Optical transport network

We consider meshed optical transport networks having multiple levels of hierarchy whereby cross-connects in different levels perform multiplexing and demultiplexing functions at different granularities. We present a traffic grooming approach that can be implemented in a centralized or distributed fashion, based on the novel design that takes advantage of algorithm efficiency and a simple threshold mechanism to decide when grooming is economical. Our approach allows nodes to perform grooming and degrooming automatically, which is desired in the next-generation optical network where circuits are setup and torn-down dynamically through signaling. We present several experiments using different network topologies. The results indicate that the flow pattern influences the port requirement behavior, and that the flow thickness influences the optimal value of the threshold.

We present a new optics-based transport architecture that emulates fast switching in the network core via emerging fast tunable lasers at the network edge, and bypasses the need for fast optical switching and buffering. The new architecture is capable of handling both asynchronous and synchronous traffic, for dealing with various bandwidth granularities and responding to dynamic changes in end-to-end traffic demands. The architecture also reduces the amount of layering in the transport network by eliminating packet and TDM switching, keeps the network corc light (lightweight and transparent), and pushes intelligence to the network edge. We discuss technical challenges that arise in the new architecture and describe possible approaches to address them.

The emergence of new telematic applications and services is creating significant growth in the traffic carried over the optical transport network (OTN). One potential cost-effective approach for satisfying these demands consists in applying inverse-multiplexing techniques, such as virtual concatenation (VCAT). In this context, efficient load balancing can be achieved by exploiting multipath routing at the cost of introducing differential delay in the concatenated circuits. This effect can be compensated through appropriate delay compensation techniques (e.g., electrical buffering), which can act either in a centralized way with the buffering at the end nodes, or by distributing the differential delay throughout the intermediate nodes. In order to properly solve the routing and differential delay compensation distribution problem in the OTN, we propose two novel methods: a dual-step integer linear programming (ILP) model and a tabu search multi-stage heuristic. These strategies are compared with our two former proposals consisting of a single-step ILP model and an iterative search heuristic. The four solutions are further expanded to consider the possibility of using homogeneous or heterogeneous VCAT. The performance of these optimization methods is examined in two network topologies assuming that 100 Gb/s Ethernet streams are carried over 40 Gb/s channels (homogeneous case) or over a mixed combination of 40 Gb/s and 10 Gb/s channels (heterogeneous case) in the OTN. The results obtained show that, as expected, the smallest buffering requirements are obtained by both ILP models, with the dual-step version exhibiting also a significant reduction in the number of optical-to-electrical and electrical-to-optical operations used for intermediate compensation. In addition, the novel tabu search framework is able to surpass our former heuristic by simultaneously leveraging minimum link capacities and reducing the buffer sizes.

In designing the backbone network for the province of East Kalimantan using Dense Wavelength Division Multiplexing (DWDM) and Optical Transport Network (OTN) devices which cover 10 districts and cities consisting of 34 segments, of which 34 segments consist of 10 OTN DWDM sites and 16 Optical Land Amplifier sites ( OLA). From the results of the design and simulation of the backbone network, it was found that the value of the Optical Link Power Budget (OLPB) < 50 dBm where this value is the ideal value in deploying a DWDM OTN backbone network, and the range of the Optical Signal Noise Ratio (OSNR) is between 20 dBm < OSNR < 40 dBm, which is the ideal value for OSNR, and has an Optical Rise Time Budget (ORTB) < 60 ps, and also has a segment margin system of > 7 dB.

In designing the backbone network for the province of West Kalimantan using Dense Wavelength Division Multiplexing (DWDM) and Optical Transport Network (OTN) devices which cover 14 districts and cities consisting of 30 segments, of which 30 segments consist of 14 DWDM OTN sites and 8 Optical Land Amplifier sites ( OLA). From the results of the design and simulation of the backbone network, it was found that the value of the Optical Link Power Budget (OLPB) < 50 dBm where this value is the ideal value in deploying a DWDM OTN backbone network, and the range of the Optical Signal Noise Ratio (OSNR) is between 20 dBm < OSNR < 40 dBm, which is the ideal value for OSNR, and has an Optical Rise Time Budget (ORTB) < 60 ps, and also has a segment margin system of > 7 dB.

The layered network modelling, as defined in ITU G.805 [1], provides a means to describe, in a uniform way, the information transfer capability of the different transport networks, as well as, to deal with the inter-working and the management interoperability between the different transport networks. It provides a means to describe the network functionality in an abstract way in terms of a small number of architectural components. The layering and partitioning concepts are used for the definition of the transport network layered architectures of the existing SDH network in G.803, and for the SDH-based ATM network defined in 1.311. They are also applied to the optical transport networks. The standardisation of the layered architecture model for the optical networks described in ITU G.otn [2] is currently in progress, and some other models [4], [6] are also introduced. So far, the architecture proposed deals with the optical path network [6], which is characterised by the combination of WDM transmission and the wavelength routing. The management of the optical path network is also in the scope of the project MOON (Management 2f Optical ~etworks). MOON is one of the EC's ACTS projects with a task to establish a conceptual TMN framework for the management of all-optical WDM transport networks and to demon-This work was supported in part by the European Commission. The contents of this paper is solely the responsibility of the authors.

In this paper we study different options for the survivability implementation in MPLS over Optical Transport Networks (OTN) in terms of network resource usage and configuration cost. We investigate two approaches to the survivability deployment: single layer and multilayer survivability and present various methods for spare capacity allocation (SCA) to reroute disrupted traffic. The comparative analysis shows the influence of the traffic granularity on the survivability cost: for high bandwidth LSPs, close to the optical channel capacity, the multilayer survivability outperforms the single layer one, whereas for low bandwidth LSPs the single layer survivability is more cost-efficient. For the multilayer survivability we demonstrate that by mapping efficiently the spare capacity of the MPLS layer onto the resources of the optical layer one can achieve up to 22% savings in the total configuration cost and up to 37% in the optical layer cost. Further savings (up to 9 %) in the wavelength use can be obtained with the integrated approach to network configuration over the sequential one, however, at the increase in the optimization problem complexity. These results are based on a cost model with actual technology pricing and were obtained for networks targeted to a nationwide coverage.

The Compressed Baryonic Matter (CBM) experiment is a part of the Facility for Antiproton and Ion Research (FAIR) in Darmstadt at the GSI. The CBM experiment will investigate the highly compressed nuclear matter using nucleus-nucleus collisions. This experiment will examine heavy-ion collisions in fixed target geometry and will be able to measure hadrons, electrons and muons. CBM requires precise time synchronization, compact hardware, radiation tolerance, self-triggered front-end electronics, efficient data aggregation schemes and capability to handle high data rate (up to several TB/s). As a part of the implementation of read out chain of MUCH in India, we have tried to implement FPGA based emulator of GBTx in India. GBTx is a radiation tolerant ASIC that can be used to implement multipurpose high speed bidirectional optical links for high-energy physics (HEP) experiments and is developed by CERN. GBTx will be used in highly irradiated area and more prone to be affected by multi bit error. To mitigate this effect instead of single bit error correcting RS code we have used two bit error correcting (15, 7) BCH code. It will increase the redundancy which in turn increases the reliability of the coded data. So the coded data will be less prone to be affected by noise due to radiation. Data will go from detector to PC through multiple nodes through the communication channel. In order to make the data communication secure, advanced encryption standard (AES-a symmetric key cryptography) and RSA (asymmetric key cryptography) are used after the channel coding. We have implemented GBTx emulator on two Xilinx Kintex-7 boards (KC705). One will act as transmitter and other will act as receiver and they are connected through optical fiber through small form-factor pluggable (SFP) port. We have tested the setup runtime using Xilinx Chipscope Pro Analyzer. Also measure the resource utilization, throughput, power optimization of implemented design.

The compensation of intra-channel nonlinear effects in a CSRZ 40 Gbit=s 32 Â 100 km system using an LiNbO 3 optical phase conjugator in a re-entrant, recirculating loop architecture, is experimentally demonstrated. Two decades of improvement in the bit error rate at 3200 km with phase conjugation has been achieved. Also, the performance of CSRZ and RZ-DPSK modulation formats at 3200 km with and without optical phase conjugation is compared.

With the rapid development of 5G technology, its network architecture has changed a lot compared with 4G, which brings many challenges to optical transport network. In this paper, we first discuss the network architecture difference between 4G and 5G. Then, we investigate the optical transport schemes of 5G network, including fronthaul schemes, middlehaul schemes and backhaul schemes, respectively.

Abstract—The main issue in the optical transmission is switching speed. The optical packet switching faces many significant challenges in processing and buffering. The generalized multilevel protocol switching seeks to eliminate the asynchronous transfer mode and synchronous optical ...

Flexible optical networking is identified today as the solution that offers smooth system upgradability towards Tb/s capacities and optimized use of network resources. However, in order to fully exploit the potentials of flexible spectrum allocation and networking, the development of a flexible switching node is required capable to adaptively add, drop and switch tributaries with variable bandwidth characteristics from/to ultra-high capacity wavelength channels at the lowest switching granularity. This paper presents the main concept and technology solutions envisioned by the EU funded project FOX-C, which targets the design, development and evaluation of the first functional system prototype of flexible adddrop and switching cross-connects. The key developments enable ultra-fine switching granularity at the optical subcarrier level, providing end-to-end routing of any tributary channel with flexible bandwidth down to 10Gb/s (or even lower) carried over wavelength superchannels, each with an aggregated capacity beyond 1Tb/s.

We propose and implement a network virtualization architecture for open optical (partially) disaggregated networks, based on a device hypervisor and OpenConfig and OpenROADM data models, in support of 5G network slicing over interconnected NFVI-PoPs.

We propose and demonstrate a WDM access network with downstream OFSK data and upstream OOK data. A simple and low-cost optical network unit is realized by re-modulating the downstream optical signal power with the upstream data; and the transmission performance is experimentally characterized.

We experimentally demonstrate a novel optical physical-layer network coding scheme over a time-division multiplexing passive optical network. Full-duplex error-free communications between optical network units (ONUs) at 2.5 Gb/s are shown for all-optical virtual private network (VPN) applications. Compared to the conventional half-duplex communications setup, our scheme can increase the capacity by 100% with a power penalty smaller than 3 dB. Synchronization of ONUs is not required for the proposed VPN scheme.

The aim of this paper is to move away from today's multi-tier, manually operated, and performance limited Data Centre Network (DCN) towards more scalable, flexible, and optimized architecture of tomorrow. We propose a new hybrid optical DCN architecture capable of providing a fully optical interconnection path from server to server within racks and between racks utilizing fast packet switching at the aggregation layer, and high-capacity and low latency circuit switching at the core layer. We have built the DCN control plane upon the Software Defined Networks (SDN) paradigm to leverage the added value of emerging optical technologies for providing flexible and programmable heterogeneous IT and network service. Dynamicity, flexibility, and resiliency are combined in the propose infrastructure to offer advanced services to the data centre providers in order to fulfil the requirements of upcoming applications.

As the demand for fiber optical data transmission systems and other type of applications, which require optical media, like optical sensing increases, the unauthorized parties are becoming increasingly interested in such systems. Also, with such demand, more complex optical systems are required; thus, the network infrastructure is becoming more crowded. It is vital to economize on the available resources and infrastructure to ensure the needs of all interested business, governmental or end-user sides. Therefore, the present research focuses on the development of a unified hybrid optical system. The developed hybrid optical transmission system adds additional protection to the channels, allows for the unification of standard optical data transmission channels, optical sensors and spectrally hidden data transmission channel systems, and increases the efficiency of the optical components used.

The emergence of new telematic applications and services is creating significant growth in the traffic carried over the optical transport network (OTN). One potential cost-effective approach for satisfying these demands consists in applying inverse-multiplexing techniques, such as virtual concatenation (VCAT). In this context, efficient load balancing can be achieved by exploiting multipath routing at the cost of introducing differential delay in the concatenated circuits. This effect can be compensated through appropriate delay compensation techniques (e.g., electrical buffering), which can act either in a centralized way with the buffering at the end nodes, or by distributing the differential delay throughout the intermediate nodes. In order to properly solve the routing and differential delay compensation distribution problem in the OTN, we propose two novel methods: a dual-step integer linear programming (ILP) model and a tabu search multi-stage heuristic. These strategies are compared with our two former proposals consisting of a single-step ILP model and an iterative search heuristic. The four solutions are further expanded to consider the possibility of using homogeneous or heterogeneous VCAT. The performance of these optimization methods is examined in two network topologies assuming that 100 Gb/s Ethernet streams are carried over 40 Gb/s channels (homogeneous case) or over a mixed combination of 40 Gb/s and 10 Gb/s channels (heterogeneous case) in the OTN. The results obtained show that, as expected, the smallest buffering requirements are obtained by both ILP models, with the dual-step version exhibiting also a significant reduction in the number of optical-to-electrical and electrical-to-optical operations used for intermediate compensation. In addition, the novel tabu search framework is able to surpass our former heuristic by simultaneously leveraging minimum link capacities and reducing the buffer sizes.

Wavelength division multiplexing (WDM) technology offers a large bandwidth for optical fibers to carry both today's Internet traffic and that of the future. Lightpath networks, where all-optical wavelength channels (called lightpaths) convey the traffic, have been considered to effectively utilize this WDM technology. There are two approaches to establishing lightpaths; the first is centralized and the second is distributed. In distributed lightpath networks, each node sets up and tears down the lightpath between a pair of communicating nodes. Therefore, conflicts about wavelength reservations during signaling operations may occur because of a lack of precise linkstate information. A great deal of research has been devoted to avoiding conflicts to provide more efficient operating methods, i.e., reservation protocols, and routing and wavelength assignment

This paper evaluates multi-layer switching architecture vs. all-optical and all-digital switching architectures. Further, the value of incorporating super-channels is evaluated to determine benefit. A real world network model is utilized to quantify and compare results.

Bandwidth efficiency for 100Gb/s WDM and switch architectures are compared in a North American long-haul network. Results show that OTN grooming utilizes fewest WDM wavelengths, and integrated WDM/switch architecture utilizes fewest client service interfaces.

As the capacity of optical transport networks increases, rapid fault identification and localization become increasingly important. These problems are more challenging than in traditional electronic networks because of optical transparency. In a transparent optical network which does not regenerate optical signals, a fault may propagate to various parts of the network from the origin, and multiple alarms can be generated for a single failure. Efficient alarm management and filtering requires a careful selection and placement of network monitoring equipment. In this paper, we survey the capabilities of current optical monitoring equipment and formulate a problem of selecting monitors to be placed throughout the network. Simulation results suggest that the number of monitors and generated alarms can be significantly reduced if monitor locations are selected judiciously.

The Software Defined Network (SDN) is an established network paradigm, architecture and principles, that attracted significant research effort in recent years. An SDN-enabled infrastructure decouples network control from forwarding and enables direct programming. Recently, there is an increasing effort to introduce SDN support in the transport layers of the network operators WAN infrastructure, like Layer 0 (WDM & DWDM) and Layer 1 (SONET/SDH & OTN) technologies. We refer to this infrastructure as the "Software Defined Transport Network", and benefits include network management devolvement, timely connectivity provision, improved scalability, and open and flexible programmability using well-defined API. This paper outlines the main elements of Software Defined Transport Networks and highlights relevant Application-Based Network Operations (ABNO) enabling technologies. We demonstrate how this technology will benefit network operators, and provide an overview of research results and deployment examples. Finally, we identify some of the technology gaps and future research opportunities.

The emergence of new telematic applications and services is creating significant growth in the traffic carried over the optical transport network (OTN). One potential cost-effective approach for satisfying these demands consists in applying inverse-multiplexing techniques, such as virtual concatenation (VCAT). In this context, efficient load balancing can be achieved by exploiting multipath routing at the cost of introducing differential delay in the concatenated circuits. This effect can be compensated through appropriate delay compensation techniques (e.g., electrical buffering), which can act either in a centralized way with the buffering at the end nodes, or by distributing the differential delay throughout the intermediate nodes. In order to properly solve the routing and differential delay compensation distribution problem in the OTN, we propose two novel methods: a dual-step integer linear programming (ILP) model and a tabu search multi-stage heuristic. These strategies are compared with our two former proposals consisting of a single-step ILP model and an iterative search heuristic. The four solutions are further expanded to consider the possibility of using homogeneous or heterogeneous VCAT. The performance of these optimization methods is examined in two network topologies assuming that 100 Gb/s Ethernet streams are carried over 40 Gb/s channels (homogeneous case) or over a mixed combination of 40 Gb/s and 10 Gb/s channels (heterogeneous case) in the OTN. The results obtained show that, as expected, the smallest buffering requirements are obtained by both ILP models, with the dual-step version exhibiting also a significant reduction in the number of optical-to-electrical and electrical-to-optical operations used for intermediate compensation. In addition, the novel tabu search framework is able to surpass our former heuristic by simultaneously leveraging minimum link capacities and reducing the buffer sizes.

This paper reports a FPGA-based Switch and Interface Card (SIC) and its application scenario in an all-optical, programmable disaggregated Data Centre Network (DCN). Our novel SIC is designed and implemented to replace traditional optical Network Interface Cards (NICs), plugged into the server directly, supporting Optical Packet Switching (OPS)/ Optical Circuit Switching (OCS) or Time Division Multiplexing (TDM)/ Wavelength Division Multiplexing (WDM) traffic on demand. Placing the SIC in each server/blade, we eliminate electronics from the top of rack (ToR) switch by pushing all the functionality on each blade while enabling direct intra-rack blade-to-blade communication to deliver ultra-low chip-to-chip latency. We demonstrate the disaggregated DCN architecture scenarios along with all-optical dimension-programmable N×M Spectrum Selective Switches (SSS) and an Architecture-on-Demand (AoD) optical backplane. OPS and OCS complement each other as do TDM and WDM, which can support variable traffic flows. A flat disaggregated DCN architecture is realized by connecting the optical ToR switches directly to either an optical Top of Cluster (ToC) switch or the intra-cluster AoD optical backplane, while clusters are further interconnected to an inter-cluster AoD for scaling out.

The emergence of new telematic applications and services is creating significant growth in the traffic carried over the optical transport network (OTN). One potential cost-effective approach for satisfying these demands consists in applying inverse-multiplexing techniques, such as virtual concatenation (VCAT). In this context, efficient load balancing can be achieved by exploiting multipath routing at the cost of introducing differential delay in the concatenated circuits. This effect can be compensated through appropriate delay compensation techniques (e.g., electrical buffering), which can act either in a centralized way with the buffering at the end nodes, or by distributing the differential delay throughout the intermediate nodes. In order to properly solve the routing and differential delay compensation distribution problem in the OTN, we propose two novel methods: a dual-step integer linear programming (ILP) model and a tabu search multi-stage heuristic. These strategies are compared with our two former proposals consisting of a single-step ILP model and an iterative search heuristic. The four solutions are further expanded to consider the possibility of using homogeneous or heterogeneous VCAT. The performance of these optimization methods is examined in two network topologies assuming that 100 Gb/s Ethernet streams are carried over 40 Gb/s channels (homogeneous case) or over a mixed combination of 40 Gb/s and 10 Gb/s channels (heterogeneous case) in the OTN. The results obtained show that, as expected, the smallest buffering requirements are obtained by both ILP models, with the dual-step version exhibiting also a significant reduction in the number of optical-to-electrical and electrical-to-optical operations used for intermediate compensation. In addition, the novel tabu search framework is able to surpass our former heuristic by simultaneously leveraging minimum link capacities and reducing the buffer sizes.

The high-quality telecommunications services demand has grown considerably due to the increase in the number of applications on the Internet. Optical networks are the most suitable technology to supply the high transmission rates required. With the expansion of the optical communications market, businesses related to this industry started to attract more innovation investments in this area. Optical Transport Network (OTN) arrived in the communications market bringing economic and operational benefits of virtualization to the optical network. This technology works as a superior layer to the DWDM (Dense Wavelength Division Multiplexing) network, allowing more efficient resource use. OTN switching decouples customers from DWDM line interfaces, ensuring that DWDM links work as efficiently as possible, thus avoiding wasted transmission bandwidth. This concept is carried out on a network of OTN switches, allowing traffic to be aggregated at intermediate nodes and directed to routes that are being underutilized. Planning OTN networks over DWDM is a complex problem, as it involves a whole new equipment structure and logical architecture. This problem has arisen due to academia and industry's interest in developing planning heuristics that reduce the cost of projects. This paper proposes planning OTN networks over DWDM to minimize the cost with line interfaces while meeting resilience requirements. This paper proposes to use a multi-objective evolutionary algorithm to seek a solution that optimizes the project considering conflicting decision variables, the number of used OTN interfaces, and the restoration failure rate. The experiments carried out in this work showed that the proposed solution, when evaluated in several scenarios, obtained better results concerning the number of interfaces allocated compared with previous heuristic algorithms developed with the same objective.

In designing the backbone network for the province of East Kalimantan using Dense Wavelength Division Multiplexing (DWDM) and Optical Transport Network (OTN) devices which cover 10 districts and cities consisting of 34 segments, of which 34 segments consist of 10 OTN DWDM sites and 16 Optical Land Amplifier sites (OLA). From the results of the design and simulation of the backbone network, it was found that the value of the Optical Link Power Budget (OLPB) < 50 dBm where this value is the ideal value in deploying a DWDM OTN backbone network, and the range of the Optical Signal Noise Ratio (OSNR) is between 20 dBm < OSNR < 40 dBm, which is the ideal value for OSNR, and has an Optical Rise Time Budget (ORTB) < 60 ps, and also has a segment margin system of > 7 dB.

In designing the backbone network for the province of East Kalimantan using Dense Wavelength Division Multiplexing (DWDM) and Optical Transport Network (OTN) devices which cover 10 districts and cities consisting of 34 segments, of which 34 segments consist of 10 OTN DWDM sites and 16 Optical Land Amplifier sites (OLA). From the results of the design and simulation of the backbone network, it was found that the value of the Optical Link Power Budget (OLPB) < 50 dBm where this value is the ideal value in deploying a DWDM OTN backbone network, and the range of the Optical Signal Noise Ratio (OSNR) is between 20 dBm < OSNR < 40 dBm, which is the ideal value for OSNR, and has an Optical Rise Time Budget (ORTB) < 60 ps, and also has a segment margin system of > 7 dB.

In designing the backbone network for the province of West Kalimantan using Dense Wavelength Division Multiplexing (DWDM) and Optical Transport Network (OTN) devices which cover 14 districts and cities consisting of 30 segments, of which 30 segments consist of 14 DWDM OTN sites and 8 Optical Land Amplifier sites (OLA). From the results of the design and simulation of the backbone network, it was found that the value of the Optical Link Power Budget (OLPB) < 50 dBm where this value is the ideal value in deploying a DWDM OTN backbone network, and the range of the Optical Signal Noise Ratio (OSNR) is between 20 dBm < OSNR < 40 dBm, which is the ideal value for OSNR, and has an Optical Rise Time Budget (ORTB) < 60 ps, and also has a segment margin system of > 7 dB.

In designing the backbone network for the province of West Kalimantan using Dense Wavelength Division Multiplexing (DWDM) and Optical Transport Network (OTN) devices which cover 14 districts and cities consisting of 30 segments, of which 30 segments consist of 14 DWDM OTN sites and 8 Optical Land Amplifier sites ( OLA). From the results of the design and simulation of the backbone network, it was found that the value of the Optical Link Power Budget (OLPB) &lt; 50 dBm where this value is the ideal value in deploying a DWDM OTN backbone network, and the range of the Optical Signal Noise Ratio (OSNR) is between 20 dBm &lt; OSNR &lt; 40 dBm, which is the ideal value for OSNR, and has an Optical Rise Time Budget (ORTB) &lt; 60 ps, and also has a segment margin system of &gt; 7 dB.

In designing the backbone network for the province of East Kalimantan using Dense Wavelength Division Multiplexing (DWDM) and Optical Transport Network (OTN) devices which cover 10 districts and cities consisting of 34 segments, of which 34 segments consist of 10 OTN DWDM sites and 16 Optical Land Amplifier sites ( OLA). From the results of the design and simulation of the backbone network, it was found that the value of the Optical Link Power Budget (OLPB) &lt; 50 dBm where this value is the ideal value in deploying a DWDM OTN backbone network, and the range of the Optical Signal Noise Ratio (OSNR) is between 20 dBm &lt; OSNR &lt; 40 dBm, which is the ideal value for OSNR, and has an Optical Rise Time Budget (ORTB) &lt; 60 ps, and also has a segment margin system of &gt; 7 dB.

Space division multiplexing (SDM) has been proposed as the ultimate solution to address the capacity crunch of optical transport networks. The efficient utilization of SDM requires some forms of spatial integration which is expected to bring huge cost savings for the deployment of SDM-based optical networks. Spatially integrated components with different characteristics have been largely explored and demonstrated for the realization of SDM networks, including; transmission media, transceivers with sophisticated digital signal processing (DSP) units, amplifiers, and ultimately optical switching nodes which are the key elements for the realization of transparent optical networks exploiting SDM technologies. As a consequence, in contrast to the currently deployed optical networks based on standard single mode fibers (SSMF), the next generation of optical networks exploiting SDM technologies can be realized utilizing various kinds of transmission media and the other corresponding elements. However, due in part to the physical properties of different components, their complexity, and the technology limitations not all of them meet the economic feasibility and a desired level of network-wide performance. Therefore, careful analysis should be done revealing the most appropriate and costeffective solutions. In this work, we review the recent developments and findings which pave the way for a simplified and efficient implementation of the spectrally and spatially flexible optical networks.

Recently, the importance of out-of-band signaling has been realized for next-generation intelligent optical transport networks (OTNs). This next-generation OTN will be capable of providing services like real-time point-and-click provisioning of optical channels, automatic protection and restoration, network topology auto-discovery, and bandwidth management. However, for successful deployment and usage of these services, reliability of the out-of-band signaling network, referred to as the control and communication network (CCN), is critical. Specifically, it is desired that the signaling network transparently recover from any single failure events and continue providing communication between OTN nodes. In this paper, we propose a fault-tolerant, scalable, and cost-effective architecture for IP-based control plane of next-generation OTNs. The architecture is based on multiprotocol label switching (MPLS) protocols. The essence is to provide diverse paths in the network so that any failure in the OTN, as well as the control network, can be recovered transparently. These diverse paths employ a packet dual-feed and select mechanism for fast recovery from failures. The architecture requires diverse paths between the neighboring OTN nodes, instead of all-pair of nodes, enabling the control plane to seamlessly scale with the size of the OTN network. Moreover, the architecture allows the control plane topology to be independent of the OTN topology. This gives operators considerable flexibility in the design of the CCN in a cost-effective manner by using virtual private networks (VPNs) through public data networks, or by avoiding unnecessary OTN links. We also present an implementation of the proposed architecture that will be used as the highly reliable IP-based CCN in OTNs consisting of the Lucent LambdaRouter, an optical cross-connect product. Although in this paper the architecture is discussed in the context of providing a highly reliable IP-centric CCN for optical cross-connect-based (OXC-based) OTNs, it can be extended to a general purpose fault-tolerant CCN for any nextgeneration OTN.

Evaluation of availability and unavailability of optical connections is necessary for WDM optical networks to make efficient use of optical resources. The design of a protection scheme that improves the availability of high priority optical connections is a major challenge faced by optical network operators. This paper deals with the general protection scheme in WDM optical networks and it provides the mathematical formulation to evaluate the availability/unavailability of protected optical connections. General link failure scenarios are taken into account considering that a link failure affects all the optical connections routed on that link. We have performed some numerical tests and their results are presented to investigate the availability and unavailability degrees for different number of protections.

This paper reports a FPGA-based Switch and Interface Card (SIC) and its application scenario in an all-optical, programmable disaggregated Data Centre Network (DCN). Our novel SIC is designed and implemented to replace traditional optical Network Interface Cards (NICs), plugged into the server directly, supporting Optical Packet Switching (OPS)/ Optical Circuit Switching (OCS) or Time Division Multiplexing (TDM)/ Wavelength Division Multiplexing (WDM) traffic on demand. Placing the SIC in each server/blade, we eliminate electronics from the top of rack (ToR) switch by pushing all the functionality on each blade while enabling direct intra-rack blade-to-blade communication to deliver ultra-low chip-to-chip latency. We demonstrate the disaggregated DCN architecture scenarios along with all-optical dimension-programmable N×M Spectrum Selective Switches (SSS) and an Architecture-on-Demand (AoD) optical backplane. OPS and OCS complement each other as do TDM and WDM, which can support variable traffic flows. A flat disaggregated DCN architecture is realized by connecting the optical ToR switches directly to either an optical Top of Cluster (ToC) switch or the intra-cluster AoD optical backplane, while clusters are further interconnected to an inter-cluster AoD for scaling out.

With wide deployment of optical transport networks and the emergence of bandwidthintensive applications, the idea of multicasts and groupcasts in optical networks stems from the ability to set up optical point-to-multipoint (multicast) and multipoint-to-multipoint (groupcast) sessions in wavelength-routed networks. As the technology for intelligent optical networks grows, optical groupcast applications (such as grid computing, distributed interactive simulations, multimedia-rich interactive services, virtual private network services, personalcustomized content authoring services, and Ethernet LAN services) will become widely popular. In this paper we introduce the concept of groupcast routing and wavelength assignment (GC-RWA) and evaluate the performance of GC-RWA for light-forests corresponding to the groupcast sessions, when these lightforests are composed of lightpaths and light-trees.

This document provides a security framework for the MPLS Transport Profile (MPLS-TP). MPLS-TP extends MPLS technologies and introduces new Operations, Administration, and Maintenance (OAM) capabilities, a transport-oriented path protection mechanism, and strong emphasis on static provisioning supported by network management systems. This document addresses the security aspects relevant in the context of MPLS-TP specifically. It describes potential security threats as well as mitigation procedures related to MPLS-TP networks and to MPLS-TP interconnection to other MPLS and GMPLS networks. This document is built on RFC 5920 ("Security Framework for MPLS and GMPLS Networks") by providing additional security considerations that are applicable to the MPLS-TP extensions. All the security considerations from RFC 5920 are assumed to apply.

The physical layer of the Optical Transport Network (OTN) is the weakest layer in the network, as anyone can access the optical cables from any unauthorized location of the network and stat his attack by using any type of the vulnerabilities. The paper discusses the future role of the machine learning technology in the detection of the security threats and the automatic response to overcome the security challenges in the Egyptian optical network and it presents a new proposed model for the threats detection and the response to protect the client's data on the physical layer of the optical network. The detections of the threats in the optical network will be done in our model by proposing learning algorithms from the continuous variations in the optical signal to noise ratio (OSNR) over the entire network and at the same time according to the past experiences of the proposed model it will decide if this variations are threats or normal attenuations on the optical cables. The response will be done by distributing the triggers for the encryption keys between the network elements according to the decisions of the intrusion detection system of the machine learning techniques. A new security layer will be established to the OTN frames in the infected sections only. The design of the proposed security model is done by using a structure of XOR, a Linear Feedback Shift Register (LFSR), Random Number Generator (RNG) associated with different techniques of learning algorithms, and expert system for the threats in the optical network. We propose the security model for different rates in the OTN and wavelength division multiplexing (WDM) system. The proposed model is implemented on the basis of protecting the infected sections in the physical layer only over the optical network by passing these signals into extra layer called security layer, and before forming the final frame of the OTN system, this done according to the decisions of our proposed security learning algorithms in the management layer of the optical network. The results show that using machine learning techniques in the proposed model of the OTN encryption scheme is providing a high security against any wiretapping attack and reduces the huge cost of implementing complete security algorithms over all the network sections without any benefits. Although the proposed model of the intrusion detection and response systems in the optical network will be implemented on the infected sections only the attacker who has the ability to access the fiber cables from any unauthorized location, will affect the OSNR value and as a consequences the system will detect this difference in the

Today Energy Consumption is one of the fundamental topics also for telecommunication networks. In this paper, we report a numerical investigation about energy saving in a transport network both exploiting the transmission properties that permit to reduce 3R equipments and reducing optical links during low traffic periods.

This paper focuses on the energy consumption minimization problem of an optical transport network extending over a very wide area. In particular, the specific problem of power-aware routing and wavelength assignment (PA-RWA) is addressed considering a transparent multi-fiber optical network. An integer linear programming formulation is provided for the static lightpath establishment problem and a few heuristics are proposed to solve the problem in the case of dynamic lightpath establishment. To solve the routing problem we propose a novel algorithm named load based cost; it is based on a cost function that considers the load of each optical fiber to compute link weights. We also propose two new wavelength assignment algorithms: the first one is derived from the first fit heuristic whilst the second one is based on an innovative approach. It works like a least cost routing algorithm assigning a cost to each wavelength for each link in the path and then minimizes the total cost. Our proposal is compared with a number of already known RWA algorithms showing that it is able to reduce the power consumption of the network by about 20-30%, depending on the amount of traffic treated, with respect to state of the art algorithms with a difference of about 10% with respect to the lower bound. In order to provide a complete analysis of the feasibility of the proposed heuristics, the blocking probability is evaluated: the results show that, unlike the other power-aware algorithms here considered, our proposal shows a low impairment with respect to the least congested path-first fit alternative. Another important result regards the better performance of the proposed wavelength assignment algorithm with respect to first fit.

Energy consumption is becoming a fundamental topic also for telecommunication networks, where the implementation of ''green'' infrastructures is required. In this paper, we report a numerical investigation about energy saving in a transport network both exploiting the transmission properties that permit to reduce the number of in-line equipments (optimizing wavelength path assignment) and switching off optical links when the traffic load decreases. In particular, we investigate a European transport network based on N × 40 Gbit/s transmission and the Italian network based on the M × 10 Gbit/s transmission.

Progress in network technologies and protocols is paving the road towards flexible optical transport networks, in which dynamic leasable circuits could be set up and released on a short-term basis according to customers requirements. Recently, new solutions for automatized network management promise to allow customers to on-line specify the terms of the Service Level Agreement (SLA) to be guaranteed by the service provider. Since this new information is made available, we propose to exploit the knowledge of connection holding time, among the other Service Level Specifications (SLS), to improve the routing efficiency. In this work we consider that a typical electronic-layer (e.g. SDH or MPLS) demand requires only a fraction of the capacity of the single wavelength bandwidth and we investigate a new algorithm for traffic grooming of sub-wavelength connections in an optical mesh network. We rely on the knowledge of the holding time of connection requests to efficiently exploit lightpath capacity and hence to achieve significant reduction in blocking probability for the traffic grooming problem. For a typical US nationwide network, we compare holding-time aware to holding-time-unaware, but otherwise efficient, approaches, obtaining remarkable reduction of blocking probability for practical scenarios.

Progress in network technologies and protocols is paving the road towards flexible optical transport networks, in which dynamic leasable circuits could be set up and released on a short-term basis according to customers requirements. Recently, new solutions for automated network management promise to allow customers to dinamically specify the terms of the Service Level Agreement (SLA) to be guaranteed by the service provider. Since this new information is made available, we propose to exploit the knowledge of connection holding time, among the other Service Level Specifications (SLS), to improve the routing efficiency. In this work, we consider that a typical electronic-layer (e.g., SDH or MPLS) demand requires only a fraction of the capacity of the single wavelength bandwidth and we investigate a new algorithm for traffic grooming of sub-wavelength connections in an optical mesh network. We rely on the knowledge of the holding time of connection requests to exploit lightpath capacity and hence to achieve significant reduction in blocking probability for the traffic grooming problem. Our new methodology is applied on a typical US nationwide network and results are compared with those given by previous known approaches.