ISSN:1124-318X    

DOI:10.1002/ett.4460110102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2000

数据来源: WILEY

摘要:

AbstractThis paper presents a new heuristic algorithm useful for long‐term planning of survivable WDM networks. A multi‐period model is formulated that combines network topology design and capacity expansion. The ability to determine network expansion schedules of this type becomes increasingly important to the telecommunications industry and to its customers. The solution technique consists of a Genetic Algorithm that allows to generate several network alternatives for each time period simultaneously and shortest‐path techniques to deduce from these alternatives a least‐cost network expansion plan over all time periods. The multi‐period planning approach is illustrated on a realistic network example. Extensive simulations on a wide range of problem instances are carried out to assess the cost savings that can be expected by choosing a multi‐period planning approach instead of an iterative network expansion de

ISSN:1124-318X    

DOI:10.1002/ett.4460110103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2000

数据来源: WILEY

摘要:

AbstractA WDM optical layer can provide differentiated services to various upper layer protocols by forming many virtual optical networks (VONs). Polymorphic control of an optical layer in the form of On‐demand‐reconfiguration in some VONs and Self‐reconfiguration in other VONs is proposed. The former is suitable for bursty traffic and short‐lived connections, and the latter is for steady traffic and long‐lived connections. In respect to On‐demand‐reconfiguration, efficient distributed wavelength reservation protocols, and in particular optical burst switching (OBS) protocols supporting bursty traffic (eg. Internet traffic) are described. In respect to Self‐reconfiguration, optimal algorithms to schedule all‐to‐all personalized communications (AAPC) in WDM rings and its exten

ISSN:1124-318X    

DOI:10.1002/ett.4460110104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2000

数据来源: WILEY

摘要:

AbstractFuture broadband networks must support integrated services and offer flexible bandwidth usage. Most existing proposals for wide‐area wavelength division multiplexed (WDM) networks employ circuit switching adopting the concept of lightpath, in which each circuit or lightpath occupies an entire wavelength. This, however, is not suited for end‐to‐end transport of information streams, typically with each stream having its unique traffic characteristics such as the bandwidth needed, different traffic bursty nature, and diverse service requirements. In this paper, we explore the extensions of the functions of what we refer as the optical link control (OLC) layer, native on top of optical layer, to offer finer granularity of wavelength usage and further enable the possibility of bandwidth on‐demand (BOD) service directly over WDM networks. The objective is to facilitate the support of integrated services over WDM networks and to mitigate the changes needed in the upper layers as well. The proposed approach attempts to exploit the strengths of both optics and electronics, in which packets are either routed end‐to‐end over a lightpath transparently, or forwarded from wavelength to wavelength by electronic switching, whenever required. Furthermore, in order to establish an end‐to‐end BOD connection, the issue of how to select the best wavelength to mute the given connection is also investigated. The effectiveness of the proposal is evaluate

ISSN:1124-318X    

DOI:10.1002/ett.4460110105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2000

数据来源: WILEY

摘要:

AbstractThis paper considers the problem of distributed routing with fairness improvement in wavelength‐routed wavelength‐division multiplexed (WDM) networks with dynamic traffic conditions. The wavelength continuity constraint imposed by WDM networks causes increased blocking of connection requests. The performance loss is more for connections with longer hop counts, when compared to that for connections with shorter hop counts. This is further worsened when distributed routing is used due to the reservation conflicts. We propose a distributed control protocol to select a usable wavelength and route and to improve fairness among connections with different hop counts. The proposed dynamic priority based fairness improvement scheme(DPFS) improves fairness among connections by enforcing dynamically varying priority based control to the connection requests over access to a subset of the available wavelengths. while allowing a free access to the remaining wavelengths. We study the effectiveness of the proposed protocol through extensive simulation experiments. The results show that the proposed scheme improves fairness significantly with an acceptable level of degradation in the overall network performa

ISSN:1124-318X    

DOI:10.1002/ett.4460110106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2000

数据来源: WILEY

摘要:

AbstractThis paper introduces the concept of the multicast optical path in WDM networks, and treats the strategies and the algorithms, which allow the routing of plural multicast paths together with unicast paths. This analysis was motivated by the possibility of exploit the optical layer facilities in the transport network, to carry distributive services, such as video channels (e.g. CATV), without the need of dedicated transmission networks. The strategies and algorithms reported in this paper arise from a generalisation of those ones, which have been previously reported in literature. They are wavelength path (WP: which does not make use of wavelength conversion), virtual wavelength path (VWP: which make full use of wavelength conversion), and partial virtual wavelength path (PVWP: making a parsimonious use of wavelength conversion). The analysis shows the characteristics and performance of those strategies and algorithms considering, as a figure of merit, either the number of wavelengths or the system scale (dimensions of the optical nodes), and compare one to each other in order to point out advantages and disadvantages. The main result is that multicast optical paths can favourably be accommodated in a WDM network, and the strategy we propose, making a parsimonious use of wavelength conversion, allows the lowest system scale to be obtained with a very low number of wavelength converters.

ISSN:1124-318X    

DOI:10.1002/ett.4460110107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2000

数据来源: WILEY

摘要:

AbstractThis paper considers multicast routing and wavelength assignment (MCRWA) in a wide area all‐optical network. We present static and dynamic MCRWA algorithms, and evaluate their blocking performance under various fanout splitting policies. Through simulations and comparisons with a lower bound, we demonstrate that dynamic MCRWA can perform significantly better than its static counterparts. We then quantify the throughput gain due to link sharing in multicasting, and the performance penalty that would be suffered by considering each multicast request as multiple unicast connection requests. We also present an analytical model for estimating the blocking performance of the static MCRWA algorithms. The performance improvement with multifiber networks and with wavelength conversion are also investigate

ISSN:1124-318X    

DOI:10.1002/ett.4460110108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2000

数据来源: WILEY

摘要:

AbstractWe consider the problem of supporting multipoint communication at the MAC layer of broadcast WDM networks. We first introduce themidticcut rhroughprrt asthe performance measure of interest and we show that it depends on two measures that have previously been considered in isolation, namely, the efficient use of channel bandwidth and wavelength throughput. We then present a new technique for the transmission of multicast packets based on the concept of aLzirninlreceiver, a set of physical receivers which behave identically in terms of tuning. We also demonstrate that the number of virtual receivers naturally captures the performance of the system in terms of multicast throughput. Consequently, we focus on the problem of optimally selecting the virtual receivers to maximize multicast throughput, and we prove that it is Ji'P‐complete. Finally, we present four heuristics of varying degree of complexity for obtaining a set of virtuat receivers that provide near‐optimal performance in terms of multicast through

ISSN:1124-318X    

DOI:10.1002/ett.4460110109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2000

数据来源: WILEY

摘要:

AbstractThe European Union ACTS project SONATA will define and demonstrate a cswitchlessn all‐optical network to provide a future single‐layer, advanced transport architecture on a national scale. The single‐hop, shared‐access network employs time and wavelength agility (a WDMA/TDMA protocol), using fast tunable transmitters and receivers to route individual customer connections as well as bandwidth pipes through a single wavelength router (suitably replicated for resilience). No electronic switching nodes or cross‐connects (telephony, IP, ATM, SDH) are required within the transport network, nor optical cross‐connects (save the wavelength routing node), thus providing major transport architecture simplifications and hardware reductions. The network is scalable to 200 Tbit/s throughput over 1, 000 krn, connecting 20 million terminals operating at 622 Mbit/s over 50.000‐way split c

ISSN:1124-318X    

DOI:10.1002/ett.4460110110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2000

数据来源: WILEY

摘要:

AbstractWe introduce a meshed ring communications network which employs cross‐connect switches. The crossconnect switches can be implemented as wavelength routers resulting in WDM networks, or as ATM Virtual Path (VP) switches leading to ATM compatible network systems. We show in the paper that this network architecture results in a significant increase in throughput performance in comparison with (SDHISONET) ring networks. For a certain class of meshed rings, under a uniform traffic matrix, we derive the optimal topology which achieves maximum throughput efficiency. Using such a topology, we obtain upper and lower bounds on the number of wavelengths required to achieve that efficiency level. The network is divided into (overlapping) communities of nodes. Each community is assigned a wavelength and a subnetwork (identified as a wavelength graph). Each pair of nodes in a community can communicate across the associated wavelength graph. Wavelength graphs (subnets) are constructed to demonstrate the implementation of the routing scheme using the number of wavelengths that is equal to the derived upper bound. For practical implementation reasons, we investigate the performance of networks which employ a reduced number of wavelengths. We show that by modifying the topological layout of the meshed ring network, we can reduce substantially the number of required wavelengths, while incurring just a modest reduction in throughput efficienc

ISSN:1124-318X    

DOI:10.1002/ett.4460110111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2000

数据来源: WILEY