A system for and method of, increasing provisionable bandwidth in a multiplexed communication link and a network management system incorporating the system or the method. In one embodiment, the system includes: (1) a defragmentation calculator that calculates a defragmentation of the communication link, the defragmentation containing at least one granularity, (2) a candidate slot selector, associated with the defragmentation calculator, that finds reduced cost candidate slots for the at least one granularity and (3) a circuit mover, associated with the candidate slot selector, that identifies target slots into which circuits occupying the candidate slots can be moved.