1,207 research outputs found
Considering Transmission Impairments in Wavelength Routed Networks
Abstract â We consider dynamically reconfigurable wavelength routed networks in which lightpaths carrying IP traffic are on demand established. We face the Routing and Wavelength Assignment problem considering as constraints the physical impairments that arise in all-optical wavelength routed networks. In particular, we study the impact of the physical layer when establishing a lightpath in transparent optical network. Because no signal transformation and regeneration at intermediate nodes occurs, noise and signal distortions due to non-ideal transmission devices are accumulated along the physical path, and they degrade the quality of the received signal. We propose a simple yet accurate model for the physical layer which consider both static and dynamic impairments, i.e., nonlinear effects depending on the actual wavelength/lightpath allocation. We then propose a novel algorithm to solve the RWA problem that explicitly considers the physical impairments. Simulation results show the effectiveness of our approach. Indeed, when the transmission impairments come into play, an accurate selection of paths and wavelengths which is driven by physical consideration is mandatory. I
Optimized Design of Survivable MPLS over Optical Transport Networks. Optical Switching and Networking
In this paper we study different options for the survivability implementation
in MPLS over Optical Transport Networks in terms of network resource usage and
configuration cost. We investigate two approaches to the survivability
deployment: single layer and multilayer survivability and present various
methods for spare capacity allocation (SCA) to reroute disrupted traffic. The
comparative analysis shows the influence of the traffic granularity on the
survivability cost: for high bandwidth LSPs, close to the optical channel
capacity, the multilayer survivability outperforms the single layer one,
whereas for low bandwidth LSPs the single layer survivability is more
cost-efficient. For the multilayer survivability we demonstrate that by mapping
efficiently the spare capacity of the MPLS layer onto the resources of the
optical layer one can achieve up to 22% savings in the total configuration cost
and up to 37% in the optical layer cost. Further savings (up to 9 %) in the
wavelength use can be obtained with the integrated approach to network
configuration over the sequential one, however, at the increase in the
optimization problem complexity. These results are based on a cost model with
actual technology pricing and were obtained for networks targeted to a
nationwide coverage
Practical issues for the implementation of survivability and recovery techniques in optical networks
Measurement Based Reconfigurations in Optical Ring Metro Networks
Single-hop wavelength division multiplexing (WDM) optical ring networks operating in packet mode are one of themost promising architectures for the design of innovative metropolitan network (metro) architectures. They permit a cost-effective design, with a good combination of optical and electronic technologies, while supporting features like restoration and reconfiguration that are essential in any metro scenario. In this article, we address the tunability requirements that lead to an effective resource usage and permit reconfiguration in optical WDM metros.We introduce reconfiguration algorithms that, on the basis of traffic measurements, adapt the network configuration to traffic demands to optimize performance. Using a specific network architecture as a reference case, the paper aims at the broader goal of showing which are the advantages fostered by innovative network designs exploiting the features of optical technologies
Analysis of resource sharing in transparent networks
Transparent optical networking promises a cost-efficient solution for future core and metro networks because of the efficacy of switching high-granularity trunk traffic without opto-electronic conversion. Network availability is an important performance parameter for network operators, who are incorporating protection and restoration mechanisms in the network to achieve competitive advantages. This paper focuses on the reduction in Capital Expenditures (CapEx) expected from implementing sharing of backup resources in path-protected transparent networks. We dimension a nationwide network topology for different protection mechanisms using transparent and opaque architectures. We investigate the CapEx reductions obtained through protection sharing on a population of 1000 randomly generated biconnected planar topologies with 14 nodes. We show that the gain for transparent networks is heavily dependent on the offered load, with almost no relative gain for low load (no required parallel line systems). We also show that for opaque networks the CapEx reduction through protection sharing is independent of the traffic load and shows only a small dependency on the number of links in the network. The node CapEx reduction for high load (relative to the number of channels in a line system) is comparable to the CapEx reduction in opaque OTN systems. This is rather surprising as in OTN systems the number of transceivers and linecards and the size of the OTN switching matrix all decrease, while in transparent networks only the degree of the ROADM (number and size of WSSs in the node) decreases while the number of transponders remains the same
High speed all optical networks
An inherent problem of conventional point-to-point wide area network (WAN) architectures is that they cannot translate optical transmission bandwidth into comparable user available throughput due to the limiting electronic processing speed of the switching nodes. The first solution to wavelength division multiplexing (WDM) based WAN networks that overcomes this limitation is presented. The proposed Lightnet architecture takes into account the idiosyncrasies of WDM switching/transmission leading to an efficient and pragmatic solution. The Lightnet architecture trades the ample WDM bandwidth for a reduction in the number of processing stages and a simplification of each switching stage, leading to drastically increased effective network throughputs. The principle of the Lightnet architecture is the construction and use of virtual topology networks, embedded in the original network in the wavelength domain. For this construction Lightnets utilize the new concept of lightpaths which constitute the links of the virtual topology. Lightpaths are all-optical, multihop, paths in the network that allow data to be switched through intermediate nodes using high throughput passive optical switches. The use of the virtual topologies and the associated switching design introduce a number of new ideas, which are discussed in detail
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