In transparent networks

the quality of optical signals is degraded owing to physical impairment

thus the impairment-aware-based connection provisioning has become a hot research topic.This paper studies the key issues in this respect in terms of architecture

impairment model and Impairment-aware Routing Wavelength Assignment（IRWA） algorithm

explains the necessity of full use of the intelligentization of optical networks

setting up appropriate impairment model and ensuring the signal quality in routing selection and wavelength assignment by using IRWA algorithm..