Hybrid CAM System for Network Switching Rule Optimization
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Solution Overview
Problem
Current content addressable memory (CAM) systems, such as ternary CAM (TCAM), face inefficiencies in handling a high ratio of exact match rules, leading to increased silicon area and power consumption, particularly when dealing with large numbers of rules in network devices like switches and routers.
Innovation Solution
The proposed solution involves a hybrid CAM system that includes a key generator, a content addressable memory (CAM) for range requirements and exact match pattern groups stored in hash tables or binary CAM, operating in parallel to efficiently manage memory usage and reduce power consumption by selectively using high-density memory for exact match operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCAM is used to store all switching rules, then search capability is provided, but silicon area and power consumption increase significantly when handling large numbers of exact match rules
Solution Approach 1:
The patent segments the rule storage into two distinct memory systems: TCAM for range-based switching rules and SRAM for exact match rules. This segmentation allows each memory type to be optimized for its specific function, reducing the overall silicon area required compared to storing all rules in TCAM alone.
Solution Approach 2:
The patent extracts exact match rules from the TCAM storage and places them in separate SRAM memory structures. This extraction removes the burden of storing numerous exact match rules in TCAM, thereby reducing silicon area and power consumption while maintaining search capability through the hybrid approach.
2Reliability
If TCAM is used to store all switching rules, then search capability is provided, but power consumption increases significantly when handling large numbers of exact match rules
Solution Approach 1:
The patent segments the rule storage into two distinct memory systems: TCAM for range-based switching rules and SRAM for exact match rules. This segmentation allows each memory type to be optimized for its specific function, reducing the overall silicon area required compared to storing all rules in TCAM alone.
Solution Approach 2:
The patent extracts exact match rules from the TCAM storage and places them in separate SRAM memory structures. This extraction removes the burden of storing numerous exact match rules in TCAM, thereby reducing silicon area and power consumption while maintaining search capability through the hybrid approach.
3Productivity
If hybrid CAM system with parallel operation is used, then search efficiency is enhanced, but device complexity increases
Solution Approach 1:
The patent segments the rule storage into two distinct memory systems: TCAM for range-based switching rules and SRAM for exact match rules. This segmentation allows each memory type to be optimized for its specific function, reducing the overall silicon area required compared to storing all rules in TCAM alone.
Solution Approach 2:
The patent merges TCAM and SRAM into a hybrid search system where both memory types operate in parallel. The TCAM handles range-based searches while SRAM handles exact match searches, and the results are combined by a controller. This merging provides enhanced search efficiency by leveraging the strengths of both memory types simultaneously.
Data Source
AI summary
Aspects of the disclosure provide an apparatus that includes a key generator, a first memory, a second memory, and a controller. The key generator is configured to generate a first search key, and one or more second search keys in response to a pattern. The first memory is configured to compare the first search key to a plurality of entries populated in the first memory, and determine an index of a matching entry to the first search key. The second memory is configured to respectively retrieve one or more exact match indexes of the one or more second search keys from one or more exact match pattern groups populated in the second memory. The controller is configured to select a search result for the pattern from among the index output from the first memory and the one or more exact match indexes output from the second memory.