Backup Preferred Path Routes for Fast Network Rerouting
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Solution Overview
Problem
Existing mechanisms for determining end-to-end path failures in networks implementing source routing are slow and prone to micro-loops, and they do not effectively implement backup paths that satisfy original traffic engineering parameters.
Innovation Solution
The method involves provisioning backup preferred path routes (PPRs) based on attributes defining traffic engineering parameters, where backup PPR information is sent to network elements to reroute traffic through backup elements or end-to-end paths when an element on the original PPR becomes unavailable, ensuring that the rerouted path satisfies the original traffic engineering parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing failure detection mechanisms are used in source routing networks, then network operations continue normally, but path failure detection becomes slow and causes micro-loops
Solution Approach 1:
The patent pre-computes and stores backup PPRs and LFA paths before failures occur. When a failure is detected, the network element can immediately switch to the pre-computed backup path without performing complex real-time calculations, thus reducing failure detection time and preventing micro-loops
Solution Approach 2:
The patent provisions backup paths in advance as a cushion against potential failures. By having pre-calculated backup PPRs that satisfy traffic engineering parameters, the system is prepared to absorb the shock of failures without causing micro-loops or significant service interruption
2Reliability
If backup paths are provisioned to satisfy original traffic engineering parameters, then rerouted traffic maintains service quality, but network complexity increases
Solution Approach 1:
The control entity performs the complex task of finding and validating backup paths that satisfy traffic engineering parameters in advance, before failures occur. Network elements only need to store and switch to these pre-validated paths, reducing their computational complexity while maintaining service quality
Solution Approach 2:
The control entity acts as an intermediary that handles the complex path computation and validation. It receives traffic engineering parameters, computes appropriate backup paths, and provides them to network elements, thereby isolating the complexity from the data plane devices
3Speed
If fast rerouting is implemented using backup PPRs, then traffic can be rapidly redirected upon failure, but the network requires additional backup path information storage
Solution Approach 1:
The patent implements local fast rerouting by storing backup paths at individual network elements where they are needed. Each element stores only the backup paths relevant to its local failures, rather than maintaining global backup information, optimizing the balance between rerouting speed and storage requirements
Data Source
AI summary
A method implemented by a network element (NE) in a network, comprising receiving, by the NE, an advertisement comprising preferred path route (PPR) information and backup PPR information, the PPR information describing a PPR between a source and a destination in the network, the backup PPR information describing a backup PPR between the source and the destination, the PPR information comprising a PPR identifier (PPR-ID) and a plurality of PPR description elements (PPR-PDEs) each representing an element on the PPR, updating, by the NE, a local forwarding database to include the PPR information and the backup PPR information in association with a destination address of the destination, and transmitting, by the NE, a data packet based on the backup PPR information instead of the PPR information in response to an element on the PPR being unavailable due to a failure of an element along the PPR.