An Eeective and Comprehensive Approach for Traac Grooming and Wavelength Assignment in Sonet/wdm Rings

Tra c Grooming and Wavelength Assignment in SONET/WDM Rings1 Xijun Zhang and Chunming Qiao Abstract|In high-speed SONET rings with point-to-point WDM links, the cost of SONET Add-Drop Multiplexers (SADMs) can be dominantly high. However, by grooming tra c (i.e. multiplexing lower rate streams) appropriately and using wavelength ADMs (WADMs), the number of SADMs can be dramatically reduced. In this paper, we propose optimal or near-optimal algorithms for tra c grooming and wavelength assignment to reduce both the number of wavelengths and the number of S-ADMs. The algorithms proposed are generic in that they can be applied to both unidirectional and bidirectional rings having an arbitrary number of nodes under both uniform and non-uniform (i.e. arbitrary) tra c with an arbitrary grooming factor. Some lower bounds on the number of wavelengths and S-ADMs required for a given tra c pattern are derived, and used to determine the optimality of the proposed algorithms. Our study shows that using the proposed algorithms, these lower bounds can be closely approached in most cases or even achieved in some cases. In addition, even when using a minimum number of wavelengths, the savings in S-ADMs due to tra c grooming (and the use of WADMs) are signi cant, especially for large networks.