This paper experimentally demonstrates a novel blockage prediction based on exhaustive beam-pair scans in millimeter wave (mmWave) networks toward 6G. In particular, the prediction uses the signal strength of all transmit/receive beam-pairs through a two-sided scan rather than that of all transmit beams through the one-sided scan assumed in existing studies. It is also possible to predict future line-of-sight (LOS) blockages. The mapping from the signal strength of all beam pairs to future blockages was learned with LightGBM. The experimental results confirm that the blockage prediction through a two-sided scan of all beam pairs is more accurate than that through a one-sided scan.