SR-BE Fault Protection via Pre-calculated Backup Tunnels
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Solution Overview
Problem
In segment routing best effort (SR-BE) services across multiple IGP domains, the topology-independent loop-free alternate (TI-LFA) algorithm fails to automatically switch packet forwarding to a secondary cross-domain node when the primary cross-domain node is faulty, leading to prolonged packet loss and reduced network reliability.
Innovation Solution
A fault protection method is introduced where a backup tunnel is pre-calculated to avoid the primary cross-domain node, allowing for a direct switch to this tunnel when the primary node fails, ensuring packet forwarding continues through a strict explicit path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the TI-LFA algorithm is used for backup tunnel calculation in cross-domain scenarios, then the network can handle same-domain node failures, but it cannot automatically switch to a secondary cross-domain node when the primary cross-domain node fails
Solution Approach 1:
The patent pre-calculates backup paths that specifically avoid primary cross-domain nodes before failures occur. When a cross-domain node failure is detected, the system can immediately switch to these pre-computed backup paths without requiring complex real-time calculations, thus achieving fast automatic switching in cross-domain scenarios.
Solution Approach 2:
The patent introduces secondary cross-domain nodes as intermediary backup paths. When the primary cross-domain node fails, traffic is routed through secondary cross-domain nodes which act as mediators to maintain connectivity between different IGP domains, enabling automatic failure recovery.
2Reliability
If IGP convergence is used to detect primary cross-domain node failure, then the system can detect the fault, but packet forwarding continues through the faulty node causing prolonged packet loss
Solution Approach 1:
The system performs preliminary calculations of backup paths that avoid primary cross-domain nodes before failures occur. When a failure is detected through IGP convergence, the pre-computed backup paths are immediately activated, eliminating the need for time-consuming real-time path recalculation and reducing packet loss duration.
Solution Approach 2:
The patent enables the system to skip the slow IGP convergence process by having pre-computed backup paths ready. Upon detecting primary cross-domain node failure, traffic is rapidly switched to backup paths without waiting for IGP convergence to complete, thus rushing through the failure recovery process and minimizing packet loss.
3Loss of time
If a backup path is pre-calculated avoiding the primary cross-domain node, then immediate switching is possible, but the path calculation complexity increases
Solution Approach 1:
The patent applies local quality by making path calculations specific to cross-domain scenarios rather than general-purpose calculations. The backup path calculation focuses specifically on routes that avoid primary cross-domain nodes and utilize secondary cross-domain nodes, making the calculation more targeted and manageable despite the increased complexity.
Data Source
AI summary
This application discloses a fault protection method, including: A first node determines that a first cross-domain node is faulty. The first node is a head node of a segment routing best effort SR-BE service tunnel, the SR-BE tunnel is a cross-domain tunnel that passes through a first IGP domain and a second IGP domain, the SR-BE tunnel passes through the first cross-domain node, and the first cross-domain node is a node that crosses the first IGP domain and the second IGP domain. The first node switches a service transmission path from the SR-BE tunnel to a backup tunnel. The backup tunnel does not pass through the first cross-domain node, and the backup tunnel is a tunnel with a strict explicit path.