TCAM and SRAM Hybrid Engine for Network Rule Lookup
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Solution Overview
Problem
Current content addressable memory (CAM) systems, particularly ternary CAM (TCAM), face challenges in efficiently storing and searching for both exact match and range requirements due to high silicon area and power consumption, as well as complexity in managing different data patterns.
Innovation Solution
The implementation of an electronic device with both an exact match engine using static random access memory (SRAM) and a TCAM engine, operating in parallel to store and search for entries, allowing for efficient storage and retrieval of criteria by selectively using SRAM for exact matches and TCAM for range requirements, thereby reducing silicon area and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If TCAM is used to store both exact match and range requirements, then searching capability is provided, but silicon area and power consumption increase significantly
Solution Approach 1:
The patent divides the CAM system into two separate engines: an exact match engine for precise matching and a TCAM engine for range matching. This segmentation allows each engine to be optimized for its specific function, reducing the overall silicon area required compared to using a single TCAM for both purposes.
Solution Approach 2:
Different memory technologies are assigned to different matching requirements: SRAM is used for exact match entries where precision is critical, while TCAM is used for range match entries where flexibility is needed. This local quality approach ensures that each part of the system uses the most appropriate technology for its specific function.
2Adaptability or versatility
If TCAM is used to store both exact match and range requirements, then searching capability is provided, but power consumption increases
Solution Approach 1:
By segmenting the matching functions into separate engines, the patent reduces power consumption because SRAM-based exact match operations consume less power than TCAM operations. The system only activates the TCAM engine when range matching is required, rather than continuously powering TCAM for all matching operations.
3Device complexity
If a single TCAM engine is used, then structure is simplified, but managing different data patterns becomes complex
Solution Approach 1:
The patent simplifies data pattern management by creating separate engines for exact match and range match operations. Each engine is dedicated to handling specific data patterns, which simplifies the control logic and entry management compared to trying to manage both patterns in a single TCAM engine.
4Area of stationary object
If SRAM is used for exact match engine, then silicon area is reduced, but search speed may be affected
Solution Approach 1:
The patent merges two different memory technologies (SRAM and TCAM) into a unified CAM system that operates through a single search key interface. This combination allows the system to leverage the speed advantages of SRAM for exact matches while maintaining the versatility of TCAM for range matches, achieving both area efficiency and search performance.
Data Source
AI summary
Aspects of the disclosure provide an electronic device that includes an exact match engine, a ternary content addressable memory (TCAM) engine, a search key generator and an output module. The exact match engine is configured to store a first set of entries. The TCAM engine is configured to store a second set of entries including at least some entries that are different from entries of the first set of entries. The search key generator is configured to generate a search key and provide the search key to the exact match engine and to the TCAM engine. The output module is configured to select one of a first output from the exact match engine and a second output from the TCAM engine in response to a signal that indicates whether the search key exactly matches one of the first set of entries.