Rie Hayashi

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.

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.

Latest Trends in Traffic Matrix Modeling and Its Application to Multilayer TE

We survey traffic matrix models, whose elements represent the traffic demand between source-destination pair nodes. Modeling the traffic matrix is useful for multilayer Traffic Engineering (TE) in IP optical networks. Multilayer TE techniques make the network so designed flexible and reliable. This is because it allows reconfiguration of the virtual network topology (VNT), which consists of a set of several lower-layer (optical) paths and is provided to the higher layer, in response to fluctuations (diurnal) in traffic demand. It is, therefore, important to synthetically generate traffic matrices as close to the real ones as possible to maximize the performance of multilayer TE. We compare several models and clarify their applicability to VNT design and control. We find that it is difficult in practice to make an accurate traffic matrix with conventional schemes because of the high cost for data measurement and the complicated calculations involved. To overcome these problems, we newly introduce a simplified traffic matrix model that is practical; it well mirrors real networks. Next, this paper presents our developed server, the IP Optical TE server. It performs multilayer TE in IP optical networks. We evaluate the effectiveness of multilayer TE using our developed IP Optical server and the simplified traffic matrix. We confirm that multilayer TE offers significant CAPEX savings. Similarly, we demonstrate basic traffic control in IP optical networks, and confirm the dynamic control of the network and the feasibility of the IP Optical TE server.

Impact of Traffic Correlation on the Effectiveness of Multilayer Traffic Engineering

Multi-layer network (MLNW) consisting of packet and optical layer networks has been widely studied as an important next generation network. In the MLNW, the virtual network topology (VNT) formed by a set of optical paths can be dynamically reconfigured by GMPLS protocols. By reconfiguring VNT, called multilayer traffic engineering, network performance factors can be optimized based on the traffic matrices. Thus, the effectiveness of multilayer traffic engineering is considered to be highly dependant on the correlation among traffic demand of different source-destination flows. We propose an analytical model of the dynamics exhibited by traffic matrices and then investigate how the correlation between different pairs of source-destination flows impacts the performance possible with multilayer traffic engineering. We confirm that the effectiveness of periodical multilayer traffic engineering increases with the correlation among source-destination flows

Novel impairment-aware traffic engineering in all-optical networks

We propose a novel traffic engineering (TE) technique that can readily handle impairments so as to satisfy quality-of-signal (QoS) requirements in alloptical networks. The existence of impairment limits the maximum transmission distance of optical signals given the need to satisfy QoS requirements. The problem is that impairment-aware route computation must consider many parameters and so is rather complicated. We, therefore, propose the new TEconstraint of “logical distance” which covers several impairment factors converted into distance. It reflects the degree of impairment created by external conditions, and a transmission distance constraint can be checked easily by summing up each elements distance. Logical distance makes it simple and effective to judge whether a computed route satisfies the desired QoS or not. We confirm the feasibility of our proposal by developing a TE system for a real optical network.

Novel traffic engineering for reservation services network

We propose a heuristic routing and reservation algorithm for networks providing reservation services. Important requirements of a reservation service network are to increase network resource utilization, to provide routes satisfying specified levels of quality of service (QoS), and to minimize service interruption under the situation that it is difficult to tell exactly when, how many, and what kinds of requests will arrive in the future. To satisfy these requirements, our proposal includes the following key ideas. First, it calculates rerouting targets only when a newly requested path competes with paths in service or reserved for future use, and reroutes competing path routes, or the rerouting targets, if necessary. Additionally, rerouting is executed so as to satisfy userspsila QoS demands. This ensures that the userspsila QoS demands are satisfied, network resource utilization is increased, and changes to path routes that are in service are minimized. Our algorithm can be adopted for advance reservation requests as well as immediate ones. Numerical results indicate rerouting only a few paths improves the request acceptance success rate by 50% o compared to the do-nothing approach.

Resolution of network topology using fast graph mining

We propose algorithms that uses fast graph mining for resolving the network topology to a locally regulated area defined as a component of network topology. Though the IP backbone network should be reconfigured periodically in accordance with environmental changes, reconfiguration results in heavy workload, such as routing re-designs or testing these re-designs for network operators. If a network can be reconfigured within the component, however, we can drastically reduce the operation workload for network reconfiguration. For finding the components from the network topology, we should solve the subgraph isomorphism problem, which is NP-hard. We propose the heuristic graph mining algorithm that reduces the size of search space by considering network operating conditions. We visualize the results of components analysis, and show that the computation finishes within the practical time.

Effectiveness of dynamic reconfiguration of path protection for Carrier's backbone network

Path protection is essential in a carriers backbone transport network that requires high reliability. Furthermore, it is preferable for a carrier to repair failed facilities as quickly as possible because path protection is not effective against multiple failures, which impair both primary and secondary paths at the same time. To reduce the operating expenditure involved in quick repair, a dynamic reconfiguration of path protection was proposed and its performance was evaluated in a scenario where failure occurs on a link-by-link basis. For this study, we evaluated the amount of bandwidth necessary for the dynamic reconfiguration of path protection in realistic failure scenarios, in which some paths accommodated in a link are impaired due to failure of a transponder module. Through simulation experiments, we confirm that the success ratio of dynamic reconfiguration of path protection amounts to 72% in case that half the capacity of a transponder is available as a backup on every link and 83% in case full capacity of a transponder is available as a backup on every link.

Construction of GMPLS virtual networks on Xen virtual machine

We constructed virtual GMPLS nodes on Xen virtual machines by using GMPLS software operated in a real network, and emulated GMPLS networks. We confirmed that OSPF-TE worked successfully in a GMPLS virtual network.