Label Stack TTL Matching for Path Detection Accuracy
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Solution Overview
Problem
In communications networks, traceroute path detection methods for label forwarding paths are inaccurate due to response packets following label TTL procedures, leading to delayed and faulty link detection.
Innovation Solution
A path detection method where the initial quantity of layers in the label stack matches the initial TTL value, allowing response packets to be sent directly through the IP route when TTL expires, reducing link detection delay and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If response packets follow label TTL timeout procedures in label forwarding paths, then packet forwarding completeness is maintained, but link detection delay increases and detection accuracy deteriorates
Solution Approach 1:
The patent extracts the response packet from the label forwarding path and redirects it through the IP routing path. When the ingress node receives a path detection request packet, it sets the quantity of label layers to match the TTL value, causing intermediate nodes to forward the packet via IP routing rather than label switching. This extraction of the response packet from the label TTL procedure eliminates the delay and inaccuracy caused by following the label forwarding path back to the source.
2Reliability
If all labels on the label forwarding path are encapsulated in the path detection request packet, then complete path coverage is achieved, but response packet routing complexity increases
Solution Approach 1:
The patent inverts the traditional approach by making the label stack quantity equal to the TTL value instead of having TTL be independent. This inversion causes intermediate nodes to decrement TTL to zero and forward packets through IP routing rather than continuing label switching. This simplifies response packet routing by eliminating the need for complex label processing at intermediate nodes while maintaining complete path detection coverage.
Data Source
AI summary
A path detection method and apparatus for forwarding at least two layers of labels includes generating, by a first network device, a first request packet used for path detection, where the first request packet includes a label stack and a time to live (TTL), and an initial quantity of layers of the label stack matches an initial value of the TTL, and sending the first request packet, where the first request packet instructs a second network device to send a first response packet to the first network device when the TTL is 0 after being reduced by 1, and the first response packet reaches the first network device through an internet protocol route.