Akeo Masuda

Application-network collaborative bandwidth on-demand for uncompressed HDTV transmission in IP-optical networks

In this paper, we present an architecture design of application-network collaborative bandwidth on-demand (BoD) network service. For emerging ultra-high-bandwidth data transmission, such as HDTV streaming and Tera-byte class remote file transfer, network providers are expected to offer flexible use of the high performance of the optical network resources. This paper addresses the uncompressed HDTV transmission as the application, IP-optical networking as the network control, and the collaboration interface of those designed in order to enable three different types of network allocation: immediate BoD, reservation for future bandwidth, and planned bandwidth reservation for file transfer. Experimental deployment and the results are also shown.

High-performance network virtualisation for multilayer GMPLS networks

The recent trends in emerging network applications require more flexible network infrastructures. For this purpose, we consider the architecture and enabling technologies of high-performance network virtualisation using multilayer GMPLS networking technologies. The network virtualisation enables virtual network to utilise high-capacity bandwidth of optical network infrastructures without the provision of physical infrastructures. Furthermore, to improve robustness against network environmental changes such as failures and sudden traffic demand fluctuations, the network infrastructure provides virtual networks resource optimisation and on-demand resource distribution functions. One possible problem regarding virtualisation technologies lies in resource contention among multiple virtual networks sharing limited resources on the infrastructure. We thus propose a resource management model for efficient contention resolutions. We also present the design of a network virtualisation platform and the specification of interfaces to virtual network agents. We also developed prototype systems based on our system design and demonstrated the proposed high-performance lower-layer network virtualisation technologies in conjunction with commercially available routers and OXCs that support GMPLS protocols in our experimental network.

Scalable Support of Interdomain Routes in a Single AS

The Internet has grown extremely fast in the last two decades. The number of routes to be supported by the routers has become very large. Moreover, the number of messages exchanged to distribute the routes has increased even faster. To keep up with the increase, network operators regularly have to perform costly upgrades of the routers. It is unclear whether advances in hardware will be able to keep up with the increasing routing load. More importantly, the large number of routes and iBGP messages negatively impacts iBGP convergence time leading to long connectivity losses. In this paper, we propose a scalable way to support the Internet routes in a Service Provider network. We make use of distributed servers that select routes on behalf of the routers. Then, routes are stored in a Distributed Hash Table (DHT). We adapted the concept of DHT for that purpose. Each router maintains its share of Internet routes in addition to a cache of routes currently in use to forward the Internet traffic. We call our proposal SpliTable. We show that our proposal is more scalable in the number of routes supported in each router than current iBGP route distribution solutions. Moreover, the number of control messages exchanged with our proposal is bounded contrary to current sparse iBGP route distribution solutions which may never converge.

Contention Based Cooperative Multiple Access for Wireless Packet Networks

We propose a contention based multiple access scheme that enables packet level cooperation in wireless packet network, where the idle nodes help the source nodes by offering relay of the failed packet. Also a prioritization scheme is implemented to optimize to the contention whose complexity is added by participation of relay nodes. Throughput and delay performance improvement is confirmed by computer simulations considering wireless links that have different packet error rates according to the radio condition which suffer from propagation loss and Rayleigh fading. Analysis shows that the addition of active nodes for cooperation rather eases the number of waiting nodes in the contention, and that the reduction of retries needed for transmission reduces the average delay.

Experiments on Multi-layer Network Virtualization towards the Software Defined Transport Network

This paper proposes a novel architecture which enables software defined networking not only at the routing layer but also at the transport layer. Proposed architecture provides multiple SDTNs with wide range of controllability level, in spite that the SDTNs coexist upon a shared multilayered network infrastructure. We have conducted a nationwide experiment where we have provided SDTNs to practical users such as broadcasting studios. Through the experiments, we have successfully verified the resource management mechanism and network control functionalities.

Efficient Load-Balanced IP Routing Scheme Based on Shortest Paths in Hose Model

This paper proposes a simple shortest-path-based load-balanced Internet-Protocol (IP) routing scheme based on the hose model. The proposed scheme is an extension of the Smart-OSPF (S-OSPF) scheme. The proposed scheme, the same as S-OSPF, splits traffic demand only at source edge nodes and transmits the traffic along the shortest path routes. In S-OSPF, the split ratios are determined for each source-destination edge node pair by assuming that the traffic demand between all source-destination edge node pairs are known, in other words, the exact traffic matrix is completely given. This, however, is difficult to measure and predict accurately because of the measurement costs and rapid traffic fluctuations. On the other hand, in the proposed scheme, we assume the use of the hose model; in this model, only the total amount of traffic that a node injects into the network and the total amount of traffic it receives from the network are known. This simplicity makes it easy for network operators to apply the hose model for IP routing. This is because measuring just the total amount of traffic is less expensive than measuring the traffic demands between all source-destination edge node pairs. In addition, the aggregated traffic exhibits less fluctuation and is easier to predict than the traffic demand between each source-destination pair. Any extension of the Linear Programming (LP) formulation that optimizes S-OSPF to suit the hose model cannot be solved as a simple LP problem, because the traffic matrix is not known. By introducing a duality theorem, we successfully formulate our problem as an LP formulation that can be easily solved yielding the desired split ratios. Numerical results show that the proposed scheme dramatically reduces the network congestion ratio compared to the classical shortest path routing scheme and it provides performance close to that provided by the sophisticated traffic-engineering (TE) scheme of Multi-Protocol Label Switching (MPLS)-TE.

High-speed calculation method for large-scale multi-layer network design problem

Multi-layer network optimization has been studied for efficient use of network resources by solving Mixed Integer Linear Programming (MILP) problem. Here, the multi-layer network consists of lambda-layer network and IP-layer network. However, when applying this MILP problem for a large-scale network with a few hundred nodes, huge amount of variables are used and cannot be handled by middle size computers. In order to cope with this problem, some heuristic methods have been proposed and evaluated from viewpoints of accuracy and calculation time for their computation results. These heuristic methods reduce variables at lambda-layer and also decompose the original MILP problem into smaller sub-problems and induce an approximate solution by solving these smaller MILP problems. However, these heuristic methods cannot obtain accurate results in many cases. In this paper, we propose a novel variable reduction method at both lambda-layer and IP-layer by excluding long hop routes. We evaluate our proposed method and the conventional methods and show the availability of our method.

Low power consumption Intelligent Local Avoided Collision (iLAC) MAC protocol for WLAN

Mobile wireless communication systems aim at using battery energy efficiently. One of the main source of depleting precious battery of wireless handheld devices is failure frame transmissions due to collision. This paper provides a detailed analysis of the power consumption of newly introduced MAC protocol called Intelligent Local Avoided Collision (iLAC). Analytical solution confirms the correctness of this solution and simulations with different types of Wireless LAN 802.11b cards show that the proposed algorithm is able to significantly reduce the wasteful energy in colliding transmissions.

Scalable network emulator architecture to support IP+optical network management

This paper proposes a scalable network emulator architecture to support IP optical network management. The network emulator uses the same router interfaces to communicate with the IP optical TE server as the actual IP optical network, and behaves as an actual IP optical network between the interfaces. The network emulator mainly consists of databases and three modules: interface module, resource simulator module, and traffic generator module. To make the network emulator scalable in terms of network size, we employ TCP/IP socket communications between the modules. The proposed network emulator has the benefit that its implementation is not strongly dependent on hardware limitations. We develop a prototype of the network emulator based on the proposed architecture. A virtual machine (VM) technology is employed to reduce the hardware amounts required for this implementation. Our design and experiments show that the proposed architecture is effective. Thanks to the scalability and flexibility of the proposed architecture, it is expected that network-size can be easily scaled up.

Virtual network designs and evaluations for IP over WDM networks

In recent years, the virtual network (VN) for services by IP over WDM has been studied for the flexible and efficient use of network resources. The VNs are constructed by optical paths on the WDM network. Furthermore, by configuring VNs dynamically, resources which have been used for some VN at previous period can be allocated to another VN at the next period, which improves the utilization ratio of network resources. In this paper, we propose the SVN (Static Virtual Network configuration) method and the DVN (Dynamic Virtual network configuration) method for the VN configuration method. We formulate the MILP (Mixed Integer Linear Programming) for the SVN method and the DVN method and evaluate them from viewpoints of resource cost and availability by calculation experiments.