Numerous "on-demand" immediate request (IR) schemes have been developed for provisioning connection requests in optical networks. Lately more complicated advance reservation (AR) schemes are also being investigated by the research community. However, implementing AR across multiple network domains is a very challenging problem owing to key challenges in the area of limited inter-domain visibility, wavelength conversion limitations, signaling concerns, etc. To address this problem area, in this paper we propose a prioritized routing algorithm to handle both IR and AR requests. With the priority added, we argued that preemption of IR requests in the advent of AR ones is not always justified. Future direction and simulation setting are also discussed.