To optimize the performance of the Routing and Wavelength Assignment（RWA）algorithm based on a physical impairment model for optical（transparent）networks

this paper constructs a simplified impairment model by analyzing the features of multiple physical impairments and proposes a directed flooding RWA algorithm based on Resource Reservation Protocol-Traffic Engineering（RSVP-TE）

i.e.KDF-IRWA algorithm

which allows the source node to send PATH packets to the destination node through multiple candidate paths.These PATH packets independently collect the path information of various links in the selected path

which converge at the destination node and is calculated and compared

thus avoiding packet re-sending arising from the failure in path setup for the first time in the classical algorithms and improving the efficiency of the algorithm.The simulation results indicate that this algorithm can effectively reduce the time

increase the probability of success in path setup and reduce network blocking rate.