Hardware Table Download Using Valid and Diff Entries
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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 and downloading only valid or differing entries from software tables to hardware tables, while omitting unused or unchanged entries, thereby reducing the duration of traffic outage by minimizing the data to be transferred.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all entries in software tables are downloaded to hardware tables during control plane reboot, then forwarding information is fully updated, but traffic outage time increases significantly
Solution Approach 1:
The patent extracts only the necessary changed entries from software tables for download to hardware tables, rather than transferring the complete table. By identifying and downloading only modified entries (such as specific routing table entries, MAC address table entries, or ARP cache entries that have actually changed), the system reduces the data transfer volume and download time, thereby minimizing traffic outage duration while ensuring forwarding information is fully updated.
Solution Approach 2:
The patent segments the software table into changed entries and unchanged entries, and selectively downloads only the changed entries to the hardware table. This segmentation approach allows the system to maintain forwarding information completeness for affected entries while reducing the overall download time by excluding unchanged entries from the transfer process.
2Reliability
If traffic is halted during control plane reboot to enable software table download, then hardware tables are updated correctly, but network connectivity is disrupted
Solution Approach 1:
The patent extracts only the minimal set of changed entries that need to be downloaded to hardware tables, rather than halting traffic for a complete table refresh. By identifying and downloading only the necessary changed entries (such as specific routing entries or MAC address entries that have actually changed during control plane reboot), the system achieves accurate hardware table updates without requiring complete traffic halt, thereby maintaining network connectivity.
Solution Approach 2:
The patent applies partial action by downloading only the necessary changed entries rather than the complete table. This partial download approach is sufficient to achieve accurate hardware table updates for affected entries while avoiding the excessive action of halting all traffic for a complete table transfer, thus balancing update accuracy with network connectivity.
3Reliability
If complete software tables are relearned and recomputed during control plane upgrade, then forwarding policies are fully updated, but upgrade time and traffic disruption increase
Solution Approach 1:
The patent extracts only the changed entries from software tables during control plane upgrade, rather than relearning and recomputing the complete tables. By identifying and processing only the modified entries (such as specific routing policies, MAC address entries, or ARP cache entries that have changed), the system achieves complete forwarding policy updates for affected entries while significantly reducing upgrade time and traffic disruption.
Solution Approach 2:
The patent segments the software table update process into changed entries and unchanged entries, selectively processing only the changed entries during control plane upgrade. This segmentation allows the system to maintain forwarding policy completeness for affected entries while improving upgrade speed by excluding unchanged entries from the relearning and recomputation process.
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.