Papers by Jean-François Labourdette
John Wiley & Sons, Ltd eBooks, Oct 2, 2007
2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference, 2006
Carriers are often faced with the need to scale the switching capacity of a central office site b... more Carriers are often faced with the need to scale the switching capacity of a central office site by installing multiple switches at that site. In this paper, we first provide a strong argument that multiple colocated switches should always be interconnected together because of the uncertainty in future traffic requests. However, this results in an inefficient use of a portion of the switching capacity as a number of ports are used to interconnect the switches together (the so-called "interconnect penalty"). We develop and apply a quantitative model that analyzes the interconnection capacity required to achieve certain performance criteria as a function of traffic uncertainty. We also derive bounds on the interconnection capacity required between multiple switches for different interconnection approaches and traffic patterns. The practical implication of this work is the realization of the need to eventually deploy an additional layer of highercapacity switches of higher switching granularity in the context of optical networks to handle high bandwidth services and relieve the capacity needs of lower granularity switches.
2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference, 2006
We model and measure the impact of multi-port cards and circuit-pack diversity constraints on the... more We model and measure the impact of multi-port cards and circuit-pack diversity constraints on the routing of protected lightpaths in optical networks and the resulting network capacity. We describe an offline routing and channel assignment algorithm combined with a multiport card configuration algorithm, and experiments with these algorithms on various network designs. We show in particular that the impact is negligible, even in the case of shared-mesh protection architectures protecting against single multi-port card failures.
Optical Fiber Communication Conference and Exhibit
The 13th IEEE Workshop on Local and Metropolitan Area Networks, 2004. LANMAN 2004.
OFC 2003 Optical Fiber Communications Conference, 2003., 2003
Networks that transport optical connections using Wavelength Division Multiplexed (WDM) systems a... more Networks that transport optical connections using Wavelength Division Multiplexed (WDM) systems and route these connections using intelligent optical cross-connects (OXCs) are firmly established as the core constituent of next generation long-haul networks. In such networks, preventing and restoring link and node failures is increasingly becoming one of the most important network features [1-6]. Dynegy's network implements shared mesh restoration using intelligent optical switches to protect against single link and node failures. In shared mesh restoration (Figure 1), backup paths can share capacity if the corresponding primary paths are mutually diverse. Diversity of routes in Dynegy's optical network is defined using the notion of Shared Risk Groups [7]. A set of optical channels that have the same risk of failure is called a Shared Risk Group (SRG). SRGs are configured by Dynegy's network operators with the knowledge of the physical fiber plant of the optical network.
Proceedings.Twenty-First Annual Joint Conference of the IEEE Computer and Communications Societies
In this paper we assess the benefits of using statistical techniques to ascertain the shareabilit... more In this paper we assess the benefits of using statistical techniques to ascertain the shareability of protection channels when computing shared mesh restored lightpaths. Current deterministic approaches require a detailed level of information proportional to the number of active lightpaths, and do not scale well as traffic demands and network grow. With the proposed approach we show that less information, independent of the amount of traffic demand, is sufficient to determine the shareability of protection channels with remarkable accuracy. Experiments also demonstrate that our approach yields faster computation times with no significant penalty in terms of capacity usage.
At the heart of IP backbone networks are the core IP routers with throughput of hundreds of Gb/s.... more At the heart of IP backbone networks are the core IP routers with throughput of hundreds of Gb/s. These routers with interfaces operating at the per-wavelength bit rates are directly connected via point-to-point WDM optical-transport systems. For acceptable service reliability even for best effort services typically two interconnected routers are used for redundancy in each backbone node. It has been established that the majority of the traffic in a node is transit traffic and a significant cost reduction can be achieved by siphoning off the transit traffic from the IP layer into the optical layer. In this paper we discuss the current trend in the IP backbone network which is poised to take over other premium services, in addition to best effort IP services, as an integrated transport platform. We discuss several network architecture options with the critical attribute being that it must be as resilient as the current SONET transport network. We propose an innovative architecture op...
Optical Transmission Systems and Equipment for WDM Networking III, 2004
ABSTRACT For distributed control, network topology and link resource information is required at t... more ABSTRACT For distributed control, network topology and link resource information is required at the ingress nodes to compute and route optical paths. It is the responsibility of routing protocols to disseminate this information. Generalized MPLS has extended traditional IP routing protocols such as OSPF for explicit path computation and traffic engineering (TE) in optical transport networks. However it is noted that the current version of GMPLS-extended OSPF-TE does not carry sufficient link state information to compute shared mesh restored paths. This paper describes the new extensions to the GMPLS OSPF-TE protocol to support the path computation for shared mesh restoration in optical networks. The efficient methods for aggregation and dissemination of link resource availability and sharing information are proposed. Especially these new extensions support both Shared Risk Link Group (SRLG) disjoint and node disjoint restoration paths, which provides more flexibility to the network operators. The network operators can choose to guarantee recovery from a SRLG failure or from a node/SRLG failure based upon the applications and the service level agreements with their customers. Furthermore, the paper presents an analytical model to estimate the performance of the GMPLS OSPF-TE protocol and the proposed extensions, including control bandwidth and memory requirements.
2004 IEEE International Conference on Communications (IEEE Cat. No.04CH37577), 2004
Distributed, IP-based control architecture has been proposed for switched optical mesh networks, ... more Distributed, IP-based control architecture has been proposed for switched optical mesh networks, as a means to automate operations, enhance interoperability and facilitate the deployment of new applications. While distributed control in general enhances scalability and flexibility, it also offers challenges to path computation, especially for shared mesh restored paths, because of the summarization of link state information disseminated by the routing protocol. This paper discusses the tradeoffs between the path computation efficiency and the abstraction level of link state information. Several heuristic algorithms for computing shared mesh restored paths are described, which require different levels of abstraction and summarization of link resource sharing information. The performance of these algorithms is compared in term of the efficiency of network capacity utilization, the computation complexity, and the amount of required network information. We show that with appropriately aggregated link state information the proposed path computation algorithms are able to utilize the network resource very efficiently.
Emerging Optical Network Technologies, 2005
... Ramu Ramamurthy Zbigniew Bogdanowicz Shahrokh Samieian Debanjan Saha Bala Rajagopalan Su... more ... Ramu Ramamurthy Zbigniew Bogdanowicz Shahrokh Samieian Debanjan Saha Bala Rajagopalan Sudipta Sengupta Sid Chaudhuri and Krishna Bala Capacity Perfor-mance of Dynamic Provisioning in Optical networks IEEE Journal of Lightwave Tech-nology vol. ...
IEEE Journal on Selected Areas in Communications, 2004
AbstractOptical mesh network infrastructure has emerged as the technology of choice for next-gen... more AbstractOptical mesh network infrastructure has emerged as the technology of choice for next-generation transport networks. At the same time, distributed, IP-based, control architecture has been proposed for intelligent optical networks, as a means to automate operations, ...
IEEE/ACM Transactions on Networking, 2004
In this paper we assess the benefits of using statistical techniques to ascertain the shareabilit... more In this paper we assess the benefits of using statistical techniques to ascertain the shareability of protection channels when computing shared mesh restored lightpaths in optical mesh networks. These optical networks support wavelength conversion everywhere as a byproduct of the electronic nature of the switching in the OEO optical cross-connect used. Current deterministic approaches require a detailed level of information proportional to the number of active lightpaths. Although this is not an issue for good size networks in the foreseeable future, these approaches are not practicable for distributed route computation involving larger networks. On the other hand, distributed approaches that do not make use of shareability information require a significant amount of additional capacity compared to a centralized approach with access to complete shareability information. With the proposed approach we show that even with less information, independent of the amount of traffic demand, it is possible to predict the shareability of protection channels with remarkable accuracy. In addition, we propose a local distributed channel assignment scheme that is used in conjunction with our distributed route computation proposal to assign shared channels when provisioning the backup path. This channel assignment scheme can also be used to further optimize capacity usage in individual links upon certain events or at regular intervals. Experiments are provided, that demonstrate that our approach yields faster computation times with no significant penalty in terms of capacity usage than a centralized approach using complete information.
IEEE/ACM Transactions on Networking, 2005
In this paper we study two algorithms to re-optimize lightpaths in resilient mesh optical network... more In this paper we study two algorithms to re-optimize lightpaths in resilient mesh optical networks. A complete re-optimization algorithm that reroutes both primary and backup paths, and a partial reoptimization algorithm that reroutes the backup paths only. We show that on average, these algorithms allow bandwidth savings of 3 to 5% of the total capacity in scenarios where the backup path only is rerouted, and substantially larger bandwidth savings when both the working and backup paths are rerouted .
IEEE/ACM Transactions on Networking, 2005
This paper presents a collection of approximation formulas that allow a network planner to quickl... more This paper presents a collection of approximation formulas that allow a network planner to quickly estimate the size of a mesh optical network with limited inputs. In particular, it provides a set of equations that relate number of sites, average fiber connectivity, demand load and capacity for various mesh protection architectures. These results can be used to easily and quickly estimate the amount of traffic that can be carried over a given network, or, conversely, given the traffic to be supported, to assess the characteristics of the topology required (in terms of number of nodes, connectivity). Finally, this analysis can be used to estimate the restoration performance that can be expected without requiring any extensive simulation studies.
Historical Trends As Digital Cross-Connect Systems (DCSs) have been introduced into digital core ... more Historical Trends As Digital Cross-Connect Systems (DCSs) have been introduced into digital core transport networks over the past 25 years, the rate of the core transmission speed has traditionally been about 20 to 40 times the rate of the core "switching" (cross-connect) rate. 1 DS0 (64 kb/s) signals were switched when core transport systems were on the order of DS1 signals (1.5 Mb/s); similarly, DS1 signals were switched within DS3 (~45 Mb/s) signals. Most recently, DS3 signals were switched with DCSs when the core transmission speeds were on the order of 1.5 Gbps to 3 Gbps (~STS-48). Now, when the core transmission speeds are on the order of multiple 10Gbps wavelengths, by historical analogy the rate of core transport switching should be on the order of an STS-48 (2.5Gbps). Current Networks Client devices are now being produced and installed with interfaces at the rates of 2.5 Gbps and 10 Gbps. 2 As these devices are deployed more frequently, it makes sense that these customer interface rates also 825 National Fiber Optic Engineers Conference 2002 Technical Proceedings
IEEE/LEOS Annual …, 2002
We present Dynegy's long-haul optical mesh network utilizing Tellium's intelligent optical switch... more We present Dynegy's long-haul optical mesh network utilizing Tellium's intelligent optical switches. Shared mesh restoration is used to protect against failures and a re-optimization algorithm is implemented to regain portion of the protection capacity used.
At the heart of IP backbone networks are the core IP routers with throughput of hundreds of Gb/s.... more At the heart of IP backbone networks are the core IP routers with throughput of hundreds of Gb/s. These routers with interfaces operating at the per-wavelength bit rates are directly connected via point-to-point WDM opticaltransport systems. For acceptable service reliability even for best effort services typically two interconnected routers are used for redundancy in each backbone node. It has been established that the majority of the traffic in a node is transit traffic and a significant cost reduction can be achieved by siphoning off the transit traffic from the IP layer into the optical layer. In this paper we discuss the current trend in the IP backbone network which is poised to take over other premium services, in addition to best effort IP services, as an integrated transport platform. We discuss several network architecture options with the critical attribute being that it must be as resilient as the current SONET transport network. We propose an innovative architecture option in which a resilient network is built with current router technology. In another option we assume that the router layer can be as resilient as the current SONET layer with the emerging resilient router technology. We perform an economic evaluation and discuss the reliability of these network architectures.
IEEE/ACM Transactions on Networking, 2004
In this paper we assess the benefits of using statistical techniques to ascertain the shareabilit... more In this paper we assess the benefits of using statistical techniques to ascertain the shareability of protection channels when computing shared mesh restored lightpaths in optical mesh networks. These optical networks support wavelength conversion everywhere as a byproduct of the electronic nature of the switching in the OEO optical cross-connect used. Current deterministic approaches require a detailed level of information proportional to the number of active lightpaths. Although this is not an issue for good size networks in the foreseeable future, these approaches are not practicable for distributed route computation involving larger networks. On the other hand, distributed approaches that do not make use of shareability information require a significant amount of additional capacity compared to a centralized approach with access to complete shareability information. With the proposed approach we show that even with less information, independent of the amount of traffic demand, it is possible to predict the shareability of protection channels with remarkable accuracy. In addition, we propose a local distributed channel assignment scheme that is used in conjunction with our distributed route computation proposal to assign shared channels when provisioning the backup path. This channel assignment scheme can also be used to further optimize capacity usage in individual links upon certain events or at regular intervals. Experiments are provided, that demonstrate that our approach yields faster computation times with no significant penalty in terms of capacity usage than a centralized approach using complete information.
… Conference and Exposition …, 2006
Wavelength Division Multiplexed (WDM) networks that route optical connections using intelligent o... more Wavelength Division Multiplexed (WDM) networks that route optical connections using intelligent optical cross-connects are firmly established as the core constituent of next generation networks. It is a well-known fact that the demand for bandwidth has been growing at a ...
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Papers by Jean-François Labourdette