Switching circuit implementing variable string matching
US7353332B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 11, 2005 |
| Grant date | Apr 1, 2008 |
| Priority date | — |
| Expiry date | Sep 6, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L69/22
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A content matching engine (CME) uses a content addressable memory (CAM) array that stores a plurality of strings in separate entries. The strings define one or more rules to be matched. The strings of each rule are linked, thereby providing a required order. The strings of each rule can be linked by per-entry counters associated with each string, or by a state machine. The strings in the CAM array are compared with a packet, which is shifted one symbol at a time (because the strings can start on any boundary). When the CAM detects a match, the CAM skips over the string that resulted in the match, thereby preventing erroneous matches. The CAM allows parallel matching to be performed for multiple rules. If the contents of a packet match all of the strings of a rule, in order, then the CME asserts a match/index signal that identifies the matched rule.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.