In this paper, we address the Grooming, Routing and Wavelength Assignment (GRWA) problem under the minimization of the total number of optical ports. Even if many studies have been conducted on this problem under potentially restrictive assumptions, its difficulty only allows producing solutions that are not proved optimal and that may be far from being optimal. We present an enhanced hierarchical optimization procedure, based on an integer linear program and on the previous work of Hu and Leida (2004), subject to constraints on the number of optical hops and on the length of the physical paths in order to bound the end-to-end delays. It provides near optimal solutions with a proved optimality gap. Experiments show that allowing more than two optical hops do not lead to a significant decrease of the solution cost. Moreover, experiments allow us to conclude that restricting the physical paths to the first three shortest paths is appropriate, not only to obtain good solutions but also to keep the problem tractable.