Hiroaki Harai

Software defined networking (SDN) over space division multiplexing (SDM) optical networks: features, benefits and experimental demonstration

We present results from the first demonstration of a fully integrated SDN-controlled bandwidth-flexible and programmable SDM optical network utilizing sliceable self-homodyne spatial superchannels to support dynamic bandwidth and QoT provisioning, infrastructure slicing and isolation. Results show that SDN is a suitable control plane solution for the high-capacity flexible SDM network. It is able to provision end-to-end bandwidth and QoT requests according to user requirements, considering the unique characteristics of the underlying SDM infrastructure.

High-speed buffer management for 40 Gb/s-based photonic packet switches

We develop a method of high-speed buffer management for output-buffered photonic packet switches. The use of optical fiber delay lines is a promising solution to constructing optical buffers. The buffer manager determines packet delays in the fiber delay line buffer before the packets arrive at the buffer. We propose a buffer management method based on a parallel and pipeline processing architecture consisting of (log/sub 2/N+1) pipeline stages, where N is the number of ports of the packet switch. This is an expansion of a simple sequential scheduling used to determine the delays of arriving packets. Since the time complexity of each processor in the pipeline stages is O(1), the throughput of this buffer management is N times larger than that of the sequential scheduling method. This method can be used for buffer management of asynchronously arriving variable-length packets. We show the feasibility of a buffer manager supporting 128 /spl times/ 40 Gb/s photonic packet switches, which provide at least eight times as much throughput as the latest electronic IP routers. The proposed method for asynchronous packets overestimates the buffer occupancy to enable parallel processing. We show through simulation experiments that the degradation in the performance of the method resulting from this overestimation is quite acceptable.

Development of optical packet and circuit integrated ring network testbed

We developed novel integrated optical packet and circuit switch-node equipment. Compared with our previous equipment, a polarization-independent 4 × 4 semiconductor optical amplifier switch subsystem, gain-controlled optical amplifiers, and one 100 Gbps optical packet transponder and seven 10 Gbps optical path transponders with 10 Gigabit Ethernet (10GbE) client-interfaces were newly installed in the present system. The switch and amplifiers can provide more stable operation without equipment adjustments for the frequent polarization-rotations and dynamic packet-rate changes of optical packets. We constructed an optical packet and circuit integrated ring network testbed consisting of two switch nodes for accelerating network development, and we demonstrated 66 km fiber transmission and switching operation of multiplexed 14-wavelength 10 Gbps optical paths and 100 Gbps optical packets encapsulating 10GbE frames. Error-free (frame error rate < 1×10(-4)) operation was achieved with optical packets of various packet lengths and packet rates, and stable operation of the network testbed was confirmed. In addition, 4K uncompressed video streaming over OPS links was successfully demonstrated.

Development of an Autonomous Distributed Control System for Optical Packet and Circuit Integrated Networks

In this paper, we describe an autonomous distributed control system that we have been developing for an optical packet and circuit integrated network, and we experimentally evaluate its performance. Colored (i.e., multi-wavelength) optical packet-switched links transfer both control signals for circuit switching (e.g., signaling and routing) and best-effort packet data. We successfully transmitted high-definition uncompressed real-time video signals on two lightpaths established by our control system without degradation of video quality, simultaneously with other optical packet data transferred on the same optical fibers. Our developed control system not only achieved autonomous distributed signaling and routing but also has a function that can adjust wavelength resources for optical packet and circuit switching autonomously in each link at each node. Controllers achieved lightpath establishment within approximately 360 ms and dynamic resource adjustment within approximately 454 ms, in the best possible case in our experimental setup.

40 Gbit/s interface, optical code based photonic packet switch prototype

A 40 Gbit/s interface, optical code based photonic packet switch prototype is developed for the first time. Photonic packet switching with 200 Gchip/s all-optical label processing, 40 Gbit/s/port packet switching, and optical buffering to avoid packet collision is experimentally demonstrated.

Multi-hop, 40 Gbit/s variable length photonic packet routing based on multi-wavelength label switching, waveband routing and label swapping

Three-hop, 40 Gbit/s, variable length all-optical packet routing with over 120 km transmission based on multi-wavelength label switching, waveband routing (label merge), and all-optical label swapping has been demonstrated experimentally for the first time. The details are expressed in the presentation.

Contention resolution using multi-stage fiber delay line buffer in a photonic packet switch

We focus on contention resolution using an optical fiber delay line (FDL) buffer in a photonic packet switch. A scheduler for contention resolution may not have a high-speed electronic processor, which limits performance of a photonic packet switch. We thus propose a multi-stage buffer based on tree structure. The buffer has multiple schedulers to compensate for the slow processing speed of each scheduler. We show the performance of the multistage buffer with respect to packet loss probability through simulation experiments. As a result, we find that the performance of a multistage buffer is strongly affected by the small number of FDLs in the first stage. We also show the number of FDLs in a multi-stage buffer needed to get the same performance as a high-speed one-stage buffer.

Optical fiber-delay-line buffer management in output-buffered photonic packet switch to support service differentiation

We study optical fiber-delay-line buffer management schemes for supporting service differentiation with less complexity, with the objective of achieving ultra-high-speed packet forwarding in a photonic packet switch. We propose the vPBSO (Variable-length-packet-capable Partial Buffer Sharing with Overwriting) method, which is a prioritized buffer management scheme for providing DiffServ Assured Forwarding. This method can handle asynchronously arriving variable-length packets. vPBSO is based on a single queue, and its complexity is Oscr(p), where p is the number of priority classes. We show that vPBSO is effective when the arrival rate of higher priority packets is lower than that of lower priority packets, which is a likely situation in a prioritized system. vPBSO provides better performance than vPBS (an extension of partial buffer sharing) for high-priority packets, and the performance for low-priority packets is also better or at least almost the same. vPBSO provides service differentiation in the case of two or more priority classes in which the difference of packet loss probability in each class is made larger than one order of magnitude by appropriate tuning of thresholds

Photonic packet routing based on multiwavelength label switch using multisection fiber Bragg gratings

We are developing photonic packet switching system called multi-wavelength label switching node (Ml-LSN). This is a desired system to build ultra high-speed packet switching. The Ml-LSN analyzes the label all-optically. The photonic packet switching can be achieved with a help of optical packet with a multi-wavelength label. Different from an optical cross-connect (OXC) in a wavelength routing network, the Ml-LSN inherently has fine granularity. The Ml-LSN consists of photonic forwarding (label lookup), photonic switching, electronic scheduling, and photonic buffering. We describe demonstrations of photonic packet routing using the forwarding and the photonic switching in the Ml-LS. We report recent developments in the photonic packet routing based on multi-wavelength label switch. All-optical functions, variable data rate switching, variable length packet switching, label swapping, and label merge (replacing multiple labels by a single label) are demonstrated. We describe multi-stage fiber delay line buffer architecture to compensate for gap between electronic scheduling speed and optical data rate.

A 31-FDL Buffer Based on Trees of 1x8 PLZT Optical Switches

We have demonstrated a 31-fiber-delay-line buffer based on 1x8 PLZT optical switches in a tree structure. Error-free optical buffering with BERs of less than 10-10 has been achieved at 10 Gbit/s.