Masaru Katayama

Proposal of scale-out control architecture of virtual wide area layer-2 switch on metro network

Power consumption of network equipment has been rapidly increasing, so it is therefore necessary to build a resource efficient network (NW). Router virtualization, which involves dynamically reallocating virtual routers to physical resources as a server virtualization, is becoming more common as a way to use network equipment effectively and robustly. Especially, edge router which is gateway of core network should be virtualized, because edge routers have many functions and resources just as servers do. A metro NW is wide area layer-2 aggregation NW that connects each users residential gateway to edge routers. To achieve edge router virtualization, the metro NW must trace the dynamic edge router reallocation by changing a route of each Ethernet flow. Furthermore, access/metro NWs occupy a large proportion of the total NW power consumption, so logically centralized control architecture suits to the metro NW to change routes flexibly because it can use resources effectively by avoiding resource deployment in many locations. However, it is not scalable. When many Ethernet flows need to be accommodated in a metro NW, it can not change routes of the flows quickly enough. Therefore, we propose a virtual wide area layer-2 switch architecture with scale-out control that can improve the route control performance even in a worst case edge router node failure by processing in parallel flow-by-flow, by considering route information, and by rebalancing the load between parallel processes dynamically. We evaluated the proposed architecture through theoretical analysis and experiments with prototype. The results showed that the proposed architecture can increase the number of flows accommodated in a metro NW.

Flow burst conversion for large-scale optical layer-2 switch network based on scale-out flow control method

We report a flow burst conversion system for efficient flow aggregation corresponding to virtual machine migration in future metro networks. Experimental results show the routes of flows were changed at high speed via optical TDM paths while accommodating 100k flows.

Optical TDM fast reroute method for bufferless metro ring networks with arbitrary fiber length

We propose an optical TDM fast reroute method for bufferless metro ring NWs to achieve high reliability and cost-effectiveness. Experimental results show the time to reroute and accuracy of timeslots were under 2 ms and 30 ns by local restoration.

Proposed optical multicasting method using tunable lasers and cyclic AWGs

We present a wavelength-routing multicast (MC) packet switch based on simultaneous modulation of multi-wavelengths and symmetrical wavelength switching between two cyclic arrayed-waveguide grating (AWG) filters and tunable lasers (TLs). The proposed method requires fewer active devices compared to conventional methods. We clarify the power budget conditions needed to apply this method, and we evaluate the switch scale for the proposed method by using the specifications of commercially supplied optical devices. The feasibility of the proposed method is demonstrated through experiments on devices.

The method for improving TCP performance in bandwidth-guaranteed network

This paper discusses the efficiency of TCP transmission over a bandwidth-guaranteed network, where the bandwidth for each flow is guaranteed by traffic policing at edge nodes. In particular, it explores a method for improving TCP performance focusing on the size of the buffer to absorb jitter and promote a faster increase in the congestion window size. We propose a rate control method at an edge node based on controlling the advertised window for improving TCP performance in a bandwidth-guaranteed network. We also evaluate the effectiveness of the proposed method using a prototype.

Timeslot synchronization to share bandwidth for any route in bufferless bidirectional ring networks

We are developing a future metro network based on a 10 Gigabit Ethernet Passive Optical Network system to achieve both cost-effectiveness and high reliability. We propose a timeslot (TS) synchronization method to achieve a TS from a burst mode transceiver shared between any route of arbitrary fiber length by changing both the route of TS and the TS timing on each transceiver. We show the effectiveness of proposed method in exchange TSs in a bidirectional bufferless WDM/TDM ring networks during link failure through prototype systems.

Dynamic bandwidth protection in optical subwavelength switched ring network

We propose a cost-effective adaptive protection scheme appropriate for optical subwavelength switched bursty metro networks. Simulation results show that 1-digit improvement in required number of wavelengths and 70% reduction in active transceivers was achieved compared with traditional pre-planned protection scenarios.