Virtual Chassis Split Prevention via Role-Based Mode Assignment
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Solution Overview
Problem
In network environments with virtual chassis, failures lead to splits that disrupt connectivity and cause network disruptions, especially when multiple virtual chassis share the same IP address and resources, and subsequent splits or merges can further complicate the issue.
Innovation Solution
Network devices detect failures and execute a splitting process to form new virtual chassis, determining whether each split portion operates as a functioning or nonfunctioning virtual chassis based on specific criteria, such as including a master and backup device or reaching a certain size, to prevent multiple functioning virtual chassis from existing simultaneously and maintain network stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a virtual chassis splits into multiple sections due to failure, then each section can function independently, but network disruptions occur due to shared IP addresses and configuration resources
Solution Approach 1:
The patent applies local quality by assigning different operational modes to different split sections based on their characteristics. The master-eligible section operates in master mode with full configuration access, while non-master sections operate in backup or pass-through modes with restricted access. This localized differentiation resolves the contradiction by allowing independence while preventing resource conflicts through role-based access control.
Solution Approach 2:
The patent inverts the traditional approach by having the non-master sections operate in a pass-through mode where they forward traffic without processing it locally. Instead of each section trying to function as a complete virtual chassis, the inversion makes only the master section the functional decision-maker, while non-master sections become transparent conduits. This resolves the network disruption issue by eliminating duplicate configuration processing.
2Productivity
If multiple virtual chassis share the same IP address and configuration resources, then resource utilization is efficient, but network stability deteriorates during splits and merges
Solution Approach 1:
The patent implements dynamics by making the operational mode of each section adaptive rather than static. Sections can transition between backup mode and pass-through mode based on real-time conditions such as master availability and section size. This dynamic behavior allows the system to maintain resource sharing efficiency while adapting to stability requirements during various failure scenarios and merge operations.
Solution Approach 2:
The master section acts as an intermediary that mediates access to shared configuration resources. Instead of multiple sections directly accessing shared resources which causes conflicts, the master section intermediates by maintaining the authoritative configuration and distributing necessary information to other sections. This mediator approach preserves resource sharing efficiency while eliminating stability issues caused by concurrent resource access.
3Adaptability or versatility
If split virtual chassis operate with full configuration access, then operational flexibility is maintained, but conflicts arise from multiple instances using the same resources
Solution Approach 1:
The patent applies segmentation by dividing the virtual chassis into distinct operational segments with different access privileges. The master section segment retains full configuration access and operational flexibility, while non-master segments are segmented into backup mode (with limited access) or pass-through mode (with minimal access). This segmentation resolves the contradiction by preserving flexibility where needed while eliminating conflicts in resource-constrained segments.
Solution Approach 2:
The patent implements asymmetry by creating unequal access rights among split sections based on their roles. The master section has asymmetric privileged access to all configuration resources, while non-master sections have asymmetric restricted access depending on their mode. This asymmetric permission structure maintains operational flexibility for the master while preventing resource conflicts in non-master sections, as they cannot initiate conflicting configuration changes.
Data Source
AI summary
A method performed by network devices that includes operating in a normal mode, where the network devices form a virtual chassis that corresponds to a single logical network device; detecting when a failure within the virtual chassis occurs; executing a splitting process to form one or more new virtual chassis in correspondence to the failure; determining whether one of the one or more new virtual chassis operates as a functioning virtual chassis based on whether at least one of a set of criteria is satisfied, where the functioning virtual chassis operates according to resources configured for the virtual chassis; and operating as a nonfunctioning virtual chassis when it is determined that the one of the one or more virtual chassis does not satisfy the at least one of the set of criteria, where the nonfunctioning virtual chassis operates in a pass-through mode.