Network Device Loop Detection Frame Timing and Port Shutoff Release
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Solution Overview
Problem
In network configurations, incorrect connections can generate loops, leading to communication interference and broadcast storms, which prevent the detection of loop detection frames (LDF) and thus fail to shut off affected ports, preventing loop dissolution.
Innovation Solution
A network device with a communication controller and shutoff release unit that detects linkups, sends loop detection frames after a predetermined period, and only releases communication shutdown if the frame is not detected, ensuring accurate loop detection and prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If communication is shut off on ports to prevent loops, then loop detection accuracy is improved, but broadcast storms cannot be transmitted/received before LDF detection
Solution Approach 1:
The system performs preliminary actions by shutting off communication on ports before loop detection is complete. This prevents broadcast storms from being transmitted or received during the detection process, ensuring that the detection environment remains clean and accurate while maintaining network safety.
2Speed
If loop detection frame is sent immediately after linkup detection, then detection speed is improved, but false positives may occur due to premature detection
Solution Approach 1:
The system performs preliminary actions by sending the loop detection frame after a predetermined period following linkup detection. This delay ensures that the link is fully established and stable before detection begins, preventing false positives while maintaining efficient detection timing.
3Productivity
If communication shutoff is released immediately after linkup, then network availability is improved, but loops may form before detection
Solution Approach 1:
The system uses feedback control by monitoring whether the loop detection frame is successfully received. The communication shutoff is released only after confirming that no loop exists (i.e., the LDF was not received back). This feedback mechanism ensures network availability is restored only when it is safe to do so, preventing loop formation.
4Ease of operation
If broadcast frames are allowed during linkup establishment, then network functionality is maintained, but broadcast storms interfere with LDF detection
Solution Approach 1:
The system extracts and isolates the loop detection function from normal broadcast traffic. By shutting off communication except for link test pulses and loop detection frames, the system creates a dedicated detection channel free from broadcast storm interference, ensuring accurate LDF detection while maintaining essential network functions.
Data Source
AI summary
According to the present invention, a network device includes a plurality of ports which are connected to a LAN; a communication controller; and a communication shutoff release unit. The communication controller includes: a linkup detection unit, a loop detection frame sending out unit that sends out the loop detection frame from a linkup detected port, which is a port for which the linkup is detected, after a predetermined period from a time point when the linkup is detected by the linkup detection unit to the local area network, and a loop detection frame detection unit that detects the loop detection frame if the loop detection frame is received on the each port. The communication shutoff release unit releases the shutoff of the communication on the linkup detected port only if the loop detection frame is not detected by the loop detection frame detection unit.