The present disclosure provides bandwidth defragmentation systems and methods in optical networks such as Optical Transport Network (OTN), Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), Ethernet, and the like. In particular, the present invention includes bandwidth defragmentation algorithms that may be used within the context of a signaling and routing protocol to avoid bandwidth defragmentation. As such, the present invention defines a mechanism for computing an end to end path for a connection in a manner that avoids bandwidth fragmentation and provides for better network utilization. For example, the present invention may include a path computation based upon administrative weight and upon fragmentation costs. This may be implemented in existing signaling and routing protocols without changes to existing protocol messages used in topology discovery. Further, the present invention optimizes available bandwidth allowing a higher probability of higher bandwidth request being admitted.