Spanning Tree Reconfiguration via Root Failure Notification
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Solution Overview
Problem
Current packet-switched communication networks experience significant downtime when a root bridge fails, as the reconfiguration of a new spanning tree typically takes at least 30 seconds, disrupting data exchange and failing to meet quality of service requirements.
Innovation Solution
A method that rapidly reconfigures a packet-switched communication network by detecting the failure of a direct link to the root bridge, declaring an alternative bridge as the new root, and propagating Root Failure Notification (RFN) frames to other bridges, allowing for the establishment of a new spanning tree within a few milliseconds, thereby reducing downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the standard STP reconfiguration process is used after root bridge failure, then the spanning tree can be restored, but the network downtime is at least 30 seconds
Solution Approach 1:
The patent applies preliminary action by pre-identifying candidate root bridges and preparing alternative spanning tree configurations before actual failure occurs. When the root bridge fails, the pre-prepared alternative configuration can be immediately activated, eliminating the need for lengthy reconfiguration processes and reducing network downtime from 30 seconds to a few milliseconds.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of a control unit that manages the switching between primary and alternative spanning tree configurations. This control unit receives failure notifications, coordinates the activation of pre-prepared alternative configurations, and ensures smooth transition, thereby resolving the contradiction between reliable restoration and minimal downtime.
2Reliability
If the network waits for BPDU timeout to detect root bridge failure, then false positives are avoided, but the detection time is delayed by at least 30 seconds
Solution Approach 1:
The patent introduces an intermediary notification mechanism where bridges directly connected to the root bridge can immediately notify the control unit of failure through a dedicated notification interface. This intermediary channel bypasses the slow BPDU timeout mechanism while maintaining reliability through controlled validation, enabling immediate failure detection without the 30-second delay.
Solution Approach 2:
The patent implements a feedback mechanism where the control unit receives real-time failure notifications from bridges and immediately triggers the activation of alternative spanning tree configurations. This feedback loop enables rapid response to failures while maintaining system stability through the pre-prepared alternative configurations, resolving the contradiction between detection speed and accuracy.
3Speed
If alternative spanning tree configurations are pre-prepared for all possible failures, then reconfiguration speed is maximized, but the device complexity increases
Solution Approach 1:
The patent applies local quality by preparing alternative spanning tree configurations only for specific critical failure scenarios (such as root bridge failure) rather than all possible failures. The control unit intelligently determines which alternative configurations are needed based on the network topology and failure probability, reducing the overall complexity while maintaining fast reconfiguration speed for the most critical scenarios.
Solution Approach 2:
The patent changes the parameter of configuration management from static pre-preparation of all possible configurations to dynamic preparation based on failure notifications. The control unit receives failure notifications, determines the appropriate alternative configuration needed, and activates it on-demand, thereby reducing the burden of managing all possible configurations while maintaining rapid reconfiguration capability.
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E
AI summary
The invention relates to a method for reconfiguring a packet-switched communication network using a network protocol, which makes it possible to install a logic topology of the network formed as a spanning tree, characterized by the following steps: Detecting the failure of a direct link (L12) to the root bridge (1) of the spanning tree by a first bridge (2), which has no alternative root-ports and is directly connected with the root bridge (1) via a link (L12), and starting a timer; detecting the failure of a direct link (L13) to the root bridge (1) by at least one second bridge (3), which is directly connected with the root bridge (1) via a link (L13) and has alternative root ports, within a selectable interval of the timer; transmission of a first configuration frame generated by the first bridge to the other bridges of the network, wherein the first configuration frame contains the identifier for the first bridge (2) as the origin identifier; receiving the first configuration frame by at least one third bridge (4) and transmission of a second configuration frame, generated by the third bridge (4), to the other bridges in the network, wherein in the second configuration frame a flag is set, indicating the failure of the direct link (L12) between the first bridge (2) and the root-bridge (1), and the identifier for the first bridge (2) is contained as the origin identifier; detecting the first or second configuration frame by at least one second bridge (3) and transmission of the third configuration frame generated by the second bridge to the other bridges of the network, wherein in the third configuration frame, the flag indicating the failure of the direct link (L12) between the first bridge (2) and the root-bridge (1) is deleted and the identifier for the second bridge (2) is contained as the origin identifier; receiving the third configuration frame by the other bridges of the network and triggering a reconfiguration of the network with detection of a new spanning tree by means of the network protocol.