Point-to-Multipoint Traffic Path Encoding in MPLS Networks

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Solution Overview

Problem

Existing methods for setting up point-to-multipoint (P2MP) Label Switched Paths (LSPs) in Multi-Protocol Label Switching (MPLS) networks require a large amount of signaling information, especially in complex topologies, leading to inefficient data transmission and increased processing costs.

Innovation Solution

A new encoding scheme that uses a common explicit route object to list nodes common to all source-to-leaf sub-paths, reducing the repetition of node addresses in path messages and minimizing the amount of signaling information required, while maintaining computational efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If explicit routes are encoded from ingress to egress for each S2L sub-LSP, then complete path information is provided, but processing overhead and message size increase significantly

Engineering Contradiction:

Improvepath information completenessVSAvoidprocessing overhead

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the P2MP LSP encoding into two distinct parts: (1) a common explicit route object containing the shared path from ingress to the branching point, and (2) individual S2L sub-LSP specific route segments. This segmentation allows the common path to be encoded once and reused, eliminating redundant processing while maintaining complete path information for each sub-LSP.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges the common path segments from multiple S2L sub-LSPs into a single common explicit route object. By combining the identical path portions that appear in multiple sub-LSPs into one shared structure, the patent reduces the total amount of data that needs to be processed and transmitted, directly addressing the processing overhead issue.

Inventive Principle:

Principle #5Merging (Combining)

2Quantity of substance

If compression mechanism is used for encoding P2MP LSP, then message size is reduced, but signaling information requirements increase for complex topologies

Engineering Contradiction:

Improvemessage sizeVSAvoidsignaling information

Core Design Contradiction:

Quantity of substanceVSLoss of information

Solution Approach 1:

The patent implements a nested structure where the common explicit route object contains the shared path information, and individual S2L sub-LSP descriptors are nested within or associated with this common structure. This nesting allows the common path to be defined once at a higher level, with individual sub-LSPs referencing or extending from it, thereby reducing total message size while preserving all necessary routing information.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

Instead of encoding each complete S2L sub-LSP path from ingress to egress individually, the patent inverts the approach by encoding the common shared path once and then specifying only the divergent segments for each sub-LSP. This inversion fundamentally changes the encoding strategy from redundant full-path specification to efficient differential encoding.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS8923295B2Methods and devices for point to multipoint traffic path encoding

Publication Date: 2014.12.30 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

The present invention relates to network nodes and methods that use an encoding scheme for encoding a point-to-multipoint traffic path from one ingress node to a plurality of egress nodes in, for example, a Multi-Protocol Label Switching network. According to the encoding scheme a so-called common ERO is used. The common ERO specifies a list consisting of nodes that are common to several sub paths in order to provide a compression mechanism that reduces the size of path messages that are used for signaling the point-to-multipoint traffic path.