| 1. |
- Abedifar, Vahid, et al.
(författare)
-
Routing, Modulation and Spectrum Assignment in Programmable Networks based on Optical White Boxes
- 2018
-
Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 10:9, s. 723-735
-
Tidskriftsartikel (refereegranskat)abstract
- Elastic optical networks (EONs) can help overcome the flexibility challenges imposed by emerging heterogeneous and bandwidth-intensive applications. Among the different solutions for flexible optical nodes, optical white box switches implemented by architecture on demand (AoD) have the capability to dynamically adapt their architecture and module configuration to the switching and processing requirements of the network traffic. Such adaptability allows for unprecedented flexibility in balancing the number of required nodal components in the network, spectral resource usage, and length of the established paths. To investigate these trade-offs and achieve cost-efficient network operation, we formulate the routing, modulation, and spectrum assignment (RMSA) problem in AoD-based EONs and propose three RMSA strategies aimed at optimizing a particular combination of these performance indicators. The strategies rely on a newly proposed internal node configuration matrix that models the structure of optical white box nodes in the network, thus facilitating hardware-aware routing of connection demands. The proposed strategies are evaluated in terms of the number of required modules and the related cost, spectral resource usage, and average path length. Extensive simulation results show that the proposed RMSA strategies can achieve remarkable cost savings by requiring fewer switching modules than the benchmarking approaches, at a favorable trade-off with spectrum usage and path length.
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| 2. |
- Abeywickrama, Sandu, et al.
(författare)
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Protecting core networks with dual-homing: A study on enhanced network availability, resource efficiency, and energy-savings
- 2016
-
Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 381, s. 327-335
-
Tidskriftsartikel (refereegranskat)abstract
- Core network survivability affects the reliability performance of telecommunication networks and remains one of the most important network design considerations. This paper critically examines the benefits arising from utilizing dual-homing in the optical access networks to provide resource-efficient protection against link and node failures in the optical core segment. Four novel, heuristic-based RWA algorithms that provide dedicated path protection in networks with dual-homing are proposed and studied. These algorithms protect against different failure scenarios (i.e. single link or node failures) and are implemented with different optimization objectives (i.e., minimization of wavelength usage and path length). Results obtained through simulations and comparison with baseline architectures indicate that exploiting dual-homed architecture in the access segment can bring significant improvements in terms of core network resource usage, connection availability, and power consumption.
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| 3. |
- Ahmed, Jawwad, et al.
(författare)
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Enhancing restoration performance using service relocation in PCE-based resilient optical clouds
- 2014
-
Ingår i: Optical Fiber Communication Conference, OFC 2014. - : Optical Society of America.
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates the benefits of dynamic restoration with service relocation in resilient optical clouds. Results from the proposed optimization model show that service availability can be significantly improved by allowing a few service relocations.
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| 4. |
- Ahmed, Jawwad, et al.
(författare)
-
Survivability strategies for PCE-based WDM networks offering high reliability performance
- 2013
-
Ingår i: National Fiber Optic Engineers Conference, NFOEC 2013. - Washington, D.C. : Optical Society of America.
-
Konferensbidrag (refereegranskat)abstract
- Two approaches based on backup reprovisioning and path restoration are proposed for dynamic failure recovery in survivable, PCE-based, WDM networks. Results show that proposed schemes can achieve high connection availability in double link failure scenarios.
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| 5. |
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| 6. |
- Ajmal, Muhammad, et al.
(författare)
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Trading Quality of Transmission for Improved Blocking Performance in All-Optical Networks
- 2013
-
Ingår i: Asia Communications and Photonics Conference 2013. - 9781557529893 ; , s. AF4E.5-
-
Konferensbidrag (refereegranskat)abstract
- We propose a connection provisioning strategy in dynamic all-optical networks, which exploit the possibility to allow a tolerable signal quality degradation during a small fraction of holding-time resulting in a significant improvement of blocking performance.
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| 7. |
- Aladin, Sandra, et al.
(författare)
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Detecting Anomalies in the Optical Layer Using Unsupervised Machine Learning
- 2024
-
Ingår i: 2024 Optical Fiber Communications Conference and Exhibition, OFC 2024 - Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- We propose an unsupervised machine learning (ML) approach using field data for the detection of optical layer anomalies. We show how multivariate ML models can forecast hard failures by detecting soft failures.
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| 8. |
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| 9. |
- Cardoso, Diego, et al.
(författare)
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Joint planning of small cells and optical transport deployment in heterogeneous mobile networks
- 2016
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Ingår i: Asia Communications and Photonics Conference, ACP. - : OSA - The Optical Society.
-
Konferensbidrag (refereegranskat)abstract
- We investigate how to reduce the deployment cost of heterogeneous mobile networks by joint dimensioning small cells and optical transport resources. The proposed heuristic is able to save 24% of total network deployment cost. Asia Communications and Photonics Conferene (ACP)
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| 10. |
- Cavdar, Cicek, 1977-, et al.
(författare)
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Cutting the electric bill by routing and wavelength assignment with time-zones and time-of-use prices
- 2011
-
Ingår i: 2011 Asia Communications and Photonics Conference and Exhibition. - : SPIE. - 9780819489616
-
Konferensbidrag (refereegranskat)abstract
- We consider an energy-aware WDM core network, where the electric prices differ according to time intervals of the day, referred to as time-of-use rates. Since a large backbone network may have nodes scattered over several time zones, we exploit the time-of-use rates to lower the electric bill of the network provider. By using an ILP formulation of the bill minimization problem, we investigate the gain of total electric bill over two approaches where capacity and energy are optimized under different network traffic load conditions.
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| 11. |
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| 12. |
- Chan, Vincent, et al.
(författare)
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Network-wide localization of optical-layer attacks
- 2020
-
Ingår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. ; 11616 LNCS, s. 310-322
-
Konferensbidrag (refereegranskat)abstract
- Optical networks are vulnerable to a range of attacks targeting service disruption at the physical layer, such as the insertion of harmful signals that can propagate through the network and affect co-propagating channels. Detection of such attacks and localization of their source, a prerequisite for secure network operation, is a challenging task due to the limitations in optical performance monitoring, as well as the scalability and cost issues. In this paper, we propose an approach for localizing the source of a jamming attack by modeling the worst-case scope of each connection as a potential carrier of a harmful signal. We define binary words called attack syndromes to model the health of each connection at the receiver which, when unique, unambiguously identify the harmful connection. To ensure attack syndrome uniqueness, we propose an optimization approach to design attack monitoring trails such that their number and length is minimal. This allows us to use the optical network as a sensor for physical-layer attacks. Numerical simulation results indicate that our approach obtains network-wide attack source localization at only 5.8% average resource overhead for the attack monitoring trails.
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| 13. |
- Chen, Jiajia, et al.
(författare)
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Fast fault monitoring technique for reliable WDM PON : Achieving significant operational saving
- 2013
-
Ingår i: 2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2013. - : IEEE. ; , s. 6532499-
-
Konferensbidrag (refereegranskat)abstract
- We propose a fast fault supervision technique compatible with an efficient resilience scheme for WDM PON. Several drop fibres can be monitored simultaneously so that a significant reduction of operational cost can be achieved.
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| 14. |
- Chen, Jiajia, 1981, et al.
(författare)
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Photonics in intra-datacenter networks: Architecture and future developments
- 2021
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Ingår i: Optics InfoBase Conference Papers.
-
Konferensbidrag (refereegranskat)abstract
- We review architectures of optical intra-datacenter networks, where photonics plays an important role for interconnecting the servers. Resource disaggregation and spatial division multiplexing are identified for addressing future challenges related to resource utilization and capacity.
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| 15. |
- Chen, Jiajia, et al.
(författare)
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Reducing the Impact of Failures in Next Generation Optical Access Networks
- 2012
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Ingår i: 2012 Asia Communications And Photonics Conference (ACP). - 9781467362740 ; , s. AS1D.2-
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Konferensbidrag (refereegranskat)abstract
- Reliability performance of next generation optical access (NGOA) networks offering high bandwidth and large service coverage is evaluated. A particular attention is paid to the reduction of the impact of failures in NGOA.
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| 16. |
- Cheng, Yuxin, et al.
(författare)
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Centralized Control Plane for Passive Optical Top-of-Rack Interconnects in Data Centers
- 2016
-
Ingår i: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings. - : IEEE conference proceedings. - 9781509013289
-
Konferensbidrag (refereegranskat)abstract
- To efficiently handle the fast growing traffic inside data centers, several optical interconnect architectures have been recently proposed. However, most of them are targeting the aggregation and core tiers of the data center network, while relying on conventional electronic top-of-rack (ToR) switches to connect the servers inside the rack. The electronic ToR switches pose serious limitations on the data center network in terms of high cost and power consumption. To address this problem, we recently proposed a passive optical top-of-rack interconnect architecture, where we focused on the data plane design utilizing simple passive optical components to interconnect the servers within the rack. However, an appropriate control plane tailored for this architecture is needed to be able to analyze the network performance, e.g., packet delay, drop rate, etc., and also obtain a holistic network design for our passive optical top-of-rack interconnect, which we refer to as POTORI. To fill in this gap, this paper proposes the POTORI control plane design which relies on a centralized rack controller to manage the communications inside the rack. To achieve high network performance in POTORI, we also propose a centralized medium access control (MAC) protocol and two dynamic bandwidth allocation (DBA) algorithms, namely Largest First (LF) and Largest First with Void Filling (LFVF). Simulation results show that POTORI achieves packet delays in the order of microseconds and negligible packet loss probability under realistic data center traffic scenarios.
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| 17. |
- Cheng, Yuxin
(författare)
-
Optical Interconnects for Next Generation Data Centers : Architecture Design and Resource Allocation
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The current data center architectures based on blade servers and elec- tronic packet switches face several problems, e.g., limited resource utilization, high power consumption and cost, when handling the rapidly growing of data traffic. Optical networks offering ultra-high capacity and requiring low energy consumption are considered as a good option to address these problems. This thesis presents new data center architectures based on optical interconnects and transmissions, and evaluates performance by extensive simulations.The first main contribution of the thesis is to introduce a passive optical top-of-rack interconnect (POTORI) architecture. The data plane of POTORI mainly consists of passive components to interconnect the servers within the rack. Using the passive components makes it possible to significantly reduce power consumption while achieving high reliability in a cost-efficient way. In addition, the POTORI’s control plane is based on a centralized controller, which is responsible for coordinating the communications among the servers in the rack. A cycle-based medium access control (MAC) protocol and a dy- namic bandwidth allocation (DBA) algorithm are designed for the POTORI to efficiently manage the exchange of control messages and the data transmis- sion inside the rack. Simulation results show that under realistic DC traffic scenarios, the POTORI with the proposed DBA algorithm is able to achieve an average packet delay below 10 μs with the use of fast tunable optical transceivers.The second main contribution of the thesis is to investigate rack-scale disaggregated data center (DDC) architecture for improving resource utiliza- tion. In contrast to the traditional DC with blade servers that integrate various types of resources (e.g., central processing unit (CPU), memory) in a chassis, the rack-scale DDC contains fully decoupled resources held on differ- ent blades, referred to as resource blades. The resource blades are required to be interconnected within the rack by an ultra-high bandwidth optical in- terconnect through the optical interfaces (OIs). A resource allocation (RA) algorithm is proposed to efficiently schedule the resources in the DDC for virtual machine requests. Results show that with sufficient bandwidth on the OIs, the rack-scale DDC with the proposed RA algorithm can achieve 20% higher resource utilization and make 30% more revenue comparing to the traditional DC.
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| 18. |
- Cheng, Yuxin
(författare)
-
Passive Optical Top-of-Rack Interconnect for Data Center Networks
- 2017
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Optical networks offering ultra-high capacity and low energy consumption per bit are considered as a good option to handle the rapidly growing traffic volume inside data center (DCs). However, most of the optical interconnect architectures proposed for DCs so far are mainly focused on the aggregation/core tiers of the data center networks (DCNs), while relying on the conventional top-of-rack (ToR) electronic packet switches (EPS) in the access tier. A large number of ToR switches in the current DCNs brings serious scalability limitations due to high cost and power consumption. Thus, it is important to investigate and evaluate new optical interconnects tailored for the access tier of the DCNs.We propose and evaluate a passive optical ToR interconnect (POTORI) architecture for the access tier. The data plane of the POTORI consists mainly of passive components to interconnect the servers within the rack as well as the interfaces toward the aggregation/core tiers. Using the passive components makes it possible to significantly reduce power consumption while achieving high reliability in a cost-efficient way.Meanwhile, our proposed POTORI’s control plane is based on a centralized rack controller, which is responsible for coordinating the communications among the servers in the rack. It can be reconfigured by software-defined networking (SDN) operation. A cycle-based medium access control (MAC) protocol and a dynamic bandwidth allocation (DBA) algorithm are designed for the POTORI to efficiently manage the exchange of control messages and the data transmission inside the rack.Simulation results show that under realistic DC traffic scenarios, the POTORI with the proposed DBA algorithm is able to achieve an average packet delay below 10 μs with the use of fast tunable optical transceivers. Moreover, we further quantify the impact of different network configuration parameters on the average packet delay.
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| 19. |
- Cheng, Yuxin, et al.
(författare)
-
POTORI : A Passive Optical Top-of-Rack Interconnect Architecture for Data Centers
- 2017
-
Ingår i: Journal of Optical Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0620 .- 1943-0639. ; 9:5, s. 401-411
-
Tidskriftsartikel (refereegranskat)abstract
- Several optical interconnect architectures inside data centers (DCs) have been proposed to efficiently handle the rapidly growing traffic demand. However, not many works have tackled the interconnects at top-of-rack (ToR), which have a large impact on the performance of the data center networks (DCNs) and can introduce serious scalability limitations due to their high cost and power consumption. In this paper, we propose a passive optical ToR interconnect architecture (POTORI) to replace the conventional electronic packet switch (EPS) in the access tier of DCNs. In the data plane, POTORI relies on a passive optical coupler to interconnect the servers within the rack and interfaces toward the aggregation/core tiers. The POTORI control plane is based on a centralized rack controller responsible for managing the communications among the servers in the rack. We propose a cycle-based medium access control (MAC) protocol to efficiently manage the exchange of control messages and the data transmission inside the rack. We also introduce and evaluate a dynamic bandwidth allocation algorithm for POTORI, namely largest first (LF). Extensive simulation results show that, with the use of fast tunable optical transceivers, POTORI and the proposed LF strategy are able to achieve an average packet delay below 10 μs under realistic DC traffic scenarios, outperforming conventional EPSs. On the other hand, with slower tunable optical transceivers, a careful configuration of the network parameters (e.g., maximum cycle time of the MAC protocol) is necessary to obtain a good network performance in terms of the average packet delay.
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| 20. |
|
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| 21. |
- De Andrade, Marilet, et al.
(författare)
-
Enhanced IPACT : solving the over-granting problem in long-reach EPON
- 2013
-
Ingår i: Telecommunications Systems. - : Springer Science and Business Media LLC. - 1018-4864 .- 1572-9451. ; 54:2, s. 137-146
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we address an issue referred to as "over-granting problem", which is inherent in the existing dynamic bandwidth allocation algorithms for Ethernet-based Passive Optical Networks (EPON), in particular when deployed for multi-threaded scheme in long-reach scenario. In order to solve this problem we design a scheme for the algorithm of Interleaved Polling with Adapted Cycle Time (IPACT) with the limited service discipline. We evaluate the proposed scheme through simulations for single-thread and double-thread cases and demonstrate that, the network performance can be significantly improved by our solution in terms of average delay, jitter, and throughput.
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| 22. |
- de Sousa, Amaro, et al.
(författare)
-
Structural Methods to Improve the Robustness of Anycast Communications to Large-Scale Failures
- 2020
-
Ingår i: Guide to Disaster-Resilient Communication Networks. - Cham : Springer International Publishing. - 9783030446857 ; , s. 401-425
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter is dedicated to the description of structural methods aiming to improve the robustness of anycast communications to large-scale failures, either due to natural disasters or malicious human activities. The chapter considers both software-defined networks (SDNs) where the anycast nodes are the nodes hosting SDN controllers, and content delivery networks (CDNs) where the anycast nodes are the nodes hosting content replicas. Most of the structural methods described in this chapter aim to optimally select the anycast nodes in a given network. The chapter first addresses the robustness of anycast communications to natural disasters based on geodiversity routing. Then, different methods are described to select the SDN controller locations aiming to maximize the SDN control plane robustness to malicious node attacks. Finally, the chapter addresses the robustness of CDNs to malicious link cuts by describing methods for the network upgrade (based either on the addition of new links or new replica locations) and for the optimal selection of content replica locations.
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| 23. |
- Di Giglio, A., et al.
(författare)
-
Towards the distributed core for ubiquitous superfast broadband optical access
- 2014
-
Ingår i: 2014 European Conference on Networks and Communications (EuCNC). ; , s. 1-5
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we describe recent architectural and technological advances of the end to end optical network architecture proposed by the DISCUS project (the DIStributed Core for unlimited bandwidth supply for all Users and Services). The two main targets of DISCUS are the principle of equivalence in the access and the reduction of optical-to-electronic conversions in the metro-core network. Technological advances and techno-economic evaluation of Long-Reach Passive Optical Networks (LR-PON), as well as the optimal metro-core node architecture and the required network control plane framework are reported. Network infrastructure sharing challenges are also discussed.
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| 24. |
- Dixit, A., et al.
(författare)
-
Protection strategies for Next Generation Passive Optical Networks -2
- 2014
-
Ingår i: 2014 International Conference on Optical Network Design and Modeling. ; , s. 13-18
-
Konferensbidrag (refereegranskat)abstract
- Next Generation Passive Optical Networks-2 (NG-PON2) are being considered to upgrade the current PON technology to meet the ever increasing bandwidth requirements of the end users while optimizing the network operators’ investment. Reliability performance of NG-PON2 is very important due to the extended reach and, consequently, large number of served customers per PON segment. On the other hand, the use of more complex and hence more failure prone components than in the current PON systems may degrade reliability performance of the network. Thus designing reliable NG-PON2 architectures is of a paramount importance. Moreover, for appropriately evaluating network reliability performance, new models are required. For example, the commonly used reliability parameter, i.e., connection availability, defined as the percentage of time for which a connection remains operable, doesn’t reflect the network wide reliability performance. The network operators are often more concerned about a single failure affecting a large number of customers than many uncorrelated failures disconnecting fewer customers while leading to the same average failure time. With this view, we introduce a new parameter for reliability performance evaluation, referred to as the failure impact. In this paper, we propose several reliable architectures for two important NG-PON2 candidates: wavelength division multiplexed (WDM) PON and time and wavelength division multiplexed (TWDM) PON. Furthermore, we evaluate protection coverage, availability, failure impact and cost of the proposed schemes in order to identify the most efficient protection architecture.
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| 25. |
- Dixit, Abhishek, et al.
(författare)
-
Protection strategies for Next Generation Passive Optical Networks-2
- 2014
-
Ingår i: 2014 INTERNATIONAL CONFERENCE ON OPTICAL NETWORK DESIGN AND MODELING. - : IEEE. ; , s. 13-18
-
Konferensbidrag (refereegranskat)abstract
- Next Generation Passive Optical Networks-2 (NGPON2) are being considered to upgrade the current PON technology to meet the ever increasing bandwidth requirements of the end users while optimizing the network operators' investment. Reliability performance of NG-PON2 is very important due to the extended reach and, consequently, large number of served customers per PON segment. On the other hand, the use of more complex and hence more failure prone components than in the current PON systems may degrade reliability performance of the network. Thus designing reliable NG-PON2 architectures is of a paramount importance. Moreover, for appropriately evaluating network reliability performance, new models are required. For example, the commonly used reliability parameter, i.e., connection availability, defined as the percentage of time for which a connection remains operable, doesn't reflect the network wide reliability performance. The network operators are often more concerned about a single failure affecting a large number of customers than many uncorrelated failures disconnecting fewer customers while leading to the same average failure time. With this view, we introduce a new parameter for reliability performance evaluation, referred to as the failure impact. In this paper, we propose several reliable architectures for two important NGPON2 candidates: wavelength division multiplexed (WDM) PON and time and wavelength division multiplexed (TWDM) PON. Furthermore, we evaluate protection coverage, availability, failure impact and cost of the proposed schemes in order to identify the most efficient protection architecture.
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| 26. |
- Dlas, M. P. I., et al.
(författare)
-
Delay-Constrained Framework for Road Safety and Energy-Efficient Intelligent Transportation Systems
- 2018
-
Ingår i: 2017 European Conference on Optical Communication (ECOC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538656242 ; , s. 1-3
-
Konferensbidrag (refereegranskat)abstract
- We propose a novel approach that exploits a delay-constrained framework to meet stringent delay requirements and achieves energy-savings in Intelligent Transportation Systems (ITS). Analytical results show 40% energy-savings in a network that delivers delay-sensitive safety information over ITS.
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| 27. |
- Dobrijevic, O., et al.
(författare)
-
Another price to pay : An availability analysis for SDN virtualization with network hypervisors
- 2018
-
Ingår i: Proceedings of 2018 10th International Workshop on Resilient Networks Design and Modeling, RNDM 2018. - : Institute of Electrical and Electronics Engineers Inc.. - 9781538670309
-
Konferensbidrag (refereegranskat)abstract
- Communication networks are embracing the software defined networking (SDN) paradigm. Its architectural shift assumes that a remote SDN controller (SDNC) in the control plane is responsible for configuring the underlying devices of the forwarding plane. In order to support flexibility-motivated network slicing, SDN-based networks employ another entity in the control plane, a network hypervisor (NH). This paper first discusses different protection strategies for the control plane with NHs and presents the corresponding availability models, which assume possible failures of links and nodes in the forwarding plane and the control plane. An analysis of these protection alternatives is then performed so as to compare average control plane availability, average path length for the control communication that traverses NH, and infrastructure resources required to support them. Our results confirm the intuition that the NH introduction generally results in a reduction of the control plane availability, which stresses the need for appropriate protection. However, the availability achieved by each of the considered strategies is impacted differently by the node availability and the link failure probability, thus calling for a careful selection that is based on the infrastructure features.
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| 28. |
- Etezadi, Ehsan, 1993, et al.
(författare)
-
Deep reinforcement learning for proactive spectrum defragmentation in elastic optical networks [Invited]
- 2023
-
Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 15:10, s. E86-E96
-
Tidskriftsartikel (refereegranskat)abstract
- The immense growth of Internet traffic calls for advanced techniques to enable the dynamic operation of optical networks, efficient use of spectral resources, and automation. In this paper, we investigate the proactive spectrum defragmentation (SD ) problem in elastic optical networks and propose a novel deep reinforcement learning-based framework DeepDefrag to increase spectral usage efficiency. Unlike the conventional, often threshold-based heuristic algorithms that address a subset of the defragmentation related tasks and have limited automation capabilities, DeepDefrag jointly addresses the three main aspects of the SD process: determining when to perform defragmentation, which connections to reconfigure, and which part of the spectrum to reallocate them to. By considering services attributes, spectrum occupancy state expressed by several different fragmentation metrics, as well as reconfiguration cost, DeepDefragmis able to consistently select appropriate reconfiguration actions over the network lifetime and adapt to changing conditions. Extensive simulation results reveal superior performance of the proposed scheme over a scenario with exhaustive defragmentation and a well-known benchmark heuristic from the literature, achieving lower blocking probability at a smaller defragmentation overhead.
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| 29. |
- Etezadi, Ehsan, 1993, et al.
(författare)
-
DeepDefrag: A deep reinforcement learning framework for spectrum defragmentation
- 2022
-
Ingår i: 2022 IEEE Global Communications Conference, GLOBECOM 2022 - Proceedings. ; , s. 3694-3699
-
Konferensbidrag (refereegranskat)abstract
- Exponential growth of bandwidth demand, spurred by emerging network services with diverse characteristics and stringent performance requirements, drives the need for dynamic operation of optical networks, efficient use of spectral resources, and automation. One of the main challenges of dynamic, resource-efficient Elastic Optical Networks (EONs) is spectrum fragmentation. Fragmented, stranded spectrum slots lead to poor resource utilization and increase the blocking probability of incoming service requests. Conventional approaches for Spectrum Defragmentation (SD) apply various criteria to decide when, and which portion of the spectrum to defragment. However, these polices often address only a subset of tasks related to defragmentation, are not adaptable, and have limited automation potential. To address these issues, we propose DeepDefrag, a novel framework based on reinforcement learning that addresses the main aspects of the SD process: determining when to perform defragmentation, which connections to reconfigure, and which part of the spectrum to reallocate them to. DeepDefrag outperforms the well-known Older-First First-Fit (OF-FF) defragmentation heuristic, achieving lower blocking probability under smaller defragmentation overhead.
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| 30. |
|
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| 31. |
- Etezadi, Ehsan, 1993, et al.
(författare)
-
Proactive Spectrum Defragmentation Leveraging Spectrum Occupancy State Information
- 2023
-
Ingår i: International Conference on Transparent Optical Networks. - 2162-7339. ; 2023-July
-
Konferensbidrag (refereegranskat)abstract
- One of the main obstacles to efficient resource usage under dynamic traffic in elastic optical networks (EONs) is spectrum fragmentation (SF), leading to blocking of incoming service requests. Proactive spectrum defragmentation (SD) approaches periodically reallocate services to ensure better alignment of available spectrum slots across different links and alleviate blocking. The services for reallocation are commonly selected based on their properties, e.g., age, without detailed consideration of prior or posterior spectrum occupancy states. In this paper, we propose a heuristic algorithm for proactive SD that considers different spectrum fragmentation metrics to select services for reallocation. We analyze the relationship between these metrics and the resulting service blocking probability. Simulation results show that the proposed heuristic outperforms the benchmarking proactive SD algorithms from the literature in reducing blocking probability.
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| 32. |
- Etezadi, Ehsan, 1993, et al.
(författare)
-
Programmable Filterless Optical Networks: Architecture, Design and Resource Allocation
- 2024
-
Ingår i: IEEE/ACM Transactions on Networking. - 1558-2566 .- 1063-6692. ; 32:2, s. 1096-1109
-
Tidskriftsartikel (refereegranskat)abstract
- Filterless optical networks (FONs) are a costeffective optical networking technology that replaces reconfigurable optical add-drop multiplexers, used in conventional, wavelength-switched optical networks (WSONs), by passive optical splitters and couplers. FONs follow the drop-and-waste transmission scheme, i.e., broadcast signals without filtering, which generates spectrum waste. Programmable filterless optical networks (PFONs) reduce this waste by equipping network nodes with programmable optical white box switches that support arbitrary interconnections of passive elements. Cost-efficient PFON solutions require optimal routing, modulation format and spectrum assignment (RMSA) to connection requests, as well as optimal design of the node architecture. This paper presents an optimization framework for PFONs. We formulate the RMSA problem in PFONs as a single-step integer linear program (ILP) that jointly minimizes the total spectrum and optical component usage. As RMSA is an NP-complete problem, we propose a two-step ILP formulation that addresses the RMSA sub-problems separately and seeks sub-optimal solutions to larger problem instances in acceptable time. Simulation results indicate a beneficial trade-off between component usage and spectrum consumption in proposed PFON solutions. They use up to 64% less spectrum than FONs, up to 84% fewer active switching elements than WSONs, and up to 81% fewer optical amplifiers at network nodes than FONs or WSONs.
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| 33. |
- Farias, Fabricio S., et al.
(författare)
-
Green backhauling for heterogeneous mobile access networks : What are the challenges?
- 2013
-
Ingår i: 2013 9th International Conference on Information, Communications and Signal Processing (ICICS). - : IEEE Computer Society. - 9781479904334 ; , s. 6782868-
-
Konferensbidrag (refereegranskat)abstract
- Heterogeneous network (HetNet) deployment strategies have the potential to improve the energy efficiency of mobile access networks. One key aspect to consider in HetNets is the impact of the power consumption of the backhaul, i.e., the overall energy efficiency of a HetNet deployment is affected by the backhaul technology and architecture. This paper presents a preliminary assessment of the design challenges of a future green backhaul segment for a HetNet deployment. The study is based on the analysis of the medium term future outlook (i.e., between now and the year 2025) of the main technologies used in todays'* backhaul networks (i.e., fiber, microwave and copper). It can be concluded that, even if there arc no doubts that both microwave and fiber will be predominately used in the future, the possible migration paths leading to such fiber- and microwave-dominated scenarios might be different, depending on factors such as spectrum and license costs, time to deployment, availability of equipment, and required Quality of Service (QoS) levels.
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| 34. |
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| 35. |
- Fiorani, M., et al.
(författare)
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Flexible architecture and control strategy for metro-scale networking of geographically distributed data centers
- 2016
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Ingår i: European Conference on Optical Communication, ECOC. - : Institute of Electrical and Electronics Engineers Inc.. ; , s. 166-168
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a flexible architecture and control strategy to enable adaptive resource allocation in metro-scale inter data center networks. Experimental implementation and numerical evaluations are presented, proving substantial benefits in terms of transmission time and resource usage.
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| 36. |
- Fiorani, Matteo, et al.
(författare)
-
Optical networks for energy-efficient data centers
- 2014
-
Konferensbidrag (refereegranskat)abstract
- The growing popularity of cloud and multimedia services is increasing the traffic volume that each datacenter (DC) needs to handle. As a consequence, the serious bottlenecks in DC networks in terms of both capacity and energy consumption need to be addressed. DC networks typically consist of edge tier, aggregation tier and core tier, which interconnect different servers within a DC as well as provide the interfaces to the Internet. Current large-scale DC network architectures are based on the fat-tree three-tiers topology [1] and on electronic switches, which are not able to scale to meet future traffic requirements in a sustainable manner. Reducing the power required by the inter- and intra-rack communication inside DCs through use of optical technology opens a way to solve this problem. However, the current optical switching technologies are not able to support the dynamic DC traffic, and hence, new optical interconnect architectures are needed. Several optical switching architectures have been recently proposed to replace the aggregation and core tiers of current DC networks with a high-capacity optical switch [1][2]. However, the largest amount of energy in current DC networks is consumed in the edge tier by the electronic top-of-the-rack (ToR) switches. Therefore, the optical switching in the aggregation-core tier doesn’t solve the problem. Moreover, the majority of the optical DC network architectures proposed so far can be categorized as optical circuit switching or optical packet switching. Unfortunately, there are certain limitations associated with these optical switching technologies for their application in DC networks. Namely, optical circuit switching architectures are not able handle the bursty and highly variable DC traffic while optical packet switching usually makes use of electronic buffers, which limit scalability and increase energy consumption. To reduce the energy consumption in the edge tier, we propose a novel optical broadcast-and-select - rchitecture at the ToR. In this architecture, each server is equipped with an optical network interface (ONI) and is connected to the other servers in the same rack through a N?2 coupler, where N represents the number of servers in the rack. In addition, in order to provide both fine switching granularity and high scalability, we propose the use of the elastic optical networking paradigm [3]. Consequently, each ONI will be equipped with a bandwidth variable transceiver (BVT), which provides the ability to tune wavelength and change dynamically the number of the occupied spectral slots. In this way, the capacity can be varied from 1 Gb/s to 100 Gb/s and beyond on a per-server level. On the other side, the inter-rack communications are handled by a large singlesided optical core switch. One of the commercially available single-sided switches is fabricated using the beam steering technology [4], where the maximum number of switch ports available so far is 192 and a 500-port matrix is under development. Larger single-sided switches can be realized by combining several stages of smaller switch matrices. The results of a preliminary study show that the proposed architecture is able to significantly reduce the energy consumption with respect to other solutions [1][2].
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| 37. |
- Furdek, Marija, 1985-, et al.
(författare)
-
Attack-aware dedicated path protection in optical networks
- 2016
-
Ingår i: Journal of Lightwave Technology. - : IEEE. - 0733-8724 .- 1558-2213. ; 34:4, s. 1050-1061
-
Tidskriftsartikel (refereegranskat)abstract
- Due to the high data rates in optical networks,physical-layer attacks targeting service degradation, such as powerjamming, can potentially lead to large data and revenue losses.Conventional network survivability approaches which establishlink-disjoint working and backup paths to protect from componentfaults may not provide adequate protection for such attacks.Namely, the working and the backup paths, although link-disjoint,might both be affected by a single attack scenario due to specificattack propagation characteristics. To enhance the existing survivabilityapproaches, we utilize the concept of an attack group(AG) which incorporates these characteristics to identify connectionswhich can simultaneously be affected by a single attack. Weapply this concept to dedicated path protection (DPP) and developattack-aware DPP (AA-DPP) approaches which aim to establishAG-disjoint primary and backup paths in a cost-effective manner.We provide a two-step ILP formulation for the routing and wavelengthassignment of the working and backup paths, as well as aheuristic for larger problem instances. Numerical results indicatethat the proposed approaches provide dedicated path protectionschemes with enhanced attack protection without using more resources(i.e., wavelengths, average path lengths) than standardDPPmethods.
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| 38. |
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| 39. |
- Furdek, Marija, 1985-, et al.
(författare)
-
Programmable Filterless Network Architecture Based on Optical White Boxes
- 2016
-
Ingår i: 20Th International Conference On Optical Network Design And Modeling (Ondm 2016). - : IEEE conference proceedings.
-
Konferensbidrag (refereegranskat)abstract
- We propose and evaluate a novel architecture enabling high-capacity, resource efficient and agile elastic optical networks. It is based on sliceable bandwidth-variable transponders and optical white box switches which route optical signals without filtering them. Instead of using active filtering components, each node is equipped with an optical white box based on a programmable optical switch that serves as an optical backplane. It provides interconnections between input/output ports and passive splitters and couplers. Due to signal broadcast and the absence of filtering (so-called drop-and-waste transmission), some of the signals appear on unintended links which can lead to an overhead in spectrum usage. To address this issue, we formulate the problem of signal routing, modulation format and spectrum assignment in programmable filterless networks based on optical white boxes as an integer linear program (ILP) with the objective to minimize the total spectrum usage. Simulation results indicate that our proposed solution obtains a beneficial tradeoff between component usage and spectrum consumption, using a drastically lower number of active switching elements than the conventional networks based on hard-wired reconfigurable add/drop multiplexers, and lowering the maximum used frequency slot by up to 48% compared to existing passive filterless networks.
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| 40. |
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| 41. |
- Furdek, Maria, et al.
(författare)
-
Shared path protection under the risk of high power jamming
- 2014
-
Ingår i: 2014 19th European Conference on Networks and Optical Communications, NOC 2014. - 9781479938728 ; , s. 23-28
-
Konferensbidrag (refereegranskat)abstract
- Transparent optical networks are sensitive to high-power jamming which can degrade legitimate user signals via out-of-band effects in optical fibers and amplifiers, and in-band crosstalk in optical switches. Jamming signals can be inserted in the network either deliberately as an attack, with the intention to deteriorate service, or accidentally, due to component miscon-figuration. This type of attack/failure can potentially propagate through the network causing high data and revenue losses, requiring tailored survivability approaches which take these harmful effects into consideration. Namely, conventional network survivability approaches which protect transmission in case of component faults might not provide adequate protection from jamming since the working and backup paths of a connection may both be within reach of the same jamming signal, even if they are link/node disjoint. Previously, we proposed the concept of an Attack Group (AG) of an all-optical connection (referred to as a lightpath), comprised of all other lightpaths which potentially can affect it in case they carry a high-power jamming signal. Furthermore, we developed a jamming attack-aware dedicated path protection algorithm which establishes AG-disjoint working and backup paths for each connection. Herein, we extend this work by proposing an approach for Jamming-Aware Shared Path Protection (JA-SPP) to achieve survivability in the presence of jamming signals in a more resource-efficient way. We formulate the JA-SPP problem as an Integer Linear Problem (ILP) to obtain optimal solutions for smaller network instances. Comparison with standard SPP for single component faults (without jamming-awareness) shows that JA-SPP obtains solutions which offer protection from high-power jamming, in addition to single component faults, while using the same amount of resources (in terms of link and wavelength usage) as the standard SPP.
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| 42. |
- Furdek, Maria, et al.
(författare)
-
Vulnerabilities and security issues in optical networks
- 2014
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Ingår i: Transparent Optical Networks (ICTON), 2014 16th International Conference on. - : IEEE conference proceedings. - 9781479956005 ; , s. 1-4
-
Konferensbidrag (refereegranskat)abstract
- The paper provides a comprehensive overview of security issues in state-of-the-art optical networks. It identifies and describes the main vulnerabilities of today’s and future networks and outlines potential methods of attack which could exploit these vulnerabilities.
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| 43. |
- Furdek Prekratic, Marija, 1985, et al.
(författare)
-
Demonstration of Machine-Learning-Assisted Security Monitoring in Optical Networks
- 2019
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Ingår i: Proceedings of the 45th European Conference on Optical Communication, ECOC 2019.
-
Konferensbidrag (refereegranskat)abstract
- We report on the first demonstration of machine-learning-assisted detection, identification and localisation of optical-layer attacks integrated into network management system and verified on real-life experimental attack traces from a network operator testbed.
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| 44. |
- Furdek Prekratic, Marija, 1985, et al.
(författare)
-
Design of Programmable Filterless Optical Networks
- 2020
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Ingår i: 2020 Photonics North, PN 2020.
-
Konferensbidrag (refereegranskat)abstract
- We present the main operating principles and guidelines for the design of programmable filterless networks.
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| 45. |
- Goscien, R., et al.
(författare)
-
Impact of high-power jamming attacks on SDM networks
- 2018
-
Ingår i: 22nd Conference on Optical Network Design and Modelling, ONDM 2018 - Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783903176072 ; , s. 77-81
-
Konferensbidrag (refereegranskat)abstract
- Space Division Multiplexing (SDM) is a promising solution to provide ultra-high capacity optical network infrastructure for rapidly increasing traffic demands. Such network infrastructure can be a target of deliberate attacks that aim at disrupting a large number of vital services. This paper assesses the effects of high-power jamming attacks in SDM optical networks utilizing Multi-Core Fibers (MCFs), where the disruptive effect of the inserted jamming signals may spread among multiple cores due to increased Inter-Core CrossTalk (ICo-XT). We first assess the jamming-induced reduction of the signal reach for different bit rates and modulation formats. The obtained reach limitations are then used to derive the maximal traffic disruption at the network level. Results indicate that connections provisioned satisfying the normal operating conditions are highly vulnerable to these attacks, potentially leading to huge data losses at the network level.
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| 46. |
- Grigoreva, Elena, et al.
(författare)
-
Energy Consumption and Reliability Performance of Survivable Passive Optical Converged Networks: Public ITS Case Study
- 2017
-
Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 9:4, s. C98-C107
-
Tidskriftsartikel (refereegranskat)abstract
- Access networks are evolving fast by increasing their capacity and coverage area, coping with a larger number of users and variety of terminals. Operators aim at keeping high network performance and quality of service but limiting their capital and operational expenditures by, e.g., minimizing investments and energy consumption using power saving at the network components. To address these challenges this paper evaluates the energy consumption, connection availability, and failure detection time of three protection schemes applicable for converged access networks: disjoint fiber protection, energy-efficient disjoint fiber protection, and reflective disjoint fiber protection. The schemes are assessed by a case study considering a public intelligent transport system (ITS). The studied ITS deploys a dedicated short-range communications radio access network connected to the service server through a protected passive access network. Comparison with unprotected architecture shows that reflective disjoint fiber protection offers low energy consumption and high connection availability, while it significantly reduces the failure detection time and, hence, the connection interruption time.
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| 47. |
- Hasegawa, Hiroshi, et al.
(författare)
-
Design strategies for survivable Grouped Routing Entity (GRE)-based optical networks
- 2013
-
Ingår i: Design of Reliable Communication Networks (DRCN), 2013 9th International Conference on the. - 9781479900497 ; , s. 148-154
-
Konferensbidrag (refereegranskat)abstract
- In bandwidth abundant optical networks, the Grouped Routing Entity (GRE) concept is a cost-efficient alternative used instead of waveband routing. It offers all the benefits of the waveband routing (i.e., reduced number of ports), without using expensive wavelength cross connects (WXCs) required in hierarchical optical networks. In fact in a GRE-based optical network wavelength channel add/drop operations are accomplished via Wavelength Selective Switches (WSS) or with optical couplers. The objective of this paper is to further investigate the benefits of GRE-based optical networks in a scenario where survivability is required. In this paper a dedicated protection scheme is proposed, where wavelength paths are efficiently routed using mostly disjoint working and backup GRE pipes (i.e., working and backup pipes are allowed to share some common nodes along their paths). Numerical experiments demonstrate that significant hardware scale reduction at the switching nodes can be obtained by using the proposed network design algorithm.
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| 48. |
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| 49. |
- Izquierdo-Zaragoza, J. -L, et al.
(författare)
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On the dimensioning of survivable optical metro/core networks with dual-homed access
- 2016
-
Ingår i: IEEE International Conference on High Performance Switching and Routing, HPSR. - : IEEE Computer Society.
-
Konferensbidrag (refereegranskat)abstract
- Long-reach passive optical networks (LR-PONs) are able to effectively support the growing demand of traffic originating from residential and business customers. Failures of metro/core (M/C) nodes serving the traffic to/from the access networks covered by LR-PONs, may potentially affect hundreds or thousands of customers. One way of guaranteeing 100% survivability from single-node failures is to apply dual-homing, where each LR-PON is connected to two M/C nodes, and combine it with node-disjoint dedicated-path protection (DPP). In this paper, we present a new approach to provide network survivability against single M/C node failures. Instead of applying dedicated path protection (DPP) strategy, which can require huge amount of extra resources, we combine an unprotected network design with a dynamic multilayer restoration algorithm. Our aim is to determine a suitable amount of resource overbuild (in terms of extra transponders) needed to provide average connection availability close to that guaranteed by DPP. Preliminary results show that dimensioning for the worst-case scenario among a set of predefined M/C node failures, i.e., the one disrupting the highest number of connections, yields to a cost-effective strategy requiring up to 35% less transponders than DPP, while offering the same average connection availability.
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| 50. |
- Jalalinia, Shabnam Sadat, et al.
(författare)
-
Survivable green optical backbone networks with shared path protection
- 2012
-
Ingår i: Optics InfoBase Conference Papers. - Washington, D.C. : Optica Publishing Group. - 9781557529381
-
Konferensbidrag (refereegranskat)abstract
- We propose a novel energy-efficient and survivable routing algorithm addressing the trade-off caused by conflicting objectives of energy saving and survivability, i.e. energy-efficient routing tends to pack while survivable strategies try to spread the traffic.
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