Simulation Model of Photonic Switch for Optical Packet Switching Networks

In this paper authors propose the approach for investigation of photonic switches performance metrics in modern all-optical networks. The approach includes photonic switches analytical and simulation modeling. The analytical model of the $$4\times 4$$ -photonic switch is based on the M/M/1/4 queuing model using so-called probability translation matrix method that allows to investigate functioning of the system in transient mode. The analytical expressions of such performance metrics as a loss probability, a buffer size and a transient time are obtained. A comparison of analytical and simulation modeling results was carried out. The analysis show that the steady-state loss probability obtained in results of analytical modeling is greater than the analogous parameter obtained in results of simulation modelling by 8%. The study of simulation models of $$4\times 4$$ and $$16\times 16$$ -photonic switches show that the buffer size of these systems does not exceed one packet. Analysis of the $$16\times 16$$ -photonic switch buffer show that the buffer size of the first cascade is four times larger than the buffer of the second cascade. The results of the investigation show that the proposed type of photonic switches can be used in the high-performance all-optical network designed to transmit information from the ground module to tethered high-altitude unmanned module and vice versa.

As data centers enter the exascale computing era, the traffic exchanged between internal network nodes, increases exponentially. Optical networking is an attractive solution to deliver the high capacity, low latency, and scalable interconnection needed. Among other switching methods, packet switching is particularly interesting as it can be widely deployed in the network to handle rapidly-changing traffic of arbitrary size. Nanosecond-reconfigurable photonic integrated switch fabrics, built as multi-stage architectures such as the Clos network, are key enablers to scalable packet switching. However, the accompanying control plane needs to also operate on packet timescales. Designing a central scheduler, to control an optical packet switch in nanoseconds, presents a challenge especially as the switch size increases. To this end, we present a highly-parallel, modular scheduler design for Clos switches along with a proposed routing scheme to enable nanosecond scalable scheduling. We synthesize our scheduler as an application-specific integrated circuit (ASIC) and demonstrate scaling to a 256 × 256 size with an ultra-low scheduling delay of only 6.0 ns. In a cycle-accurate rack-scale network emulation, for this switch size, we show a minimum end-to-end latency of 30.8 ns and maintain nanosecond average latency up to 80% of input traffic load. We achieve zero packet loss and short-tailed packet latency distributions for all traffic loads and switch sizes. Our work is compared to state-of-the-art optical switches, in terms of scheduling delay, packet latency, and switch throughput.

Optical Switching Networks describes all the major switching paradigms developed for modern optical networks, discussing their operation, advantages, disadvantages and implementation. Following a review of the evolution of optical WDM networks, an overview of the future trends out. The latest developments in optical access, local, metropolitan, and wide area networks are covered, including detailed technical descriptions of generalized multiprotocol label switching, waveband switching, photonic slot routing, optical flow, burst and packet switching. The convergence of optical and wireless access networks is also discussed, as are the IEEE 802.17 Resilient Packet Ring and IEEE 802.3ah Ethernet passive optical network standards and their WDM upgraded derivatives. The feasibility, challenges and potential of next-generation optical networks are described in a survey of state-of-the-art optical networking testbeds. Animations showing how the key optical switching techniques work are available via the web, as are lecture slides (www.cambridge.org/9780521868006).

The present work analyzes the performance of photonic switching networks, optical packet switching (OPS) and optical burst switching (OBS), in mesh topology of different sizes and configurations. The “lossless” photonic switching node is based on a semiconductor optical amplifier, demonstrated and validated with experimental results on optical power gain, noise figure, and spectral range. The network performance was evaluated through computer simulations based on parameters such as average number of hops, optical packet loss fraction, and optical transport delay (Am). The combination of these elements leads to a consistent account of performance, in terms of network traffic and packet delivery for OPS and OBS metropolitan networks. Results show that a combination of highly connected mesh topologies having an ingress e-buffer present high efficiency and throughput, with very low packet loss and low latency, ensuring fast data delivery to the final receiver.

This book presents an in-depth deliberation on optical networks in four parts, capturing the past, present, and ensuing developments in the field. Part I has two chapters presenting an overview of optical networks and the enabling technologies. Part II has three chapters dealing with the single-wavelength optical networks: optical LANs/MANs, optical access networks using passive optical network architecture, SONET/SDH, optical transport network and resilient packet ring. Part III consists of four chapters on WDM-based optical networks, including WDM-based local/metropolitan networks (LANs/MANs) using single and multihop architectures over passive-star couplers, WDM/TWDM access networks as an extension of PONs with WDM transmission, WDM metro ring networks covering circuit-switched (using point-to-point WDM and wavelength-routed transmission) plus packet-switched architectures and WDM long-haul backbone networks presenting the offline and online design methodologies using wavelength-routed transmission. Part IV deals with some selected topics in six chapters. The first deals with transmission impairments and power-consumption issues in optical networks, while the next three chapters deal with the survivable optical networks, network control and management techniques, including GMPLS, ASON, and SDN/SDON, and datacenter networks using electrical, optical, and hybrid switching techniques. The final two chapters present elastic optical networks using flexible grid for better utilization of the optical-fiber spectrum and optical packet and burst-switched networks. The three appendices present the basics of the linear programming techniques, noise processes encountered in the optical communication systems, and the fundamentals of queuing theory and its applications in telecommunication networks. (238 words)

We describe a comparative analysis of the power consumption of optical cross-connect (OXC) equipment based on electrical and /or photonic matrix switching, which will be used for future large-capacity optical networks. The switch configurations used for both types of OXCs are also comprehensively discussed. For optical networks that accommodate traffic with a capacity of several Tb/s, the power consumption of the OXC equipment based on electrical switching could reach more than 50 kW; this can be reduced to 8 – 30 kW if photonic switching is used instead . In photonic switching-based OXC equipment, the power consumption of transponders becomes the most significant, and its reduction is the key issue for power-efficient large-capacity OXC equipment.

We present a model of the edge router between electronic and all optical networks. Arriving electronic packets of variable sizes are stored at a buffer the volume of which is equal to the fixed size of optical packet. When the buffer is filled, its content becomes an optical buffer and dispatched to optical network. To avoid excessive delays, the optical packet is sent also after a specified deadline. The model is based on diffusion approximation and validated by discrete event simulation. Its goal is to determine the probability distribution of the effective optical packet sizes an distribution of their interdeparture times as a function of the interarrival time distribution, distribution of the electronic packet sizes, the value of deadline and the size of buffer. We use real traffic data from the CAIDA (Center for Applied Internet Data Analysis) repositories.

The photonic crystal optical switch is one of the most important applications of photonic crystals in telecommunication networks. Switching is a main process in digital computers and signal processing systems. The growth of optical signal processing systems draws particular attention to the design of ultra-fast optical switches. In this reported work, first a directional coupler switch based on photonic crystals is designed and the linear state has been analysed and simulated. Then, the principles of nonlinear optics are used to perform optical switching at a wavelength of 1550 nm by COMSOL Multiphysics in micron dimension. The dielectric rods of this photonic crystal lattice are made of AlGaAs. The central row is an important factor for attaining the required power in nonlinear switching performance. Finally, the radius of rods in the central nonlinear row is changed several times and the results are compared with each other. In this switch, the output power ratio, called the extinction ratio, and the required refractive index change for the nonlinear status are taken into account. The former is for the evaluation of directional coupler efficiency and the latter is generally an important factor in optical nonlinear switches.

Scheduling traffic for maximum switch lifetime in optical data center fabrics

Extending the researches on wavelength switched optical networks (WSON), efficient integration of the novel optical packet switching network and wavelength switching-based optical circuit switching network technologies which offers both best-effort packet delivery and QoS guaranteed lightpath services has been being studied. In addition, researches on the optical-layer transparent data processing, such as all-optical wavelength multicasting, all-optical 3R regeneration, etc, are conducted simultaneously. It is believed that future innovative optical network services (INSes) would be built on these novel future-proof technologies, and foster colorful applications in the new generation networks. Before the wide applications of INS in different fields, there would be a foreseeable strong requirement for INS firstly posed by pioneer grid applications, e.g., e-science, e-government, and e-banking, etc, which would require the high-performance underlying networks. Our research here is motivated to glue the optical networks and grid applications by integrating lightpath, geographically distributed INS systems and grid resources (e.g., computers, storages, instruments, etc.), and finally offering an easy-to-use high performance networked grid computing environment-optical grid network (OGN) to user applications. In this paper, we introduce our research activities of a distributed optical grid network infrastructure (OGNI), and the creation of the future easy-to-use INS based on OGNI. The proposals have been validated through fieldtrial experiments over a developed WSON testbed.

Surface-Emitting-Laser-based optical functional devices have promising features for photonic switching and optical data processing. All photonic switching networks need control signals to be sent into the nodes to allow for appropriate routing of traffic.') Control injection, thus, must be taken into consideration more in photonic switches. An optical self-routing switch has been proposed where a node consists of pnpn-Vertical to Surface Transmission ElectroPhotonic Devices with Vertical Cavities (VC-VSTEPS).~) The routing for optical data signals are controlled by an optical pilot signal placed at the head of the optical data signals. However, this switch still needs electric timing signals to be applied to the VC-VSTEPs, which might cause electromagnetic interferences among a large number of internal electric lines, and a delay in the timing signals due to parasitic capacitances. Therefore, it is desirable that the timing signals are further injected optically. This paper reports on VSTEP-based pixels aiming for optically controllable nodes. The pixel consists of a VSTEP using a four-terminal pnpn structure with two distributed Bragg reflectors (DBRs) (Fig. 1). The fabrication process includes two-step mesa etching: 1) to the n-doped gate layer, and 2) to the n-doped DBR layer. The n- and p-gate electrodes are formed on the second mesa with Zn diffusion for the p-gate. In comparison to twoterminal VC-VSTEPs3), the structure provides variable switching voltage characteristics and gate turn-off operation by means of carrier injectiodextraction through the gate terminals. Also, this structure allows the formation of a hetero-junction bipolar transistor (HBT), or a hetero-junction photo-transistor (HPT) together with the pnpn-structure. These two features, in combination, expand flexibility in device configuration to meet the demands of photonic switching and processing systems. As an example, a pixel has been demonstrated for an optical self-routing switch with optical gating and optical reset operations. Figure shows an equivalent circuit of the pixel. When the optical gate pulse is incident on the HFT1, current is injected to the pnpn device, resulting in a reduction of switching voltage, and allowing turn-on by the input optical pulse. Applying the gate pulses to the pixels with proper time delays, the pilot signal can select one pixel in which the pilot signal coincides with the gate signal. 2 is used for the optical reset. The optical reset pulse incident on the HPT2 removes the stored charge in the pnpn-device through the ngate. Figure 3 shows voltage-current and light-current characteristics of the fabricated device with various current injections from the n-gate. The switching voltage without n-gate injection is 3.8 V and the threshold current is 35 mA. A common-emitter current gain of 180 is obtained for the npn-HPT using an n-gate as a collector and a cathode as an emitter. Figure 4(a) shows the optical gating operation. A bias voltage of 3V was applied to the anode. The reset is also achieved as shown in Fig. 4(b). Optical energies obtained for the input, gate and reset are 8.0 pJ, 0.5 pJ and 10 pJ, respectively. Reduction in these values will be achieved by a decrease in device size.

Statistical multiplexing at the optical layer has been considered a critical requirement in order to build the next generation of ultra-high capacity optical transport networks in a cost-efficient manner. However, even today, the state of the art of commercially available optical core networks is based on mature wavelength switching and routing technologies, which lack a transport and control plane architecture that can support statistical traffic multiplexing with guaranteed Quality of Service (QoS) across a wide range of QoS parameters even if they can support fast reconfiguration at msec time scales. For several years, most research efforts have focused on the concepts of Optical Burst Switching (OBS) and Optical Packet Switching (OPS), which are based on the hybrid use of electronic nodes and optical switches to exploit Time Division Multiplexing (TDM) in order to achieve statistical multiplexing and dynamic resource reservation over optical networks. While burst switching has been experimentally proven as a technically feasible technique, its performance suffers especially under strict requirements for QoS guarantees. In this paper we evaluate the performance gains that can be achieved exploiting statistical multiplexing over a large scale core optical network and we demonstrate the efficiency of the CANON architecture (Clustered Architecture for Nodes in an Optical Network) as a viable alternative to OBS, which can achieve both targets for statistical multiplexing gains and QoS guarantees at the same time.

The wide deployment of wavelength-division multiplexing technology and new transmission techniques have resulted in significant increases in the transmission capacity in optical fibers, both in the number of wavelengths and the bandwidth of each wavelength channel. Meanwhile, the fast growth of the Internet demands more data switching capacity in the network in order to deliver high bandwidth to end users. Although the capacity of electronic routers has been increasing consistently in the past, optical switching appears to be a more cost-effective way to switch individual wavelengths. As the bit rate per wavelength channel continues to grow, optical subwavelength switching emerges as a new paradigm capable of dynamically delivering the vast bandwidth WDM offers. This article discusses one of such techniques, namely optical packet switching, and its performance perceived by end users in optical mesh networks. Specifically, our investigation reveals the benefit of using electrical ingress buffering and traffic aggregation to reduce packet-loss rate of optical packet-switched networks. Through simulation experiments, we present an evaluation of the network's TCP-level performance based on the proposed architecture.

An optical router with multistage distributed management features for the asynchronous optical packet switching (OPS) network is presented, which can improve switching capacity and all-optical scalability. A compact recycling-fiber-delay-line (Rec-FDL) based collision resolution mechanism is proposed to resolve the contentions for asynchronous and variable length optical packets. The analysis models of stabilities, packet loss rates (PLR) and average packet waiting latencies (PWL) for the router are developed based on the timer based optical packet assembly algorithm. The simulation shows that PLR and PWL for a 400-byte optical packet transmitted in the 32 wavelengths dense wavelength division multiplexing (DWDM) system equal to 3.48 × 10?4 and 0.072 ns, respectively. The non-blocking switching can be realized for the packets with lengths less than the buffer granularity of the Rec-FDL, and the optimized performance for the proposed router can be obtained through properly selecting of the system parameters.

Photonic switches play a vital role in optical communications and computer networks for establishing and releasing connections of optical signals. With the growing demand for ultra‐compact switches in high‐speed optical computing and communications, thermally reconfigurable optical switches have gained significant attention. These switches offer simplicity, ease of fabrication, and leverage a wide range of thermo‐optic materials. Silicon remains an ideal platform for making photonic devices including the switches due to its compatibility with complementary metal‐oxide‐semiconductor (CMOS) technology and cost‐effectiveness. The article presents a drop cast sub‐stoichiometric vanadium oxide (VO2−x) nanoparticles combined with a silicon ridge waveguide to make a compact thermally reconfigurable optical switch with low transition temperature and accelerated phase transition. Furthermore, the design achieves high modulation depth in addition to its scalability and simplicity. This study demonstrates the potential of solution‐based VO2−x nanoparticles in combination with silicon waveguides for efficient optical switch design for various applications.