Minimization of the number of ADMs in SONET rings with maximum throughput with implications to the traffic grooming problem
SONET ADMs are dominant cost factors in WDM/SONET rings. Whereas most previous papers on the topic concentrated on the number of wavelengths assigned to a given set of lightpaths, recent papers argue that the number of ADMs is a more realistic cost measure. The minimization of this cost factor has been investigated in recent years, where single-hop and multi-hop communication models, with arbitrary traffic and uniform traffic loads have been investigated. As a first attempt to understand the trade-off between the number of wavelengths and the number of ADMs, we concentrate on the all-to-all, uniform traffic instance with multi-hop, splittable communication. We look for a solution which makes full use of the bandwidth and uses the minimum possible number of ADMs. We develop an architecture based on successive nested polygons and present a necessary and sufficient condition for a solution in this architecture to be feasible. This architecture leads to a solution using 0 (W log W + N) ADMs where W is the number of wavelengths used, and N is the number of nodes in the ring. This is a substantial improvement compared to N W ADMs for the basic architecture in [O. Gerstel, P. Lin, G. Sasaki, Combined wdm and sonet network design, in: INFOCOM'99, Eighteenth Annual Joint Conference of the IEEE Computer and Communications Societies, vol. 2, 1999, pp. 734-743], and optimal for W = O(N/log N). We further improve this result to O(W log 7W+ N) ADMs, where W = o(W). This architecture constitutes a solution for the traffic grooming problem, which is the subject of many recent works. (C) 2007 Elsevier B.V. All rights reserved.
sonet wavelength assignment wavelength division multiplexing (wdm) optical networks add-drop multiplexer (adm)