Showing papers on "Optical Transport Network published in 2014"

Survey on Free Space Optical Communication: A Communication Theory Perspective

Abstract: Optical wireless communication (OWC) refers to transmission in unguided propagation media through the use of optical carriers, i.e., visible, infrared (IR), and ultraviolet (UV) bands. In this survey, we focus on outdoor terrestrial OWC links which operate in near IR band. These are widely referred to as free space optical (FSO) communication in the literature. FSO systems are used for high rate communication between two fixed points over distances up to several kilometers. In comparison to radio-frequency (RF) counterparts, FSO links have a very high optical bandwidth available, allowing much higher data rates. They are appealing for a wide range of applications such as metropolitan area network (MAN) extension, local area network (LAN)-to-LAN connectivity, fiber back-up, backhaul for wireless cellular networks, disaster recovery, high definition TV and medical image/video transmission, wireless video surveillance/monitoring, and quantum key distribution among others. Despite the major advantages of FSO technology and variety of its application areas, its widespread use has been hampered by its rather disappointing link reliability particularly in long ranges due to atmospheric turbulence-induced fading and sensitivity to weather conditions. In the last five years or so, there has been a surge of interest in FSO research to address these major technical challenges. Several innovative physical layer concepts, originally introduced in the context of RF systems, such as multiple-input multiple-output communication, cooperative diversity, and adaptive transmission have been recently explored for the design of next generation FSO systems. In this paper, we present an up-to-date survey on FSO communication systems. The first part describes FSO channel models and transmitter/receiver structures. In the second part, we provide details on information theoretical limits of FSO channels and algorithmic-level system design research activities to approach these limits. Specific topics include advances in modulation, channel coding, spatial/cooperative diversity techniques, adaptive transmission, and hybrid RF/FSO systems.

A tutorial on the flexible optical networking paradigm: State of the art, trends, and research challenges

Abstract: Rigid fixed-grid wavelength division multiplexing (WDM) optical networks can no longer keep up with the emerging bandwidth-hungry and highly dynamic services in an efficient manner. As the available spectrum in optical fibers becomes occupied and is approaching fundamental limits, the research community has focused on seeking more advanced optical transmission and networking solutions that utilize the available bandwidth more effectively. To this end, the flexible/elastic optical networking paradigm has emerged as a way to offer efficient use of the available optical resources. In this work, we provide a comprehensive view of the different pieces composing the “flexible networking puzzle” with special attention given to capturing the occurring interactions between different research fields. Only when these interrelations are clearly defined, an optimal network-wide solution can be offered. Physical layer technological aspects, network optimization for flexible networks, and control plane aspects are examined. Furthermore, future research directions and open issues are discussed.

Coherent Ultra Dense WDM Technology for Next Generation Optical Metro and Access Networks

Abstract: Coherent optical communication has been well established as the technology of choice for long haul and high bit rate communication systems since a decade ago. Recent technology advances and ongoing price erosion further open the window of opportunity for the application of coherent optical transmission technology in other domains. This paper describes in detail the capabilities, design and implementation of a coherent ultra dense WDM technology for optical metro and access networks. Its capabilities enable a number of attractive options, such as variable downstream bit rates from 150 Mbit/s up to 10 Gbit/s per user, embedded OTDR and the coexistence with legacy systems such as GPON, EPON, XGPON or RF-Video in optical distribution networks. Due to its flexibility and capacity, it is also suitable for deployments in metropolitan networks, as well as for mobile front-haul and back-haul applications.

Multi-Band OFDM Transmission at 100 Gbps With Sub-Band Optical Switching

Abstract: In this paper, we present an original work on sub-wavelength optical switching performed over a coherent multi-band orthogonal frequency-division multiplexing (MB-OFDM) super-channel operating at 100 Gbps. After having demonstrated that dual-polarization MB-OFDM (DP-MB-OFDM) is as efficient as single-carrier dual-polarization quaternary phase shift keying (DP-QPSK) technology to transport 100 Gbps data-rate over a 10 × 100-km G.652 fiber-based transmission line, we show that optical add-drop of OFDM sub-bands as narrow as 8 GHz inside a 100 Gbps DP-MB-OFDM signal constituted of four sub-bands is feasible in the middle of this 1000-km transmission line. The flexible optical add-drop multiplexer (FOADM) implemented here is constituted by the association of an ultra-narrow pass-band and stop-band optical filter. The design and realization of such ultra-selective optical filters is presented, while the impact of their physical features over the quality of transmission is discussed. To prove that several add-drop multiplexers can be cascaded, our FOADM is introduced into a G.652 fiber-based recirculating loop and the impact of the cumulated filtering transfer function as well as the crosstalk inside the OADM are investigated. A typical use case for the introduction of such FOADM into long-haul transport networks is given, and the capital expenditure (CAPEX) cost advantage for the multi-layer transport networks is highlighted. By the proof of concept delivered here, combination of super-channel and sub-wavelength optical switching pushes network flexibility far away of what is today proposed by system vendors, opening new horizons for an optimized use of multi-layer transport networks.

Green optical orthogonal frequency-division multiplexing networks

Abstract: Orthogonal frequency-division multiplexing (OFDM) has been proposed as an enabling technique for elastic optical networks to support heterogeneous traffic demands by enabling rate and modulation adaptive bandwidth allocation. The authors investigate the energy efficiency of optical OFDM-based networks. A mixed integer linear programming model is developed to minimise the total power consumption of rate and modulation adaptive optical OFDM networks. Considering a symmetric traffic, the results show that optical OFDM-based networks can save up to 31% of the total network power consumption compared to conventional Internet protocol over wavelength division multiplexing (WDM) networks. Considering the power consumption of the optical layer, the optical OFDM-based network saves up to 55% of the optical layer power consumption. The results also show that under an asymmetric traffic scenario, where more traffic is destined to or originates from popular nodes, for example data centres, the power savings achieved by the optical OFDM-based networks are limited as the higher traffic demands to and from data centres reduce the bandwidth wastage associated with conventional WDM networks. Furthermore, the achievable power savings through data compression have been investigated, considering an optical OFDM-based network.

Discrete Multi-Tone for 100 Gb/s optical access networks

Abstract: Discrete Multi-Tone (DMT) is an attractive technology for short reach optical transmission systems. We have reported several results on transmission experiments using DMT. In this paper we review this technology and these experimental results.

Optical Interconnect Networks for Data Communications

Abstract: In this invited tutorial paper, we review the changing nature of data center networks and the role played by optoelectronics in future network designs. Conventional network protocols will be reviewed, including Ethernet, Fibre Channel, and InfiniBand, and requirements for WAN connectivity between data centers. The transition to converged networks based on lossless Ethernet will be discussed, including FCoE and RoCE protocols. Industry roadmaps for bandwidth, port density, and scalability of optical links will be presented, and optical transceiver form factors including QSFP, CFP, and active optical cables will be discussed. The role of software defined networking (SDN) in next generation data center networks will also be presented in this context.

Real-time Digital Signal Processing for Optical OFDM-Based Future Optical Access Networks

Abstract: In this paper, key aspects associated with realizing real-time digital signal processing (DSP)-based optical transceivers for use in future optical access networks are considered. The fundamental principles of optical orthogonal frequency division multiplexing (OOFDM)-based transceivers and their associated DSP implementation are presented. This is followed by an extensive review of the real-time DSP implemented in the end-to-end OOFDM transceivers experimentally demonstrated over the past several years.

Universal method for constructing N-port non-blocking optical router based on 2 × 2 optical switch for photonic networks-on-chip

Abstract: We propose a universal method for constructing N-port non-blocking optical router for photonic networks-on-chip, in which all microring (MR) optical switches or Mach-Zehnder (M-Z) optical switches behave as 2 × 2 optical switches. The optical router constructed by the proposed method has minimum optical switches, in which the number of the optical switches is reduced about 50% compared to the reported optical routers based on MR optical switches and more than 30% compared to the reported optical routers based on M-Z optical switches, and therefore is more compact in footprint and more power-efficient. We also present a strict mathematical proof of the non-blocking routing of the proposed N-port optical router.

QuT: A low-power optical Network-on-Chip

Abstract: To enable the adoption of optical Networks-on-Chip (NoCs) and allow them to scale to large systems, they must be designed to consume less power and energy. Therefore, optical NoCs must use a small number of wavelengths, avoid excessive insertion loss and reduce the number of microring resonators. We propose the Quartern Topology (QuT), a novel low-power all-optical NoC. We also propose a deterministic wavelength routing algorithm based on Wavelength Division Multiplexing that allows us to reduce the number of wavelengths and microring resonators in optical routers. The key advantages of QuT network are simplicity and lower power consumption. We compare QuT against three alternative all-optical NoCs: optical Spidergon, λ-router and Corona under different synthetic traffic patterns. QuT demonstrates good scalability with significantly lower power and competitive latency. Our optical topology reduces power by 23%, 86.3% and 52.7% compared with 128-node optical Spidergon, λ-router and Corona, respectively.

Design of DPSS based fiber bragg gratings and their application in all-optical encryption, OCDMA, optical steganography, and orthogonal-division multiplexing.

Abstract: The future information infrastructure will be affected by limited bandwidth of optical networks, high energy consumption, heterogeneity of network segments, and security issues. As a solution to all problems, we advocate the use of both electrical basis functions (orthogonal prolate spheroidal basis functions) and optical basis functions, implemented as FBGs with orthogonal impulse response in addition to spatial modes. We design the Bragg gratings with orthogonal impulse responses by means of discrete layer peeling algorithm. The target impulse responses belong to the class of discrete prolate spheroidal sequences, which are mutually orthogonal regardless of the sequence order, while occupying the fixed bandwidth. We then design the corresponding encoders and decoders suitable for all-optical encryption, optical CDMA, optical steganography, and orthogonal-division multiplexing (ODM). Finally, we propose the spectral multiplexing-ODM-spatial multiplexing scheme enabling beyond 10 Pb/s serial optical transport networks.

Coded Modulation for Fiber-Optic Networks: Toward better tradeoff between signal processing complexity and optical transparent reach

Abstract: In this tutorial, we study the joint design of forward error correction (FEC) and modulation for fiber-optic communications. To this end, we use an information-theoretic design framework to investigate coded modulation (CM) techniques for standard additive white Gaussian noise (AWGN) channels and fiber-optic channels. This design guideline helps us provide a comprehensive overview of the CM schemes in the literature. Then, by invoking recent advances in optical channel modeling for nondispersion-managed links, we discuss two-dimensional (2-D) and four-dimensional (4-D) CM schemes. Moreover, we discuss the electronic computational complexity and hardware constraints of CM schemes for optical communications. Finally, we address CM schemes with signal shaping and rate-adaptation capabilities to accommodate the data transmission scheme to optical links with different signal qualities.

How will optical transport deal with future network traffic growth

Abstract: Traffic will undoubtedly continue to grow, but it is important to put this into perspective. This presentation will categorize growth rates and propose cost effective solutions in Access, Metro and Long Haul without the need to replace existing fiber.

Subcarrier multiplexing using DACs for fiber nonlinearity mitigation in coherent optical communication systems

Abstract: We experimentally generate subcarrier multiplexed signals using high-speed DACs and demonstrate the improved nonlinearity tolerance over single carrier signals in long-haul coherent optical transmission systems.

Design and performance evaluation of an OpenFlow-based control plane for software-defined elastic optical networks with direct-detection optical OFDM (DDO-OFDM) transmission.

Abstract: Optical Orthogonal Frequency Division Multiplexing (O-OFDM), which transmits high speed optical signals using multiple spectrally overlapped lower-speed subcarriers, is a promising candidate for supporting future elastic optical networks. In contrast to previous works which focus on Coherent Optical OFDM (CO-OFDM), in this paper, we consider the direct-detection optical OFDM (DDO-OFDM) as the transport technique, which leads to simpler hardware and software realizations, potentially offering a low-cost solution for elastic optical networks, especially in metro networks, and short or medium distance core networks. Based on this network scenario, we design and deploy a software-defined networking (SDN) control plane enabled by extending OpenFlow, detailing the network architecture, the routing and spectrum assignment algorithm, OpenFlow protocol extensions and the experimental validation. To the best of our knowledge, it is the first time that an OpenFlow-based control plane is reported and its performance is quantitatively measured in an elastic optical network with DDO-OFDM transmission.

Reconfigurable 100 Gb/s silicon photonic network-on-chip

Abstract: We report the first intra-chip 10×10 Gb/s wavelength-division multiplexing optical link based on a large-scale silicon photonic integrated circuit with 72 functional elements, which is also reconfigurable as a 10×10 non-blocking switch and a broadcasting network.

Evolving Traffic Grooming in Multi-Layer Flexible-Grid Optical Networks With Software-Defined Elasticity

Abstract: Recently, flexible grid and elastic-rate transponders have emerged as evolutionary technologies to satisfy the ever-increasing demand for higher spectrum efficiency and operational flexibility. In this study, we first briefly review the evolution of traffic grooming from SONET/SDH to currently-deployed WDM networks, and summarize the essence of the current traffic-grooming paradigm based on electronic circuit or packet switching and multi-layer collaboration. Then, the role of traffic grooming in flexible-grid and elastic-rate optical networks is re-examined. The impact of some new optical-layer technologies on traffic-grooming paradigm is discussed. Particularly, sliceable optical layer based on sliceable transponders and BV-ROADM is identified as a novel technology that could impact the future grooming paradigm by offloading considerable amount of traffic and part of electronic grooming function to the optical layer. We propose two novel network architectures based on sliceable optical layer and numerically compare them with the traditional packet-over-optical network architecture. It is found that packet-over-sliceable network architecture consumes the fewest transponders and at the same time achieves either the “lowest-possible” latency or least spectrum usage. Finally, traffic grooming, which involves multi-layer resource orchestration, should be controlled by software with a centralized view of the network to accommodate the dynamic requirements of applications.

Flexible Optical Cross-Connect Structures Supporting WDM Multicast With Multiple Pumps for Multiple Channels

Abstract: We not only propose three flexible optical cross-connect (OXC) structures, with the ability of wavelength-division multiplexing (WDM) multicast, but also experimentally demonstrate two WDM multicast schemes based on four-wave mixing in a semiconductor optical amplifier (SOA). One-to-ten WDM multicast of 25-Gb/s QPSK signals is achieved with three pumps, and the power penalties for all signals are less than 1.7 dB. For the first time, dual-channel WDM multicasts are simultaneously realized with only two pumps. One-to-six multicast for one input with the largest power penalty of 1.28 dB is obtained, whereas one-to-three multicast for the other input with the power penalty of 1.27 dB is also realized. The demonstrated schemes can be applied to the proposed OXC structures, according to the different requirements. The effect of bias current on conversion efficiency and optical signal-to-noise ratio is also discussed, and the optimal value is given.

System-Level Modeling and Analysis of Thermal Effects in WDM-Based Optical Networks-on-Chip

Abstract: Multiprocessor systems-on-chip show a trend toward integration of tens and hundreds of processor cores on a single chip. With the development of silicon photonics for short-haul optical communication, wavelength division multiplexing (WDM)-based optical networks-on-chip (ONoCs) are emerging on-chip communication architectures that can potentially offer high bandwidth and power efficiency. Thermal sensitivity of photonic devices is one of the main concerns about the on-chip optical interconnects. We systematically modeled thermal effects in optical links in WDM-based ONoCs. Based on the proposed thermal models, we developed OTemp, an optical thermal effect modeling platform for optical links in both WDM-based ONoCs and single-wavelength ONoCs. OTemp can be used to simulate the power consumption as well as optical power loss for optical links under temperature variations. We use case studies to quantitatively analyze the worst-case power consumption for one wavelength in an eight-wavelength WDM-based optical link under different configurations of low-temperature-dependence techniques. Results show that the worst-case power consumption increases dramatically with on-chip temperature variations. Thermal-based adjustment and optimal device settings can help reduce power consumption under temperature variations. Assume that off-chip vertical-cavity surface-emitting lasers are used as the laser source with WDM channel spacing of 1 nm, if we use thermal-based adjustment with guard rings for channel remapping, the worst-case total power consumption is 6.7 pJ/bit under the maximum temperature variation of 60°C; larger channel spacing would result in a larger worst-case power consumption in this case. If we use thermal-based adjustment without channel remapping, the worst-case total power consumption is around 9.8 pJ/bit under the maximum temperature variation of 60°C; in this case, the worst-case power consumption would benefit from a larger channel spacing.

Experimental performance evaluation of software defined networking (SDN) based data communication networks for large scale flexi-grid optical networks.

Abstract: Software defined networking (SDN) has become the focus in the current information and communication technology area because of its flexibility and programmability. It has been introduced into various network scenarios, such as datacenter networks, carrier networks, and wireless networks. Optical transport network is also regarded as an important application scenario for SDN, which is adopted as the enabling technology of data communication networks (DCN) instead of general multi-protocol label switching (GMPLS). However, the practical performance of SDN based DCN for large scale optical networks, which is very important for the technology selection in the future optical network deployment, has not been evaluated up to now. In this paper we have built a large scale flexi-grid optical network testbed with 1000 virtual optical transport nodes to evaluate the performance of SDN based DCN, including network scalability, DCN bandwidth limitation, and restoration time. A series of network performance parameters including blocking probability, bandwidth utilization, average lightpath provisioning time, and failure restoration time have been demonstrated under various network environments, such as with different traffic loads and different DCN bandwidths. The demonstration in this work can be taken as a proof for the future network deployment.

Multidimensional Signaling and Coding Enabling Multi-Tb\/s Optical Transport and Networking: Multidimensional aspects of coded modulation

Abstract: The design of next-generation optical transmission systems and networks should address the concerns with respect to a limited bandwidth of information infrastructure, high energy consumption, as well as the need to support the network heterogeneity and demand for an elastic and dynamic bandwidth allocation. To address these concerns simultaneously, we propose an adaptive, software-defined, low-density parity check (LDPC)-coded multiband approach that involves spatial-multiple-input, multiple-output (MIMO) and an all-optical orthogonal frequency-division multiplexing (OFDM) scheme since it can enable energy efficient high-bandwidth delivery with fine granularity and elastic model of bandwidth utilization. The modulation is based on multidimensional signaling to improve the tolerance to fiber nonlinearities and imperfect compensation of channel impairments and has a hybrid nature with both electrical and optical degrees of freedom employed. Optical degrees of freedom include spatial and polarization modes in optical fibers supporting spatial-division multiplexing (SDM), while electrical degrees of freedom are based on 2M orthogonal basis functions. The adaptive coding has been performed by partial reconfiguration of the corresponding parity-check matrix. The proposed scheme is suitable for the conveyance of the information over optical fibers with bit rates exceeding 10 Tb/s. At the same time, the multitude of degrees of freedom will enable finer granularity and elasticity of the bandwidth, the features essential for next generation networking.

Secure Communication in Fiber-Optic Networks

Abstract: Providing data security in the optical layer enables low latency data encryption and enlarges the capacity for secure data transmission. As the demand for both secure and high speed transmission grows dramatically, secure data transmission is pushing the requirements for processing speed and network capacity. As fiber-optic systems form the backbone of communication networks, optical approaches for protecting the network security increases the available capacity of the network. Moreover, compared to electric circuits, fiber-optic systems are immune to electromagnetic interference and have high processing speeds. In this chapter, we discuss using fiber-optic-based techniques to defend against threats in the network, including optical encryption, optical code-division multiple access (CDMA), optical key distribution, optical steganography, anti-jamming, and optical chaos-based communication. These approaches are categorized by their different applications for protecting the properties of network security, including confidentiality, privacy, and availability.

Hybrid optical switching for data center networks

Abstract: Current data centers networks rely on electronic switching and point-to-point interconnects When considering future data center requirements, these solutions will raise issues in terms of flexibility, scalability, performance, and energy consumption For this reason several optical switched interconnects, which make use of optical switches and wavelength division multiplexing (WDM), have been recently proposed However, the solutions proposed so far suffer from low flexibility and are not able to provide service differentiation In this paper we introduce a novel data center network based on hybrid optical switching (HOS) HOS combines optical circuit, burst, and packet switching on the same network In this way different data center applications can be mapped to the optical transport mechanism that best suits their traffic characteristics Furthermore, the proposed HOS network achieves high transmission efficiency and reduced energy consumption by using two parallel optical switches We consider the architectures of both a traditional data center network and the proposed HOS network and present a combined analytical and simulation approach for their performance and energy consumption evaluation We demonstrate that the proposed HOS data center network achieves high performance and flexibility while considerably reducing the energy consumption of current solutions

Free-space optical network with agile beam-based protection switching

Abstract: A system includes a network having multiple network nodes (102-110) each configured for free-space optical communication. Each network node includes one or more apertures through which optical beams are transmitted and received over optical links (112). The optical links include (i) a traffic link (112a) that transports higher-rate traffic between nodes and (ii) an acquisition/tracking link (112b) that transports lower-rate signals used to establish and maintain location knowledge of other nodes. Each network node also includes a network processor configured to determine one or more backup paths through the network. Each network node further includes a beam steering unit (420) configured to redirect an optical beam from the traffic link onto the acquisition/tracking link to create a backup traffic link.

All Optical Switching Networks With Energy-Efficient Technologies From Components Level to Network Level

Abstract: The key current challenges for the industrial application of all optical switching networks are energy consumption, transmission rate, spectrum efficiency, and switching throughput. The energy consumption problem is mainly researched in this paper. From the perspective of components and modules, node equipment, and network levels, different enabling technologies are proposed to overcome this problem, which are also evaluated through different experimental demonstrations. First, high-sampling-rate digital-to-analog converters (DACs) and WSS-based ROADM modules are demonstrated as components and modules for energy-efficient all optical switching networks. Then, an all optical transport network test-bed consisting of 10 Pbit/s level all optical switching nodes based on multi-level and multi-planar switching architecture is experimentally demonstrated for the first time, which can reduce power consumption by 43%. A control architecture for energy-efficient all optical switching networks is built with OpenFlow based software defined networking (SDN), and experimental results are given to verify the performance of this control architecture. Finally, we describe an All Optical Networks Innovation (AONI) project in China, which aims to explore transmission, switching, and networking technologies in all optical switching networks, and then two application scenarios are forecast based on the technical breakthroughs of this project.

Energy-efficiency improvements for optical access

Abstract: This article discusses novel approaches to improve energy efficiency of different optical access technologies, including time division multiplexing passive optical network (TDM-PON), time and wavelength division multiplexing PON (TWDM-PON), point-to-point (PTP) access network, wavelength division multiplexing PON (WDM-PON), and orthogonal frequency division multiple access PON (OFDMA-PON). These approaches include cyclic sleep mode, energy-efficient bit interleaving protocol, power reduction at component level, or frequency band selection. Depending on the target optical access technology, one or a combination of different approaches can be applied.

Optical free-space wavelength-division-multiplexing transport system

Abstract: An optical free-space wavelength-division-multiplexing (WDM) transport system employing vertical cavity surface emitting lasers and spatial light modulators with 16-quadrature amplitude modulation orthogonal frequency-division multiplexing modulating signals over a 17.5 m free-space link is proposed and demonstrated. With the help of a low-noise amplifier and data comparator, good bit error rate performance is obtained for each optical channel. Such an optical free-space WDM transport system would be attractive for providing services including data and telecommunication services.

O-band 400 Gbit/s client side optical transmission link

Abstract: We present an O-band 400 Gbit/s optical client side Ethernet link with 40 km SSMF reach employing four LAN-WDM lanes, MultiCAP modulation and direct detection.

Energy Saving via Dynamic Wavelength Sharing in TWDM-PON

Abstract: Time- and wavelength-division multiplexed passive optical network allows wavelength sharing by optical network units (ONUs) in a time-division multiplexing fashion. When ONUs are lightly loaded, they can share fewer wavelengths to reduce energy consumption. In such a dynamic system, the configuration of wavelength sharing should adapt to the traffic changes for energy saving and load balancing (which affects the quality of service). However, going from one configuration to another is nontrivial, as it usually involves wavelength reassignment and potential service disruptions. The optimization and algorithm design have to account for such reconfiguration (along with other aspects). In this study, we have developed optimization models and online algorithms that incorporate the reconfiguration dimension. Various underlying tradeoffs (e.g., energy saving versus reconfiguration and load balancing versus reconfiguration) are investigated for both static planning and dynamic operations.

Multi-objective design of survivable flexible-grid DWDM networks

Abstract: Emerging trends in optical transport networks aiming to support increasing data rates are reshaping the possibilities for network planning. The deployment of a flexible grid with multiple available channel bit rates and spectral widths gives way to a more clearly defined trade-off between spectrum and cost in the planning process. Furthermore, providing redundancy in these types of services is both crucial and costly. For this reason, it is important to consider all these aspects simultaneously in order to have an accurate view of the cost/spectrum trade-off in the optical backbone. This paper presents an evolutionary based multi-objective framework for optimizing network deployments with flexible-grid channel formats ranging from 40 to 400 Gbits/s with varying degrees of resilience to both link and transponder failures. The multi-objective algorithm can consider all these different aspects simultaneously and highlight the degree to which cost can be traded for spectrum, and how the protection/restoration schemes influence both parameters. After benchmarking the proposed algorithm on both objectives, we use it on two reference networks to trace the non-dominated front for multiple resilience schemes, offering different levels of protection against link and/or transponder failures. We also evaluate how the channel format selection for each demand evolves when considering single-rate or bit-rate variable transponders.