Link State Spanning Tree for Ethernet SPB

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Solution Overview

Problem

Current Shortest Path Bridging (SPB) protocols in Ethernet networks rely on the path vector approach, which prioritizes the shortest path but fails to consider other objectives, leading to temporal inconsistencies and excessive broadcasting, and implementing link state protocols directly can result in transient loops and resource taxation.

Innovation Solution

A method and system that implement a link state spanning tree approach to support multiple spanning trees in SPB, using link state advertisements and topology databases to calculate and configure trees, ensuring symmetric forwarding paths and reducing recovery time by maintaining backup topologies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If path vector approach is used in SPB protocols, then shortest path is prioritized, but temporal inconsistencies and excessive broadcasting occur

Engineering Contradiction:

Improvedata traffic forwarding speedVSAvoidtemporal consistency

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent replaces the path vector approach with a link state approach, substituting the mechanical routing mechanism with a state-based system. Each bridge maintains a complete topology database and uses link state advertisements to propagate network state information, enabling consistent routing decisions across all bridges without temporal inconsistencies.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements feedback mechanisms through link state advertisements that continuously propagate topology changes throughout the network. Each bridge receives feedback about network state changes and adjusts its routing tables accordingly, ensuring temporal consistency in forwarding decisions while maintaining fast data traffic routing.

Inventive Principle:

Principle #23Feedback

2Productivity

If link state protocols are implemented directly, then routing efficiency improves, but transient loops and resource taxation occur

Engineering Contradiction:

Improverouting efficiencyVSAvoidtransient loops

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by having bridges pre-establish complete topology databases before routing decisions are needed. Bridges continuously maintain updated topology information through link state advertisements, so when routing decisions are required, the necessary network state information is already available, eliminating transient loops.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements beforehand cushioning by maintaining backup topologies and pre-configured routing paths. When link failures occur, bridges have pre-prepared alternative routes that can be activated immediately, cushioning against the harmful effects of transient loops and resource taxation that would otherwise occur during recovery.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If multiple spanning trees are maintained, then path diversity improves, but system complexity increases

Engineering Contradiction:

Improvepath diversityVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies universality by implementing a single link state protocol framework that serves multiple functions: topology discovery, routing decision-making, loop prevention, and failure recovery. This unified approach enables path diversity through multiple spanning trees without proportionally increasing system complexity, as the same protocol mechanisms handle all these functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8837329B2Method and system for controlled tree management

Publication Date: 2014.09.16 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

There is disclosed a method and apparatus for facilitating a network, such as an Ethernet LAN, for efficient forwarding of data traffic by collecting neighbor information, generating and distributing link state advertisements, populating a topology database for the network, and calculating trees for each bridge serving as a root bridge. In a preferred embodiment the method and system also prepare one or more backup topologies, and store them for use if they are needed due to a failure condition detected in the network. In a particularly preferred embodiment, probabilities are assigned to various potential failure conditions, and the probability values are used to decide which backup topologies to calculate, store, or use.