Multi-Domain Path Computation Failure Handling in PCE Networks

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Solution Overview

Problem

Existing multi-domain path computation methods, such as BRPC, fail to effectively handle computation failures, particularly in PCEs of head, intermediate, and rear domains, leading to incomplete or failed path calculations without practical methods to bypass failed topological areas.

Innovation Solution

The method involves determining a second domain sequence by excluding the domain with the failed link from candidate sequences, selecting the shortest sequence to avoid the failed link, and initiating a new path computation using a path computation request that includes the failed link for exclusion by downstream PCEs, ensuring resource management and efficient re-computation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the BRPC-based cross-domain path computation is implemented, then path computation can be performed across multiple domains, but the system cannot effectively handle computation failures leading to incomplete or failed path calculations

Engineering Contradiction:

Improvepath computation capabilityVSAvoidcomputation failure handling

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-identifying and recording failed links during the path computation process. When a computation failure occurs, the system has already captured the failed link information, enabling rapid response and alternative path calculation without restarting the entire computation process from scratch.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback mechanisms where downstream PCEs send failure information (failed links) back to upstream PCEs. This feedback loop enables the head domain PCE to receive real-time failure status and dynamically adjust the path computation based on the returned failed link information, ensuring reliable path determination despite computation failures.

Inventive Principle:

Principle #23Feedback

2Reliability

If the system attempts to compute alternative paths after failure, then path availability increases, but computation time and complexity increase

Engineering Contradiction:

Improvepath computation success rateVSAvoidcomputation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the path computation process by domain, with each domain's PCE independently computing paths within its scope. When a failure occurs, only the affected segment needs re-computation rather than the entire end-to-end path, significantly reducing the time and complexity of alternative path calculation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary actions by having downstream PCEs pre-compute and cache path information before upstream PCEs need it. When failures occur, this pre-computed information is already available, eliminating the need for time-consuming re-computation of entire paths and enabling rapid alternative route determination.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If failed link information is transmitted and processed, then accurate alternative path selection is achieved, but communication overhead between PCEs increases

Engineering Contradiction:

Improvepath selection accuracyVSAvoidcommunication overhead

Core Design Contradiction:

Manufacturing precisionVSLoss of information

Solution Approach 1:

The patent extracts only the essential failed link information from the computation failure and transmits it upstream, rather than transmitting entire path computation datasets. This selective extraction minimizes communication overhead while providing sufficient information for accurate alternative path selection by the head domain PCE.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent inverts the traditional feedback direction by having downstream PCEs actively send failure information upstream rather than waiting for upstream PCEs to query for status. This inversion reduces communication overhead by eliminating unnecessary query-response cycles and directly providing the critical failure information needed for alternative path computation.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentEP3026850B1Method for processing multi-zone path computation failure and path computation element (PCE)

Publication Date: 2019.07.31 ZTE CORP

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AI summary

A method for processing a failure of a multi-domain path computation and a Path Computation Element (PCE) are provided. The method for the PCE of a head domain includes: a failed link leading to a failure to compute a path according to a first domain sequence is acquired; the failed link is deleted from a first topology to obtain a second topology; a second domain sequence is determined according to the second topology; and a path computation for the second domain sequence is initiated. In the solution disclosed herein, when a PCE computes a path from a source node to a destination node according to a first domain sequence, if the path is computed unsuccessfully for a failed link, then the failed link leading to a failure to compute the path is deleted from the topology of the PCE of the head domain to obtain a second topology, then a second domain sequence is generated according to the second topology and a path computation is carried out according to the second domain sequence, thereby determining a final path from a source node to a destination node.