Finite Automata Walking for Wire-Speed Pattern Matching

The patent segments the pattern matching process into distinct phases: preprocessing the regular expression into a finite automaton (NFA/DFA), then executing the automaton in discrete steps by processing one input character per cycle. This segmentation allows the system to maintain intelligent processing capability while achieving high-speed wire-rate forwarding by breaking down complex pattern matching into simple, repeatable operations that can be efficiently executed on network processors.

The patent applies preliminary action by preprocessing the regular expression patterns into finite automata (NFA or DFA) before the actual packet inspection occurs. This compilation phase creates optimized state transition structures that can be rapidly executed during packet processing. By performing this complex pattern analysis in advance, the system achieves both complete security breach detection and wire-speed processing during actual network traffic inspection.

The patent applies parameter changes by allowing the system to switch between different automaton types (NFA or DFA) and by optimizing the state transition representation. The compiler can generate NFAs that use less memory but require more processing steps, or DFAs that use more memory but execute faster. This flexibility in parameter selection allows the system to adapt to different hardware constraints and performance requirements, balancing memory consumption against processing speed.

The patent applies continuity of useful action by implementing efficient NFA execution that maintains multiple active state paths simultaneously without redundant processing. The system processes input characters and updates all active states in each cycle, ensuring that useful computation continues along every potential matching path. This approach minimizes memory consumption while maintaining processing speed by avoiding unnecessary state transitions and efficiently managing the set of active states throughout the pattern matching process.