Method and apparatus for providing internal table extensibility based on product configuration
View Patent ↗A configurable lookup table system including a first controller coupled to a first lookup table and a second controller coupled to a second lookup table is disclosed. The first controller configures the first lookup table for a first type lookup, which can be a Layer 2 or Media Access Control (MAC) type. The second controller configures the second lookup table based on a mode determination. If in a first mode, the second lookup table can be configured for a second type lookup, which can be a Layer 3 or Internet Protocol (IP) type. If in a second mode, the second lookup table can be configured for the first type lookup. This approach provides an efficient scheme for controlling and using multiple internal lookup tables for a variety of product configurations.
1. A configurable lookup table system, comprising:
a first controller coupled to a first lookup table, wherein the first controller configures the first lookup table for a first type lookup; and
a second controller coupled to a second lookup table, wherein:
in a first mode, the second controller configures the second lookup table for a second type lookup; and
in a second mode, the second controller configures the second lookup table for the first type lookup, and splits the first type lookup into a first level and a second level for using the second lookup table for the first level and using the first lookup table for the second level.
2. The configurable lookup table system of claim 1 , wherein:
the first type lookup includes a Layer 2 lookup.
3. The configurable lookup table system of claim 2 , wherein:
the Layer 2 lookup includes a Media Access Control (MAC) address lookup.
4. The configurable lookup table system of claim 1 , wherein:
the second type lookup includes a Layer 3 lookup.
5. The configurable lookup table system of claim 4 , wherein:
the Layer 3 lookup includes an Internet Protocol (IP) address lookup.
6. The configurable lookup table system of claim 1 , wherein:
a lookup in the second mode includes:
the first level in the second lookup table; and
the second level in the first lookup table.
7. The configurable lookup table system of claim 6 , wherein:
the second level in the first lookup table is configured:
to be performed if a miss indication from the first level in the second lookup table; and
to not be performed if a hit indication from the first level in the second lookup table.
8. The configurable lookup table system of claim 6 , wherein:
the second lookup table includes a usable entry width of at least 72-bits.
9. A method of controlling a lookup table system, comprising:
determining a first mode or a second mode; and
when in the first mode:
using a first lookup table for a first type lookup; and
using a second lookup table for a second type lookup;
when in the second mode:
splitting the first type lookup into a first level and a second level;
using the second lookup table for the first level; and
using the first lookup table for the second level.
10. The method of controlling the lookup table system of claim 9 , wherein:
the first type lookup includes a Layer 2 lookup.
11. The method of controlling the lookup table system of claim 10 , wherein:
the Layer 2 lookup includes a Media Access Control (MAC) address lookup.
12. The method of controlling the lookup table system of claim 9 , wherein:
the second type lookup includes a Layer 3 lookup.
13. The method of controlling the lookup table system of claim 12 , wherein:
the Layer 3 lookup includes an Internet Protocol (IP) address lookup.
14. The method of controlling the lookup table system of claim 9 , wherein:
the second lookup table includes a usable entry width of at least 72-bits.
15. The method of controlling the lookup table system of claim 9 , wherein:
the splitting the first type lookup into the first level and the second level includes configuring for a parallel operation.
16. The method of controlling the lookup table system of claim 9 , wherein:
the splitting the first type lookup into the first level and the second level includes configuring for a serial operation.
17. The method of controlling the lookup table system of claim 16 , wherein:
the using the first lookup table for the second level is dependent on a miss indication from the using the second lookup table for the first level.
18. A means for controlling a lookup table, comprising:
a means for determining a first mode or a second mode; and
when in the first mode:
a means for using a first lookup table for a first type lookup; and
a means for using a second lookup table for a second type lookup;
when in the second mode:
a means for splitting the first type lookup into a first level and a second level;
a means for using the second lookup table for the first level; and
a means for using the first lookup table for the second level.
19. The means for controlling the lookup table of claim 18 , wherein:
the means for splitting the first type lookup into the first level and the second level includes means for configuring for a parallel operation.
20. The means for controlling the lookup table of claim 18 , wherein:
the means for splitting the first type lookup into the first level and the second level includes means for configuring for a serial operation.
21. The configurable lookup table system of claim 1 , wherein, in the second mode, a hash table is used for a split lookup.
22. The configurable lookup table system of claim 21 , wherein the second level is indexed by the hash table.