Fast Reroute Table for Link Failure Switchover
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Solution Overview
Problem
Existing Fast Re-route (FRR) implementations in label switching networks are resource-intensive and cause significant CPU overhead, leading to traffic drops due to the need for duplicate tables and dynamic computations, especially during link failures.
Innovation Solution
A resource-optimized FRR implementation that pre-programs backup paths and uses a small FRR table with a backup indicator to switch traffic to a backup link in negligible time, minimizing CPU overhead and traffic loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If known FRR implementations are used, then backup paths can be pre-determined for link protection, but CPU overhead increases significantly and traffic drops occur
Solution Approach 1:
The patent pre-determines backup paths and configures FRR tables in advance before link failures occur. The backup paths are pre-calculated and stored in FRR tables at network nodes, so that when a link failure is detected, the switchover to backup paths can be executed immediately without requiring real-time computation, thus reducing CPU overhead during failure events.
Solution Approach 2:
The patent creates a simplified copy of the FRR functionality using a reduced FRR table that stores only essential backup path information. Instead of maintaining full duplicate routing tables for both primary and backup paths, the system uses a streamlined FRR table with backup indicators, reducing the computational burden on the CPU while preserving the essential link protection capability.
2Adaptability or versatility
If duplicate tables are used for FRR implementation, then backup paths can be stored, but hardware and compute resources are overconsumed
Solution Approach 1:
The patent extracts only the essential backup path information from the full routing table structure and stores it in a reduced FRR table. Instead of maintaining complete duplicate tables for both primary and backup paths, the system extracts and stores only the necessary backup path entries with associated backup indicators, thereby reducing hardware and compute resource requirements while preserving backup path storage capability.
Solution Approach 2:
The patent uses a partial FRR table that stores only the necessary backup path information rather than complete routing table copies. This partial action approach maintains sufficient backup path storage for link protection while avoiding the excessive resource consumption associated with full duplicate tables, achieving a balance between adaptability and resource efficiency.
3Adaptability or versatility
If dynamic computations are performed during link failures, then backup paths can be calculated, but switchover time increases and traffic loss worsens
Solution Approach 1:
The patent performs path computation in advance by pre-determining backup paths and storing them in FRR tables before link failures occur. When a link failure is detected, the system simply needs to read the pre-computed backup paths from the FRR table and execute the switchover, eliminating the need for real-time path computation and reducing switchover time to negligible levels.
Solution Approach 2:
The patent replaces the mechanical process of real-time path computation with a static lookup mechanism using FRR tables. Instead of performing dynamic computations during link failures, the system uses pre-computed backup path information stored in tables, substituting the computational mechanism with a simpler data lookup and execution mechanism, thereby reducing switchover time.
Data Source
AI summary
A fast reroute (FRR) implementation utilizes an optimized FRR table to implement a fast switchover to a backup link upon detecting a primary link failure on a label switched path (LSP). The switchover can be performed in a negligible amount of time (close to zero milliseconds) based on a backup indicator flag which can be dynamically updated. The FRR table stores pre-determined backup egress interfaces and FRR labels corresponding to primary egress interfaces to minimize the switchover time.