PARTIAL UPDATE IN A TERNARY CONTENT ADDRESSABLE MEMORY

摘要

A TCAM may have a plurality of rows of cells. Each row may have a match line. Each cell may have elements for storing first and second bits, and compare circuitry associated to determine matches between a bit of a search word and data stored in the cell. For at least one first row of the rows, the TCAM includes a valid row cell having at least one element to store a partial update indication. The valid row cell may cause the match line associated with the first row to signal that the first row does not match a search word when the partial update indication associated with the first row is enabled. When the partial update indication associated with the first row is disabled, the determination of matches with a search word is performed solely by the compare circuitry wi thout influence of the valid row cell.

主权项

1. A method for accessing a ternary content addressable memory (TCAM), the TCAM having a plurality of rows of cells, each row having a match line, each cell having storage elements for storing first and second bits, each cell including compare circuitry for determining matches between a bit of a search word and data stored in the cell, the compare circuitry to signal a match on a match line of an associated row, comprising:
storing a first bit in a first storage element of a cell in a first row of the TCAM, wherein a valid row cell is associated with the first row, the valid row cell having at least one element to store a partial update indication; in response to storing the first bit in the first storage element, enabling the partial update indication of the valid row cell; and in response to a signal to determine matches between bits of a search word and data stored the cells, signaling by the valid row cell that the first row of the TCAM does not match the search word when the partial update indication associated with the first row of the TCAM is enabled.