilities, so the operation must be automated. To do so we propose to use an autonomic resource control architecture. In this paper, we formalize the architecture and discuss how it is able to detect the CPU load changes of a networked service by analyzing heterogeneous observations, including both resource load measurements and external events, and adapt (increase or decrease) the allocated resources consequently. The key benefit of our proposal is that, in most situations, including external information into the analysis, such as seismometer measurements, allows the control architecture to detect new situations earlier than analyzing only load measurements. We demonstrate such claims with the results obtained from the execution of a proof-of-concept implementation of the architecture we propose on an emergency scenario.

In this paper, we propose a mechanism for autoconfiguration of name-bound virtual networks (NBVNs) for Internet of Things (IoT). Some IoT standardization groups have defined APIs for IoT device communications, in which they indicate the correspondent nodes and resources by names. However, current technologies for the construction of Virtual Networks (VNs) rely on VLANs, IP routing, and OpenFlow control, thus they do not provide a name-based solution. Our proposal fills this gap. We first define business players that construct and use the NBVNs. They are Application Service Provider (ASP), Virtual Network Operator (VNO), and Infrastructure Provider (InP). We then specify the roles of ASP/VNO/InP, including the tasks that must be performed by their managers, and the required interactions for the purpose of autoconfiguration. Subsequently, we describe the system we developed to implement the operations of ASP/VNO/InP and thus construct NBVNs automatically. For each NBVN, the required IPv6 addresses are automatically allocated and assigned to the network nodes, including the IoT devices. Moreover, data forwarding and name resolution mechanisms are also configured automatically. Thus, the proposed system constructs area-and/or time-bound VNs for offering network services to event-centric IoT applications, such as outdoor concerts and sporting events. Finally, we demonstrate that the constructed NBVNs are capable to configure thousands of addresses and name entries within a minute, thus IoT devices can communicate among them by using their correspondent node names instead of their addresses. Moreover, both ASP and VNO can operate the servers, switches, and routers pertaining to the NBVNs by also using their names.

In this paper, we propose a novel dynamic data flow platform for Internet of Things (IoT) applications in edge computing environments. To avoid the overloads on network and computational resources that are caused by IoT applications, the proposed platform replicates processes and changes the structure of the data flow dynamically on the distributed computational resources located at network edges and data centers. The proposed platform adds the notion of "index" to the existing distributed topic-based pub/sub (TBPS) messaging method to support flexible data flow definitions and process allocations. In addition, we propose a peer-to-peer-based data stream routing algorithm called "Locality-Aware Stream Routing (LASR)" which can change the data stream destination dynamically on extended TBPS in accordance with structural changes of a data flow, considering network communication localities. By simulation, we confirm that our proposed platform using LASR can change the data stream destination quicker than existing methods with a small overhead in an edge computing environment, even when running applications involving video analysis data flow with a high data rate.

To enable billions of devices to communicate with each other simultaneously, small end-to-end latency and high scalability and reliability are the essential characteristics for the Internet of Things (IoT). The transition from today's Internet to IoT has demanded a new information and communications infrastructure. In this paper we implement and deploy a scalable and reliable inter-domain infrastructure, LORIF proposed in our previous work, to meet the requirements of IoT. Based on two local network testbeds and an intercontinental network testbed, we evaluate the scalability, resilience, and mobility of LORIF. The results demonstrate that LORIF can provide low end-to-end latency and high scalability and reliability.

We propose a method of constructing a layer 3 (L3) network that consists of a large number of virtual machines (VMs) for a large-scale IoT emulation testbeds by utilizing Hierarchical/Automatic Number Allocation Protocol (HANA). The L3 network consists of several subnets, and suppresses the number of MAC addresses that must be distinguished from each other. HANA releases a burden of an L2 switch, compared to a flat L2 network. In addition, a network failure is restricted to a subnet. HANA also simplifies configuration of VMs in each physical machine (PM) by making MAC addresses and names of the VMs common among the PMs. The method of constructing the L3 network by HANA provides researchers with a large-scale IoT emulation testbed, which is easy to construct and extensible, and supports multihoming and renumbering. Researchers can define VMs as IoT devices and cloud/edge/fog computing servers, and perform various experiments on the testbed.

In this paper, we investigate the effect of which different pricing algorithms have on a flexible optical choice-based network. Our pricing algorithms attempts to perform proactive collaborative optimization by offering some network service choice, as more attractive than others, and thus encourage users to buy services that are in surplus instead of those which use resources that are viewed more precious due to their scarcity. We evaluate these pricing algorithm's performance on the system by analyzing the impact on the network utilization, customer utilization, and the generated revenue.

Edge computing enables application services to leverage low-latency responses, e.g., for augmented reality. Infrastructure-as-a-service for edge computing (EC-IaaS) allows multiple application service providers (ASPs) to use a virtualized resource (i.e., virtual machines (VMs) and virtual networks) for various applications services on the common edge computing infrastructure. For ASPs, the proximity of the VMs to the end-user devices (i.e., the location of the host edge servers) is a significant factor in guaranteeing low-latency response times. The existing method allows ASPs to select the edge server locations so that the VMs satisfy the proximity requirement. However, the amount of information transmitted from the EC-IaaS provider to the ASP becomes large, because it has to include the latencies between all edge server locations and all wireless base stations. We propose a method that reduces the amount of information while ensuring that ASPs obtain VMs that satisfy the proximity requirement. An EC-IaaS provider suggests groups of wireless base stations that have VMs within a suitable proximity, which helps the ASPs to estimate the necessary number of VMs. Instead of the ASP, the EC-IaaS provider determines which edge servers should contain the VMs. We confirm that the proposed method reduces the transmitted information. The EC-IaaS provider also has a benefit that detail latency information is kept closed to ASPs and the power draw is sustained compared to the existing method.

Network virtualization techniques enable network operators to implement and provide multiple virtual networks (VNs) on a common substrate network infrastructure. The network resources should be able to be dynamically reallocated among VNs or migrated from a place to another one in various situations, such as to construct a new urgent VN in case of occurrence of some urgent contingency, or to satisfy quality of service (QoS) requirements of non-urgent VNs in case of time-varying network traffic conditions as much as possible. In this paper, we propose methods to automatically and dynamically select and migrate resources of non-urgent VNs. In particular, our proposal applies reinforcement learning for the selection of resources from alternate places to satisfy the QoS requirements. We evaluate the performances in terms of the satisfaction level of QoS requirement with various frequency of network traffic variation in a given duration and learning parameter configurations. Simulation results show that the proposed dynamic resource migration method can increase the number of times that non-urgent VNs' QoS requirements are satisfied in comparison with a static resource assignment method. Moreover, we show that, depending on traffic variation and parameter configuration, applying reinforcement learning can increase the number of times the QoS requirement is satisfied compared to the dynamic method with completely random resource selection.

A low-latency and reliable message switching network is critical for constructing high-speed datacenter networks. In this paper, we present the design, implementation, and evaluation of a novel Location basEd Source Switching (LESS) for datacenter networks. LESS enables lightweight source switching through a location-based addressing scheme. Each switch and host can independently derive a source route to reach a destination without requiring the full knowledge of the network topology. We demonstrate that using location-based source routes as forwarding labels allows LESS to eliminate the need for routing tables and integrate with minimum required functionality for packet forwarding. Moreover, we propose a fast rerouting solution to address the issue of fault tolerance in source routing. Each switch can locally derive an alternative source route during a failure. The paper evaluates the performance of LESS. Our evaluation results suggest that LESS improves the performance of datacenter networks in terms of latency, throughput, and reliability.

This paper proposes route advertisement policies (RAP) for the Border Gateway Protocol (BGP) with provider aggregatable (PA) addressing. The proposed RAP takes the advantage of address aggregation opportunity. If multiple address spaces are allocated to each of autonomous systems (ASes) that are multihomed to multiple upper ASes, reduction of the Forwarding Information Base (FIB) and quick convergence are achieved. However, multihoming based on PA addressing poses two limitations. One, more specific address information is hidden due to address aggregation. Two, multiple allocated address spaces per AS cause an address selection problem. To cope with these two limitations, we propose RAP to ensure connectivity among ASes with fewer routes installed in the FIB of each top layer AS. We implement the proposed RAP in an emulation environment with BGP (using the Quagga software suite) and our developed Hierarchical Automatic Number Allocation (HANA) protocols. We use HANA as a tool to automatically allocate hierarchical PA addresses to ASes. We confirm that with our proposed policies the FIB and RIB (Routing Information Base) sizes in top layer ASes do not change with the increase of stub ASes, and number of exchanged BGP update messages are reduced up to 67.3% than that of the case with conventional BGP RAP.

As the Internet of Things technologies evolve, billions of smart devices will be connected to the Internet. Therefore, the accelerated growth of users, applications and devices pose a great demand on the scalability of the Internet. In this paper, we develop a new Internet architecture -- Multiple-inherited Locators (MiL) -- to meet the future demand on addressing. MiL is based on Locator/ID addressing and hierarchical address allocation. The benefit of this new addressing scheme is the improved scalability of Internet routing by enhancing the prefix aggregation of locators. The number of locators which are needed grows with the Internet scale. In order to represent each locator as a unique binary representation by as few bits as possible, we develop a distributed encoding method to efficiently encode locators. As the Internet topology evolves, the distributed encoding method renumbering locators' codeword for the optimal encoding performance, and meanwhile endeavors to keep their codewords unchanged as much as possible. Because, we want to represent locators by fewer bits as well as keep addressing stable. We adopt an Encoding Table Adjustment algorithm to find a "sweet spot" that balances these two goals. According to our experiment, within a 2% increase on the expected locator length, our algorithm reduces the cost of renumbering locator by 99.9%.

The Internet is facing the accelerating growth of routing table size. Backbone routers' routing table has already reached 512k entries, which has a negative effect on the scalability of the Internet. Hierarchical addressing and locator/ID separation solutions have been proposed to address the scalability issue. However, there has been little focus on how to efficiently represent hierarchical location addresses for a large scale distributed network, such as today's Internet. In this paper, we present a variable-length address encoding method to represent hierarchical location addresses. Our analysis and evaluation results show that 1) it is difficult to use fixed-length encoding to represent hierarchical location addresses for a large scale network; and 2) the proposed variable-length addresses could guarantee the scalability property of hierarchical addressing, and alleviate the inefficiency of address space due to fixed-length addresses.

Hierarchical address allocation and hierarchical routing design has long been suggested to reduce the forwarding information base (FIB) size in the Internet core. However, the hierarchical design is not put into practice. We implemented the hierarchical and automatic number allocation (HANA) protocol for allocation of IPv4 and IPv6 address spaces to autonomous systems (ASes) and the FIB size reduction. The HANA protocol allocates multiple address spaces to an AS from the upper ASes. Multihoming using multiple addresses provides an AS with multiple paths. That is, detour paths are inevitably prepared in advance, even when a network failure does not occur. In this paper, we provide the highest flexibility to HANA-based networking, namely, supporting variable-length addressing scheme. The variable-length addressing schemes suppress renumbering caused by the address space extension that occurs in the fixed-bit-length addressing schemes. In addition, we propose a new function of exchanging allocated numbers, and implement it in the current HANA system. The flexible HANA system provides locator allocation with low renumbering costs and realizes scalable addressing in future internetworking.

Domain Name System (DNS) is the most widely used name resolution system for computers and services in the Internet. The number of domain name registrations is reaching 276 million across all top level domains (TLDs) today and the DNS query count is increasing year over year. The main reason of the high DNS query count is the increase of out-of-bailiwick domain name delegation since it (NS without glue A record) makes the client send extra DNS queries for the glue A record. On the other hand, the master/slave model is not compatible with address renumbering in DNS since the master is indicated by its IP address in the slave. Thus it is necessary to redesign the current DNS protocol considering lower name resolution latency as well as the enhancement of automatic convergence after the address renumbering for the effective and sustained name resolution service. In this paper, we propose two mechanisms: one is the secure glue A cache and update to reduce the name resolution latency by cutting the DNS query count with low security risk, the other is the automatic zone transfer which automatically recovers the DNS based on FQDN (Fully Qualified Domain Name) after address renumbering. We successfully implemented the prototype in Linux as an extended form of BIND (Berkeley Internet Name Domain). The evaluation results confirmed approximately 25% down of the DNS query count and the successful automatic DNS recovery after address renumbering.

We have been developing an optical packet and circuit integrated network (OPCInet) to provide diverse services on the same metro/core fiber network. In this paper, we propose and develop a control method to realize automatic and programmable data transfers from OpenFlow networks (OFNs) to the OPCInet. An OpenFlow controller (OFC) determines how and where to transfer each flow on the OPCInet (i.e. resource selection) on the basis of the information of users' quality-of- service (QoS) requirements, performances in the OPCInet and network traffic in the OFNs. For this, we define QoS mapping between type-of-service (ToS) and ITU-T Y.1541 service classes so that the OPCInet can provide performances satisfying each user's QoS requirement. The proposed method enables effective utilization of wavelength resources with satisfying users' QoS requirements. We implement the automatic wavelength resource selection control in the OFC. We demonstrate that the OFC selects wavelength resources successfully in accordance with our policy of wavelength resource selection.

We newly developed a layer 3 switch prototype that has one 100 Gbps optical packet interface and twelve 10 GbE interfaces. This is a gateway node to the optical packet switched network. While similar nodes made by the authors just have conversion capability from/to Ethernet frames to/from optical packets, this switch provides full layer 3 switching capability among the 13 ports, namely, packets incoming from any input port can be sent to any output port via destination IP address lookup. We show 12,000 prefixes are looked-up and 4,000 destination addresses of optical packets are added as a result of the lookup. We also show that the layer 3 switch is connected to the access line to the Internet.

We design and develop architecture against hardware failures arisen on an optical packet and circuit integrated (OPCI) network. The control plane regularly collects hardware failures' information from the data plane, automatically notifies the failures to the management plane (M-plane), and recovers the status of path usage. For the M-plane, we develop and install a management system based on a hierarchical management model constructed as a relational database to visually manage various OPCI network elements and their correlative relationships over multiple layers. The M-plane contributes to faster discovery of resources affected by hardware failures than the existing OPCI network without any management systems. In verification experiments, we show that hardware failures and resources affected by the failures are successfully displayed on the management window. Besides, the empirically-estimated time to detect a hardware failure and specify affected resources indicates indispensability of the M-plane in that the network administrator can work on recovery operations much faster and earlier and enhance availability of the OPCI network.

The Internet is facing the double-challenge of accelerating growth of routing table size and ever higher reliability requirements. Considerable progress has been made toward the scalability and reliability of the Internet. However, most of the proposals are only partial solutions that address some of the challenges. In this paper, we present a new addressing encoding scheme and a corresponding forwarding mechanism for Internet routing to solve the aforementioned problems. Underlying our design is a succinct data structure that allows us to compactly embed a set of addresses into packet headers. At the same time, the structure allows the data plane to efficiently extract multiple address information for the same destination without decompression. We provide time and space complexity analysis, and present experimental results evaluating the performance of our encoding method. It shows that the proposed encoding method can achieve a good compression factor without degrading packet-forwarding performance.

Introduction of ID/locator split into the future Internet architecture can make distributed and dynamic mobility management functions simpler and native. Unlike conventional IP mobility solutions, the new approach can offer smooth mobility across heterogeneous network-layer protocols (e.g. IPv4, IPv6) and other benefits. This paper first gives an overview of new features that ID/locator split-based architecture can bring about besides overcoming the limitations of conventional IP mobility protocols and then discusses the architecture, implementation, and performance of HIMALIS as an example of ID/locator split-based architecture. The performance results validate that HIMALIS has end-to-end throughputs and latencies similar to those of the conventional TCP/IP network. Moreover, the results verify that HIMALIS is capable to provide seamless handover across heterogeneous network-layer protocols.

Optical packet switch systems with fiber-delay-line (FDL) buffers provide high-throughput, energy-efficient, and transparent forwarding. However, the FDL buffer experiences scalability issues, and thus, cannot accommodate a large amount of network traffic. In this paper, we first investigate network performance of the FDL buffer. Due to the discrete-time nature of the FDL buffer, throughput is not improved drastically in spite of adding extra FDLs. Then, we propose optical and electronic combined buffer architecture. The combined buffer is composed of the FDL buffer and a supplementary electronic buffer having power management functions according to its occupancy. The combined buffer uses only the FDL buffer and keeps its energy efficiency when traffic volume is low. In doing so, this architecture reduces power consumption to 70% of the buffer composed only of electronic devices under non-peak traffic. As the traffic volume increases, the combined buffer turns on its electronic devices and accommodates the increased traffic. Simulation results reveal that the proposed buffer architecture obtains 70% larger throughput than that of the existing FDL buffer.

An optical packet and circuit integrated network (OPCInet) will allow diverse services, enhanced functional flexibility, and efficient energy consumption, as optical packet switching (OPS) and optical circuit switching (OCS) links are provided on the same infrastructure. In this paper, we design and develop a control system consisting of header processing for optical packets, signaling and routing for optical path setup, and wavelength resource control and link switching between OPS and OCS for the efficient use of resources. Our onboard optical packet header processor is capable of 16-bit longest prefix matching by embedding a 0.6W (5% of TCAM technology on the same condition), 200 million search-per-second (equivalent to 100 Gbps) forwarding engine LSI, and a statistical memory LSI for retaining the statistical information of processed headers. Reactive control automatically selects a packet or circuit link according to the statistical traffic information from the header processor and works with signaling for optical paths. We present an experimental demonstration of a new control system using a previously developed OPCInet testbed.

Due to the continuously expanding scale of the Internet and increasing demand for highly available networks, there is strong desire for provider-aggregatable (PA) addressing and the accompanying multi-address-based multihoming scheme, which can efficiently reduce the size of the global routing table in core routers and boost the availability of networks. The growing demands on PA addressing (e.g., address space allocation, renumbering) will require that network service providers (NSPs) put more efforts into addressing-related management tasks in the future. To relieve NSPs from the complex tasks and heavy burden of manual operation, in this paper we introduce an inter-autonomous system (inter-AS) address space (re)allocation planning scheme (ASAP) in the context of hierarchical automatic address number allocation (HANA). By introducing multiple functionalities, (i) chained request, (ii) defragmentation with the minimum renumbering overhead, and (iii) parallel Probe/Reservation processes, into HANA, HANA/ASAP offers NSPs an easy-to-use and powerful tool supporting inter-AS automated address space (re)allocation adjustment in a distributed manner. Simulations have been conducted to observe the effect of HANA/ASAP in PA from the aspects of address efficiency, address conservation, and renumbering overhead.

We have proposed an optical packet and circuit integrated (OPCI) network which provides over Tbps capacity with low power consumption by optical technologies and deals with diversity of services from best-effort service to quality of service guaranteed service by packet and circuit switching schemes. Recently, we developed an integrated optical packet and circuit switch (OPS/OCS) node and constructed an OPCI ring network testbed. The integrated OPS/OCS node has a function to encapsulate Internet Protocol (IP) packets coming from client networks into optical packets. In this paper, we discuss about how to incorporate OPCI networks into current IP-based wide area networks. For the first time, we experimentally demonstrate an OPCI network testbed incorporated into a multihomed network where IP addresses are hierarchically allocated. The multihomed network provides multiple links with different characteristics such as a 100 Gbps optical packet link for high capacity and shared bandwidth services, a 10 Gbps optical path link for high quality and dedicated bandwidth services, and a 10Gbit Ethernet link for low cost services. Therefore, users can choose adequate link technologies according to application or traffic conditions. We successfully verify that high definition video data is efficiently transported by switching link technologies in the multihomed network.

We are designing authentication framework for a regional network with concerns on fast authentication and disaster robustness. To achieve this goal, we previously proposed a proactive and distributed authentication framework (PDAF). In this paper, to enhance the robustness of PDAF, we add temporary registration and authentication procedures in a disaster scenario and the distributed regional network key server (RNKS) mechanism. Meanwhile, we optimize PDAF messaging through reducing redundancy to improve the performance. The proposed PDAF is a fully distributed design, which is intrinsically more robust than the existing authentication framework. In particular, we implement the PDAF over an existing regional network and measure the performance of PDAF. This shows that network scale and offered traffic load do not influence the PDAF's authentication time, which is usually around 31 ms under our experiment environment, because neighboring networking devices directly authenticate end devices.

For the sake of better scalability and flexibility in the mobile and multihoming environments, future networks are expected to be based on the concept of ID/locator split. The ID/locator split architectures require storing, updating and retrieving of ID/locator mappings frequently, for which they need built-in security. To address this issue, this paper presents an integrated security scheme for securely storing, updating and retrieving hostnames to IDs and locators mapping records in two layers of name registries: domain name registries and host name registries. It then utilizes the mapping records retrieved from the registries for securing the network access, communication sessions, and mobility management functions. The scheme provides comprehensive protection of the ID/locator split architecture through an effective combination of asymmetric and symmetric cryptographic functions.

The ID/locator split-based approach has been widely recognized as a promising approach for the design of future networks. However, the existing ID/locator split architectures are still vulnerable to various attacks, such as impersonation attacks and man-in-the-middle attacks. They cannot be simply protected by the existing security mechanisms, which have the limitations especially on scalability. To solve these problems, we propose a proactive scheme for securing ID/locator split architecture, which embeds built-in security features to enable proactive protections of the architecture. Through this scheme, hosts register their information to the network securely, obtain trustworthy information of destination hosts, authenticate each other, and securely update their locators without requiring an involvement of a trusted third party (TTP). Compared to other existing security mechanisms, the proposed scheme does not require additional authentication mechanism and it can provide the thorough protections of the whole architecture.

We target energy efficiency of municipal access networks. A municipal access network typically provides coverage for city-wide area, and is characterized by diverse and dynamic traffic profiles. Most existing approaches to energy savings adapt network state to traffic variation. However, these approaches fail to capture the potential of energy savings by exploiting the traffic that has already existed in the network. We study network dimensioning for municipal mesh access networks to save energy by rearranging existing traffic and adjusting link rate. The problem of energy-efficient network dimensioning is formulated using mixed integer linear programming. We also propose an efficient heuristic algorithm that consists of both traffic engineering and link-rate adaptation. Numerical experimental results show that our scheme is more effective than link-rate adaptation in saving energy, and achieves a good balance between energy efficiency and resource efficiency.

Wireless/wired hybrid network offers a promising solution to future broadband access. Exploiting the potential of a hybrid network requires an integrated effort on network design and optimization. We discuss the inter-network traffic and intra-network traffic that commonly exist in an access network, and study to improve transmission efficiency for the two types of traffic. We propose a three-step holistic design and optimization: 1) optimizing the locations of gateway access points (GAP) to reduce wireless hops traffic needs to travel before reaching the wired part; 2) connecting GAPs by "shortcuts" to reduce wireless hops for intra-network traffic; and 3) routing with infrastructure awareness to optimize transmission. In particular, we propose a novel idea of "Virtual Channel" using only existing wired infrastructure to achieve inter-GAP connectivity. Simulation experiments show that a combination of these three steps jointly reduces transmission cost in hybrid networks, with a good scalability when network size grows.

Cognitive radio in network core devices such as basestations is being considered as a spectrum management solution for future society's communication demands. Aside from new resource allocation algorithms, efficient inter- and intra-protocol processing should be considered. We propose an opportunistic cross layer architecture called COmmon Layer Architecture (COLA) for information exchange between arbitrary layers for New Generation Networks (NWGN) with network-oriented cognitive radio. Through COLA, information from different protocols, as well as different layers, can be efficiently processed with minimized performance degradation. Emulation and simulation results showed improved aggregate throughput, handoff delay, connectivity and packet drop ratio.

We introduce our optical grid infrastructure where end-to-end, bandwidth-guaranteed lightpaths are established simultaneously. This is developed on a lightpath network that employs wavelength-routing. One application may send a request for multiple lightpaths to the network, which establishes the lightpaths one-by-one. Thus, several lightpaths may be rejected due to simultaneous reservation of an identical wavelength or undesired wavelength use. The proposed control-layered structure consisting of application, optical-grid control, and optical-network control layers bridges the gap between applications and optical networks. The optical-grid control layer translates an application request to form a set of lightpaths into multiple requests for the network. This layer is also capable of adjusting the available network interfaces of the hosts and the available wavelengths of the network such that all the lightpaths are likely to be established. We address our testbed network in the Tokyo metropolitan area and a collaborative work with e-VLBI (Very Long Baseline Interferometry), which requires long-distance, high-speed, and non-data loss communication circuits in the network.

In future, lightpaths will be dynamically provided to users by the use of GMPLS but lightpath networks may be overlaid to the users. When the users want to find idle wavelengths by probing for lightpath provisioning, they may not be able to obtain information about all the idle wavelengths along the route in the overlaid lightpath network. They are only allowed to include a limited number of wavelengths for probing. In order to avoid wavelength contention and reduce blocking probability, we present a method for performance estimation of overlaid lightpath networks from a user side. In this method, we try to find wavelengths that are likely to be idle. This is done by the wavelength- based rank accounting for each pair of a source and a destination. Rank is calculated each time a lightpath is provisioned at a pair regardless of the success or failure of the provisioning. We demonstrate that the method of estimation is effective through simulation experiments and also present an initial implementation of a lightpath-provisioning system that uses our performance estimation method based on the GMPLS RSVP-TE mechanism.

In order both to solve the unfairness of the burst loss probability in terms of the number of hops and to decrease the overall burst loss probability, we propose the hop-based burst cluster transmission. In this method, bursts with different numbers of hops are assembled simultaneously, and a hop-based burst cluster is generated so that the bursts in the cluster are arranged in order from the smallest number of hops to the largest one. Then the hop-based burst cluster is transmitted along with multiple control packets according to the burst transmission scheduling. Here, a burst with a small number of hops in the cluster is transmitted before the transmission of a burst with a large number of hops in the same cluster. We evaluate the performance of the burst-cluster transmission for a unidirectional ring network by simulation. Numerical examples show that the proposed method not only improves the fairness of the burst loss probability but also decreases the overall burst loss probability significantly.

We design a buffer management scheme for shared feedback buffer-type optical packet switches. The buffer is of the fiber-delay-line type and handles variable-length optical packets. The buffer limits the number of feedbacks of a packet to avoid degradation of the physical characteristic. We try to reduce packet loss probability in the packet switch by adopting new buffer management methods in which void spaces at output ports are reduced, packets are aligned in the buffer to avoid contention at output ports, and buffer utilization is increased. Through simulation, we find that the proposed methods provide better packet loss probability and delay performance than existing methods. We show that the improvement is obtained when we use buffer structures in which a variety of delay lengths are installed. The proposed methods are also better when wavelength conversions are allowed and when unbalanced traffic enters.

In multi-domain WDM networks, a lightpath establishment method based on rank accounting in order to establish end-to-end lightpaths without wavelength conversion has previously been proposed. In this method, the end-to-end lightpaths are established with small blocking probability based on ranking databases for wavelengths; however, the performance of the method deteriorates when the ranking databases are not frequently updated. Therefore, in this paper, we propose aggressive rank accounting (ARA). In this method, every time a lightpath establishment is processed, ranking databases for multiple nodes are updated simultaneously. In order to update the database for each node effectively, edge-node information is used, in addition to wavelength-state information. First, from the edge-node information, accuracies of the wavelength-state information for each node are computed. Then, the ranking database for each node is updated with the wavelength-state information and the computed accuracies. Numerical examples show that the ARA method provides smaller blocking probability than the conventional, conservative method when end-to-end lightpaths are not frequently established. In addition, the ARA method has a 60% lower blocking probability than the conservative method. Finally, we investigate parameter setting and show that the ARA method still provides smaller blocking probability even if routes of the end-to-end lightpaths change.

We study optical fiber-delay-line buffer management schemes for supporting service differentiation with less complexity, with the objective of achieving ultra-high-speed packet forwarding in a photonic packet switch. We propose the vPBSO (Variable-length-packet-capable Partial Buffer Sharing with Overwriting) method, which is a prioritized buffer management scheme for providing DiffServ Assured Forwarding. This method can handle asynchronously arriving variable-length packets. vPBSO is based on a single queue, and its complexity is Oscr(p), where p is the number of priority classes. We show that vPBSO is effective when the arrival rate of higher priority packets is lower than that of lower priority packets, which is a likely situation in a prioritized system. vPBSO provides better performance than vPBS (an extension of partial buffer sharing) for high-priority packets, and the performance for low-priority packets is also better or at least almost the same. vPBSO provides service differentiation in the case of two or more priority classes in which the difference of packet loss probability in each class is made larger than one order of magnitude by appropriate tuning of thresholds

We focus on contention resolution using an optical fiber delay line (FDL) buffer in a photonic packet switch. A scheduler for contention resolution may not have a high-speed electronic processor, which limits performance of a photonic packet switch. We thus propose a multi-stage buffer based on tree structure. The buffer has multiple schedulers to compensate for the slow processing speed of each scheduler. We show the performance of the multistage buffer with respect to packet loss probability through simulation experiments. As a result, we find that the performance of a multistage buffer is strongly affected by the small number of FDLs in the first stage. We also show the number of FDLs in a multi-stage buffer needed to get the same performance as a high-speed one-stage buffer.

Previous analytic approaches for all-optical networks have only allowed a random wavelength assignment policy in spite of the fact that network performance can be improved by other wavelength assignment policies such as first-fit wavelength assignment. We develop an approximate analytic method to allow flexible wavelength assignment policies by virtue of a layered-graph approach. Our analysis is also applicable to the networks that wavelength conversion is limitedly provided. By comparing with simulation results, we show that our analytic approach has good accuracies when the number of wavelengths is not large. We also show that our analysis is applicable to general network topologies.

Previous works have shown that wavelength conversion can considerably improve the performance in all-optical networks. However, it is an unrealistic assumption under the current technology and wavelength conversion with a limited range, not a full range, is more promising. In this paper, we propose a new analytic approach for such networks by virtue of the layered-graph where each wavelength is virtually assigned a separate link. Our analytic approach can allow a flexible routing method. For example, wavelength assignment and routing selection can be considered at the same time, which has never been treated in the past literature.

We study routing methods in all-optical switching networks. In all-optical switching networks, the connection with more hops encounters more call blocking, and it is especially true in optical networks with no wavelength conversions. We therefore consider an alternate routing method with limited trunk reservation in which connections with more hops are prepared more alternate routes. Through developing an approximate analytic approach, we show that our method keeps good performance when compared with the existing alternate routing methods, and also that the fairness among connections can be improved. Further performance improvement is investigated by introducing a wavelength assignment policy and a dynamic routing method. An effectiveness of the proposed method is investigated through simulation.