Optical Switching Networks Research Articles

High spectral efficiency scheme for future all optical label switching network

A high spectral efficiency scheme for all optical label switching (AOLS) network is introduced. The vestigial sideband (VSB) payload with wavelength labeling is proposed in beyond 40Gb/s AOLS networks. Two different label wavelength schemes are considered. The minimum 20dB channel bandwidth of payload and label is 0.40nm in 43Gb/s systems which confirm the payload power penalty less than 1dB at the receiver.

An Ant-Based Approach for Dynamic RWA in Optical WDM Networks

In this paper, we propose a new ant-based algorithm for the dynamic routing and wavelength assignment (RWA) problem in optical WDM networks under the wavelength continuity constraint. Unlike conventional approaches, which usually require centralized global network information, our new RWA algorithm constructs the routing solution in a distributed manner by means of cooperative ants. To facilitate the ants’ foraging task, we adopt in our algorithm a probabilistic routing table structure for route selection. The new algorithm is highly adaptive in that it always keeps a suitable number of ants in the network to cooperatively explore the network states and continuously update the routing tables, so that the route for a connection request can be determined promptly by the current states of routing tables with only a small setup delay. Some new schemes for path scoring and path searching are also proposed to enhance the performance of our ant-based algorithm. Extensive simulation results upon three typical network topologies indicate that the proposed algorithm has a very good adaptability to traffic variations and it outperforms both the fixed routing algorithm and the promising fixed–alternate routing algorithm in terms of blocking probability. The ability to guarantee both a low blocking probability and a small setup delay makes the new ant-based routing algorithm very attractive for both the optical circuit switching networks and future optical burst switching networks

Burstification Queue Management in Optical Burst Switching Networks

Among the various issues lying in optical burst switching (OBS) networks, burstification, i.e., assembling multiple IP packets into bursts, is an important one. Between the two important aspects related to burst assembly, the burst assembly algorithm aspect has been extensively studied in the literature. However, as far as we know, there is no research about the burstification queue management (BQM) aspect, which refers to how many burstification queues (BQ) we should set at each OBS edge node and how to manage these BQs. Suppose there are G destinations (egress edge nodes) and the OBS network provides S different quality of service (QoS) classes. Traditionally, it is simply regarded that each ingress edge node needs G· S queues to sort incoming packets, one for each possible destination and QoS class. For simplicity, we call this policy the static dedicate BQM (SDB) policy. The SDB policy, though simple, lacks scalability since we have to add S BQs at each OBS edge node if an extra OBS edge node is added to the OBS network. To solve this problem, we propose in this paper two BQM policies: quasi-static BQM (QSB) policy and dynamic BQM (DB) policy. For the QSB policy, we derive the packet loss probability due to lacking BQs based on a Markov chain, from which we can work out the employed number of BQs for a given packet loss probability. Based on these results, the scalability of the QSB policy is also studied. With the DB policy, we not only can dynamically assign BQs for incoming packets, but also can dynamically allocate buffer capacity for each BQ by using a least-mean-square (LMS)-based linear prediction filter. The performance of the DB policy is investigated by analysis and extensive simulations. We also compared the performance of the QSB policy and the DB policy. Results from analysis and simulation demonstrate that the DB policy is the best.

Call for Papers: Nanoscale Integrated Photonics for Optical Networks

Call for Papers: Nanoscale Integrated Photonics for Optical Networks Keren Bergman, Coordinating Associate Editor Madeleine Glick, Guest Feature Editor Submission Deadline: 15 August 2006 Recent dramatic advances in nanoscale materials and nanophotonic device fabrication have yielded unprecedented control over the optical properties of synthetic structures. These extraordinary innovations at the nanoscale offer the possibility of creating high-functionality photonic devices in ultradense integration platforms. We can now envision nanoscale integrated photonics modules that may be application-specific designed in a similar fashion to integrated electronics for applications ranging from ultra-long-haul telecommunications to on-chip networks and high-performance computing. The applications of these advances to the transformation of optical networking is the theme of this Journal of Optical Networking (JON) feature issue. Scope of Submission The Editors of JON are soliciting papers on Nanoscale Integrated Photonics for Optical Networks. The aim in this feature issue is to publish original research on topics including--but not limited to--the following nanoscale materials and device fabrication as related to Novel optical network architectures Photonic switching fabrics and network elements Advances enabling new network functionalities such as novel solutions for optical buffering, packet or label processing, and routing modules Miniature mux/demux technology Application-specific design Integration and high-volume manufacture of photonics devices/modules Network interface and control planes Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON and select ``Integration' in the features indicator of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line ``Integration.' Additional information can be found on the JON website: http://www.osa-jon.org/journal/jon/author.cfm. Submission Deadline: 15 August 2006

Call for Papers: Nanoscale Integrated Photonics for Optical Networks

Call for Papers: Nanoscale Integrated Photonics for Optical Networks Keren Bergman, Coordinating Associate Editor Madeleine Glick, Guest Feature Editor Submission Deadline: 1 August 2006 Recent dramatic advances in nanoscale materials and nanophotonic device fabrication have yielded unprecedented control over the optical properties of synthetic structures. These extraordinary innovations at the nanoscale offer the possibility of creating high-functionality photonic devices in ultradense integration platforms. We can now envision nanoscale integrated photonics modules that may be application-specific designed in a similar fashion to integrated electronics for applications ranging from ultra-long-haul telecommunications to on-chip networks and high-performance computing. The applications of these advances to the transformation of optical networking is the theme of this Journal of Optical Networking (JON) feature issue. Scope of Submission The Editors of JON are soliciting papers on Nanoscale Integrated Photonics for Optical Networks. The aim in this feature issue is to publish original research on topics including--but not limited to--the following nanoscale materials and device fabrication as related to Novel optical network architectures Photonic switching fabrics and network elements Advances enabling new network functionalities such as novel solutions for optical buffering, packet or label processing, and routing modules Miniature mux/demux technology Application-specific design Integration and high-volume manufacture of photonics devices/modules Network interface and control planes Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON and select ``Integration' in the features indicator of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line ``Integration.' Additional information can be found on the JON website: http://www.osa-jon.org/journal/jon/author.cfm. Submission Deadline: 1 August 2006

Call for Papers: Nanoscale Integrated Photonics for Optical Networks

Call for Papers: Nanoscale Integrated Photonics for Optical Networks Keren Bergman, Coordinating Associate Editor Madeleine Glick, Guest Feature Editor Submission Deadline: 1 August 2006 Recent dramatic advances in nanoscale materials and nanophotonic device fabrication have yielded unprecedented control over the optical properties of synthetic structures. These extraordinary innovations at the nanoscale offer the possibility of creating high-functionality photonic devices in ultradense integration platforms. We can now envision nanoscale integrated photonics modules that may be application-specific designed in a similar fashion to integrated electronics for applications ranging from ultra-long-haul telecommunications to on-chip networks and high-performance computing. The applications of these advances to the transformation of optical networking is the theme of this Journal of Optical Networking (JON) feature issue. Scope of Submission The Editors of JON are soliciting papers on Nanoscale Integrated Photonics for Optical Networks. The aim in this feature issue is to publish original research on topics including--but not limited to--the following nanoscale materials and device fabrication as related to Novel optical network architectures Photonic switching fabrics and network elements Advances enabling new network functionalities such as novel solutions for optical buffering, packet or label processing, and routing modules Miniature mux/demux technology Application-specific design Integration and high-volume manufacture of photonics devices/modules Network interface and control planes Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON and select ``Integration' in the features indicator of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line ``Integration.' Additional information can be found on the JON website: http://www.osa-jon.org/journal/jon/author.cfm. Submission Deadline: 1 August 2006

Call for Papers: Nanoscale Integrated Photonics for Optical Networks

Call for Papers: Nanoscale Integrated Photonics for Optical Networks Keren Bergman, Coordinating Associate Editor Madeleine Glick, Guest Feature Editor Submission Deadline: 1 August 2006 Recent dramatic advances in nanoscale materials and nanophotonic device fabrication have yielded unprecedented control over the optical properties of synthetic structures. These extraordinary innovations at the nanoscale offer the possibility of creating high-functionality photonic devices in ultradense integration platforms. We can now envision nanoscale integrated photonics modules that may be application-specific designed in a similar fashion to integrated electronics for applications ranging from ultra-long-haul telecommunications to on-chip networks and high-performance computing. The applications of these advances to the transformation of optical networking is the theme of this Journal of Optical Networking (JON) feature issue. Scope of Submission The Editors of JON are soliciting papers on Nanoscale Integrated Photonics for Optical Networks. The aim in this feature issue is to publish original research on topics including--but not limited to--the following nanoscale materials and device fabrication as related to Novel optical network architectures Photonic switching fabrics and network elements Advances enabling new network functionalities such as novel solutions for optical buffering, packet or label processing, and routing modules Miniature mux/demux technology Application-specific design Integration and high-volume manufacture of photonics devices/modules Network interface and control planes Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON and select ``Integration' in the features indicator of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line ``Integration.' Additional information can be found on the JON website: http://www.osa-jon.org/journal/jon/author.cfm. Submission Deadline: 1 August 2006

Multigranular integrated services optical network

Feature Issue on Waveband Switching, Routing, and GroomingBased on all-optical switches without requiring fiber delay lines and optical-electrical-optical interfaces, the multigranular optical switching (MGOS) network integrates three transport services via unified core control to efficiently support bursty and stream traffic of subwavelength to multiwavelength bandwidth. Adaptive robust optical burst switching (AR-OBS) aggregates subwavelength burst traffic into asynchronous light-rate bursts, transported via slotted-time light paths established by fast two-way reservation with robust blocking recovery control. Multiwavelength optical switching (MW-OS) decomposes multiwavelength stream traffic into a group of timing-related light-rate streams, transported via a light-path group to meet end-to-end delay-variation requirements. Optical circuit switching (OCS) simply converts wavelength stream traffic from an electrical-rate into a light-rate stream. The MGOS network employs decoupled routing, wavelength, and time-slot assignment (RWTA) and novel group routing and wavelength assignment (GRWA) to select slotted-time light paths and light-path groups, respectively. The selected resources are reserved by the unified multigranular robust fast optical reservation protocol (MG-RFORP). Simulation results show that elastic traffic is efficiently supported via AR-OBS in terms of loss rate and wavelength utilization, while connection-oriented wavelength traffic is efficiently supported via wavelength-routed OCS in terms of connection blocking and wavelength utilization. The GRWA-tuning result for MW-OS is also shown.

Architecture design and performance evaluation of multigranularity optical networks based on optical code division multiplexing

Feature Issue on Waveband Switching, Routing, and GroomingIn traditional lambda-based multigranularity optical networks, a lambda is always treated as the basic routing unit, resulting in low wavelength utilization. On the basis of optical code division multiplexing (OCDM) technology, a novel OCDM-based multigranularity optical cross-connect (MG-OXC) is proposed. Compared with the traditional lambda-based MG-OXC, its switching capability has been extended to support fiber switching, waveband switching, lambda switching, and OCDM switching. In a network composed of OCDM-based MG-OXCs, a single wavelength can be shared by distinct label switched paths (LSPs) called OCDM-LSPs, and OCDM-LSP switching can be implemented in the optical domain. To improve the network flexibility for an OCDM-LSP provisioning, two kinds of switches enabling hybrid optical code (OC)-wavelength conversion are designed. Simulation results indicate that a blocking probability reduction of 2 orders can be obtained by deploying only five OCs to a single wavelength. Furthermore, compared with time-division-multiplexing LSP (TDM-LSP), owing to the asynchronous accessibility and the OC conversion, OCDM-LSPs have been shown to permit a simpler switch architecture and achieve better blocking performance than TDM-LSPs.

Performance modelling for vertically stacked optical banyan networks with extra stage

A combination of horizontal expansion and vertical stacking of optical banyan (HVOB) is the general scheme for building banyan-based optical switching networks. The HVOB networks usually require either higher hardware cost or larger depth to guarantee the nonblocking property. In this paper, we analyse the blocking probabilities of HVOB networks with one extra stage and develop their upper bound. The bound depicts accurately the overall blocking behaviours of HVOB networks and reveals the inherent relationships among blocking probability, network depth and network hardware cost and enables a desirable tradeoff to be made among them.

Label erasure using an imbalanced NOLM and its application in a 40-gb/s label switching optical network

A novel scheme based on the nonlinear transmission function of an imbalanced nonlinear optical loop mirror (NOLM) is used to realize label erasure. The scheme has been successfully applied in a 40 Gb/s label switching optical network with a transmission distance of 200 km.

Dynamic RWA Based on the Combination of Mobile Agents Technique and Genetic Algorithms in WDM Networks with Sparse Wavelength Conversion

Genetic Algorithms (GA) provide an attractive approach to solving the challenging problem of dynamic routing and wavelength assignment (RWA) in optical Wavelength Division Multiplexing (WDM) networks, because they usually achieve a significantly low blocking probability. Available GA-based dynamic RWA algorithms were designed mainly for WDM networks with a wavelength continuity constraint, and they cannot be applied directly to WDM networks with wavelength conversion capability. Furthermore, the available GA-based dynamic RWA algorithms suffer from the problem of requiring a very time consuming process to generate the first population of routes for a request, which may results in a significantly large delay in path setup. In this paper, we study the dynamic RWA problem in WDM networks with sparse wavelength conversion and propose a novel hybrid algorithm for it based on the combination of mobile agents technique and GA. By keeping a suitable number of mobile agents in the network to cooperatively explore the network states and continuously update the routing tables, the new hybrid algorithm can promptly determine the first population of routes for a new request based on the routing table of its source node, without requiring the time consuming process associated with current GA-based dynamic RWA algorithms. To achieve a good load balance in WDM networks with sparse wavelength conversion, we adopt in our hybrid algorithm a new reproduction scheme and a new fitness function that simultaneously takes into account the path length, number of free wavelengths, and wavelength conversion capability in route selection. Our new hybrid algorithm achieves a better load balance and results in a significantly lower blocking probability than does the Fixed-Alternate routing algorithm, both for optical networks with sparse and full-range wavelength converters and for optical networks with sparse and limited-range wavelength converters. This was verified by an extensive simulation study on the ns-2 network simulator and two typical network topologies. The ability to guarantee both a low blocking probability and a small setup delay makes the new hybrid dynamic RWA algorithm very attractive for current optical circuit switching networks and also for the next generation optical burst switching networks.

Efficient Job Scheduling Algorithms with Multi-Type Contentions

In this paper, we consider an interesting generalization of the classic job scheduling problem in which each job needs to compete not only for machines but also for other types of resources. The contentions among jobs for machines and for resources could interfere with each other, which complicates the problem dramatically. We present a family of approximation algorithms for solving several variants of the problem by using a generic algorithmic framework. Our algorithms achieve a constant approximation ratio (i.e., 3) when there is only one type of resources or certain dependency relation exists among multiple types of resources. When the r resources are unrelated, the approximation ratio of our algorithm becomes k+2, where k≤ r is a constant depending on the problem instance. As an application, we also show that our techniques can be easily applied to optical burst switching (OBS) networks to design more efficient wavelength scheduling algorithms.

Comparative Account of Bandwidth Efficiency in Optical Burst Switching and Optical Circuit Switching Networks

The performance of Optical Burst Switched (OBS) networks is compared to that of Optical Circuit Switched (OCS) networks in terms of bandwidth efficiency. Two traffic flow models are employed to investigate the effects of traffic grooming, packetization, buffering and burst assembly on bandwidth efficiency and utilization. Traffic is represented by fluid-flow continuous bit streams in the first model and by packet-based discrete flows in the second model. It is shown that the parameters of traffic characteristics and burst assembly have significant impact on the relative bandwidth savings of OBS. The bandwidth efficiency of OBS compared to OCS should not be taken for granted and has to be examined carefully on a case by case basis.

A generic-traffic optical buffer modeling for asynchronous optical switching networks

Delay-line buffering has emerged as the current time-domain contention; solution in optical switching networks. Due to the unpredictability of future Internet traffic and the existence of various buffer architectures and wavelength scheduling policies, the study of such buffers under different traffic conditions is a very important issue. In this paper we present a generic-traffic analytical model for the FIFO delay-line buffer in an asynchronous network scenario that may be useful for buffer planning and performance evaluation. The model is traffic generic as it may assume any inter-arrival time process and packet length distribution.

All optical labeling scheme with vestigial sideband payload

A novel scheme based on 40Gb/s vestigial sideband modulation for optical payload and label multiplex and separation in all optical label switching (AOLS) networks is firstly proposed and experimentally demonstrated. The payload is combined and separated with wavelength labels by optical filters. The experiment results show that after label separation, the power penalties of payload and label are both very little. The influence of the wavelength difference between label and payload is also discussed. The power penalty of payload can be less than 1dB as long as the wavelength difference is larger than 0.1nm. This scheme highly reduces the channel bandwidth of payload and label and is proposing to be used in future optical Internet.

All-optical label processor∕erasure for label swapping of 12.5 Gbit∕s spectrally separated bit-serial DPSK label and payload

A novel all-optical label processor/erasure for DPSK spectrally separated label and payload is demonstrated. Experimental results show the recognition of two different labels at 12.5 Gbit/s at distinct outputs, while the label is simultaneously erased allowing for a new label insertion. The low power and asynchronous label processor/erasure can be scaled to distinguish a larger number of labels, to operate at higher bit rate, and then can be potentially used in an optical label switching network.

Design and application of Simple Data Link (SDL) framing protocol

The Simple Data Link (SDL) framing protocol is uniquely designed to delineate packets in high-speed communications. SDL can identify the boundaries of variable length frames by using length indication and Header Error Correction (HEC) check. In this paper, we derive an HEC hunting algorithm for bit-level and octet-level operations and propose a hardware circuit to simplify the implementation of an SDL framer. By employing only one CRC detector, the proposed framer can reduce the hunting time of packet delineation just like using multiple framers in parallel. To evaluate the performance of SDL in next generation optical networks, the packet loss probability of Optical Burst Switching (OBS) networks is examined. Analytical results reveal that receivers with SDL framers can greatly reduce packet loss probability than those with only pure IP headers.

Guest Editorial on Advances in Optical Network Switching and Routing

Guest Editorial on Advances in Optical Network Switching and Routing

Cutting-Edge Technologies on Broadband and Scalable Photonic-Network?Packet switched networks based on all-optical label processing?

Ultra-high speed all-optical label processing methods are proposed and experimentally demonstrated. These methods dramatically increase the label processing capability. Optical packet switch (OPS) systems and networks based on OPS nodes are expressed as an application of optical processing technologies. First, the 40 Gbit/s/port OPS prototype with all-optical label processor, optical switch, optical buffer, and electronic scheduler is described. The feasibility of OPS networks is verified by experimental demonstrations.