Delay Time Measuring Apparatus for Accurate RTT
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Solution Overview
Problem
Conventional methods for measuring round trip time (RTT) in data communication with delayed confirmation responses cannot distinguish between ACKs made in accordance with the first and second patterns, leading to unreliable RTT measurements that may include delay time for intentional 'Delayed ACKs', thereby compromising network communication quality.
Innovation Solution
A delay time measuring apparatus that captures data and ACK packets, analyzes sequence numbers and data lengths, and calculates RTT by identifying packets transmitted without waiting for ACKs, ensuring that only RTT measurements not including 'Delayed ACK' delays are recorded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the destination host returns an ACK instantly upon receiving data, then the network response time is reduced, but the receiving buffer fills up quickly requiring smaller window sizes which reduces data transmission efficiency
Solution Approach 1:
The destination host periodically returns ACKs at predetermined intervals rather than instantly, creating a rhythmic acknowledgment pattern that balances buffer management with transmission efficiency
2Stability of the object's composition
If the destination host delays the ACK return for predetermined time, then the receiving buffer management is improved, but the RTT measurement includes artificial delay time compromising measurement accuracy
Solution Approach 1:
A determination flag is set in advance when an ACK is delayed for buffer management purposes, allowing the RTT measurement function to identify and exclude these delayed ACKs from measurement calculations
Solution Approach 2:
The determination flag acts as an intermediary marker that distinguishes between ACKs suitable for RTT measurement and those delayed for buffer management, enabling selective measurement
3Productivity
If the source host transmits data continuously without waiting for ACK, then the data transmission efficiency is improved, but the reliability of data delivery cannot be ensured
Solution Approach 1:
The source host preliminarily transmits multiple data packets within a window size before waiting for ACK confirmation, enabling continuous transmission while maintaining reliability through subsequent acknowledgment verification
Data Source
AI summary
In a delay time measuring apparatus a sequence number, data length, and receiving time of a data packet transmitted from a source unit to a destination unit are stored in a storage section. In addition, an ACK number and receiving time of an ACK packet returned from the destination unit to the source unit are stored in the storage section. After that, a calculation section obtains an ACK packet an ACK number of which is equal to a value obtained by adding data length of a second data packet of two successive data packets transmitted without waiting for the ACK packet to a sequence number of the second data packet of the two successive data packets from the storage section. Then the calculation section calculates round trip time from receiving time of the second data packet of the two successive data packets and receiving time of the ACK packet obtained.