Standalone Network ISSU with Forwarding State Freeze
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Solution Overview
Problem
Existing software updates on standalone network devices cause disruption in network traffic processing due to the lack of redundancy, leading to inefficiencies in home or small business networks and campus deployments where additional hardware is not feasible.
Innovation Solution
Implementing an in-service software update (ISSU) process that orchestrates software updates in phases, including memory optimization, database migration, and daemon updates, while maintaining network traffic processing by using an ISSU orchestrator to manage the update process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional software updates are performed on standalone network devices, then software can be updated, but network traffic processing is disrupted
Solution Approach 1:
The update process is segmented into multiple phases (pre-update, during-update, post-update) with specific tasks assigned to each phase. The ISSU orchestrator divides the software update into manageable segments that can be executed without disrupting network traffic processing, allowing continuous operation during the update cycle.
Solution Approach 2:
Before the actual software update, the system performs preliminary actions including creating backup copies of critical data, pre-loading updated software modules, and preparing the update environment. This ensures that when the update executes, network traffic processing can continue uninterrupted as the backup and preparation work was already completed.
2Reliability
If redundant hardware is added to enable continuous updates, then update disruption is avoided, but device complexity and cost increase
Solution Approach 1:
The standalone network device performs self-service updates using its existing processing resources. The ISSU orchestrator manages the update process internally without requiring external redundant hardware. The device creates its own backup copies, manages memory resources during updates, and maintains traffic processing continuity through coordinated phase execution.
Solution Approach 2:
Instead of adding redundant hardware dimensions to the system, the solution adds a temporal dimension by executing updates in phased sequences. The update process operates in time slots separated by synchronization points, allowing the single device to handle updates without hardware redundancy by utilizing time-based resource allocation.
3Reliability
If software updates are performed without disruption, then network traffic processing continues, but update complexity increases
Solution Approach 1:
The ISSU orchestrator implements feedback mechanisms that continuously monitor the update process status, memory usage, and traffic processing health. Based on this feedback, the orchestrator dynamically adjusts update timing, resource allocation, and synchronization points to maintain continuity while managing complexity through real-time monitoring and adaptive control.
Solution Approach 2:
The ISSU orchestrator acts as an intermediary between the update management system and the network device operations. This intermediary coordinates the complex interactions between software modules, memory resources, and traffic processing functions, abstracting the complexity from the overall system while enabling disruption-free updates through centralized coordination.
Data Source
AI summary
In certain embodiments, a method includes stopping platform daemons of a standalone network device; creating an ISSU cache; storing forwarding information in the ISSU cache to freeze the forwarding information; installing an updated state database; storing the forwarding information from the ISSU cache in the updated state database; generating a warm boot file for a line card daemon; installing an updated line card daemon; recovering an internal state of a line card to the updated line card daemon using the warm boot file; connecting the updated line card daemon to the updated state database; syncing the updated state database to a non-updated state database; unfreezing the forwarding information by allowing the updated line card daemon to update the forwarding information of the line card using information from the updated state database; updating control plane daemons of the standalone network device; and updating the platform daemons of the standalone network device.