The shared wavelength path (SHWP) and the scattered wavelength path (SCWP) were proposed under the WASPNET (wavelength switched packet network) project. They are the envisaged operating mode competing alternatives for optical packet switching in the WDM networking context. A maximum matching model is presented to evaluate the performance of the input-buffered wavelength-routed (IB-WR) optical packet switch, under both SHWP and SCWP switching modes. We conduct a necessary set of modifications for this architecture, which was not originally conceived with a SCWP/SHWP scheme in mind. The characterization proposed is based on the establishment of independent maximum size matching or maximum weight matching optimization problems. It provides a method to calculate the optimum performance achievable by this architecture in terms of switch throughput and average delay, for both the SHWP and SCWP operational modes. The modeling may consider additional conditions to maintain, or not, the packet sequence. Besides that, our approximation establishes a framework for the study of simple scheduling processes which take benefit of the simple hardware requirements associated with IB-WR architecture. As an example, a sequential SHWP scheduler presented by IB-WR switch designers, and its SCWP evolution, which we present, are evaluated and compared.