ISC Word Rate Adjustment for SONET Buffer Overflow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Repeating devices in SONET communication networks with different clock speeds can cause over-running or under-running conditions when transmitting ISC words, leading to buffer overflow or insufficient data transmission.
Innovation Solution
A data mapping device with a FIFO buffer and transceiver that adjusts the transmission rate by deleting ISC words during over-running conditions and adding pairs of words during under-running conditions, using specific rules to maintain a stable data stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the data mapping device operates at a different clock speed than the transmitting device, then the device can function with varying performance characteristics, but over-running or under-running conditions occur causing buffer overflow or data loss
Solution Approach 1:
The patent introduces an intermediary mechanism (the buffer and control logic) between the transmitting device and the data mapping device to mediate the clock speed differences. The buffer temporarily stores ISC words when clock speeds differ, and the control logic monitors buffer status to regulate word deletion, ensuring reliable data transmission despite clock speed variations.
Solution Approach 2:
The patent dynamically changes the transmission parameter (deletion of ISC words) based on the clock speed mismatch condition. When the buffer becomes full due to over-running conditions caused by clock speed differences, the system changes the transmission rate by deleting ISC words, thereby adapting to the parameter change in clock speed.
2Reliability
If ISC words are deleted during over-running conditions, then buffer overflow is prevented, but data loss occurs
Solution Approach 1:
The patent applies the principle of discarding and recovering by selectively deleting ISC words during over-running conditions and recovering (preventing) data loss through intelligent selection criteria. The system discards redundant or less critical ISC words when the buffer is full, but recovers from potential data loss by using control logic that determines which words to delete based on buffer status and transmission requirements.
Solution Approach 2:
The patent converts the harmful effect of over-running conditions (which would cause buffer overflow) into a beneficial outcome by using the deletion mechanism to prevent overflow. The harmful clock speed mismatch that causes over-running is transformed into a controlled situation where selective deletion protects the buffer while maintaining overall transmission reliability.
3Productivity
If the transmission rate is increased to match faster clock speeds, then data throughput improves, but over-running conditions occur causing buffer overflow
Solution Approach 1:
The patent implements a feedback mechanism where the control logic continuously monitors the buffer status (full, empty, or intermediate states) and adjusts the transmission rate accordingly. When the buffer becomes full due to increased transmission rate, the feedback loop triggers deletion of ISC words, thereby maintaining buffer stability while allowing high throughput during normal operation.
Solution Approach 2:
The patent makes the transmission rate dynamic rather than fixed. The system can adjust the transmission rate by deleting ISC words when clock speed differences cause over-running conditions, allowing the transmission mechanism to adapt dynamically to varying buffer states and maintain both productivity and reliability.
Data Source
AI summary
A data mapping device, a method, and an article of manufacture for adjusting a transmission rate of ISC words are provided. The GFP data mapping device has a FIFO buffer and a transceiver operably coupled to the FIFO buffer. The method includes reading first and second ISC words from the FIFO buffer that were received from a transmitting device. The method further includes determining whether a first number of ISC words stored in the FIFO buffer are greater than a second predetermined number indicating an over-running condition. The method further includes determining whether the first and second ISC words indicate either an ISC continuous sequence of words or an ISC idle sequence of words, if the first number is greater than the second predetermined number. The method further includes deleting the first and second ISC words if the first and second ISC words indicate either the ISC continuous sequence of words or the ISC idle sequence of words. The method further includes reading a third ISC word from the FIFO buffer and transmitting the third ISC word from the transceiver.