Layer 3 Host Table Update via Packet Miss Count Thresholds
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Solution Overview
Problem
Conventional layer 3 packet forwarding devices face issues with limited space in LPM and host tables, leading to excessive replacement of entries using the least recently used (LRU) algorithm, which does not account for packet volume, resulting in inefficient routing and longer lookup times.
Innovation Solution
A method for controlling the updating of a layer 3 host table based on packet forwarding lookup miss counts, where remote destination entries in the host table are replaced only when their miss counts exceed a threshold, ensuring that high-volume entries are prioritized and avoiding thrashing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LRU algorithm is used to replace host table entries, then older entries are replaced with newer entries, but excessive replacement occurs leading to processor intensive operations
Solution Approach 1:
The patent changes the replacement criterion from time-based (LRU) to count-based (miss count threshold). Instead of replacing entries based on least recently used time, the system replaces entries when their miss count exceeds a predetermined threshold, reducing unnecessary replacements and processor intensive operations
Solution Approach 2:
The system implements feedback by monitoring miss counts for each host table entry and using this information to control replacement decisions. The miss count serves as feedback that triggers replacement only when necessary, preventing excessive updates and reducing processor load
2Adaptability or versatility
If LRU algorithm replaces entries based on individual packets, then entries are updated frequently, but packet volume is not considered leading to suboptimal routing
Solution Approach 1:
The patent changes the replacement parameter from time-based LRU to miss-count-based selection. The system considers the volume of packets (miss count) for each destination and replaces entries with the highest miss counts, thereby adapting to actual traffic patterns and improving packet forwarding efficiency
Solution Approach 2:
The system uses miss count as feedback to make informed replacement decisions. By monitoring how many times each entry results in a miss, the system can prioritize replacement of entries that contribute most to forwarding failures, improving overall routing efficiency
3Quantity of substance
If host table space is limited, then entries must be replaced, but replacement increases lookup time when software forwarding is required
Solution Approach 1:
The patent changes the replacement strategy from time-based LRU to miss-count-based selection. By replacing entries that have the highest miss counts, the system maximizes the benefit of each replacement, reducing the likelihood of future misses and thereby reducing the frequency of slower software lookups
Data Source
AI summary
Methods, systems, and computer program products for controlling updating of a layer 3 host table based on packet forwarding miss counts are disclosed. According to one method, layer 3 packets are routed using at least one of a layer 3 host table containing entries corresponding to remote hosts and a longest prefix matching table containing prefixes corresponding to remote hosts. For each layer 3 destination address for which a lookup in at least one table fails, a number of packets received within a time period are counted. Remote destination entries in the host table are replaced based on the counts.