Hardware Table Downloads Using Valid Entries to Reduce Traffic Outage
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Solution Overview
Problem
Software upgrades in the control plane of network devices often result in significant traffic outages due to the recomputation of lookup tables and the need to download updated forwarding information to hardware tables, which can take several seconds and disrupt network traffic.
Innovation Solution
The solution involves identifying valid and invalid entries in software tables based on usage ratios and coalescing adjacent blocks or chunks of valid entries for download, while omitting invalid entries, thereby reducing the time required for traffic outage by minimizing the data transferred during the upgrade process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all entries in software tables are downloaded to hardware tables during control plane updates, then forwarding information consistency is ensured, but traffic outage time increases
Solution Approach 1:
The patent segments the software table entries into two distinct groups: valid entries and invalid entries. This segmentation allows the download process to selectively transfer only valid entries to hardware tables, excluding invalid ones. By dividing the table content based on validity status, the system maintains forwarding consistency for active routes while reducing unnecessary data transfer time, thus resolving the contradiction between reliability and time loss.
Solution Approach 2:
The patent extracts and identifies invalid entries from the software tables using a validity bitmap or validation logic before the download process. By taking out invalid entries (those pointing to non-existent or deprecated data) from the download set, the system prevents wasteful transfer of obsolete information. This extraction process ensures that only necessary valid entries are transferred to hardware tables, maintaining consistency where needed while minimizing outage time by excluding redundant data.
2Adaptability or versatility
If software tables are fully recomputed during upgrades, then policy updates are complete, but download duration increases
Solution Approach 1:
The patent performs preliminary identification and marking of valid versus invalid entries in the software tables before initiating the download process to hardware tables. By pre-processing the table contents and tagging each entry's validity status, the system prepares the data in advance for selective transfer. This preliminary action ensures complete policy updates are ready while enabling the subsequent download phase to skip invalid entries, thereby reducing download duration without compromising policy completeness.
Solution Approach 2:
The patent applies partial action by downloading only the necessary subset of table entries (valid ones) rather than performing a full download of all entries. This partial transfer approach maintains the essential policy update functionality while significantly reducing the download duration. The system performs exactly the amount of action needed (transferring valid entries) without the excessive action of transferring all entries including invalid ones, thus resolving the contradiction between policy completeness and download time.
Data Source
AI summary
Software tables in the control plane of a network device are downloaded into the data plane hardware after a reboot of the control plane. Valid entries are identified and downloaded while reducing the downloading invalid or otherwise unused entries to improve download times and reduce disruption of traffic resulting from the download. In some instances, blocks of entries containing a high ratio of valid to invalid entries are identified and downloaded to the hardware. In some instances, entries in the software tables that differ from corresponding entries in the hardware (diff entries) are identified and downloaded. In some instances, chunks containing diff entries and non-diff entries are identified and downloaded.