Masahiro Hayashitani

Torus-Topology Data Center Network Based on Optical Packet/Agile Circuit Switching with Intelligent Flow Management

We review our work on an intra-data center (DC) network based on co-deployment of optical packet switching (OPS) and optical circuit switching (OCS), conducted within the framework of a five-year-long national R&D program in Japan (~March 2016). For the starter, preceding works relevant to optical switching technologies in intra-DC networks are briefly reviewed. Next, we present the architecture of our torus-topology OPS and agile OCS intra-DC network, together with a new flow management concept, where instantaneous optical path on-demand, so-called Express Path is established. Then, our hybrid optoelectronic packet router (HOPR), which handles 100 Gbps (25 Gbps × 4-wavelength) optical packets and its enabling device and sub-system technologies are presented. The HOPR aims at a high energy-efficiency of 0.09 [W/Gbps] and low-latency of 100 ns regime. Next, we provide the contention resolution strategies in the OPS and agile OCS network and present the performance analysis with the simulation results. It is followed by the discussions on the power consumption of intra-DC networks. We compare the power consumption and the throughput of a conventional fat-tree topology with the N-dimensional torus topology. Finally, for further power saving, we propose a new scheme, which shuts off HOPR buffers according to the server operation status.

Advanced Wavelength Reservation Method Based on Deadline-Aware Scheduling for Lambda Grid Networks

A deadline-aware-scheduling scheme for the lambda grid system is proposed to support a huge computer grid system based on an advanced photonic network technology. The assignment of wavelengths to jobs in order to efficiently carry various services is critical in lambda grid networks. Such services have different requirements such as the job-completion deadlines, and wavelength assignment must consider the job deadlines. The conventional job scheduling approach assigns a lot of time slots to a call within a short period in order to finish the job as quickly as possible. This raises the blocking probability of short deadline calls. Our proposal assigns wavelengths in the lambda grid networks to meet quality-of-services guarantees. The proposed scheme assigns time slots to a call over time according to its deadline, which allows it to increase the system performance in handling short deadline calls, for example, lowering their blocking probability. Computer simulations show that the proposed scheme can reduce the blocking probability by a factor of 100 compared with the conventional scheme under the low load condition in which the ratio of long deadline calls is high. The proposed scheduling scheme can realize more efficient lambda grid networks.

Optical packet and path switching intra-data center network: Enabling technologies and network performance with intelligent flow control

We review recent development of energy-efficient, low-latency intra-data center network, emphasizing on intelligent flow control capability, which simultaneously supports both OPS and OCS on-demand on a 100-Gbps (25-Gbps × 4-wavelength) platform consisting of hybrid optoelectronic packet routers.

Source-based wavelength-path protection scheme with tree-shaped backup-path configuration in WDM networks

This paper proposes a source-based high-speed wavelength-path protection scheme configuring a tree-shaped backup path in WDM networks. In the proposed scheme, a failure-detecting node on a primary path starts protection by sending a failure notification to a source node of the primary path through the tree-shaped backup path. Intermediate nodes on the backup path and the source node which receive the failure notification switch to the backup path autonomously. Therefore, the proposed scheme provides high-speed protection. The simulation results revealed that the proposed scheme reduces the failure-recovery time compared with the conventional protection schemes.

Flexible and automated operational control in SDN transport-base virtual router

We propose and demonstrate a virtual router based on SDN transport which has automatic topology discovery function. We show that the virtual router contributes to flexible and automated operational control.

OPS/OCS Intra-Data Center Network with Intelligent Flow Control

We review recent development of energy-efficient, low-latency intra-data center network which simultaneously supports OPS and OCS with inteligent flow control on a single platform of 100-Gbps hybrid optoelectronic packet routers.

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.