Method and apparatus for determining precedence in a classification engine
View Patent ↗A precedence determination system including a first type memory bank configured to receive a first search signal and to provide first search result indications, a second type memory bank configured to receive a second search signal and to provide second search result indications, a precedence number table coupled to the first and second type memory banks and configured to provide programmable precedence numbers, and a precedence determination circuit coupled to the first and second type memory banks and the precedence number table and configured to provide a third search result indication is disclosed. In one embodiment, the first type memory bank can be a static random access memory (SRAM) and the second type memory bank can be a ternary content addressable memory (TCAM).
1. A precedence determination system, comprising:
a first type memory bank receiving a first search signal and providing a plurality of first search result indications;
a second type memory bank receiving a second search signal and providing a plurality of second search result indications;
a precedence number table coupled to the first and second type memory banks and configured providing a plurality of programmable precedence numbers; and
a precedence determination circuit coupled to the first and second type memory banks and the precedence number table and configured providing a third search result indication.
2. The precedence determination system of claim 1 , wherein:
the first type memory bank includes static random access memory (SRAM).
3. The precedence determination system of claim 2 , wherein:
the first type memory bank includes a plurality of entries.
4. The precedence determination system of claim 3 , wherein:
each of the plurality of entries is configured to select one of the plurality of programmable precedence numbers.
5. The precedence determination system of claim 1 , wherein:
the second type memory bank includes ternary content addressable memory (TCAM).
6. The precedence determination system of claim 5 , wherein:
the first type memory bank includes a plurality of entries.
7. The precedence determination system of claim 6 , wherein:
each of the plurality of entries is configured to select one of the plurality of programmable precedence numbers.
8. The precedence determination system of claim 1 , wherein:
the first search signal includes a hash function signal.
9. The precedence determination system of claim 8 , wherein:
each of the plurality of first search result indications includes a hit or miss indication in response to the hash function signal.
10. The precedence determination system of claim 1 , wherein:
the second search signal includes a search key.
11. The precedence determination system of claim 10 , wherein:
each of the plurality of second search result indications includes at most one hit indication in response to the search key.
12. The precedence determination system of claim 11 , wherein:
the at most one hit indication is provided in response to a physical address based precedence.
13. The precedence determination system of claim 1 , wherein:
the third search result indication includes an overall hit or miss indication.
14. The precedence determination system of claim 13 , wherein:
the overall miss indication includes a default precedence value.
15. A method of determining a precedence, comprising the steps of:
searching a first type memory to provide a plurality of first search results;
searching a second type memory to provide a plurality of second search results;
selecting a plurality of programmable precedence numbers from a precedence number table in response to the first and second search results;
determining a precedence in response to the plurality of programmable precedence numbers; and
providing a third search result.
16. The method of determining the precedence of claim 15 , wherein:
the first type memory includes static random access memory (SRAM).
17. The method of determining the precedence of claim 15 , wherein:
the second type memory includes ternary content addressable memory (TCAM).
18. The method of determining the precedence of claim 15 , wherein:
the steps of searching the first type memory and searching the second type memory are performed substantially in parallel.
19. The method of determining the precedence of claim 15 , wherein:
the third search result includes an overall hit or miss indication.
20. The method of determining the precedence of claim 19 , wherein:
the overall miss indication includes a default precedence value.
21. The method of determining the precedence of claim 15 , wherein:
the plurality of precedence numbers are programmable.
22. A means for determining a precedence, comprising:
a means for searching a first type memory to provide a plurality of first search results;
a means for searching a second type memory to provide a plurality of second search results;
a means for selecting a plurality of precedence numbers from a precedence number table in response to the first and second search results;
a means for determining a precedence in response to the plurality of precedence numbers; and
a means for providing a third search result.