Apparatus and methods to store data in a network device and perform longest prefix match (LPM) processing

摘要

The present disclosure describes systems and techniques relating to processing of network communications. According to an aspect of the described systems and techniques, a network device includes a random access memory (RAM); a buffer coupled with the RAM; circuitry configured to copy data from a location in the RAM to the buffer responsive to a received identifier corresponding to a search key corresponding to a received packet; and circuitry configured to compare the data copied to the buffer with the search key to provide a result for use in forwarding of the packet, wherein don't care bits for the comparison are determined from a count of don't care bits encoded in a portion of the location in the RAM indicated by the identifier.

主权项

1. A network device comprising:
a random access memory (RAM); a buffer coupled with the RAM; circuitry configured to copy data from a location in the RAM to the buffer responsive to a received identifier corresponding to a search key corresponding to a received packet; and circuitry configured to compare the data copied to the buffer with the search key to provide a result for use in forwarding of the packet, wherein don't care bits for the comparison are determined from a count of don't care bits encoded in a portion of the location in the RAM indicated by the identifier, and wherein the circuitry configured to compare comprises (i) circuitry configured to generate a vector mask from the count, (ii) an XOR gate coupled to compare a predetermined bit of the search key with a corresponding predetermined bit of the data copied to the buffer, and (iii) an AND gate coupled to compare a predetermined bit of the vector mask with an output of the XOR gate.