Disjoint MPLS Pseudo Wire Redundancy Setup

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Solution Overview

Problem

Existing MPLS networks face challenges in establishing primary and redundant pseudo wires over disjoint paths, leading to potential total loss of VLL services due to shared physical links, which can fail simultaneously, despite redundant pseudo wires being configured for resiliency.

Innovation Solution

The establishment of primary and redundant pseudo wires over disjoint bidirectional and unidirectional RSVP-TE LSPs is achieved by using label distribution protocol (LDP) label mapping messages with Transport Path Include and Exclude fields to ensure that the primary and redundant paths do not share common physical links, thereby preventing simultaneous failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If redundant pseudo wires share the same physical link for transport, then device complexity is reduced, but reliability deteriorates because simultaneous failure of the shared link causes total service loss

Engineering Contradiction:

Improvecomplexity of establishing redundant pathsVSAvoidresiliency of VLL services

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent segments the transport paths of primary and redundant pseudo wires into disjoint MPLS LSPs, ensuring they do not share common physical links. This segmentation is achieved by establishing separate RSVP-TE LSPs with different downstream paths, thereby eliminating the single point of failure while maintaining redundancy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces path diversity by routing primary and redundant pseudo wires through different dimensional paths in the network topology. Specifically, it uses disjoint MPLS LSPs that traverse different physical links and network segments, creating spatial separation that prevents simultaneous failure.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If disjoint MPLS transport paths are established for primary and redundant pseudo wires, then reliability is improved, but device complexity increases due to additional path management requirements

Engineering Contradiction:

Improveresiliency of VLL servicesVSAvoidcomplexity of path establishment and management

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent enables the network infrastructure to automatically establish and manage disjoint MPLS LSPs through standardized protocols (RSVP-TE and LDP). The PE routers autonomously perform path computation, resource reservation, and label distribution without requiring manual configuration, thereby reducing operational complexity despite the increased path management requirements.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent implements feedback mechanisms through LDP label mapping messages that include transport path information. This feedback allows the receiving PE router to verify the disjoint nature of the paths and automatically adjust label bindings to ensure proper traffic forwarding over the redundant paths, simplifying the overall management process.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If standard LDP label mapping messages are extended with transport path information, then ease of operation is improved through automated path selection, but device complexity increases due to message format modifications

Engineering Contradiction:

Improveautomated transport path selectionVSAvoidcomplexity of protocol message processing

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent performs preliminary action by pre-establishing disjoint MPLS LSPs and embedding their identification information into LDP label mapping messages before traffic forwarding begins. This preliminary configuration enables automated path selection and binding without requiring real-time computation or complex runtime decisions, thereby simplifying operational processes.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9025442B2Pseudo wire end-to-end redundancy setup over disjoint MPLS transport paths

Publication Date: 2015.05.05 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

According to one embodiment, a method for establishing a primary and redundant PW over disjoint bidirectional RSVP-TE LSPs include establishing a first bidirectional RSVP-TE LSP that includes a first upstream path and a first downstream path. The method includes transmitting a first label distribution protocol (LDP) label mapping message that includes a first transport path include field that causes the second PE router to use the first downstream path for the primary PW. The method includes establishing a second bidirectional RSVP-TE LSP that includes a second upstream path and a second downstream path. The method includes transmitting a second LDP label mapping message that includes a second transport path include field that causes the second PE router to use the second downstream path for the redundant PW.