TCAM with efficient range search capability

摘要

An embodiment of the invention includes a ternary content addressable memory (TCAM) that has input search data bits, TCAM words and range search input data bits. Each TCAM word is operable to store a match pattern and provide a match output. The match output indicates a match when the match pattern of the TCAM word matches the TCAM input search data bits. The range search input data bits are separated into groups. Each group has a bit width N where N is the number of range search input data bits. For the match pattern in each group, there is a Boolean function that uses the N range of search input data bits. (2N)/2 TCAM bits are provided for each TCAM word. 2N internal TCAM search lines are operable to search the (2N)/2 TCAM bits. Decoder logic is associated with each group that decodes the N range search input data bits.

主权项

1. A Ternary Content Addressable Memory (TCAM) comprising:
input search data bits, the input search data bits separated into a plurality of groups wherein each group in the plurality of groups can be configured as range search bits or as search bits; a plurality of TCAM words; wherein each TCAM word of the plurality of TCAM words is operable to store a match pattern; wherein each TCAM word of the plurality of TCAM words provides a match output; wherein the match output indicates a match when the match pattern of the TCAM word matches the TCAM input search data bits; wherein for each group in the plurality of groups, each group has a bit width N wherein N is a number of range search bits; wherein for the match pattern for each group in the plurality of groups when the group is range search bits there is a Boolean function, the Boolean function using N range search bits; wherein (2N)/2 TCAM bits are provided for each TCAM word in the plurality of TCAM words; where 2N internal TCAM search lines associated are operable to search the (2N)/2 TCAM bits; wherein decoder logic associated with each group decodes the N range search bits; wherein the decoder logic associated with each group drives the 2N internal TCAM search lines; wherein each of the TCAM bits identifies two TCAM memory bit-cells; wherein each TCAM memory bit-cell of the 2N TCAM memory bit-cells is associated with an associated input value of the N range search bits; wherein each of the 2N TCAM memory bit-cells is programmed with a match enabling value when the Boolean function indicates a match; and wherein each of said 2N TCAM memory bit-cells is programmed with a match disabling value when said Boolean function indicates a mismatch.