Spanning Tree Protocol Bridge Mode Switching

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Solution Overview

Problem

The Spanning Tree Protocol experiences significant performance degradation under high load conditions, particularly in networks with a large number of ports, due to the substantial workload required for recalculating bridge states and exchanging information, which can lead to network saturation and failure.

Innovation Solution

Implementing a method that allows a network bridge to operate in either active or defer mode, where the spanning tree protocol process is only run in response to triggering events after a delay period, reducing the workload and preventing overload by storing events and processing them in batches, thereby minimizing the frequency of state machine operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the spanning tree protocol process is run immediately in response to every triggering event, then the network responds quickly to topology changes, but the processing burden on controllers increases significantly under high load conditions

Engineering Contradiction:

Improveresponse speed to topology changesVSAvoidprocessing capacity of controllers

Core Design Contradiction:

SpeedVSProductivity

Solution Approach 1:

The system dynamically adjusts its operating mode between active and defer based on load conditions. Under normal conditions, the protocol runs immediately for fast response. Under high load, it switches to defer mode to limit processing frequency, thus adapting the system's behavior to current conditions rather than maintaining a fixed response strategy

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements periodic deferral where the protocol process is delayed by a delay period before execution. This periodic action mechanism prevents continuous immediate processing under high load, effectively throttling the frequency of state machine operations to match controller processing capacity

Inventive Principle:

Principle #19Periodic action

2Productivity

If the spanning tree protocol process is deferred under high load conditions, then the processing burden on controllers is reduced, but the response time to topology changes increases

Engineering Contradiction:

Improveprocessing capacity of controllersVSAvoidresponse time to topology changes

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The system dynamically switches between immediate execution and deferred execution based on real-time load assessment. This dynamic behavior allows the system to optimize between speed and capacity utilization, running fast when possible and deferring when necessary to avoid overload

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the execution timing parameter of the spanning tree protocol based on system state. By adjusting whether the protocol runs immediately or after a delay period, the system adapts its temporal behavior to match processing capacity constraints while maintaining acceptable response performance

Inventive Principle:

Principle #35Parameter changes

3Reliability

If state machines are run frequently to maintain network stability, then topology changes are processed quickly, but the network becomes more vulnerable to saturation under high load

Engineering Contradiction:

Improvenetwork stabilityVSAvoidnetwork saturation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potentially harmful effect of frequent state machine execution (which causes saturation) into a beneficial load management mechanism. By implementing defer mode, the system intentionally limits execution frequency to prevent saturation, transforming what would be a vulnerability into a protective feature that maintains stability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS10892936B2Spanning tree protocol

Publication Date: 2021.01.12 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

The invention provides a method and apparatus for managing operation of a spanning tree protocol process in a network bridge. This comprises setting the network bridge to either an active mode or a defer mode in which a spanning tree protocol process is not run in response to a triggering event. The system remains in the defer mode for a period of time in which no further operations of the state machines will take place, before reverting to the active mode and normal processing of triggering events is carried out.