Node Protection for Stacked Labels in SPRING Networks
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Solution Overview
Problem
In Source Packet Routing in Networking (SPRING) networks, it is challenging to determine a node-protecting backup path for packets with multi-label stacks during route installation, especially for one-hop tunnels based on adjacency segments, as it is not always possible to identify a backup path that bypasses a failing router without updating or modifying existing label stacks.
Innovation Solution
A first router generates context tables for adjacent nodes, including backup paths that bypass the second router, by computing a shortest path downstream from the failing router and determining a backup label stack corresponding to this path, allowing it to redirect network traffic when the second router fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a primary path through the second router is used for forwarding packets, then normal network traffic flow is maintained, but node protection capability is lost when the second router fails
Solution Approach 1:
The patent pre-computes backup paths and generates context tables before any failure occurs. The first router identifies downstream adjacent nodes and calculates alternative paths in advance, storing them in context tables with associated backup label stacks. This preliminary preparation ensures that when a failure occurs, the router can immediately switch to the pre-computed backup path without complex real-time calculations.
Solution Approach 2:
The patent segments the network path into adjacency segments and identifies specific downstream adjacent nodes. By breaking down the backup path computation into individual adjacency segments and their corresponding label stacks, the system can efficiently manage and switch between different path segments without dealing with the entire end-to-end path as a single complex unit.
2Reliability
If backup paths are pre-computed for all possible failures, then node protection is available, but routing information storage requirements increase
Solution Approach 1:
The patent generates context tables specifically for downstream adjacent nodes that are relevant to backup path computation. Rather than pre-computing all possible backup paths to all destinations, the system focuses on computing backup paths to immediate downstream adjacent nodes. This localized approach reduces the overall volume of routing information while maintaining effective node protection capability.
3Reliability
If the backup path computation includes all downstream nodes, then complete node protection is provided, but the computation time and processing load increase
Solution Approach 1:
The patent extracts and focuses computation on only the necessary downstream adjacent nodes rather than all possible downstream nodes. By identifying and computing backup paths only for the immediate downstream adjacent nodes that are directly relevant to the failure scenario, the system significantly reduces computation time and processing load while maintaining comprehensive protection for the actual failure cases that matter.
Data Source
AI summary
Techniques are described for providing node protection in a Source Packet Routing in Networking (SPRING) network. In some examples, a first network device, responsive to detecting a configuration request to provide node protection to a second network device that is adjacent to the first network device: generate at least one context table; configure at least one forwarding entry that indicates: a primary path between the first network device and a third network device, and a backup path, based at least in part on the at least one context table, between the first network device and the third network device that bypasses the second network device; while the second network device has not failed, forward network packets to the third network device using the primary path; and responsive to determining that the second network device has failed, forward network packets to the third network device using the backup path.