In this paper, we propose two availability-aware connection provisioning algorithms, namely Global Differentiated Availability-aware Provisioning (G-DAP) and Link-by-link Differentiated Availability-aware Provisioning (LBL-DAP) for the connections of differentiated availability classes. G-DAP attempts to provide a global feasible sharing degree for each availability class on all of the wavelengths throughout the network. LBL-DAP provides a feasible sharing degree for each class on the wavelengths of each link separately. We evaluate the performance of the proposed schemes by simulation under NSFNET topology, and compare the results with a reliable connection provisioning scheme. The connections arrive with various availability requirements. We show that GDAP and LBL-DAP provide an enhanced blocking ratio and resource overbuild globally and for the high priority classes.