Packet Switching Device False-Positive Pattern Matching Filter
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Solution Overview
Problem
Packet switching devices often experience false-positive matches when using pattern matching techniques, leading to inefficient processing and potential misclassification of packets in high-speed communications networks.
Innovation Solution
A method involving a packet switching device that uses a combination of table lookup operations and a second validation technique, such as generating a hash key and performing a lookup in a hash table, to filter out false-positive matches and ensure accurate pattern matching, thereby reducing processing time and improving packet classification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pattern matching techniques are used for packet classification, then packet classification capability is improved, but false-positive matches increase leading to reduced accuracy
Solution Approach 1:
The patent performs preliminary pattern matching to identify potential matches, then follows up with additional validation checks (such as verifying packet length, protocol type, or other packet characteristics) to confirm whether the match is genuine. This two-stage approach allows the system to quickly filter out non-matching packets while maintaining high accuracy by validating suspected matches.
Solution Approach 2:
The patent introduces intermediary validation mechanisms between the initial pattern matching and final classification decisions. These intermediaries (additional validation rules, verification steps, or cross-checks) act as mediators to distinguish true matches from false positives, thereby improving accuracy without sacrificing the speed benefits of pattern matching.
2Measurement precision
If additional validation techniques are applied to reduce false positives, then match accuracy is improved, but processing time increases
Solution Approach 1:
The system performs preliminary pattern matching on all packets to identify potential matches quickly, then applies additional validation techniques only to those packets that show promising matches. This selective validation approach maintains high accuracy for true matches while minimizing the time overhead by avoiding unnecessary validation of clearly non-matching packets.
Solution Approach 2:
The patent applies validation techniques partially - not to every packet, but only to those that pass initial pattern matching thresholds. This partial action approach achieves sufficient accuracy for the application while avoiding the excessive processing time that would result from validating every single packet equally.
3Speed
If simple pattern matching is used, then processing speed is maintained, but false-positive matches occur reducing reliability
Solution Approach 1:
The patent uses simple pattern matching as a preliminary filtering stage to maintain high processing speed, then applies reliability checks (such as verifying packet characteristics against expected patterns for the matched protocol) only to packets that pass the initial filter. This ensures that the majority of packets are processed quickly while maintaining high reliability for the subset that requires verification.
Solution Approach 2:
The system introduces intermediary reliability verification steps between simple pattern matching and final classification. These intermediaries validate that the packet characteristics are consistent with the matched pattern, thereby improving reliability without significantly impacting processing speed since they are applied selectively rather than universally.
Data Source
AI summary
In one embodiment, a packet switching device determines that a packet matches one of a plurality of predetermined patterns, however, this matching may produce a false-positive match of one of the underlying rules corresponding to the plurality of predetermined patterns. In one embodiment, determining the packet matches one of the plurality of predetermined patterns includes determining a first pattern match of a packet when each particular portion of a plurality of different portions of the packet is found to be matching a corresponding particular pattern portion by performing a table lookup operation based on the particular portion as an address in a corresponding different current portion-iteration table to retrieve a corresponding partial result. In one embodiment, the first pattern match is filtered using a second validation technique for removing false-positive first pattern matches. In one embodiment, the second validation technique includes using hashing.