In traditional floorplanners, area minimization is an important issue. Due to the recent advances in VLSI technology, the number of transistors in a design and their switching speeds are increasing rapidly. This results in the increasing importance of interconnect delay and routability of a circuit. We should consider interconnect planning and buffer planning as soon as possible. In this paper, we propose a method to reduce interconnect cost of a floorplan by searching alternative packings. We found that if a floorplan F contains some rectangular supermodules, we can rearrange the blocks in the supermodule to obtain a new floorplan with the same area as F but possibly with a smaller interconnect cost. Experimental results show that we can always reduce the interconnect cost of a floorplan without any penalty in area and runtime by using this method.