This work deals with the end-to-end QoS aware path computation problem under three separate parts: a distributed inter-domain scheme, a joint inter- layer/inter-domain path computation scheme and traffic engineering, and an inter-layer path computation algorithm for GMPLS networks. It first presents a distributed pre-reservation based procedure for inter-domain path computation of LSPs within a PCE based architecture. This allows the computation of optimal inter-domain paths with efficient setup times. It then extends this solution by considering the joint inter-layer/inter-domain problem for a complete view and global optimization. Finally it presents a novel mathematical program specific to GMPLS multi-layer path computation that solves the problem of nesting and un-nesting LSPs from one switching region to another.