Availability analysis of multilayer optical networks

ABSTRACT The complexity of multi-layer resilience schemes and the high availability parameters provided by these methodsrequire efficient availability analysis techniques, as well. In the paper the effectiveness of stratified sampling inavailability analysis is demonstrated by the investigation of different protection strategies in SDH/SONET overWDM networks. The numerical results show that the application of stratified sampling results in sufficiently accurateestimation of the performance degradation with some hundreds of sample states even in the case of very efficient resilience schemes. Keywords: Optical networks, network reliability, statistical methods, stratified sampling 1. INTRODUCTION Wavelength division multiplexing (WDM) technique has been recognized as the key technology to upgrade existingfiber plants to real optical networks. Due to the fast progress in optical technology WDM multiplex systems withtens of optical channels are commercially available, and systems with more then hundred wavelengths are foreseenin the near future. The WDM systems can carry 2.5 Gbps, 10 Gbps or even 40 Gbps per optical channel.The rapid development in network capacities accelerates the introduction of wide-band and Internet-based ser-vices. However, because of the huge capacity of transmission systems even the failure of a single network elementhas significant impact on the network performance. Therefore, the availability of WDM networks has become a veryimportant analysis issue.