Atsushi Hiramatsu

A torus datacenter network based on OPS/OCS/VOCS enabled by smart flow management

We present an energy-efficient, low-latency, torus-topology intra-data center network with the deployment of 100-Gb/s hybrid optoelectronic routers, where OPS, OCS and virtual OCS are all supported on a single hardware platform enabled by smart flow management.

Torus data center network with smart flow control enabled by hybrid optoelectronic routers [Invited]

A torus-topology photonic data center network with smart flow control is presented, where optical packet switching (OPS), optical circuit switching (OCS), and virtual OCS (VOCS) schemes are all enabled on a unified hardware platform via the combination of hybrid optoelectronic routers (HOPR) and a centralized network controller. An upgraded HOPR is being developed with the goal of handling 100 Gbps optical packets with a high energy efficiency of 90 mW/Gbps and low latency of less than 100 ns. The architecture of HOPR and its enabling technologies are reviewed, including a label processor, optical switch, and optoelectronic shared buffer. We also explain the concept and operation mechanisms of both the data and control planes in the hybrid OPS/OCS/VOCS torus network. The performance of these three transmission modes is evaluated by numerical simulations for a network composed of 4096 HOPRs.

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.

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.

Bypassing routes strategy for optical circuits in OPS-based data center networks

In OPS-based data center networks, setting up temporal OCS paths for high-reliability-required large data transmissions is preferred. However, inappropriate OCS path selection could severely affect the original OPS traffic, which is because OCS path may break the network topology and cause OPS packet circulations. We propose to hold bypassing routes for every link of the OCS path when it is established. Then, the OPS packets could bypass the OCS links by being deflected to the bypassing routes. Therefore, this method facilitates the coexistence of OCS in OPS-based data center networks. Simulations demonstrate the benefit achieved by our proposal compared to no-bypassing-route scenarios.

Green, smart optical packet switching network with flow control for data centers

Hybrid optoelectronic packet routers with 100Gbps (25Gbps × 4 wavelengths) links are introduced in an intra-DC network. A novel “Express path” enables the flow control to reduce the latency and the power consumption.

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.

Hypermedia Photonic Information Networks

The broadband communication network based on ATM has been considered as a key issue for the near-future multimedia world, and the technologies and deployment strategies to achieve this goal have been discussed for many years [1, 2]. This paper proposes a novel “hypermedia world”, extending the concept of the multimedia network. The hypermedia network integrates, on a universal network interface, various information services, such as telecommunication, newspapers, magazines and TV broadcasts, plus the growing collection of information servers. In this network, users can send and receive many kinds of useful information, at anytime, from and to anywhere. Users will be able to watch high-quality videos without concern about the cost since the communication charge will be almost independent of distance and time. Moreover, users will have the capability to not only receive but to transmit information to a specific person or to an anonymous group of people. The explosive growth of World Wide Web (WWW) services on the Internet is a clear sign that people are demanding what hypermedia is going to provide.