| 1. |
- Monti, Paolo, et al.
(författare)
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New Dimensions for Survivable Service Provisioning in Optical Backbone and Access Networks
- 2012
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Ingår i: Resilient Optical Network Design. - : IGI Global. - 9781613504260 - 1613504268 ; , s. 227-252
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Bokkapitel (refereegranskat)abstract
- Originally, networks were engineered to provide only one type of service, i.e. either voice or data, soonly one level of resiliency was requested. This trend has changed, and today’s approach in serviceprovisioning is quite different. A Service Level Agreement (SLA) stipulated between users and serviceproviders (or network operators) regulates a series of specific requirements, e.g., connection set-up timesand connection availability that has to be met in order to avoid monetary fines. In recent years this hascaused a paradigm shift on how to provision these services. From a “one-solution-fits-all” scenario, wewitness now a more diversified set of approaches where trade-offs among different network parameters(e.g., level of protection vs. cost and/or level of protection vs. blocking probability) play an important role.This chapter aims at presenting a series of network resilient methods that are specifically tailored for adynamic provisioning with such differentiated requirements. Both optical backbone and access networksare considered. In the chapter a number of provisioning scenarios - each one focusing on a specificQuality of Service (QoS) parameter - are considered. First the effect of delay tolerance, defined as theamount of time a connection request can wait before being set up, on blocking probability is investigatedwhen Shared Path Protection is required. Then the problem of how to assign “just-enough” resources tomeet each connection availability requirement is described, and a possible solution via a Shared PathProtection Scheme with Differentiated Reliability is presented. Finally a possible trade off between deploymentcost and level of reliability performance in Passive Optical Networks (PONs) is investigated. The presented results highlight the importance of carefully considering each connection’s QoS parameterswhile devising a resilient provisioning strategy. By doing so the benefits in terms of cost saving andblocking probability improvement becomes relevant, allowing network operators and service providersto maintain satisfied customers at reasonable capital and operational expenditure levels.
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| 2. |
- Razo, Miguel, et al.
(författare)
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Limiting Wavelength Converter Usage in Resilient WDM Networks
- 2010
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Ingår i: 2010 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS. - 9781424464043
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Konferensbidrag (refereegranskat)abstract
- A careful wavelength assignment (WA) to lambda services must be performed to reduce the total number of wavelength converters (WCs) that are required when the wavelength continuity constraint cannot be met in wavelength division multiplexing (WDM) networks. With the successful introduction of reconfigurable optical add-drop multiplexers (ROADMs), WDM networks are now growing in size, both in the number of optical nodes and the number of wavelengths supported. Fast and memory efficient WA algorithms are required to design cost effective large WDM networks. This paper presents a scalable and efficient WA heuristic algorithm aimed at reducing the total number of WCs that are required in (large) WDM networks bearing static lambda services. The WA algorithm is applied to both unprotected and (dedicated) protected lambda services. In the latter case, the wavelength continuity constraint between the working and protection path of a lambda service is taken into consideration when non-tunable optical transceivers are employed.
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| 3. |
- Tang, Limin, et al.
(författare)
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A customizable two-step framework for general equipment provisioning in Optical Transport Networks
- 2011
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Ingår i: ONDM 2011 - 15th Conference on Optical Network Design and Modeling. - 9783901882425
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Konferensbidrag (refereegranskat)abstract
- Optical Transport Network (OTN) is a standard approach to offering transport support to a variety of existing service technologies, e.g., ESCON, HDTV, GE, etc. Multiple service technologies can be concurrently multiplexed onto one common transport network, which offers hierarchical transmission rate wrappers physically supported by Wavelength Division Multiplexing (WDM) lambda channels. Algorithms to perform grooming and routing in OTN are expected to be complicated due to the large number of grooming options that are available in the standard. In addition, these algorithms are likely to be designed by the vendor engineers, who have full knowledge of the grooming, switching, and routing capabilities of their own equipment. Yet the authors of this paper propose a relatively simple algorithm framework for equipment provisioning in OTN that can be customized by the network designer. Taking advantage of the multi-rate nature of supported services in OTN, traffic demands can be divided into two groups based on their bandwidth requirement. Demands with bandwidth request below a bandwidth threshold are placed on newly provisioned resources and demands with bandwidth request above the threshold are preferably routed over already provisioned resources. The latter procedure is more time consuming but yields more efficient traffic grooming when compared to the former procedure. The bandwidth threshold can be set by the network designer either to decrease running time of the algorithm, or conversely, to increase optimality of the solution found.
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| 4. |
- Tang, Limin, et al.
(författare)
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Computing alternate multicast trees with maximum latency guarantee
- 2010
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Ingår i: 2010 International Conference on High Performance Switching and Routing, HPSR 2010. - 9781424469710 ; , s. 82-87
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Konferensbidrag (refereegranskat)abstract
- The growing demand for online media content delivery and multi-player gaming is expected to increase the amount of multicast service requests in both public and private networks. Careful traffic engineering of multicast service requests is becoming increasingly essential, as establishing the lowest cost tree, e.g., shortest path tree, in the network for every individual multicast request does not always ensure a global optimization. In this paper, the authors investigate the use of alternate tree routing, according to which multiple sub-optimal tree candidates are computed for each multicast request. When performing global routing optimization, each request is then assigned one of the tree candidates, in a way that yields the desired result, e.g., to minimize the number of (active) links that are required in the network to bear the entire set of requests. A key component of the investigated approach is the timely construction of the set of alternate trees for every given root and destination set. An algorithm is proposed to compute multiple sub-optimal tree candidates with a guaranteed upper bound on the maximum end-to-end transmission latency. The algorithm builds on the widely used K shortest path algorithm, generalizing the technique of computing K candidate shortest paths to obtain a number of candidate sub-optimal trees with desirable properties. Simulation experiments obtained for a multi-protocol label switching (MPLS) traffic engineering network are discussed to investigate the effectiveness, performance, and scalability of the proposed algorithm.
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