This is the companion low-side threshold in the same store-and-forward/cut-through hysteresis scheme as cat2600TsCrcThresholdHi, and crossing it likewise triggers a mode change and a trap -- the two thresholds together prevent a port from oscillating rapidly between switching modes right at a single boundary value. An admin sets this lower than the Hi threshold to give the port some margin before it reverts back to cut-through once CRC errors subside. For example, Hi might be set at 50 errors and Low at 10, so the port only returns to cut-through once errors drop well below the level that triggered store-and-forward.