This contribution concentrates on dynamic routing in WDM (Wavelength Division Multiplexing) networks. It is shown that a strategy based on precalculated alternatives and an adaptive dynamic path search performs very well over a wide load range. Moreover, specific effects for the impact of resource allocation strategies in photonic WDM networks are highlighted, especially the influence of wavelength converter usage strategies in networks with partial conversion. The paper also investigates the way non-Poisson traffic behaviour affects performance of routing strategies and presents how results from dynamic routing investigation can help to optimize the network planning process.