Command redundancy trap makes the whole program completely stable, which is completely without any conditions. First, the entire program must land in the area of the program being bounced. Second, redundant instructions must be executed in the program area. The so-called software redundancy trap is a set of instructions used to guide a program to force a program error to be captured at random to a program-specified entry address, where there is a program dedicated to tracking and handling the program's errors. If we take such a program of instruction and entry address label for nopnerr, software redundancy trap is a unconditional transfer wrong instruction, in order to further strengthen its error capture effect, generally two in front of it and then added to the nop instruction, so the real software redundancy traps formed by three redundant instruction: