Alternating Flow Entry Refresh for Packet Loss Prevention
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Solution Overview
Problem
In traditional network devices, delays in refreshing flow entries can result in packets escaping or being misrouted due to the lack of a backup mechanism, especially when the processor is busy, leading to potential security or monitoring disruptions.
Innovation Solution
Implementing a first and second flow entry with the same match parameters and actions, refreshed alternately, acting as backups for each other, to ensure continuous packet handling even during refresh delays, with the use of a single fixed rate scheduler to manage their periodic updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single flow entry is used in the forwarding table, then the device complexity is reduced, but packet loss occurs during refresh delays when the processor is busy
Solution Approach 1:
The patent creates a copy of the flow entry (backup flow entry) in the forwarding table. When the primary flow entry needs to be refreshed, the backup flow entry continues to handle packet forwarding, preventing packet loss. This copying approach maintains reliability without significantly increasing device complexity.
Solution Approach 2:
The patent pre-establishes a backup flow entry before the primary flow entry expires or is refreshed. This beforehand cushioning ensures that if the primary flow entry becomes invalid during refresh, the backup is already in place to immediately take over, preventing packet loss and maintaining continuous forwarding.
2Manufacturing precision
If flow entries are refreshed frequently to maintain validity, then forwarding accuracy is improved, but processor load increases causing delays
Solution Approach 1:
The patent implements periodic refresh of flow entries with alternating primary and backup entries. Instead of continuously refreshing a single flow entry, the system periodically switches between two entries, reducing the frequency of refresh operations on any single entry and lowering processor load while maintaining forwarding accuracy.
Solution Approach 2:
The patent performs preliminary action by creating and validating a backup flow entry before the primary flow entry expires. This allows the refresh operation to be prepared in advance, and the switch to backup entry to occur smoothly without interruption, maintaining accuracy without excessive processor burden during critical forwarding moments.
3Ease of operation
If a single flow entry is refreshed, then the refresh process is simple, but packets may escape or be misrouted during the refresh delay
Solution Approach 1:
The patent maintains a backup copy of the flow entry in the forwarding table that can immediately take over if the primary entry becomes invalid during refresh. This copying mechanism ensures routing reliability without significantly complicating the refresh operation, as the backup entry is simply activated when needed.
Solution Approach 2:
The patent prepares a backup flow entry in advance before the primary entry expires or becomes invalid. This beforehand cushioning ensures that if any issue occurs during the refresh process, packets will not escape or be misrouted because a valid backup entry is already in place to handle forwarding.
Data Source
AI summary
A first flow entry includes match parameters and an action. A second flow entry includes match parameters and which are the same as the match parameters and the action of the first flow entry. The first flow entry and the second flow entry are refreshed.