Shigeo Urushidani

Rerouting network: a high-performance self-routing switch for B-ISDN

A high-performance self-routing switch is proposed for ATM (asynchronous transfer mode) switch systems. Switching performance is enhanced by a rerouting algorithm applied to a particular multistage interconnection algorithm. The interconnection algorithm offers many access points to the output and resolves output contention by layering buffers at each switching stage. The author analyzes switching performance and shows that this switch can be easily engineered to have high throughput and low cell loss probability by increasing the number of switching stages. The author also illustrates that the number of switching stages required for a given cell loss probability shows gradual growth with increasing switch size. Analysis shows that the proposed switch is robust even with respect to nonuniform traffic. >

PopCache: Cache more or less based on content popularity for information-centric networking

Due to a mismatch between downloading and caching content, the network may not gain significant benefit from the sophisticated in-network caching of information-centric networking (ICN) architectures by using a basic caching mechanism. This paper aims to seek an effective caching decision policy to improve the content dissemination in ICN. We propose PopCache-a caching decision policy with respect to the content popularity-that allows an individual ICN router to cache content more or less in accordance with the popularity characteristic of the content. We propose an analytical model to evaluate the performance of different caching decision policies in terms of the server-hit rate and expected round-trip time. The analysis confirmed by simulation results shows that PopCache yields the lowest expected round-trip time compared with three benchmark caching decision policies, i.e., the always, fixed probability and path-capacity-based probability, and PopCache provides the server-hit rate comparable to the lowest ones.

Design of versatile academic infrastructure for multilayer network services

This paper describes the network design and configurations of the new Japanese academic infrastructure, called SINET3, which provides a rich variety of network services to more than 700 universities and research institutions. Since the start of full-scale operations in June 2007, the network has expanded its services to include multi-layer transfer services (IP, Ethernet, and layer-1), enriched virtual private network services (L3VPN, L2VPN, VPLS, and L1VPN), enhanced QoS services (packet-based and circuit-based), and brand-new layer-1 bandwidth-on-demand (BoD) services. This paper explains how the network provides these various network services on a single network platform by effectively configuring leading-edge networking components, such as high-performance IP routers, layer- 1 switches, and a BoD server. Evaluations of the network design and configurations confirmed that the networking functions were effectively coordinated. The procedures and techniques related to the configuration validation that covered all phases of the network design and construction are also presented.

A new self-routing switch driven with input-to-output address difference

A self-routing switch for fast packet switching is proposed. The routing method uses the difference between the input and output addresses as a routing header value. Every information block with a routing header is easily routed to its destination line with no congestion in the switch. It is suitable for VLSI technology: a throughput of 1.6 Gb/s for a 16*16 switch is possible in a chip using CMOS technology. The switch consists of multistage circulated shift registers and output buffers. Multipoint connection can also be provided without additional complex hardware. The routing algorithm, mechanism, and applications of the switch are presented.<<ETX>>

Impact of Tohoku earthquake on R&E network in Japan

The Internet is one of the important infrastructures in our daily life, and its highly distributed and autonomous natures have been said to be robust against failures. This paper reports an impact of an unexpectedly large earthquake (M9.0) hit to the northern part of Japan at 14:46:18 on 11th March (UTC+9), 2011(the East Japan Earthquake) [2] on a nation-wide research and education network (SINET4 [10, 12, 13]) in Japan. We show that the network managed to run even after the earthquake thanks to two different levels of redundancies, though some physical links were damaged; consequently, the impact on the routing (both BGP and OSPF) was insignificant. At the epicenter area, some network nodes (i.e., universities) were disconnected from the network by the blackout upto 70 hours. In the view of long-term traffic trend, it took 5--6 weeks for recovery of the traffic volume there. On the other hand, in the backbone network, the rapid decrease (40--50%) in the traffic volume only lasted for a few hours due to the blackout near the epicenter, and the impact of the traffic decrease in the epicenter area on the backbone traffic is estimated to 15--25%. Furthermore, we confirmed the increases of the traffic generated by users who rushed to access to the network for obtaining up-to-date information and videostreams.

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

Scalable multicast MPLS protocol for next generation broadband service convergence network

With explosive dissemination of broadband IP access services, like xDSL and FTTH, many service providers seek a chance for deploying new IP based broadband services networks for their customers. Among multiple candidates, content distribution (CD), interactive multi-media (IMM) and virtual private network (VPN) services are the most attractive broadband services for service provider and their customers. The quality of service (QoS) control and traffic engineering (TE) mechanism with strict reliability are essential functions to differentiate these services from conventional best effort IP access service and to make this broadband services network as a new communication infrastructure. Because MPLS already has all of these mechanisms in its protocol architecture, it is assumed that developing broadband IP service network by MPLS technology is the most promising way. But many of these services, such as video broadcasting, video conference and VPN multicast service require not only point-to-point (P2P) transmission capability but also point-to-multipoint (P2MP) transmission capability with much stricter QoS control, more sophisticated TE and more stable reliability control requirement. Therefore, P2MP capability extension is required to conventional MPLS. This paper proposes a scalable multicast MPLS protocol that can establish P2P and P2MP LSP simultaneously. The P2MP extension is realized on RSVP-TE (RFC3209). By introducing tree explicit route object (TERO) and enhancing conventional Path/Resv signaling procedures to enable tree based LSP setup, the proposed protocol can set any kind of P2MP LSPs; cost minimum (Steiner) P2MP LSP, delay-constrained P2MP LSP according to application demands. The proposed protocol also supports dynamic partial tree modification mechanism; Grafting and Pruning to handle dynamic multicast traffic. Therefore, P2MP LSP is modified easily. Several scalability and performance evaluations are conducted in this paper to prove its feasibility. This paper also proposes a multicast constrained shortest path fast (CSPF) mechanism to support dynamic QoS constrained P2MP LSPs setup. We confirmed that proposed schemes are scalable and has enough performance to be applied to future large scale IP service convergence network.

Layer-1 Bandwidth on Demand Services in SINET3

This paper describes brand-new layer-1 bandwidth on demand (BoD) services implemented in the new Japanese academic backbone network, called SINET3. SINET3 is an advanced converged network that provides multi-layer transfer, enriched VPN, enhanced QoS, and layer-1 BoD services. The layer-1 BoD services are dynamic layer-1 resource allocation services directly triggered by users and artfully achieved on the multi-service platform by using a layer-1 BoD server. This paper first explains how the network accommodates a wide variety of network services by effectively combining leading-edge technologies. The paper next describes the overall mechanism for the dynamic layer-1 path setup on the multi-service platform and details the functions of the BoD server in many aspects. The designs focus on the tangible achievement of these services over a nationwide network composed of 75 layer-1 switches and 12 IP/MPLS routers.

Implementation and Evaluation of Layer-1 Bandwidth-on-Demand Capabilities in SINET3

This paper describes the implementation and evaluation of layer-1 bandwidth-on-demand (BoD) capabilities in the Japanese academic backbone network, called SINET3. The network has a nationwide GMPLS-based layer-1 platform and provides reservation-based and signaling-based BoD services. The overall architecture for providing BoD services including its capabilities, user interface, path calculation, and interface to drive the layer-1 platform are described. Actual examples of BoD services and evaluations of the path setup/release time in the network are also presented.

Resource Allocation and Provision for Bandwidth/Networks on Demand in SINET3

This paper describes flexible resource allocation and provision methods for bandwidth on demand and networks on demand in the new Japanese academic backbone network, called SINET3. SINET3 has provided a wide variety of network services such as IPv4/IPv6 dual stack, L3VPN, L2VPN/VPLS, and L1VPN services for the research and education community and started layer-1 bandwidth-on-demand services in February 2008. In SINET3 each service network is implemented as a logical service network on a single network platform by effectively combining latest technologies including logical router capabilities of IP/MPLS routers and flexible resource allocation capabilities of layer-1 switches. SINET3 can also easily create logically separated experimental network environments for new research projects. Evaluation results on some capabilities in experimental environments and demonstration results on bandwidth-on-demand capabilities in the real network are also shown in this paper.