Optical Burst Switching (OBS) is a promising switching paradigm to efficiently support Internet Protocol (IP) packets over optical networks, under current and foreseeable limitations of optical technology. The prospects of OBS networks would greatly benefit, in terms of cost and ease of implementation, from limiting the wavelength conversion capabilities at the network nodes. This paper presents a framework for contention minimization/resolution combining traffic engineering in the wavelength domain to minimize contention in advance and optical buffering at the core nodes to resolve contention. Simulation results show that with the proposed contention minimization/resolution framework the large number of expensive all-optical wavelength converters used at the core nodes of an OBS network can be replaced by a moderate number of shared optical delay lines without compromising network performance.