TCAM Sub-range Segmentation for ACL Entry Reduction
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Solution Overview
Problem
Existing networking technologies inefficiency in representing consecutive integer ranges using TCAMs leads to increased resource usage and processing time, especially when ACL rules involve multiple fields, resulting in a large number of required TCAM entries.
Innovation Solution
A method to break down integer ranges into sub-ranges represented by TCAM values and masks, determining the first TCAM value and mask based on the minimum and maximum values, and iteratively covering the entire range with multiple sub-ranges, reducing the number of TCAM entries needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If consecutive integer ranges are represented using single TCAM value and mask entries, then storage efficiency is improved, but the ability to accurately represent non-contiguous or complex ranges deteriorates
Solution Approach 1:
The patent segments a large integer range into multiple smaller sub-ranges, each representable by a single TCAM value and mask entry. For example, a range from 0 to 1024 is divided into sub-ranges like 0-1023 and 1024-1024, with each sub-range stored as a separate TCAM entry. This segmentation allows accurate representation of complex ranges while minimizing the total number of TCAM entries required.
2Reliability
If multiple fields in ACL rules are enumerated with individual entries, then rule accuracy is improved, but the number of required TCAM entries increases exponentially
Solution Approach 1:
The patent merges multiple ACL rules that share common field ranges into a single TCAM entry by combining the value and mask fields. For example, multiple rules with different source ports but the same destination port and action can be merged into one TCAM entry with a mask that covers all source port variations. This merging reduces the exponential growth of TCAM entries while preserving rule accuracy through proper mask configuration.
3Manufacturing precision
If administrators manually configure each TCAM entry individually, then configuration precision is improved, but configuration time and resource utilization increase
Solution Approach 1:
The patent performs preliminary automated calculations to determine the optimal segmentation of integer ranges into sub-ranges before TCAM configuration. The system automatically computes the minimum number of sub-ranges needed, calculates the appropriate value and mask for each sub-range, and prepares the configuration data in advance. This preliminary action eliminates manual trial-and-error configuration while ensuring precision, significantly improving administrator productivity.
Data Source
AI summary
Examples include receiving a first minimum value in a range of consecutive networking integers, determining a first ternary content-addressable memory (TCAM) value based on the minimum, determining a number of trailing zeros in the first TCAM value, determining a proposed TCAM mask based on the number of trailing zeros and a binary opposite of the TCAM value, comparing the proposed TCAM mask to a maximum value associated with the range, determining a first TCAM mask for the first TCAM value based on the comparison, and setting the first TCAM value and the first TCAM mask in a networking device TCAM.