Disjoint Path Computation Algorithm for MPLS Backup LSPs

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Solution Overview

Problem

Manual configuration of backup Label Switch Paths (LSPs) in MPLS networks is prone to human error and does not ensure maximum disjointedness from primary LSPs, leading to non-optimal backup solutions.

Innovation Solution

Automatically generating an optimal deterministic backup LSP by modifying link costs in the traffic engineering database to discourage use of primary LSP links, using the Constrained Shortest Path First (CSPF) algorithm to calculate a maximally disjointed backup path.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual configuration techniques (link coloring and node exclusion) are used to create backup LSPs, then administrators can configure backup paths, but the configuration is prone to human error and does not ensure maximum disjointedness

Engineering Contradiction:

Improvebackup LSP reliabilityVSAvoidconfiguration complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system performs self-service by automatically computing backup LSPs using the CSPF algorithm without requiring manual administrator intervention. The head-end node autonomously modifies link costs and calculates optimal backup paths, eliminating human error while maintaining reliability

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention changes the parameter of link cost by modifying it dynamically during backup LSP computation. By temporarily setting link costs to discourage primary LSP links, the system achieves maximum disjointedness automatically, transforming a complex manual configuration task into an automated parameter optimization process

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If administrators manually determine backup LSP constraints and requirements, then they can verify protection goals, but the process is time-consuming and error-prone

Engineering Contradiction:

Improveconstraint verification accuracyVSAvoidconfiguration time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The invention replaces the mechanical manual verification process with an automated computational system. The CSPF algorithm mechanically processes constraints and calculates optimal paths, substituting human verification with algorithmic computation that is both faster and more accurate

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs preliminary action by pre-modifying link costs in the traffic engineering database before executing the CSPF algorithm. This preliminary modification ensures that the subsequent path computation automatically satisfies all constraints and achieves maximum disjointedness without requiring time-consuming manual verification

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8681607B2Disjoint path computation algorithm

Publication Date: 2014.03.25 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A network element implementing Multiprotocol Label Switching to automatically create an optimal deterministic back-up Label Switch Path (LSP) that is maximally disjointed from a primary LSP to provide a reliable back up to the primary LSP. The network element receives a request for a generation of an LSP, determines that the request for the generation of the LSP is for the back-up LSP, locates each link of the primary LSP in a traffic engineering database, modifies each link of the primary LSP to have a link cost significantly greater than an actual link cost to discourage use of each link of the primary LSP in the back-up LSP, executes a Constrained Shortest Path First algorithm to obtain the back-up LSP, wherein the back-up LSP has a maximum disjointedness from the primary LSP due to a modified cost of each link of the primary LSP, and returns the back-up LSP.