Published papers

A domain-specific networking platform based on optically interconnected reconfigurable communication processors is proposed. Some application examples of the reconfigurable communication processor and networking experiment results are presented.

This paper proposes a new high-speed network architecture called Dynamic Transfer Mode, DTM. At the entrance of the DTM network, destination addresses such as IP addresses are converted into DTM routing information and attached to the packet header. In a DTM network, a connection is set up on-the-fly by sending a series of routing link identifiers to the destination, so burst data transfers like WWW traffic are efficiently carried. A connection between adjacent nodes is created and released dynamically within the burst transfer period. This yields higher statistical multiplexing gain and improved bandwidth efficiency compared to with conventional STM. Time division multiplexing is utilized so there is no delay jitter or cell loss, which are major drawbacks of Asynchronous Transfer Mode. This paper analyzes the performance of a DTM network and describes an implemented switching system. Because a DTM network uses source-routing and passive STM switching, it simplifies the core transit switch while localizing intelligence to edge nodes. A simplified core transit switch is well suited for future high-speed backbone networks.

Photonic Internet Lab. (PIL) is shooting for the leading edge photonic-GMPLS (Generalized Multi-protocol Label Switching) that utilizes wide-band, cost-effective photonic technology to implement IP-centric managed networks. PIL is a consortium for researching the GMPLS protocol and advancing a de facto standard in this area. Members make leading edge GMPLS code modules and test them at the lab site. The experimental results, new ideas, and protocols are contributed to standardization bodies such as IETF and OIF. This paper also describes the world's first trial of GMPLS multi-region (multi-layer), multi-route, multi-vender signaling.

A heuristic-based multilayer topology design scheme, the extended version of branch exchange with quality-of-service constraints (EBXCQ), was presented for IP photonic networks. By monitoring IP traffic loads, photonic MPLS routers were controlled to dynamically change the network configuration to efficiently utilize the network resources in a distributed manner. Numerical results to demonstrate the effectiveness of EBXCQ were presented.

Next generation carriers Internet backbone node architecture are proposed that offer sophisticated QoS support including real time voice, video streaming, and VPN. The backbone core node, MSN (multi-service network) Type-X, has 320 Gb/s throughput and IP V4/V6 dual stack forwarding capability and OC-192C full wire-rate forwarding performance. In addition, sophisticated DiffServ having 4096 virtual queue realizing full hardware is also proposed. In addition, Type-X has ATM emulation technique. Finally, the paper describes a high-reliability technique such as a newly structured non-stop software and firmware upgrade technique. This newly proposed technique and system offers the next generation, real time, high-QoS capability. © 2002 IEICE.

We propose a buffer management mechanism, called V-WFQ (Virtual Weighted Fair Queueing), for achieving an approximately fair allocation of bandwidth with a small amount of hardware in a high-speed network. The basic process for the allocation of bandwidth uses selective packet dropping that compares the measured input rate of the flow with an estimated fair share of bandwidth. Although V-WFQ is a hardware-efficient FIFO-based algorithm, it achieves almost ideal fairness in bandwidth allocation. V-WFQ can be implemented in the high-speed core routers of today's IP backbone networks to provide various high-quality services. We have investigated V-WFQ's performance in terms of fairness and link utilization through extensive simulation. The results of simulation show that V-WFQ achieves a good balance between fairness and link utilization under various simulation conditions.

The paper proposes a scaleable SRG-based restoration method in shared mesh wavelength-routed networks. We introduce a backup-SRG concept to identify which SRG is backed up by individual links. We have developed an admission control method for the backup path using the backup-SRG concept to achieve 100% recovery performance. The proposed method is extended to support networks with a large number of SRGs by introducing a hierarchical SRG assignment technique. Through computer simulation on the NSF network model, we confirmed that the proposed method achieves 100% recovery performance assuming a single link failure at the expense of 28.6% extra wavelength resource compared to the non-backup method. The proposed method requires less than 56.3% wavelength resource than that of the protection scheme while keeping 100% recovery performance. The hierarchical SRG assignment technique reduces the number of backup-SRGs to be used in admission control at each node at the expense of very little throughput degradation. © 2003 IEEE.

This paper presents two dynamic multi-layer routing policies for optical IP networks. Both policies first try to allocate a newly requested electrical path to an existing optical path that directly connects the source and destination nodes. If such a path is not available, the two policies employ different procedures. Policy 1, which has been published already, tries to find available existing optical paths with two or more hops that connect the source and destination nodes. Policy 2, which is proposed in this paper, tries to establish a new one-hop optical path between source and destination nodes. The performance of the two routing policies is evaluated. Simulation results suggest that policy 2 outperforms policy 1 if p is large, where p is the number of packet-switching-capable ports p; the reverse is true only if p is small. We observe that p is the key factor in choosing the most appropriate routing policy. © 2003 IEEE.

This paper proposes the hierarchical cloud-router network (HCRN) to solve the problem of overcoming the scal-ability limit in a multi-layer generalized multi-protocol label switching (GMPLS) network. We define a group of nodes as a virtual node, called cloud-router (CR). A CR consists of some number of nodes or lower-level CRs. A CR is modeled as a multiple switching capability (SC) node when it includes more than one kind of SC, which is fiber SC, lambda SC, time-division multiplexing (TDM) SC, packet SC, even if there are no actual multiple-SC nodes in the CR. The CR advertises its abstracted CR internal structure which is abstracted link state information inside the CR. A large-scale, multi-layer network can then achieve scalability by advertising the CR internal structure throughout the whole network. In this scheme, the ends of a link connecting between two CRs are defined as interfaces of the CRs. We adopt the CR internal cost scheme between CR's interfaces to abstract the network. This CR internal cost is advertised outside the CRs via the interfaces. Our performance evaluation has shown that HCRN can operate a larger number of nodes than a normal GMPLS network. It can also bear more frequent network topology changes than a normal GMPLS network.

This paper describes multilayer traffic engineering and signaling technologies in the photonic-GMPLS-router (Hikari-router) network. Multilayer traffic engineering, which yields the dynamic cooperation of IP and photonic layers, is described with the goal of providing IP services cost-effectively. The establishment of photonic cut-through paths is triggered when the Layer 3 traffic loads become excessive which better uses the optical layer (LI) resources. Data on traffic volumes are exchanged among edge photonic router using an extended IBGP. To realize multilayer traffic engineering, we propose an OSPF extension that advertises both the number of total wavelengths and the number of unreserved wavelengths, and an RSVP-TE extension that minimizes the number of wavelength conversions needed. In addition, this paper presents a heuristic-based multilayer topology design scheme in which IP traffic measurements are performed in generalized multiprotocol label switches (GMPLSs). Our design scheme yields the optical label switch path (OLSP) network topology, i.e. OLSP placement that minimizes network cost in the face of fluctuations in IP traffic demand. In other words, the OLSP network topology is dynamically reconfigured to match IP traffic demand. Networks are reconfigured by the proposed scheme so as to utilize the network resources cost-effectively.

When nodes that support generalized multi-protocol label switching (GMPLS) are introduced into existing networks, the GMPLS nodes co-exist with conventional Internet protocol (IP) and multi-protocol label switching (MPLS) (IP+MPLS) nodes that do not support GMPLS. In this case, the GMPLS nodes must Interwork with IP+MPLS nodes. This paper proposes an architecture for GMPLS and IP+MPLS inter-working based on extended routing and signaling. In the extended routing, information about some nodes and links in a GMPLS network emulates information that can be understood by IP+MPLS nodes. The emulated information is advertised to the IP+MPLS network. In the extended signaling, MPLS signaling packets are forwarded to the GMPLS data plane. An MPLS label switched path (LSP) is established through a GMPLS LSP tunnel. As a result, the IP+MPLS network can interwork with the GMPLS network without upgrading the IP+MPLS nodes. We developed GMPLS prototype nodes that support this interworking architecture and show interworking experimental results.

Although the Internet is playing an increasingly significant role in global communication, it remains vulnerable to malicious traffic such as worms and DoS/DDoS attacks. In the last few years, the emergence of high speed active worms, such as Code Red II, Nimda, SQL Slammer and MS Blaster, has become a serious issue. These worms cause serious damage to communication networks throughout the world by using up network bandwidth. In addition, since conventional firewall systems are located just in front of the server and do not prevent malicious traffic from entering the network, they cannot prevent such network congestion. We have developed a proto-type system of a network firewall using reconfigurable processors. In this paper, we overview the developed system and present its evaluation results. © 2005 IEEE.

We propose a scheduling algorithm for reducing unused timeslots by considering head gap and tail gap newly generated by assigning a data burst in order to improve the burst loss probability and the throughput performances in Time Sliced Optical Burst Switched (TSOBS) networks. The proposed scheduling algorithm selects the timeslot in which either head gap or tail gap newly generated becomes the minimum. We show that the proposed scheduling algorithm can improve the burst loss probability and the throughput performances as compared with the conventional one. © 2005 by International Federation for Information Processing.

We have proposed a new dtwork architecture “HOLST“ with dynamic and adaptive network configuration for reducing power consumption. This demonsata-center netration shows the method of detecting and assigning flows from traffic and application trigger.

We demonstrated the effectiveness of a portable emergency optical system in disaster recovery. The system replaces functional units of damaged optical network and recovers a controlplane network by taking the advantage of surviving wireless access.

WAN provider links are often operated at low utilization levels, which leaves large unused capacity (headroom). In this paper, we propose using Software Defined Networking (SDN) controllers to support novel Static Headroom (SH) and Dynamic Headroom (DH) services to allow customers to fill this headroom with Elephant Flows (EFs) without adversely affecting the provider's ability to meet its Best-Effort (BE) service-level agreements, and ability to absorb extra traffic load created during failure recovery periods. Our solution calls for the use of lower-priority service for EFs. We use simulations to compare SH service with BE service, and DH service with SH service. When EFs are sent on BE service, they could cause packet losses in general-purpose IP traffic, especially when the burstiness of the latter is high, while with SH service, this packet loss rate is reduced to 0. While DH service requires the added complexity of a provider SDN controller, the ability to dynamically route EFs on lower-utilized links results in higher average EF throughput. The higher the non-uniformity (from a node-pair perspective) in network traffic, the greater the DH gain factor.

Everything is being connected to the Cloud and Internet of Things, and network robots with big data analy- sis are creating important applications and services. The cloud network architecture is moving towards mega-cloud data centers (DCs) provided by companies such as Amazon and Google in combination with distributed small DCs or edge computers. While the traditional restrictions im- posed by distance and bandwidth are being overcome by the development of advanced optical interconnection, modern applications impose more complex performance and quality of service requirements in terms of processing power, response time, and data amount. The rise in cloud perfor- mance must be matched by improvements in network per- formance. Therefore, we propose an application-triggered cloud network architecture based on huge-bandwidth optical interconnections. This paper addresses edge/center cloud and edge/edge integration with the use of virtual ma- chine migration. In addition, to reduce energy consumption, an application-triggered intra-DC architecture is described. Using the proposed architectures and technologies can real- ize energy-efficient and high-performance cloud service.

The lightpath provisioning time or releasing time is adversely affected by the time that optical amplifiers require to adjust to a newly added or terminated signal power. This shortcoming is particularly true with multi-core erbium-doped amplifiers (EDFAs), as multi-core transient-suppressed EDFAs are unavailable at the current time. This paper proposes a fiber span power management scheme based on dummy wavelength signals that are used to shorten the lightpath provisioning and releasing times in multi-core fiber networks. With the shorter time of lightpath provisioning and releasing procedures, the total time that is required to reserve wavelengths in the system is decreased, which means that network resources are used more efficiently. As a result, the blocking performance and average waiting time in the system are improved. To evaluate the performance of the proposed scheme, this paper introduces both analytical model and simulation study. In the introduced model, the ratio of the number of activating and activated dummy wavelengths to the number of dummy wavelengths in each span is considered in the range between 0 and 1. The analysis reveals that the performance of the proposed scheme depends on \alpha , which is the ratio of the number of dummy wavelengths to the number of dummy and lightpath wavelengths in each span, and there exists a point of \alpha where the blocking probability becomes minimum. We further observe that the proposed scheme outperforms the conventional approaches in terms of blocking probability and average waiting time, as traffic loads increase. Finally, we provide the direction on how our introduced model can be considered for a network with multi-span routes.

Autonomous driving vehicle control network by edge computer having very short response time has been constructed. Each vehicle has an agent program on the edge and communicated with adjacent vehicle agent in the cyber network. The advantage of connected vehicle control from stand-alone vehicle is sophisticated and total/ global optimizing control. The network edge computer calculated 'social welfare' which is the best benefit for all vehicle in the society. This paper describes control architecture and method at edge computer. In addition, some experimental results for controlling autonomous vehicle are also described.