Router Label Mis-programming Detection and Correction
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Solution Overview
Problem
In label switched paths (LSPs), mis-programming of label information between the control plane and forwarding plane in routers can lead to traffic black-holing, where packets are dropped instead of being forwarded, due to incorrect label information, necessitating a method to detect and correct this issue without triggering a tear-down of the LSP.
Innovation Solution
An ingress router uses self-ping messages to detect mis-programming and sends an end-to-end path message with a reprogram flag to instruct routers to reprogram their forwarding engines with the original label information, allowing for correction of label mis-programming without immediately tearing down the LSP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mis-programming of label information is detected in a router along an LSP, then traffic black-holing occurs and packets are dropped, but immediately tearing down the LSP disrupts network stability and traffic flow
Solution Approach 1:
The system performs preliminary detection of label mis-programming using self-ping messages before traffic black-holing occurs. The ingress router sends self-ping messages along the LSP to verify label correctness at each router, enabling early detection and correction of mis-programming before it causes packet loss and LSP teardown.
Solution Approach 2:
The system implements a feedback mechanism where self-ping message responses provide information about label programming status at each router along the LSP. The ingress router receives feedback from each router's response to determine whether labels are correctly programmed, enabling continuous monitoring and correction of label information without disrupting traffic flow.
2Difficulty of detecting and measuring
If self-ping messages are sent to detect label mis-programming, then detection capability is improved, but additional network traffic and processing overhead are introduced
Solution Approach 1:
The system uses self-ping messages that are copies of standard ICMP echo requests, leveraging existing network protocols for detection. These copied message formats allow the system to use established, efficient communication mechanisms rather than creating new detection protocols, reducing overhead while maintaining detection capability.
Solution Approach 2:
The system sends self-ping messages only when necessary for detection purposes, rather than continuously monitoring all LSPs. The ingress router selectively sends self-ping messages to detect label mis-programming, performing partial monitoring that balances detection needs with network resource conservation.
3Manufacturing precision
If the forwarding engine is reprogrammed with original label information, then label accuracy is corrected, but router configuration complexity increases
Solution Approach 1:
The system enables self-service correction where the ingress router automatically detects and corrects label mis-programming without manual intervention. When a self-ping message fails to receive the expected response, the ingress router automatically reprograms the affected router's forwarding engine with the correct label information, simplifying the correction process while maintaining high accuracy.
Solution Approach 2:
The system merges the detection and correction functions into a single automated process. The same self-ping mechanism used for detection also triggers the correction process, combining monitoring and remediation into one integrated system that reduces operational complexity while ensuring label accuracy.
Data Source
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AI summary
Techniques are described for detecting and correcting mis-programming of label information in a router of a label switched path (LSP) without initially triggering a tear-down of the LSP. For example, techniques described in this disclosure enable an ingress router to determine whether label information is correctly programmed between a routing engine (e.g., control plane) and a forwarding engine (e.g., forwarding plane) of a router in the LSP, and to correct any mis-programming of label information by informing the router to reprogram the forwarding engine with original forwarding label information associated with the LSP.