Managing the management communications network in optical transport systems

Erbium-doped fiber amplifiers (EDFA’s) are now the basis for the design of a11 optical communication transport systems and networks.

United States, Europe and China is the emergence of the smart power grid construction, there is an urgent need to optimize the power optical fiber transmission network topology to meet the core services of the smart power grid reliability, real-time performance, connectivity, economy, etc. Combination analysis and evaluation methods of availability, network element ratio of optical path protection, resource use efficiency of the whole network and connectivity, grid "N-m", the six-node network topology as an example, optical fiber transport network topology optimization carrying the smart grid core services were researched. Normal optimal topology is nested linear and rings topology network. Optimal topology of high connectivity and reliability is rings topology in mesh network. The methods and results can guide the optimization of electric power optical fiber transport network topology.

Ethernet has evolved from a protocol for local area network transport to advanced carrier class metro transport as new features are brought in. Recently, industrial, automotive and 5G mobile fronthaul network applications have been addressed. Several new mechanisms are proposed and standardized, e.g. enabling deterministic latency. In light of 5G requirements, this paper reviews and discusses differences between Ethernet and ITU-T G.709 — Optical Transport Network OTN, and analyses Ethernet as an alternative to OTN for optical transport and access network applications.

DWDM optical transport network is the hotspot of the optical communications, the protection and restoration of the multiple wavelength optical transport network is the key technique in the DWDM optical transport network. In this paper, at first we introduce the concept of separate optical layer- the concept of separate optical layer has been demonstrated in some important experimental optical networks- and some advantages of the multiple wavelength optical transport networks, we also compare the DWDM optical transport networks with the SDH networks, put forward some analogies of them. The second, we analyzes the protection and restoration of the multiple wavelength optical networks, we analyze multiple fiber ring networks in detail, we analyze the span protection, line protection and path protection, discuss the advantage and the shortcoming of these different protection mode.

40-Gbit/s ETDM Channel Technologies for Optical Transport Network

Elastic optical network (EON) is a promising candidate for the next generation optical transport network because of its high spectrum efficiency and flexible spectrum allocation. However, to migrate from today’s dense wavelength division multiplexing (DWDM) network to EON, optical nodes such as reconfigurable optical add/drop multiplexers (ROADMs) should be replaced with the ones with expensive flexi-grid wavelength selective switches (WSSs). Thus, whether and how today’s optical network will be evolved to EON is still under debate. Meanwhile, with the technical maturity of optical super-channels that transmit bit rates at the level of 1 Tb/s, super-channels are expected to dominate the future optical transport network because of their attractiveness of high spectrum efficiency and superior cost effectiveness. In this paper, we propose a new quasi-coarse wavelength division multiplexing (Quasi-CWDM) optical network architecture that is compatible to today’s WDM network in spectrum operation, while still maintaining the flexibility of adaptation between the bit rate and the transparent reach of an optical super-channel, but not requiring expensive flexi-grid WSSs. Specifically, the Quasi-CWDM optical network employs large fixed frequency grids, whose spacing falls between the traditional CWDM and DWDM, e.g., 200 GHz or 400 GHz. To maintain the flexibility between the bit rate and the transparent reach of an optical super-channel, different modulation formats are chosen according to channel physical distances. To minimize network hardware cost and maximize carried user traffic demand, we develop a mixed integer linear programming (MILP) model and a heuristic algorithm that can efficiently groom upper-layer IP traffic onto the optical layer by optical super-channels. We compare the design based on the Quasi-CWDM network to those based on the DWDM network and the advanced EON. It is found that the proposed Quasi-CWDM network has a much lower hardware cost than the other two types of networks, while achieving spectrum efficiency close to EON.

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)

The volume of traffic carried on the Optical Transport Network (OTN) is continuously growing, not only due to the increase of new services, new applications, and the number of both connected users and smart devices, but also owing to the rapidly growing Data Center Interconnect (DCI) market. As a result, telecom operators need to upgrade their transport networks to cope with these new traffic requirements. This tremendous increase in bandwidth demand will also introduce energy bottlenecks in OTNs. The telecommunication networks' significant Greenhouse Gas Emissions (GGE) is another challenge that must be addressed in OTN design and planning policies. Thus, energy-efficient OTN architectures are currently attracting the attention of telecom operators. The candidate OTN architectures are: (1) the conventional Dense Wavelength Division Multiplexing (DWDM) fixed grid with high Single Line Rates (SLRs); (2) the conventional DWDM fixed grid adopting Mixed Line Rates (MLRs); and (3) the Elastic Optical Network (EON) or flexigrid-based architecture which is enabled by the Optical Orthogonal Frequency Division Multiplexing (O-OFDM) technique. This paper evaluates the power consumption of the abovementioned OTN architectures under different traffic loads and patterns, as well as different network physical topologies. In order to perform the evaluation, new heuristic algorithms are specifically developed for the green design and planning of data center optical interconnects.

The chapter discusses the security of the client signals over the optical network from any wiretapping or loosing. The physical layer of the optical transport network (OTN) is the weakest layer in the network; anyone can access the optical cables from any location and states his attack. A security layer is proposed to be added in the mapping of OTN frames. The detection of any intrusion is done by monitoring the variations in the optical signal to noise ratio (OSNR) by using intelligent software defined network. The signal cryptographic is done at the source and the destination only. The chapter shows how the multi-failure restorations in the multi-domains could be done. A new model is introduced by slicing the multi-domains to three layers to fit the needs of 5G. The results show that the multi-failure restoration improved from 25% to 100%, the revenue from some OTN domains increased by 50%, the switching time enhanced by 50%, the latency reduced from 27 msec to 742 usec, and it will take many years to figure out the right keys to perform the decryption process.

Due to widespread applications and rapid development of cloud computing and Internet services, hyperscale data centers have experienced an unprecedented demand for networking. Data center networks are required not only to handle fast-growing traffic, which doubles almost every one to two years, but also to provide high flexibility and availability to support rapidly changing businesses as well. Therefore, hyperscale data center networks have become one of the main drivers for optical interconnect technologies in recent years. In this article, technologies for scaling optical interconnects for inter-data center interconnects (DCIs) are presented. We first describe hyperscale data center network architectures and requirements, as well as the differences between carrier’s optical transport networks and DCI optical networks, with the main focus on metro-DCI and campus-DCI networks. The scale and fast growth rates of DCI networks require innovations not only in data plane technologies but also in control and management planes as well. In data planes, high-capacity flexible coherent technology, pluggable wavelength-division-multiplexing (WDM) optical transponders, including 100G direct-detection four-level pulse-amplitude modulation (PAM4) and coherent 400ZR/800ZR, and flex-grid and disaggregated reconfigurable optical add-drop multiplexer (ROADM) optical networks are described. Control and management planes are an integral part of optical transport networks and crucial for effectively operating DCI networks. We show that standard protocols, data models, and modular design of a software platform are essential to building a scalable open and disaggregated optical network, which is fundamental to enabling high automation and intelligence in an optical network. An example control and management platform is discussed in detail. With current fiber capacity approaching the nonlinear Shannon limit, challenges to further scale DCI networks and some potential technologies to support ever-increasing traffic growth are discussed at the end.

In recent years, the Optical Transport Network (OTN) systems have been introduced widely, however, wide adoption has been limited due to the immature infrastructural issues. The OTN infrastructure takes the responsibility of data and signal transmission for substratal layer, as well as provides carrying and maintaining services (mostly the IP-based traffic today) through an optical data transport control plane. Thus, this paper focuses on the latest OTN data control plane and therefore gives a comprehensive introduction on the integrated IP Optical peer control plane.

Based on the virtualization technique in optical networks, virtual transport network services (VTNS) has been introduced as a new kind of service in transport networks. With VTNS, transport providers are able to provide their customers entire virtual topologies instead of traditional end-to-end connections. This letter analyzes the new characteristics (i.e., multiple operators, diversified services) aiming at the survivability problem in virtualized optical transport networks, and proposes three novel protection schemes for VTNS against the new features. For the first time, VTNS with the proposed protection schemes are demonstrated on the flexi-grid optical networks testbed with commercial optical transport equipments. Additionally, the performances of the proposed protection schemes have been evaluated via simulations.

The increasing traffic demand resulting from the widespread use of information and communication technologies is impelling network operators to upgrade the capacity of their existing transport network facilities. Recent advances in the scientific community have led to the first developments in serial 100 Gb/s technology that could provide an adequate solution for solving the capacity expansion problem. Nevertheless, given the complexity of 100 Gb/s transceiver equipment, the initial costs may refrain early adoption of the technology, leading carriers to invest in more cost-effective alternatives. Embedded in the optical transport network (OTN) functionality portfolio, traffic grooming and virtual concatenation can be exploited in order to optimally combine 40 Gb/s and 100 Gb/s equipment for supporting mixed line rate (MLR) demands. Hence, this work proposes an optimization framework for designing optical transport infrastructures with the objective of minimizing the network costs directly related to transceiver and regenerator equipment. The framework models the problem via an integer linear programming formulation that takes into account the relative cost, the maximum optical reach, and the capacity of each optical interface, as well as the optical channel limit per fiber link. As a result, the proposed method is able to select the equipment type and the routing path for each connection which correspond to the most cost-effective solution satisfying the 100G and 40G service demands.

The technical advances in wavelength division multiplexing (WDM) techniques has made possible the introduction of optical technology into the path layer of the transport network. Besides the significant improvement in the transmission capacity, WDM technology allows the accomplishment of routing and switching functions directly in the optical domain. Thus Optical Cross-Connects (OXCs) can be realized with a throughput of a few hundreds of Gbit/s, so removing the bottleneck placed by electronic technology. The transport network node can be designed as an OXC interfacing a Digital Cross-Connect (DXC). Multi-Gigabit signals are directly routed in the optical network layer by the OXCs, while the DXCs provide demultiplexing to lower digital hierarchies and routing at the electrical level. The optical path layer can be designed so as to be transparent to the signal transmission format and speed. The aim of this paper is to assess the feasibility of transmitting sub-carrier multiplexed CATV channels in this optical path layer, by analysing the performance of the following transmission path: the CATV channels are generated in a production center, cross a geographical area through a transport network and an optical ring of a regional network, down to the access network and then to the customer.

Data security plays a crucial role in healthcare monitoring systems, since critical patient information is transacted over the Internet, especially through wireless devices, wireless routes such as optical wireless channels, or optical transport networks related to optical fibers. Many hospitals are acquiring their own metro dark fiber networks for collaborating with other institutes as a way to maximize their capacity to meet patient needs, as sharing scarce and expensive assets, such as scanners, allows them to optimize their efficiency. The primary goal of this article is to develop of an attack detection model suitable for healthcare monitoring systems that uses internet protocol (IP) virtual private networks (VPNs) over optical transport networks. To this end, this article presents the vulnerabilities in healthcare monitoring system networks, which employ VPNs over optical transport layer architecture. Furthermore, a multilayer network architecture for closer integration of the IP and optical layers is proposed, and an application for detecting DoS attacks is introduced. The proposed application is a lightweight implementation that could be applied and installed into various remote healthcare control devices with limited processing and memory resources. Finally, an analytical and focused approach correlated to attack detection is proposed, which can also serve as a tutorial oriented towards even nonprofessionals for practical and learning purposes.