Ternary Content Addressable Memory Inequality Check Encoding
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Solution Overview
Problem
Current TCAM implementations are power hungry and face challenges in achieving high throughput to keep up with network wire speeds, leading to high power consumption.
Innovation Solution
An encoding scheme is provided to encode data and operate a TCAM for implementing inequality check operations, reducing the number of TCAM cells required by approximately a factor of 2 compared to unary encoding, thereby reducing power consumption and increasing computation speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If TCAM is used to achieve high-speed network wire speed throughput, then processing speed is improved, but power consumption increases
Solution Approach 1:
The patent segments the TCAM into multiple banks, where each bank handles a portion of the lookup task. This allows parallel processing across banks, maintaining high throughput while reducing the number of active cells in each bank, thereby lowering power consumption per bank and overall.
Solution Approach 2:
The patent employs content-directed power management that activates only the necessary portions of the TCAM based on the incoming lookup key. By using partial action, the system processes data at wire speed using only the required TCAM cells rather than activating the entire array, thus reducing power consumption while maintaining processing speed.
2Quantity of substance
If the number of TCAM cells is increased to handle more data, then storage capacity is improved, but power consumption increases
Solution Approach 1:
The TCAM is divided into multiple banks, allowing the storage capacity to be distributed across segments. Each bank can be independently activated based on the lookup requirements, enabling the system to maintain large total storage capacity while consuming power only in the actively used portions.
Solution Approach 2:
The patent implements content-directed power management that applies different power states to different regions of the TCAM based on local access patterns. Frequently accessed regions remain active while less frequently accessed regions are put into lower power states, optimizing the balance between storage capacity utilization and power consumption.
3Productivity
If TCAM cells are activated to perform search operations, then processing capability is improved, but power consumption increases
Solution Approach 1:
The system activates only the minimum necessary TCAM cells required to process the incoming lookup key, rather than activating the entire TCAM array. This partial action approach maintains full processing capability for the given input while minimizing the number of active cells and their associated power consumption.
Solution Approach 2:
The patent implements dynamic power management that periodically adjusts the activation state of TCAM banks based on workload patterns. During periods of high activity, more banks are activated to maintain processing capability, while during lower activity periods, fewer banks remain active to reduce power consumption, thus optimizing the productivity-power tradeoff over time.
Data Source
AI summary
Systems and methods are provided for implementing a low power and area ternary content addressable memory (TCAM). An example of a TCAM comprises a match line, and a plurality of TCAM cells connected along the match line. Each TCAM cell stores a state of a threshold value. The TCAM cells are configured to pull down a signal over the match line in response to inequality between an input search and the threshold value. The plurality of TCAM cells comprises a number of TCAM cells that is less than the threshold value. The input values can be encoded according to a first encoding scheme and the threshold value can be encoded according to one of a second and a third encoding scheme based on an inequality check mapped to the plurality of TCAM cells.