Automatically Switched Optical Network Research Articles

Development and Application of Intelligent Optical Network Technology

Because the network application scope unceasing expansion, the demand for information is increasing, the requirements of optical transmission network technology is more and more high, so it determines the optical network technology needs continuous development and innovation, and the development trend of optical network technology is the intelligent optical network technology. Intelligent optical network technology is the typical automatic switched optical network (ASON) technology [1]. After many years of research and development, this technology has finally been applied to the actual. With the continuous progress of society and the rapid innovation of science and technology, the traditional network technology has been unable to meet the requirements of people's life and work. In the traditional network has a lot of disadvantages, such as broadband distribution of data services is not flexible, low transmission efficiency[2]. Therefore, it is very important to develop an efficient, secure and reliable network according to the people's needs and the weakness of the traditional network. Intelligent optical network is to make up for the weakness of the traditional network and was developed by the network technology, can make people's life and work more convenient and efficient.

Performance Analysis of Packet Transport Network Communication for Integrated Wide-Area Protection

As a new protection, wide-area protection enables protective relaying, and automatic control based on electric power system network communications and comprehensive judgment of multi-point information, which plays an increasingly important role in the secure and stable operation of electric power system. Interaction of wide-area information relies on communication network featuring high reliability and low time delay. On the other hand, most service of power transformation station is gradually towards IP and data oriented, along with the development of smart grid. This paper aims to introduce the wide-area protection technology supported by Packet Transport Network (PTN) communication technology, with analyzing the QoS (Quality of Service) network assurance architecture of PTN network, which establishes three planes, including transport plane, management plane, and control plane, based on ASON (Automatically Switched Optical Network) technology. After demonstrating the QoS assurance system of PTN from traffic control and transmission route, this paper introduces PTN networking test. Based on detailed parameters in the test results, the transmission performance of PTN on time delay, protection, and time synchronization of various electric power communication services are analyzed, with showing that PTN can fully meet the requirements of electric power communication.

A heuristic approach for border node selection and traffic routing in multi-domain optical networks

In this article we present a heuristic for selecting a set of domain border nodes and an improved routing scheme to route intra- and inter-domain traffic with low blocking probability in multi-domain multi-rate optical networks. The selection of border nodes is based on topological parameters and on intra-domain traffic. The routing scheme is impairment- and bandwidth-aware and searches for the optimum lightpath through the domains that meets the connection requests based on an improved system of weights assigned to links. The traffic routing is based on the Backward-Recursive Path Computation Element (PCE)-based Computation (BRPC) procedure of the Internet Engineering Task Force (IETF), which means that domains inform only a set of shortest paths that are strictly essential to route the traffic. The network model fits the Automatically Switched Optical Network (ASON) architecture of the International Telecommunication Union (ITU-T) and the operational management of the network is based on the procedures of the IETF Generalized Multi-Protocol Label Switching (GMPLS) control plane. Numerical results from computational simulations show the versatility and usefulness of the proposed scheme, which improves the blocking probability of inter-domain traffic by up to 41.5% compared to a scheme reported in the literature.

Dynamic call and connection admission control in automatically switched optical network for grid computing applications

In recent years, Grid computing applications are becoming more and more important to the scientific and business communities and are likely to open to the consumer market and widely develop in the near future, which is a great challenge brought by the potentially large number of Grid users (perhaps millions) and high frequency of their job requests. Automatically switched optical network (ASON), which is a promising high capacity intelligent transport network infrastructure, has been already deployed in the world and regarded as a promising solution to foster the expansion of Grid computing from local area networks to wide area networks. However, by theoretical analysis and simulative evaluation of Grid job blocking in the distributed call and connection setup process of ASON, this paper verifies that ASON and the conventional admission control mechanism confront a problem in supporting future large-scale Grid computing. In order to address this issue, a novel dynamic call and connection admission control (DCCAC) scheme is proposed to improve the network performance and guarantee quality of service (QoS) of Grid applications. This scheme is applicable with complete network information, no network information and partial network information. Numerical results show that the DCCAC scheme can improve the efficiency of the network to a great extent. Moreover, all the analysis and algorithms in this paper are based on ITU-T ASON recommendations, which make the DCCAC scheme more applicable in network engineering for future Grid computing.

A game equilibrated rapid dynamic restoration strategy in ASON

A dynamic equilibrated heuristic algorithm based on the D* principle and mixed-strategy game theory is proposed to resolve the restoration problem at the wavelength level in an automatically switched optical network (ASON). The cost of each edge and the wavelength occupancy was taken into account comprehensively. Nash equilibration between wavelength occupancy and path cost is solved and the evaluation function of the D* algorithm is constructed dynamically using game theory with a mixed strategy. Then, the system restores broken connections rapidly through dynamic route and wavelength assignment (RWA) and ensures a more balanced distribution of network resources in the process of dynamic channel restoration. Simulation results show that the blocking probability is reduced and the restoration probability is promoted effectively by this algorithm. In addition, the rapid and intelligent performance behavior of this algorithm can meet the requirements of restoration time.

Service differentiation in IP/MPLS over ASON/GMPLS networks

There is a general agreement that the future infrastructure for broadband communications will consist of Automatically Switched Optical Networks (ASONs) controlled by the Generalized Multi-Protocol Label Switching (GMPLS) control plane. Due to the convergence of most services on the Internet Protocol (IP) layer, ASON/GMPLS networks need to provide transport for a variety of applications having different Quality of Service (QoS) requirements. This implies that the Differentiated Service paradigm, which improves the QoS in pure IP networks, needs to be extended to the new underlying infrastructure. This article proposes and compares three schemes for the service differentiation in IP/MPLS over ASON/GMPLS networks. Simulation results demonstrate that a fair trade-off between QoS and resource utilization is achieved when combining routing policy differentiation (RPD), virtual topology differentiation (VTD), and virtual topology sharing (VTS) techniques. The RPD technique decides on the multilayer routing policy to apply depending on the Class of Service (CoS). The VTD technique transports different CoS over different independent virtual topologies. The VTS technique introduces a certain degree of resource sharing among the different virtual topologies.

Design and Implementation of a GMPLS-Controlled Grooming-Capable Optical Transport Network

Aiming at better resource utilization, an important requirement of future optical transport networks is the capability to accommodate subwavelength client flows efficiently. This can be put into action thanks to the enhanced traffic engineering (TE) protocols provided within the generalized multiprotocol label switching (GMPLS) standardization. The present paper concentrates on the design and implementation of a GMPLS-controlled grooming-capable transport infrastructure, namely, the automatically switched optical network (ASON)/GMPLS CARISMA test bed. Through the paper, the operation of a GMPLS-controlled multilayer network architecture is introduced, subsequently highlighting implementation issues that come to light. Special attention is devoted to a centralized flow reallocation module deployed in the CARISMA test bed to minimize the overall network cost. In this context, an integer linear programming (ILP) formulation to obtain its optimal cost is derived and low-weighted metaheuristics providing a nearly optimal solution are additionally proposed. All contributions in the paper are supported by illustrative experimental results.

Effects of Outdated Control Information in Control-Plane-Enabled Optical Networks With Path Protection

New signaling suites for a distributed control plane in wavelength division multiplexing (WDM) networks, such as generalized multiprotocol label switching (GMPLS) and automatic switched optical networks (ASON), allow one to cope with the increasing variability of traffic patterns to be suppor ted by operators by providing a means to dynamically set up and release connections. The dissemination of link-state information [usually provided by routing protocols such as open-shortest-path-first traffic engineering (OSPF-TE)] is essential in this kind of control-plane enabled network: in particular, this information has to be continuously updated to allow routing algorithms to efficiently carry out the path computation. Most of the studies on dynamic traffic routing tend to neglect the effect of delays in control-information distribution on routing performance: in particular, even when the control plane is considered as in testbeds, emulators, or some simulations, the analysis of the effects of control plane delays is limited to a small range of values, applicable to well-specified contexts. Applying a very general control-delay representation, we are able to provide a wide-range simulative study to quantify the effect of sig naling on routing performance, mainly by using the blocking probability metric. We are able to evaluate the effect of outdated information (1) for a wide interval of control delay values, (2) for a large set of routing scenarios, considering, e.g., unprotected, dedica ted, and shared path protection routing, and (3) quan tifying the different delay effects in the absence or in the presence of wavelength conversion capabilities.

A novel approach to counter denial of service attacks against transport network resources

A new generation of optical transport networks (OTNs) and wavelength division multiplexing (WDM) networks is currently emerging. Their control plane for fast transport path creation, protection, and restoration is inevitable for cost effectiveness. Such automatically switched optical networks (ASONs) are susceptible to denial of service (DoS) attacks at their user network interface (UNI) and external network node interface (E-NNI) access points. Attacks against transport resources aim to prevent users from setting up transport connections, such as paths in OTNs or wavelengths in WDM networks. We present novel concepts for detecting such attacks and identifying the attackers, covering both 'simple' and distributed DoS (DDoS) attacks. We have analyzed a variety of potential attack scenarios by means of simulation to validate the detection methods and the framework for effectiveness. Our results indicate that the framework exhibits good detection rates for the DDoS attacks mentioned earlier. After discussing the problem and methods chosen to address it, we explain the results of our analysis.

Shared-path protection with extra traffic in ASON-GMPLS ring networks

We implement shared-path protection (SPP) with extra traffic in automatically switched optical network (ASON) rings provided with a generalized multiprotocol label switching (GMPLS) control plane. The protection time provided by the SPP scheme is analyzed as a function of the switching time of the wavelength-selective switches (WSS), the key components to building reconfigurable optical nodes. We demonstrate that the switching time of the currently available WSS prevents the protection of the complete set of affected label-switched paths (LSPs) within 50 ms after fault detection. Therefore, two alternative strategies can be considered, namely, (1) the definition of two classes of protection with different requirements in terms of protection time, and (2) a real-time mechanism to decide, on the basis of the current number of LSPs to protect, whether the protection scheme to apply is either at the path layer or at the link layer. When protecting at the path layer, part of the extra traffic will be saved, whereas all the extra traffic will be preempted when protecting at the link layer.

New transmission systems enabling transparent network perspectives

Abstract The emergence of new devices and technologies introduces new trends and design issues for optical transport networks. The higher performance of transmission and switch systems enables the reduction of optoelectronic conversions in intermediate nodes with the introduction of transparency in the network. Simultaneously, the system of Automatic Switched Optical Networks (ASON) describes the rules for the construction of a network enabling cost reduction, above all for maintenance, and fast and automatic reconfiguration. Two axes have to evolve to make possible all these proprieties: the control plane and its relative set of protocols, to manage the network working for the network automation, and also the systems and tools enabling transparency and reconfigurability. In this article we focus on the second axis applied to an automatic transparent network. To cite this article: A. Morea et al., C. R. Physique 9 (2008).

Evolving optical layer networking: What's happening on the ground

Optical bandwidth demands continue to increase, technology continues to advance, and the market continues to demand ever greater functionality at the optical layer. Starting with a discussion of the current market environment and the recovery of the optical industry from the bursting of the optical bubble, this paper will examine current trends in optical layer networking, including the technology supporting optical/data convergence and the development of digital wrappers via the Optical Transport Network as a vehicle to introducing manageable multiwavelength networks. The paper also examines automatically switched optical network (ASON)/generalized multiprotocol label switching (GMPLS) developments enabling dynamic transport networks.

Virtual Fiber Configuration for Dynamic Lightpath Establishment in Large-scaled Optical Networks

Recently, progress has been made in the Generalized Multi-Protocol Label Switching (GMPLS) and Automatic Switched Optical Networks (ASON) standardizations. These technologies realize construction of large-scaled optical networks, interconnections among single-domain Wavelength Division Multiplexing (WDM) networks, and direct communication over multi-domain WDM networks. Meanwhile, it is known that the topology of the Internet exhibits the power-law attribute. Since the topology of the Internet, which is constructed by interconnecting ASs, exhibits the power-law, there is a possibility that large-scale WDM networks, which are constructed by interconnecting WDM networks, will also exhibit the power-law attribute. One of the structural properties of a topology that adheres to the power-law is that most nodes have just a few links, although some have a tremendous number of them. Another property is that the average distance between nodes is smaller than in a mesh-like network. A natural question is how such a structural property performs in WDM networks. In this paper, we first investigate the property of the power-law attribute of physical topologies for WDM networks. We compare the performance of WDM networks with mesh-like and power-law topologies, and show that links connected to high-degree nodes are bottlenecks in power-law topologies. To relax this, we introduce a concept of virtual fiber, which consists of two or more fibers, and propose its configuration method to utilize wavelength resources more effectively. We compare performances of power-law networks with and without our method by computer simulations. The results show that our method reduces the blocking probabilities by more than one order of magnitude.

Recovery of the control plane after failures in ASON/GMPLS networks

A reliable control plane plays a crucial role in creating high-level services in the next-generation transport network based on the generalized multiprotocol label switching (GMPLS) or automatically switched optical networks (ASON) model. Approaches to control-plane survivability, based on protection, and restoration mechanisms, are examined. Procedures for the control plane state recovery are discussed, including link and node failure recovery

PHOTO: an efficient shared-path-protection strategy based on connection-holding-time awareness

Recent trends in bandwidth markets show that customers are tending to ask providers for a large bandwidth but for a limited amount of time to support new short-term bandwidth-hungry applications. In order to meet these new requirements, progress in network technologies (fast and reconfigurable switching equipment) and protocols [such as generalized multiprotocol label switching (GMPLS) and automatically switched optical network (ASON)] is paving the road towards flexible optical transport networks in which leasable circuits could be set up and released on a short-term basis. As a result, for dynamic traffic, the holding time of connection requests can be known in advance. The authors propose to exploit knowledge of connection holding time to design an efficient algorithm, called PHOTO, for the dynamic provisioning of shared-path-protected connections in optical mesh networks. The core idea of the proposal consists of exploiting the knowledge of the holding time of connection requests to minimize resource overbuild (RO) due to backup capacity and hence achieve resource-usage efficiency. For a typical US nationwide network, savings on RO of up to 10% were obtained for practical scenarios compared to a holding-time-unaware, but otherwise shared-path-efficient, approach.

On managing optical services in future control-plane-enabled IP/WDM networks

This paper presents the design and experimental implementation of a service-oriented Internet Protocol (IP)/wavelength division multiplexing (WDM) management plane. In the proposed approach, compliant with International Telecommunication Union Telecommunication Standardization Sector (ITU-T)'s automatic-switched optical network (ASON), a distributed control plane performs signaling, routing, and discovery functions, and a decentralized management plane, both at information and architectural levels, performs cross-plane actions to enforce service establishment and monitoring with a view to guarantee service level agreements (SLAs). In-service monitoring provides status of optical resources and services by using spectral- and time-domain information. Some performance aspects of the approach are evaluated in a real testbed featuring dense wavelength multiplexing and a control plane based on the Internet Engineering Task Force (IETF)'s generalized multiprotocol label switching (GMPLS).

A hierarchical routing approach for optical transport networks

Although the automatically switched optical networks (ASON) specifications strongly recommend a hierarchical network architecture for these networks, this is still an open issue. The hierarchical network concept involves several mechanisms mainly related with signaling and routing, such as the aggregation scheme, the dissemination process, the updating policy and the routing algorithms. The existing mechanisms for flat networks must be substantially modified to be applied to a hierarchical network architecture. In this paper, authors propose a complete hierarchical routing approach mainly focusing on routing concerns, aiming to optimize the global network performance while guaranteeing scalability.

GMPLS and ASON for automatic switched transport networks

In automatic switched transport networks (ASTN), transport services of different granularity can be set up, modified and released on demand, using mechanisms in the control plane. Currently, this novel provisioning paradigm is being standardized under the umbrella of the automatic switched optical network (ASON) and the generalized multiprotocol label switching (GMPLS) framework. This paper gives an overview of the concepts and open issues of ASON and GMPLS at the current stage of their development.

ASON and GMPLS—Overview and Comparison

In automatic switched transport networks (ASTN), transport services of different granularity can be set up, modified and released on demand using the mechanisms in the control plane. Currently, this novel provisioning paradigm is being standardized under the umbrella of the automatic switched optical network (ASON) and generalized multiprotocol label switching (GMPLS) framework. This paper provides an overview of the ASON and GMPLS frameworks at the current stage of their development and aims in particular on comparing the concepts and pointing out some open issues. In this context, we first give a brief overview of ASON and GMPLS work, and then provide a concept and functionality mapping including network resource models, control plane architecture, discovery, call and control management, and resiliency. Finally we address some important provider requirements.

PNNI-based control plane for automatically switched optical networks

Much effort has been spent on the definition of control plane protocols for automatically switched optical networks (ASON). Most of the proposals brought into the standardization for an International Telecommunications Union-Telecommunication Sector, Internet Engineering Task Force, and Optical Internetworking Forum are based on Internet protocol concepts. One such proposal is the generalized multi-protocol label switching (GMPLS), an extension of the MPLS traffic engineering control plane model that includes nonpacket switched technologies (time, wavelength, and fiber switching). Recently, the potential use of private network-network interface (PNNI) in ASONs has been discussed as an alternative proposal by the standardization bodies. The goal of this paper is to appropriately adapt asynchronous transfer mode into an optical PNNI (O-PNNI) protocol that can be used as the control plane of ASONs. The paper also provides a critical viewpoint on the potential usage of either O-PNNI or GMPLS control plane and analyzes the pros and cons of each. The methodology adopted toward devising O-PNNI hinges on reviewing PNNI along with ASON recommendations in order to determine the set of PNNI features that require adaptation. Having identified these features we engineer and present appropriate solutions relating to routing, signaling and addressing aspects.