Lightpath routing with survivability requirements in WDM optical mesh networks

Ph.DDOCTOR OF PHILOSOPH

Impairment-aware Control Plane Architectures to Handle Optical Networks of the Future

In transparent (and translucent) optical networks, physical layer impairments (PLIs) incurred by nonideal optical transmission media accumulate along an optical path, and the overall effect determines the feasibility of the lightpaths. If the received signal quality is not within the receiver sensitivity threshold, the receiver may not be able to correctly detect the optical signal, and this may result in high bit-error rates. Introducing optical transparency in the physical layer reduces the possibility of client layer interaction with the optical layer at intermediate nodes along the path. The standard GMPLS protocols used for dynamic establishment of lightpaths in transparent/translucent optical networks suffer from lack of PLI information and optical component characteristics. Hence, there is a strong need for development of techniques that provide PLI information to GMPLS protocols and mechanisms that use this information efficiently to evaluate optical feasibility of lightpaths. Without the development of such mechanisms, it would be impossible to automatically initiate a lightpath establishment from client layers, for example, switch or an IP router or a label switch router (LSR). In this chapter, various impairment-aware optical control plane (IA-OCP) approaches are described and compared, namely, signaling-based approach, routing-based approach, hybrid approach, and PCE-based approach. The properties of these control plane architectures are qualitatively studied. Furthermore, the performance study of two IA-OCP approaches is discussed through extensive simulation results

Multidomain Optical Networks: Issues and Challenges

Today, many leading organizations are undertaking extensive research on a very broad range of new and evolving optical networking technologies. These efforts carry particular significance, especially in light of the “postbubble” dynamics of the optical networking market and have led to the investigation of various cost-efficient optical technologies. Today’s telecom carriers operate several independent optical domains based on diverse technologies, control solutions, standards, and protocols, making interdomain and intercarrier interworking extremely difficult. Standardized interworking across diverse multigranularity network interfaces, and interoperability across disparate vendor equipments and carrier domains are crucial to provisioning end-to-end services and achieving cost-efficient network operation. Needless to say, having an interoperable and standard control plane across multidomain optical networks can benefit carriers through the availability of a wide selection of network elements, platforms, and multiple vendor solutions resulting in faster deployment and reduced CAPEX and OPEX charges

Cross-Layer Design in Optical Networks

VI, 380 p. 155 illus., 104 illus. in color.onlin

Control plane issues in cross-layer optimized dynamic optical networks

In transparent optical networks, physical layer impairments (PLIs) incurred by non-ideal optical transmission media accumulate along an optical path, and the overall effect determines the feasibility of the lightpaths. If the received signal quality is not within the receiver sensitivity threshold, the receiver may not be able to correctly detect the optical signal. Hence it is important to understand the techniques that provide PLI information to the control plane protocols and that use this information efficiently to compute feasible routes and wavelengths. In this paper, we briefly describe and compare various control plane approaches, namely, signalling-based approach, routing-based approach, hybrid approach, and PCE-based approach. Furthermore, preliminary results for signalling-based and hybrid approaches from EU funded DICONET project are presented

Regenerator sites selection based on multiple paths considering impairments and protection requirements

We propose hitting set heuristic for regenerator sites selection considering multiple paths to provide any-to-any protected connectivity. The results indicate that parameters do not have impact for small networks for path trails greater than two

Effect of Impairment Modeling Errors on Reachability Graph Based Lightpath Setup in Translucent Optical Networks

GMPLS-based transparent optical networks suffer from accumulation of physical layer impairments (PLIs) and wavelength continuity constraint along the transparent optical path. To increase optical reach, resource utilization, and average call acceptance ratio (and hence the revenues), network operators resort to translucent optical networks. In these networks a limited number of regenerators are placed at a selected set of network nodes. Hence, it is important to develop GMPLS-based distributed optical control plane (OCP) for on-demand lightpath provisioning considering both PLIs and availability of regenerators. In this paper, we propose and study a novel three phase approach - reachability graph construction, route computation on reachability graph, and signaling, for routing lightpaths with multiple transparent segments. However, the reachability graph - which contains all network nodes and a set of new optically reachable links - is computed based on approximate PLIs models. Hence, in this paper we analyze the effect of PLIs modeling errors on the network performance in two scenarios - fixed additional OSNR penalty and adaptive cost penalty based on error feedback. The simulation results suggest that adaptive cost penalty is independent of network topological characteristics and provides a good trade-off between blocking probability and additional number of required regenerators

Towards deployment of signalling based approaches for impairment aware lightpath setup in transparent WDM optical networks

We implement extensions to intrinsic functionality of standard RSVP-TE on a commercially available GMPLS protocol stack to setup optically feasible lightpaths and study the performance and deployment feasibility in real-world transparent WDM optical networks