Lookup Operation - 2.6 English

Ternary CAM Search v2.6 LogiCORE IP Product Guide (PG318)

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2.6 English

The CAM Database stores the (key, mask, priority, response) entries and performs matching by processing a Lookup Request. If the masked lookup key matches the masked key of any entry, there is a match and the response is output. If the masked key of multiple entries match, the entry with the lowest priority wins and outputs its response. It is possible to insert entries using the same priority. If two or more entries using the same priority match at the same time, one of them is picked as the winner. If the masked lookup key does not match the masked key of any entry, a no match indication is normally output. The TCAM supports an optional default response. If the default response is used, the TCAM outputs the default response instead of outputting the no match indication. The default response entry is a special entry without any key, mask and priority parts. These are not necessary since the entry always matches if no other entry is matched.