Multiple-Bit-Flip Detection Scheme for a Soft-Error Resilient TCAM

Ternary content addressable memories (TCAMs) are special memories which are widely used in high-speed network applications such as routers, firewalls, and network address translators. In high-reliability network applications such as aerospace and defense systems, soft-error tolerant TCAMs are indispensable to prevent data corruption or faults caused by radiation. This paper proposes a novel soft-error tolerant TCAM for multiple-bit-flip errors using partial don't-care keys (X-keys), called k-TX. k-TX corrects up to k-bit flip errors and significantly enhances the tolerance of the TCAM against soft errors, where k is the maximum number of bit flips in a word of a TCAM. k-TX consists of a TCAM, a preprocessed don't-care-bit index look-up memory (X look-up), and an ECC-SRAM. First, k-TX randomly selects a search key. After that, k-TX detects multiple-bit-flip errors by the generated X-keys using the X look-up. If the keys match the different locations, then a soft error is suspected and k-TX refreshes the TCAM words by using a backup ECC-SRAM. Experimental results show that the soft-error tolerance capability of k-TX outperforms other schemes significantly. Moreover, the hardware overhead of k-TX is small due to the use of only a single TCAM. k-TX can be easily implemented and is useful for fault-tolerant packet classifiers.