Backup Path Construction in Autonomous Systems

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Solution Overview

Problem

Current methods for reducing BGP convergence time in autonomous systems during inter-domain failures are inefficient, leading to unacceptably long recovery times due to excessive BGP message exchange and reliance on source routing techniques.

Innovation Solution

Constructing and implementing backup paths within autonomous systems by identifying alternate inter-AS links and tunnels, using auto-discovery mechanisms to select optimal backup routes, and incorporating loop prevention attributes to ensure fast and reliable data forwarding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If BGP message exchange is used for inter-autonomous system routing, then routing information is distributed, but convergence time becomes unacceptably long during failures

Engineering Contradiction:

Improverouting convergence reliabilityVSAvoidconvergence time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent pre-computes and stores backup paths within the autonomous system before failures occur. When a failure is detected, traffic is immediately switched to pre-computed backup paths, eliminating the need for time-consuming BGP message exchange and convergence during failures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the routing problem into two parts: primary paths for normal operation and backup paths for failure scenarios. This segmentation allows the system to maintain fast local backup paths within the autonomous system while still using BGP for inter-autonomous system routing, thus resolving the contradiction between reliable routing information distribution and fast convergence.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If source routing techniques are implemented for backup paths, then routing flexibility is improved, but device complexity increases

Engineering Contradiction:

Improverouting flexibilityVSAvoidrouter complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements auto-discovery mechanisms that automatically identify and select optimal backup paths without requiring manual source routing configuration. The system self-services by autonomously computing backup paths based on network topology, thereby maintaining routing flexibility while reducing device complexity.

Inventive Principle:

Principle #25Self-service

3Reliability

If pre-computed backup paths are implemented, then packet loss is reduced, but system complexity increases

Engineering Contradiction:

Improvepacket delivery reliabilityVSAvoidpath management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system uses auto-discovery mechanisms to automatically identify, compute, and maintain backup paths based on current network topology. This self-service approach reduces packet loss through pre-computed paths while minimizing the complexity burden on network operators and devices.

Inventive Principle:

Principle #25Self-service

4Measurement precision

If BGP routers exchange full routing information, then routing accuracy is improved, but message overhead increases

Engineering Contradiction:

Improverouting information accuracyVSAvoidmessage overhead

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential routing information needed for backup path computation within the autonomous system, rather than exchanging full BGP routing tables. This extraction approach maintains sufficient routing accuracy for backup path selection while significantly reducing message overhead.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentEP1946499B1Constructing and implementing backup paths in autonomous systems

Publication Date: 2012.01.25 CISCO TECHNOLOGY INC

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AI summary

Method of implementing a backup path in autonomous system (AS) for failure of a first inter-AS link (210), comprising identifying an alternate inter-AS link (212) serving plurality of prefixes and constructing a tunnel.