Title :
PEDS: A Parallel Error Detection Scheme for TCAM Devices
Author :
Bremler-Barr, Anat ; Hay, David ; Hendler, Danny ; Roth, Ron M.
Author_Institution :
Efi Arazi Sch. of Comput. Sci., Interdiscipl. Center, Herzliya, Israel
Abstract :
Ternary content-addressable memory (TCAM) devices are increasingly used for performing high-speed packet classification. A TCAM consists of an associative memory that compares a search key in parallel against all entries. TCAMs may suffer from error events that cause ternary cells to change their value to any symbol in the ternary alphabet {”0”,“1”,“*”}. Due to their parallel access feature, standard error detection schemes are not directly applicable to TCAMs; an additional difficulty is posed by the special semantic of the “*” symbol. This paper introduces PEDS, a novel parallel error detection scheme that locates the erroneous entries in a TCAM device. PEDS is based on applying an error-detecting code to each TCAM entry and utilizing the parallel capabilities of the TCAM by simultaneously checking the correctness of multiple TCAM entries. A key feature of PEDS is that the number of TCAM lookup operations required to locate all errors depends on the number of symbols per entry in a manner that is typically orders of magnitude smaller than the number of TCAM entries. For large TCAM devices, a specific instance of PEDS requires only 200 lookups for 100-symbol entries, while a naive approach may need hundreds of thousands of lookups. PEDS allows flexible and dynamic selection of tradeoff points between robustness, space complexity, and number of lookups.
Keywords :
content-addressable storage; error detection codes; random-access storage; TCAM device; high speed packet classification; lookup operation; parallel access feature; parallel error detection; parallel error detection scheme; space complexity; standard error detection scheme; ternary content addressable memory; Associative memory; Computer science; Computer vision; Data security; Databases; Error correction codes; Filters; Monitoring; Robustness; Routing; error detection; error-correcting codes; error-detecting codes; packet classification; ternary content-addressable memory (TCAM);
Journal_Title :
Networking, IEEE/ACM Transactions on
DOI :
10.1109/TNET.2010.2047730