System and computer program for compressing multi-field classification rules

1. A computer-readable medium encoded with a program for storing a plurality of multi-field classification rules in a computer system, the program comprising instructions for:

providing a virtual rule table;

compressing a rule specification corresponding to each of the plurality of multi-field classification rules by storing in the provided virtual rule table at least one field definition included in the rule specification and replacing the at least one field definition included in the rule specification with an index referencing the at least one field definition stored in the virtual rule table;

storing the compressed rule specifications corresponding to the plurality of multi-field classification rules and the virtual rule table in a single entry of a memory of the computer system; and

performing a single read operation on the single entry of the memory of the computer system to retrieve the compressed rule specifications corresponding to the plurality of multi-field classification rules.

2. The computer-readable medium of claim 1 , wherein compressing the rule specification further comprises:

for each of a plurality of fields included in the rule specification, determining whether the field is relevant by analyzing a field definition for the field, wherein the field definition is also included in the rule specification.

3. The computer-readable medium of claim 2 , wherein compressing the rule specification further comprises:

responsive to the field being relevant, determining whether the field definition for the field is stored in the virtual rule table;

responsive to the field definition not being stored in the virtual rule table, storing the field definition in the virtual rule table; and

replacing the field definition included in the rule specification with an index referencing the field definition stored in the virtual rule table.

4. The computer-readable medium of claim 3 , wherein compressing the rule specification further comprises:

responsive to the field definition being stored in the virtual rule table, replacing the field definition included in the rule specification with an index into referencing the field definition stored in the virtual rule table.

5. The computer-readable medium of claim 4 , wherein compressing the rule specification further comprises:

responsive to the field not being relevant, skipping to a next field included in the rule specification.

6. The computer-readable medium of claim 2 , wherein the program further comprises instructions for:

appending a field mask to the rule specification corresponding to each of the plurality of multi-field classification rules, the field mask comprising a plurality of bits corresponding to the plurality of fields included in the rule specification; and

responsive to the field being relevant, setting a value of the bit in the field mask corresponding to the field to one (1).

7. The computer-readable medium of claim 6 , wherein the program further comprises instructions for:

utilizing the field mask appended to the rule specification corresponding to each of the plurality of multi-field classification rules to decompress the rule specification after the rule specification has been compressed.

8. The computer-readable medium of claim 1 , wherein the program further comprises instructions for:

compressing action data corresponding to each of the plurality of multi-field classification rules by

determining which of a plurality of action types is associated with the action data,

providing a bit in the action data for each of the plurality of action types, and

setting a value of the bit in the action data corresponding to each action type determined to be associated with the action data to one (1); and

storing the compressed action data corresponding to each of the plurality of multi field classification rules in the single entry of the memory of the computer system with the compressed rule specification corresponding to each of the plurality of multi field classification rules and the virtual table.

9. The computer-readable medium of claim 1 , wherein the plurality of multi-field classification rules are a plurality of filter rules.

10. A system for storing a plurality of multi-field classification rules, the system comprising:

at least one communications network;

a switch in each of the at least one communications networks;

a memory in the switch; and

a network processor in the switch, the network processor being programmed to provide a virtual rule table in the memory,

compress a rule specification corresponding to each of the plurality of multi-field classification rules by

storing in the virtual table at least one field definition included in the rule specification and

replacing the at least one field definition included in the rule specification with an index referencing the at least one field definition stored in the virtual rule table,

store the compressed rule specifications corresponding to the plurality of multi-field classification rules and the virtual rule table in a single entry of the memory, and

perform a single read operation on the single entry of the memory to retrieve the compressed rule specifications corresponding to the plurality of multi-field classification rules.

11. The system of claim 10 , wherein the network processor is further programmed to

compress action data corresponding to each of the plurality of multi-field classification rules by

determining which of a plurality of action types is associated with the action data,

providing a bit in the action data for each of the plurality of action types, and

setting a value of the bit in the action data corresponding to each action type determined to be associated with the action data to one (1), and

store the compressed action data corresponding to each of the plurality of multi field classification rules in the single entry of the memory of the computer system with the compressed rule specification corresponding to each of the plurality of multi field classification rules and the virtual table.