Multicast Forwarding Tree Construction in Ethernet Networks

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Solution Overview

Problem

Current Shortest Path Bridging (SPB) technologies consume excessive computational resources and multicast forwarding/filter entries due to the need for building multiple trees per source node and using source-specific multicast addresses, leading to inefficiencies in Ethernet-based networks.

Innovation Solution

The method determines a designated node within the network using a commonly agreed mechanism, computes a single *,G tree for multicast paths, and selects only the shortest paths traversing each node for inclusion in the forwarding tree, reducing computational resource consumption and multicast entries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If source-specific multicast trees are built for each source node, then multicast traffic can be forwarded along optimal paths, but computational resource consumption increases proportionally to the number of nodes in the network

Engineering Contradiction:
Improvemulticast forwarding efficiencyVSAvoidcomputational resource consumption
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges multiple source-specific trees into a single shared multicast tree structure. Instead of building separate shortest path trees for each source node, the invention creates one unified tree that accommodates multicast traffic from multiple sources, thereby reducing computational overhead while maintaining efficient path selection.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements a universal multicast tree structure that serves multiple source nodes simultaneously. This single tree structure performs the function of multiple source-specific trees, allowing any source node to utilize the same tree for multicast forwarding without requiring separate computational resources for each source.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple active topologies are maintained for different service instances, then service-specific multicast forwarding is enabled, but the number of multicast forwarding entries consumed at each node increases

Engineering Contradiction:
Improveservice instance supportVSAvoidmulticast forwarding entries
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent segments the network into multiple service instance subsets, where each subset shares a common multicast tree. This segmentation allows different service instances to be grouped efficiently, reducing the total number of forwarding entries required at each node while still supporting service-specific requirements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter of tree construction from source-specific to subset-specific. By organizing multicast trees based on service instance subsets rather than individual sources, the system reduces the number of trees and corresponding forwarding entries while maintaining the ability to support multiple service instances with different requirements.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2756638B1Method for shortest path bridging of multicast traffic
Publication Date: 2018.04.25 ALCATEL LUCENT SA
  • EP2756638B1 patent drawingFigure 1
  • EP2756638B1 patent drawingFigure 2
  • EP2756638B1 patent drawingFigure 3

AI summary

Method for determining shortest path bridging (SPB) of multicast frames within a communications network comprises at each of a plurality of nodes within the network, determining a designated node (DN) according to a commonly agreed mechanism; at each of the plurality of nodes, determining a shortest path between the DN and each of the plurality of nodes; and at each of the plurality of nodes, selecting for inclusion in a respective forwarding tree for multicast only those determined shortest paths from the DN traversing the respective node.