Proxy ACK Timing for WAN Data Synchronization
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Solution Overview
Problem
Existing communication systems using TCP protocols face issues with transmission bandwidth control, particularly in WANs with high RTT and discarding rates, leading to inefficient bandwidth utilization and potential data loss due to incomplete reception.
Innovation Solution
A communication device and system that manage ACK packets and data transmission to ensure synchronization between transmission and reception terminals, even in cases of network failures, by delaying ACK responses until data is fully received and processed, and using feedback mechanisms to retransmit missing data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCP communication is used with feedback-based bandwidth control, then transmission bandwidth is adapted to network conditions, but transmission bandwidth becomes greatly lower than contract bandwidth in WANs with large RTT and high discarding rates
Solution Approach 1:
The patent applies preliminary action by having the reception terminal proactively notify the transmission terminal of unreceived data locations before the transmission terminal can detect the loss through traditional ACK feedback mechanisms. This allows the transmission terminal to retransmit missing data immediately without waiting for RTT-based feedback, thereby maintaining high bandwidth utilization even in WANs with large RTT and high discarding rates.
2Speed
If ACK packets are returned immediately upon receiving data, then communication responsiveness is improved, but data loss occurs when the communication device fails after receiving final data but before returning ACK
Solution Approach 1:
The patent applies beforehand cushioning by having the reception terminal prepare and send notifications about unreceived data locations in advance, creating a protective mechanism that cushions against the risk of communication device failure. This ensures that even if the device fails after receiving data but before returning ACK, the transmission terminal can still identify and retransmit missing data, preventing data loss.
3Reliability
If retransmission bandwidth increases to compensate for discarding, then data completeness is improved, but total bandwidth consumption exceeds available bandwidth
Solution Approach 1:
The patent applies feedback by implementing a notification mechanism where the reception terminal actively informs the transmission terminal about specific unreceived data locations. This targeted feedback allows the transmission terminal to retransmit only the missing data portions rather than retransmitting all data, thereby improving data reception completeness while keeping total bandwidth consumption within available bandwidth limits.
Data Source
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AI summary
When a proxy device is used between a transmission terminal and a reception terminal, receives final data from the transmission terminal, and fails immediately thereafter, a case is prevented in which transmission is completed in the transmission terminal, and, on the other hand, reception is not completed in the reception terminal. There is provided a means for not returning ACK when a data packet is received in a state in which there is no data which waits for ACK and transmission of which is in progress, and there is no data which waits for arrangement and reception of which is in progress in the proxy device, for returning ACK for data received one step before when a data packet is received in a state in which there is data which waits for ACK and transmission of which is in progress, or there is data which waits for arrangement and reception of which is in progress in the proxy device, and for returning normal ACK at a timing when ACK is received from the reception terminal side, thus there is no data which waits for ACK and transmission of which is in progress, and there is no data which waits for arrangement and reception of which is in progress.