Line Card CPU Control System Restart with Forwarding Continuity
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Solution Overview
Problem
Existing network devices face service disruption and increased downtime when line cards need to be restarted, especially during software upgrades, as the existing methods do not effectively manage the transition between the CPU control system and the forwarding system, leading to potential system exceptions and protocol message timeouts.
Innovation Solution
A method where the CPU control system stores 'shadow' information and sets a restart flag before restarting, allowing the forwarding system to maintain operation, and a proxy process is initiated to handle protocol messages, ensuring continuous traffic forwarding and minimizing disruptions. Additionally, a smoothing operation is performed to reconcile any changes in information post-restart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the CPU control system restarts to perform software upgrades or maintenance, then the line card can be updated and maintained, but the forwarding system stops and service disruption occurs
Solution Approach 1:
The patent divides the line card into two independent parts: the CPU control system and the forwarding system. This segmentation allows the CPU control system to restart for software upgrades while the forwarding system continues to process packets independently, thus enabling maintenance without service disruption.
Solution Approach 2:
The patent introduces a proxy process as an intermediary between the CPU control system and the forwarding system. The proxy process handles protocol messages during the restart transition, ensuring that the forwarding system can continue operating smoothly while the CPU control system is being updated.
2Adaptability or versatility
If the CPU control system restarts, then software can be upgraded, but protocol messages timeout and system exceptions occur
Solution Approach 1:
The proxy process acts as a mediator that intercepts and handles protocol messages during the CPU control system restart. This prevents protocol message timeouts and system exceptions by ensuring continuous message processing even when the CPU control system is restarting.
Solution Approach 2:
The patent performs preliminary actions before the CPU control system restarts by saving necessary state information and configuring the forwarding system in advance. This preparation ensures that the forwarding system can continue operating smoothly during and after the restart without encountering protocol message timeouts.
3Ease of operation
If the line card restarts completely, then the system can be reset, but downtime increases and service disruption occurs
Solution Approach 1:
By segmenting the line card into CPU control system and forwarding system, the patent enables selective restarting of only the CPU control system while keeping the forwarding system running. This reduces downtime and service disruption compared to a complete line card restart.
Solution Approach 2:
The patent ensures continuity of useful action by allowing the forwarding system to continue processing packets during the CPU control system restart. The proxy process maintains protocol message handling, ensuring that network services continue without interruption throughout the restart process.
Data Source
AI summary
A method and a network device for preventing service disruption during a restart of a line card. The line card including a CPU control system and a forwarding system. Information on the CPU control system is stored in a predetermined storage and a flag is set prior to the restart of the line card. The stored information includes configuration information of the forwarding system and protocol state information of the CPU control system. The CPU control system is restarted while the forwarding system is maintained in a state of providing forwarding service. Upon detecting the flag is set during the restart of the CPU control system, the stored information is restored on the CPU control system.