Entry Bridge Bandwidth Registration for Multiple Spanning Tree Paths

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Solution Overview

Problem

Existing computer network technologies face challenges in efficiently managing bandwidth registration for multiple spanning tree options, leading to congestion and inability to meet Quality of Service (QoS) requirements due to single spanning tree configurations, which limits available resources and disrupts network operations.

Innovation Solution

A technique that allows entry bridges to dynamically select the best spanning tree path based on bandwidth utilization by monitoring multiple spanning tree paths and using special forwarding mechanisms, enabling efficient bandwidth registration even when the primary spanning tree is congested, without requiring manual configuration or a master network allocation facility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single spanning tree configuration is used, then network loop prevention is achieved, but bandwidth registration efficiency and QoS requirement fulfillment deteriorate due to congestion and limited available resources

Engineering Contradiction:
Improvenetwork loop preventionVSAvoidbandwidth registration efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent segments the single spanning tree into multiple spanning tree instances (MSTIs), each operating independently with separate bandwidth registration. This allows different data flows to use different spanning trees, preventing congestion on any single path while maintaining loop prevention through standardized STP/RSTP mechanisms in each instance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic spanning tree selection where entry bridges can switch between multiple spanning trees based on real-time bandwidth availability and QoS requirements. The system dynamically monitors bandwidth utilization across different MSTIs and selects optimal paths, enabling adaptive response to changing network conditions without manual reconfiguration.

Inventive Principle:
Principle #15Dynamics

2Device complexity

If a single spanning tree configuration is used, then network topology simplicity is maintained, but available bandwidth resources are limited and congestion occurs

Engineering Contradiction:
Improvenetwork topology simplicityVSAvoidavailable bandwidth resources
Core Design Contradiction:
Device complexityVSQuantity of substance

Solution Approach 1:

The patent divides the network topology into multiple independent spanning tree instances, each representing a separate logical path set. This segmentation effectively multiplies available bandwidth resources by allowing parallel transmission over different topological paths, while each individual tree remains relatively simple and manageable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent adds the dimension of multiple spanning tree instances alongside the traditional single tree approach. By operating in this expanded dimensional space, the network can utilize additional bandwidth resources through parallel paths without fundamentally complicating the basic spanning tree algorithm implementation at each node.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Measurement precision

If manual configuration is used for spanning tree selection, then control precision is achieved, but operational complexity and time consumption increase

Engineering Contradiction:
Improvespanning tree selection controlVSAvoidconfiguration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements self-service spanning tree selection where entry bridges autonomously monitor bandwidth utilization across multiple MSTIs and automatically select optimal paths based on real-time conditions. The system performs self-adjustment without requiring manual intervention, eliminating configuration time while maintaining precise control through algorithmic decision-making.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent establishes feedback mechanisms where entry bridges continuously monitor bandwidth availability and QoS metrics across different spanning trees. This feedback loop enables automatic adaptation to changing network conditions, replacing manual configuration with dynamic, data-driven selection that responds to real-time performance information.

Inventive Principle:
Principle #23Feedback

4Ease of operation

If primary spanning tree is used, then path selection simplicity is maintained, but QoS requirements cannot be met when congestion occurs

Engineering Contradiction:
Improvepath selection simplicityVSAvoidQoS requirement fulfillment
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent transforms static primary tree path selection into dynamic multi-tree selection. Entry bridges dynamically switch between multiple spanning trees based on real-time congestion conditions and QoS requirements, maintaining simple operation through automated selection while ensuring reliable QoS fulfillment through adaptive path switching.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of path selection from fixed to variable by introducing multiple spanning tree instances. This allows the system to adjust the effective path parameter based on network conditions, enabling QoS-compliant routing decisions that respond to bandwidth availability and congestion levels without complicating the basic selection mechanism.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2016715B1A technique for efficiently managing bandwidth registration for multiple spanning tree options
Publication Date: 2018.09.19 CISCO TECHNOLOGY INC
  • EP2016715B1 patent drawingFigure 1
  • EP2016715B1 patent drawingFigure 2
  • EP2016715B1 patent drawingFigure 3

AI summary

A technique efficiently manages bandwidth (BW) registration for multiple spanning tree options in a computer network. According to the novel technique, an entry bridge determines multiple spanning tree paths to other bridges of the network (namely, one or more available spanning trees rooted at one or more bridges of the network) and determines a utilized (registered) BW on each of those paths. Upon receiving a request to initiate BW registration for a data flow to a destination end point, e.g., from an application source end point, the entry bridge selects one of the spanning tree paths to utilize for the data flow. Selection of the spanning tree path from among the multiple available paths may be based on (i) available bandwidth of the paths, (ii) a shortest of the paths, and (iii) a lowest bridge identifier ID for the bridge root for the path. The entry bridge sends a registration message for the data flow towards the destination end point along the selected spanning tree path. If successful, the data flow is transmitted on the selected path. If not, the entry bridge attempts to register the data flow on a next best alternate spanning tree, e.g., until a successful registration or until a determination that no further alternate spanning trees exist.