Wavelength channel-separating and buffer-sharing routing schemes in DWDM optical packet switching nodes

We develop an integrated optical packet and circuit switching node in which signaling via optical packet switching is implemented. We demonstrate 80 (8λ × 10) Gbit/s optical packet switching with <;1E-4 packet-loss-rate, 8-lightpaths establishment, and dynamic wavelength-resources control.

Since the underlying demand for network capacity can be satisfied only by extremely increasing transmission bit rate, processing speed, and switching capacity, it definitely will lead to increased power consumption of network nodes. Energy crisis is global crisis nowadays and it has brought up many problems. Power consumption is becoming a crucial issue in designing high-performance network devices. This paper studies the power consumption model of a kind of Optical Packet Switching (OPS) node based on Semiconductor Optical Amplifiers (SOA). Our results show that by dynamically adjusting the bias current of SOAs, the power consumption on an OPS node can be reduced considerably, especially when the traffic distribution across multiple ports is not balanced and inter-nodal distances vary. The total electrical power consumption can be cut off significantly. We also show the power consumption can be further reduced by jointly optimizing the thermoelectric cooler current.

Since the underlying demand for network capacity can be satisfied only by extremely increasing transmission bit rate, processing speed, and switching capacity, it definitely will lead to increased power consumption of network nodes. Energy crisis is global crisis nowadays and it has brought up many problems. Power consumption is becoming a crucial issue in designing high-performance network devices. This paper studies the power consumption model of a kind of Optical Packet Switching (OPS) node based on Semiconductor Optical Amplifiers (SOA). Our results show that by dynamically adjusting the bias current of SOAs, the power consumption on an OPS node can be reduced considerably, especially when the traffic distribution across multiple ports is not balanced and inter-nodal distances vary. The total electrical power consumption can be cut off significantly. We also show the power consumption can be further reduced by jointly optimizing the thermoelectric cooler current.

The large growth of telecommunication traffic demand generated by multiple new applications and expected to last at least for the next decade will force telecom operators to consider offering more flexible transport services. All-optical packet switching is a powerful technique to provide this flexibility and to support in a cost-efficient way a wide range of bandwidth consuming applications. After a very brief introduction about the packet-switched network architecture studied in the framework of the ACTS KEOPS project, we describe the structure of the packet-switching node we have defined. We then move into physical and logical analysis of the network including more than 40 network sections based on 160 Gb/s throughput optical packet switching nodes could operate error free. In addition, logical simulations have proved that such networks could provide a quality of service (packet loss rate and packet transfer delay per node) compatible with a large variety of service classes. Both results validate the feasibility of the network concept and pace the way toward a flexible network based on all-optical switching techniques.

The wavelength conversion is regarded as an effective way to resolve the optical packet contention in the wavelength domain for optical packet switching. An optical packet switching node, based on shared-per-node equipped with limited range wavelength converters and parametric wavelength converters (SPN-LP), is designed to further reduce optical packet loss probability. A novel optical packet contention resolution with priority differentiation wavelength scheduling algorithm to support quality of service (QoS) for the SPN-LP architecture is put forward in the article. The simulation results show that proposed optical packet resolution enables a good QoS differentiation, namely the high priority contending optical packet has the sufficient low packet loss probability.

We present a performance model for fiber delay line (FDL) buffers having access to multiple wavelengths on an output fiber. In optical burst switching and optical packet switching, contending bursts (or packets) need to be dealt with in an effective way, and both wavelength conversion and optical buffering are viable solutions. The buffer studied here includes both solutions, with full wavelength conversion. It is situated at the output, and handles independent arrivals. We apply an analytic discrete-time queueing model to evaluate performance in terms of loss. We mainly consider the impact of burst size (fixed or varying), scheduling policy, and buffer size. Several numerical examples assess the accuracy of our approximation, and show that our approach is applicable when burst sizes are fixed, and, when a round-robin scheduling policy is adopted, also when burst sizes vary.

Correction to "Ultra-Low Latency Optical Packet Switching Node"

The performance of an optical switching network is mainly determined by its core node structure. An improved optical packet switching (OPS) node structure based on recirculation optical fiber delay line (FDL) and feedback tunable wavelength converter (TWC), and a specific scheduling algorithm for the node structure are presented. This switching structure supports both point-to-point and point-to-multi-points broadcasting transmission with superior capacity expansion performance. Its superiority in packet loss probability is proved by simulation.

Optical Packet Switching (OPS) has emerged as a promising candidate for the future all-optical core network. A crucial issue in such networks is how the packet length distribution (PLD) influences the performance under different traffic scenarios. In this paper we investigate how a deterministic, empirical and exponential PLD influences the Packet Loss Rate (PLR) in an optical packet switch in the case of a Poisson arrival process and a bursty Hyperexponential arrival process. We consider optical packet switches with and without Fibre Delay Line (FDL) contention buffers. Our results show that in the case of OPS without FDL buffering and with a Hyperexponential arrival process, the empirical PLD yields the lowest PLR. However, in the case of OPS with FDL buffering, the deterministic PLD yields the lowest PLR.

Next-generation high-speed Internet backbone networks will be required to support a broad range of emerging applications which may not only require significant bandwidth, but may also have strict quality of service (QoS) requirements. Furthermore, the traffic from such applications are expected to be highly bursty in nature. For such traffic, the allocation of static fixed-bandwidth circuits may lead to the over-provisioning of bandwidth resources in order to meet QoS requirements. Optical burst switching (OBS) is a promising new technique which attempts to address the problem of efficiently allocating resources for bursty traffic. In OBS, incoming data is assembled into bursts at the edges of the network, and when the burst is ready to be sent, resources in the network are reserved only for the duration of the burst. The reservation of resources is typically made by an out-of-band one-way control message which precedes the burst by some offset time. By reserving resources only for the duration of the burst, a greater degree of utilization may be achieved in the network. This book provides an overview of optical burst switching. Design and research issues involved in the development of OBS networks are discussed, and approaches to providing QoS in OBS networks are presented. Topics include: - Optical burst switching node and network architectures - Burst assembly - Signaling protocols - Contention resolution - Burst scheduling - Quality of service in OBS networks

With emerging trends for ubiquitous data services, the IP-optical convergence networks are gradually becoming a preferred technology. In optical transport networks (OTNs), a major obstacle in realizing all-optical switched IP network is due to the large processing delays of optical switching nodes that still need OEO conversion at the optical header (label) processing. The proposed labeling scheme requires neither table lookup nor label replacing in the stateless all-optical switching node, labeled packets/bursts will be forwarded through self-routing, and the only operation in optical switching nodes is to strip off its label part which represents the output port. Thus, the whole processing has been completed in the optical domain. The purposes of this paper are to shed light on a very active field of research on next generation all-IP photonics telecommunication and Internet, as well as to contribute on everyone’s modern style of living.

We present here the results of an analytical model describing the behavior of communication traffic in an optical packet metro-access network that is able to work without a control plane.The transparent optical node model exemplifies an application for a simple node behavior that has been experimentally demonstrated.The efficient optical nodes in 2x2 mesh architecture adequately connected to create a smart network that shows excellent performance, low latency and high throughput, with a minimum management cost.Without using control planes or complex network control protocols, the optical network functionalities emerge from simple physical properties associated with the operation of the optical packet switching node.

We propose an asynchronous optical packet switching node architecture, where congestion resolution is based on shared optical buffers and tuneable wavelength converters. We evaluated our switch by simulations and show that decreasing packet loss probability obtained by optical buffers can be efficiently boosted by adding a few shared tuneable wavelength converters, which allows for reduction of all-optical buffer size. The smaller switch size the larger impact of wavelength conversion on packet loss probability was observed. Furthermore it can be noticed that for the proposed node architecture the higher number of buffer positions the larger improvement caused by applying tuneable wavelength converters can be achieved.

We consider an asynchronous all optical packet switch (OPS) where each link consists of N wavelength channels and a pool of C ≤ N full range tunable wavelength converters. Under the assumption of Poisson arrivals with rate λ (per wavelength channel) and exponential packet lengths, we determine a simple closed-form expression for the limit of the loss probabilities Ploss(N) as N tends to infinity (while the load and conversion ratio σ=C/N remains fixed). More specifically, for σ ≤ λ2 the loss probability tends to (λ2-σ)/λ(1+λ), while for σ > λ2 the loss tends to zero. We also prove an insensitivity result when the exponential packet lengths are replaced by certain classes of phase-type distributions. A key feature of the dynamical system (i.e., set of ODEs) that describes the limit behavior of this OPS switch, is that its right-hand side is discontinuous. To prove the convergence, we therefore had to generalize some existing result to the setting of piece-wise smooth dynamical systems.

The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching (OBS) nodes with limited wavelength conversion capability (LWCC). The relevant system architectures of limited range and limited number of wavelength converters (WCs) deployed by a share-per-fiber (SPF) mode were developed, and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios, it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases, the accuracy of the analysis model worsens slightly. However, the utmost error on burst loss probability is far less than one order of magnitude and hence, still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.