Batch Content-Addressable Memory Lookup Device
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Solution Overview
Problem
Content-addressable memory (CAM) devices face inefficiencies when handling multiple applications with disparate width requirements, leading to unused bits and suboptimal performance in packet switching networks due to the need for separate CAM entries with fixed widths.
Innovation Solution
The implementation of batch content-addressable memory (CAM) entries that span multiple physical entries, allowing for flexible batch sizes and iterative lookup operations using a batch mask vector and cumulative result vector to determine matches and non-matches across multiple iterations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate CAM entries with fixed widths are used for each application, then each application can be handled independently, but unused bits occur and resource utilization decreases
Solution Approach 1:
The patent combines multiple fixed-width CAM entries into a single batch entry that spans multiple physical entries. This merging allows the batch entry to accommodate variable-width requirements of different applications while utilizing all available CAM bits, thereby eliminating unused bits and improving resource utilization while maintaining application independence through logical separation.
Solution Approach 2:
The batch entry structure serves multiple applications with different width requirements simultaneously. By making the CAM entry universal and adaptable to various widths through the batch mechanism, the system can handle multiple applications independently without leaving bits unused, thus resolving the contradiction between adaptability and resource utilization.
2Adaptability or versatility
If multiple separate CAM entries are used to handle different applications, then each application is processed independently, but the number of required lookup operations increases
Solution Approach 1:
The patent merges multiple separate CAM lookups into a single batch lookup operation. By combining multiple physical CAM entries into one batch entry, the system performs a single lookup operation that simultaneously checks all relevant entries, thereby reducing the total number of lookup operations required while maintaining the ability to handle multiple applications independently.
Solution Approach 2:
The batch mechanism creates a logical copy of the lookup operation that operates across multiple physical entries simultaneously. This allows the system to process multiple applications in parallel within a single lookup operation, improving productivity while maintaining multi-application support.
3Device complexity
If fixed-width CAM entries are used, then the structure is simple and straightforward, but flexibility in handling variable-width requirements is limited
Solution Approach 1:
The patent introduces dynamic characteristics to the CAM structure by implementing batch entries with variable widths. While the underlying physical structure remains simple and fixed-width, the batch mechanism dynamically adapts to different width requirements by logically grouping physical entries into batches of varying sizes, thus maintaining structural simplicity while achieving variable-width flexibility.
Solution Approach 2:
The patent segments the logical CAM space into batches of variable width while maintaining the physical fixed-width structure. This segmentation allows the system to present flexible variable-width entries to applications while the underlying simple fixed-width structure remains unchanged, resolving the contradiction between simplicity and adaptability.
Data Source
AI summary
In one embodiment, multiple content-addressable memory entries are associated with each other to effectively form a batch content-addressable memory entry that spans multiple physical entries of the content-addressable memory device. To match against this content-addressable memory entry, multiple lookup operations are required—i.e., one lookup operation for each combined physical entry. Further, one embodiment provides that a batch content-addressable memory entry can span one, two, three, or more physical content-addressable memory entries, and batch content-addressable memory entries of varying sizes could be programmed into a single content-addressable memory device. Thus, a lookup operation might take two lookup iterations on the physical entries of the content-addressable memory device, with a next lookup operation taking a different number of lookup iterations (e.g., one, three or more).