Wavelength-routed WDM Optical Networks Research Articles

Surveillance on Manycasting Over Optical Burst Switching (OBS) Networks under Secure Sparse Regeneration

In wavelength-routed WDM optical networks requires regeneration for few light paths, when the strength of optical signal reduced and also security and privacy are essential before Optical Burst Switching (OBS) networks can become an everyday reality. Manycasting is a communication paradigm to implement the distributed applications. In manycasting, destinations can join or exit the group, depending on the service requirements imposed on them. This dynamic movement of the destinations in the group decreases blocking effect. Each application requires its own QoS threshold attributes like physical layer properties, delay as a result of transmission and reliability of the link. If the destinations satisfy the required QoS constraints set up by the application, then only they will qualify. There are two algorithms MCM-SPT and MCM-DM required for manycasting to resolve the multiconstraint QoS drawback. For continuous burst transmission lightpath should be regenerated before it loses the information due to lack of signal strength. To recover signal strength by sparse regeneration, where OOO switches are replaced by OEO swtches. There are three algorithms 1).NDF 2).CNF 3).SQP. Sometimes, there is an opportunity for the attacker to join the group. Service provided to the attacker is restricted by providing two levels of security. Using1).RSA algorithms, data level security is provided and using 2).certificate authentication, link level security is provided.

Blocking probability optimization in wavelength routed optical WDM networks

This paper presents the mathematical models for wavelength routed WDM optical networks for optimization of blocking probability. This model works well for the networks with higher load. The proposed mathematical model is then compared with the earlier proposed mathematical model. Comparison proved that the model works better than the earlier proposed model. The value of blocking probability ranges from 0 to 10−4 in case of the proposed model whereas it lies in the range of 0–1 in earlier mathematical model.

Deadline-based connection setup in wavelength-routed WDM networks

This article addresses the ubiquitous topic of quality of service (QoS) aware connection provisioning in wavelength-routed WDM optical networks. The impact of the connection setup time of an optical connection has not been adequately addressed in the open literature. As such, this paper presents a novel approach that uses the optical connection setup time as a service differentiator during connection provisioning. The proposed approach utilizes the Earliest Deadline First (EDF) queueing algorithm to achieve deadline-based connection setup management with the deadline being the setup time requirement of an optical connection. The proposed EDF-based approach would allow the network operator to improve the QoS perceived by the end clients. Performance of this novel scheme is analyzed by accurately calculating various parameters, such as the fraction of connections provisioned on-time (i.e. prior to deadline expiration) and the average time it takes to successfully setup a connection. In addition, the presented approach is validated by a simulation that analyzes the performance of the proposed connection setup scheme in the specific context of the National Science Foundation Network (NSFNET). The obtained results show that a deadline-based setup strategy can minimize blocking probability while achieving QoS differentiation.

A New Objective Criterion and Rounding Techniques for Determining Virtual Topologies in Optical Networks

This letter addresses the problem of determining virtual topologies in wavelength-routed WDM optical networks. To solve this problem, it is necessary to determine the set of lightpaths which comprise the virtual topology. Packet-switched traffic is then routed over this set of lightpaths, completely independent of the physical topology. Common objectives include minimizing congestion or packet hop distance. In this letter, we introduce an additional objective criterion, discuss its importance, and derive an effective lower bound. Several solution approaches use MILP formulations solved using LP-relaxations and rounding techniques. Proposed are alternative rounding schemes for determining more effective virtual topologies.

Multicast routing and wavelength assignment in WDM networks: a bin packing approach

We address the problem of multicast routing and wavelength assignment (MClowbarRWA) in wavelength-routed WDM optical networks. Multicast requests are facilitated in WDM networks by setting up so-called light trees and assigning wavelengths to them. Objectives of the MClowbarRWA problem include minimizing the number of distinct wavelengths used to establish a set of multicast requests and minimizing the cost of the corresponding light trees. This cost can represent the physical length, delay, or actual cost of a tree. Applications that require quality of service (QoS) multicasting can impose additional constraints on light trees, such as a bounded end-to-end delay. Proposed are heuristic algorithms based on bin packing methods for the general MClowbarRWA problem, which is NP complete. These algorithms can consider unicast, multicast, and broadcast requests with or without QoS demands. Computational tests indicate that these algorithms are efficient, particularly for dense networks.

Sparse Wavelength Conversion in Wavelength-Routed WDM Optical Networks*

A wavelength-routed optical network can suffer inefficiencies due to the wavelength-continuity constraint (under which a signal has to remain on the same wavelength from the source to the destination). In order to eliminate or reduce the effects of this constraint, a device called a wavelength converter may be utilized. Due to the high cost of these wavelength converters, many studies have attempted to determine the exact benefits of wavelength conversion. However, most of these studies have focused on optical networks that implement full wavelength conversion capabilities. An alternative to full wavelength conversion is to employ only a sparse number of wavelength converters throughout the network, thereby reducing network costs. This study will focus on different versions of sparse wavelength conversion--namely, sparse nodal conversion, sparse switch-output conversion, and sparse (or limited) range conversion--to determine if most of the benefits of full conversion can be obtained using only sparse conversion. Simulation and analytical results on these three different classes of sparse wavelength conversion will be presented. In addition, this study will present heuristic techniques for the placement of sparse conversion facilities within an optical network.