A method of line speed sequence number checking of frames includes, in a first process, using a lowest order bit of a sequence number of a frame to assign the frame to an odd or even second process, and dispatching at least the sequence number for processing by the assigned second process. The method includes, in the first process, flagging as a first sequence error type occurrences of assigning consecutively processed frames to the same second process. The method includes, in the second processes, checking the sequence number of an incoming frame, flagging as a second sequence error type non-consecutive sequence numbers in consecutively processed incoming frames, and dispatching the frame for additional downstream processing. The method is applicable to a hierarchy of processes, and to multiplexed flows. The method can use a modulo N of the sequence number to assign the frame to one of N processes.