Hierarchical Tunnel Head-End Node Protection via Local Repair
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Solution Overview
Problem
Protecting hierarchical tunnel head-end nodes against failure is inefficient due to the need for lengthy backup tunnels that bypass the hierarchical tunnel, increasing network resource usage and complexity.
Innovation Solution
A point of local repair (PLR) establishes a backup tunnel to the hierarchical tunnel head-end node's downstream neighbor, learns the corresponding backup tunnel label, and creates a label stack including the backup, hierarchical, and child tunnel labels to reroute traffic and maintain tunnel states upon failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backup tunnels are set up from each upstream node to the tail-end node to bypass the hierarchical tunnel, then protection against head-end node failure is achieved, but the length of backup tunnels increases and network resources are wasted
Solution Approach 1:
The patent segments the backup path into two parts: a shared backup tunnel from the PLR to the hierarchical tunnel head-end node, and the existing hierarchical tunnel from the head-end node to the tail-end node. This segmentation allows the backup tunnel to be shorter while still providing protection, as it only needs to reach the head-end node rather than the entire tail-end node.
Solution Approach 2:
The hierarchical tunnel head-end node acts as an intermediary in the backup path. The PLR sends backup traffic to the head-end node through the shared backup tunnel, which then forwards it through the hierarchical tunnel to the tail-end node. This intermediary approach allows efficient resource utilization while maintaining protection.
2Reliability
If backup tunnels bypass the hierarchical tunnel entirely, then protection is achieved, but the number of tunnels per-node increases and network complexity increases
Solution Approach 1:
The patent merges the backup tunnel with the hierarchical tunnel structure. Instead of creating completely separate backup paths, the solution combines the shared backup tunnel from the PLR to the head-end node with the existing hierarchical tunnel, reducing the total number of tunnels required while maintaining protection capabilities.
Solution Approach 2:
The shared backup tunnel serves multiple child tunnels simultaneously, providing universal protection against head-end node failures for all child tunnels that share the same PLR and head-end node. This multi-functionality reduces the overall number of tunnels needed in the network.
3Reliability
If manual configuration is used for backup tunnels, then protection can be established, but the process is cumbersome and inefficient
Solution Approach 1:
The system enables automatic establishment of backup tunnels through signaling protocols. The PLR and hierarchical tunnel head-end node can automatically set up and maintain backup tunnels without manual configuration, with the system self-managing the tunnel states and label distributions.
Solution Approach 2:
The patent implements feedback mechanisms through signaling messages that allow the network to automatically detect failures and adjust backup tunnel states. The system receives feedback about tunnel status and automatically responds by establishing or modifying backup paths as needed.
Data Source
AI summary
In one embodiment, a point of local repair (PLR) for a child tunnel establishes a backup tunnel to a hierarchical tunnel head-end node's (grooming node's) downstream hierarchical tunnel neighbor (merge point) and learns a corresponding backup tunnel label. The PLR then stores a label stack having at least i) the backup tunnel label, ii) a hierarchical tunnel label for the merge point, and iii) a child tunnel label as advertised by an hierarchical tunnel tail-end node. Upon failure of the grooming node, the PLR pushes the stored label stack onto traffic for the child tunnel, and reroutes the traffic with the pushed label stack onto the backup tunnel toward the merge point (e.g., so the merge point may receive the traffic with a proper/expected label stack).