Takashi Kurimoto

OPTIMA: Tb/s ATM switching system architecture

A Tb/s throughput ATM switching architecture, OPTIMA, is proposed for a quasi-non-blocking large switch. The switch uses hardware self-rearrangement with a three stage network, that is traffic control is automatically performed by hardware. The switch thus acts as a non-blocking switch. In addition, optical wavelength routing is used to avoid interconnection limitations. An 8/spl times/8 interconnection is realized that uses 8 wavelengths to transfer 10 Gb/s signals. A 640 Gb/s OPTIMA prototype is described. The proposed OPTIMA architecture and 640 Gb/s system can be applied to realize future broadband ATM networks.

Enhancing the network scalability of link-state routing protocols by reducing their flooding overhead

We consider scalability issues of routing protocols for large-scale networks. Link-state routing protocols play an important role in generalized multiprotocol label switching (GMPLS) networks based on photonic technologies as well as in conventional packet-based IP networks. The scalability of a link-state routing protocol mainly depends on the overhead of protocol-related messages, which are disseminated by flooding. We propose ways to reduce this overhead in link-state routing protocols such as OSPF and IS-IS, and also present extensions to OSPF that provide support for our techniques. The basic approach is to limit the sets of neighboring nodes in the flooding of link-state information, while maintaining reliability in the distribution of link-state information. We also report on extensive simulation to evaluate the performance of our algorithm in terms of reducing the flooding overhead. Our algorithm provides improved network scalability as well as efficient and reliable convergence of routing information.

A disjoint path selection scheme based on enhanced shared risk link group management for multi-reliability service

We consider a mechanism for providing a multi-reliability service in multilayer GMPLS networks. By introducing GMPLS restoration techniques and shared risk link group management, we can provide a highly reliable protected connection service. However, there is a trade-off between reliability and efficiency of network resource usage. In addition, reliability requirements differ depending on the type of service (e.g., Internet access or leased line). Thus, we propose a mechanism for calculating an efficient route for a protected connection that can satisfy specific reliability conditions requested by customers. We also present simulation results that indicate our schemes are remarkably effective for achieving a better balance between end-to-end reliability and efficiency. We also demonstrate the quantitative relationship between availability of service and resource efficiency through simulation experiments

A multi-layer disjoint path selection algorithm for highly reliable carrier services

In this paper, we consider a mechanism for providing path protection in multi-region networks. Here a region includes an interior gateway protocol (IGP) area, an autonomous systems (AS) and a layer network. Many path protection schemes have been proposed, but most of them have been focused on a protection mechanism within a region network. We thus propose a mechanism for providing inter-region protection, which is used for highly reliable carrier services. We also point out inter-region protection schemes are remarkably effective in improving end-to-end reliability. The key to our proposal lies in a multilayer disjoint routing algorithm, called MLD, that enables us to find multi-layer protection paths. We investigated the performance of our scheme through extensive simulations, and the simulation results show that our approach is sure to find a set of failure-independent paths while achieving better utilization of network resources.

Active queue control scheme for achieving approximately fair bandwidth allocation

We propose a buffer management mechanism, called V-WFQ (virtual weighted fair queueing), for achieving approximately fair bandwidth allocation with a small amount of hardware in high-speed networks. The basic process for allocating bandwidth fairly uses selective packet dropping to compare the measured input rate of the flow with an estimated fair bandwidth share. Though V-WFQ is a hardware-efficient FIFO-based algorithm, it can achieve almost ideal fairness in bandwidth allocation. Simulation results show that V-WFQ achieves a good balance between fairness and link utilization under various simulation conditions.

MSN Type-X: next generation Internet backbone switch/router architecture

Next-generation Internet backbone node architectures are proposed that offer sophisticated QoS support including real-time voice, video streaming, and VPN. The backbone core node, named MSN ( multi-service network) Type-X, has 320 Gbit/s throughput and IPv4/v6 dual stack forwarding capability. Note that, through the employment of state-of-the art VLSI technology, both v4 and v6, OC-192C full wire-rate forwarding performance is achieved for the first time. In addition, sophisticated DiffServ with programmable thousands of virtual queues is also proposed to realize a complete set of hardware. In addition, Type-X uses an ATM emulation technique that can into allow the new packet-centric backbone to support conventional services. Finally, the paper describes high-reliability techniques such as newly structured service non-stop software and a firmware upgrade technique. These newly proposed techniques and systems will realize the next-generation, real-time, high-QoS capability, and VPN IP backbone network.

A fully meshed backbone network for data-intensive sciences and SDN services

This paper gives a brief report on a new 100-Gbps academic backbone network, called SINET5, which started full-scale operations in April 2016. SINET5 has more than 50 backbone routers and forms a fully meshed topology by using MPLS-TP systems to provide researchers in every Japanese prefecture with 100-Gbps access, minimized-latency, and SDN-friendly environments. SINET5 gives a multi-layer, dynamically configurable, and performance-tunable platform for a wide range of network applications including inter-cloud services. The multi-layer network design, new functions including SDN and cloud-oriented functions, and field test results on performance and reliability are reported.

Cloud provider selection models for cloud storage services to meet availability requirements

Cost-effective cloud storage services attract users with their convenience; there is a trade-off between the service availability and the usage cost. We develop two cloud provider selection models for cloud storage services to minimize the total cost of usage. The models select multiple cloud providers with considering unavailability to meet the user requirements. The first model, called a user-copy (UC) model, allows to select multiple cloud providers, where a user itself makes copies of its data for multiple providers. In addition to the user copy function of the UC model, the second model, which is called a user and cloud-provider copy (UCC) model, allows cloud providers to make copies of the data to deliver them to other cloud providers. The cloud service is available if at least one cloud provider is available. We formulate both models as integer linear programming (ILP) problems. Our performance evaluation observes that both models reduce the total cost of usage, compared to the single cloud provider selection. As the cost of bandwidth usage between a user and a cloud provider increases, the UCC model becomes more beneficial than the UC model. We implement the prototype for cloud storage services.

An offload method for traffic distribution based on service identification

Many functions for various network services (e.g. IP telephone, ISP connection and IP-VPN) are deployed on a broadband network, especially at the boundary between an access network and core network in the broadband network. The network service must be identified from each packet and the packet must be processed appropriately for that service. IP traffic in the broadband network is increasing sharply, so traffic distribution based on service identification may bottleneck when many different network services are provided in the network. Therefore, we propose an offload method for traffic distribution based on service identification to service processing parts, which process the packets for each network service appropriately. This method does not require additional functions in user terminals, and it more scalable than the method in which all traffic undergoes the service identification process. However, control of the proposed method is slightly more complex, so we established a control procedure and checked it in combination with user terminals. In addition, we evaluated by theoretical analysis the scalability of traffic distribution with offload compared to the method without offload. The results showed that the proposed offload method can increase the scalability of traffic distribution based on service identification.

Effective switching scheduling algorithm using concatenated data block to reduce guard-time for opt-electronic packet switch

A new scheduling algorithm that concatenates data blocks to increase switching throughput is proposed. The algorithm controls the degree of concatenation and reduces the number of switching instances to improve switch utilization. The switch architecture uses virtual output queue switching architecture where the core switch fabric is an optical matrix switch. The optical matrix switch requires the guard-time overhead needed for optical switch control. By reducing the number of switching instances, guard-time overhead can be reduced and switch utilization can be improved. Computer simulations show that efficiency is dramatically increased and that fairness in terms of data throughput among output ports is achieved.