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 matching entry. If there are multiple matches, the entry with the lowest priority wins and outputs its response value. If the priority is the same, the entry is selected arbitrarily. The API software ensures that two entries using the same masked key cannot be inserted.
The number of unique masks is limited to allow for efficient use of logic and memory resources. The key, priority, and response are stored in DRAM while the masks are stored in internal memory.
If the masked lookup key does not match the masked key of any entry, a no match indication is normally output. The STCAM supports an optional default response. If the default response is used; the STCAM outputs the default response instead of outputting the no match indication.