Transfer Device Packet Loss Detection via Phase ID
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Solution Overview
Problem
Conventional transfer devices face inefficiencies in utilizing network bandwidth due to network delay, leading to wasteful retransmissions of packets that have not arrived at the destination, as they rely on ACK responses and increased receive window sizes, which can result in delayed packet arrival and incorrect loss detection.
Innovation Solution
A transfer device that assigns unique identification numbers to packets and increments phase numbers at intervals, registering these on a table, allowing for accurate determination of lost packets without the need for response delay times, thereby preventing wasteful retransmissions by retransmitting only packets confirmed as lost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the receive window size is increased to transmit more data at once, then the data transmission capacity is improved, but the network delay increases and packet loss detection accuracy deteriorates
Solution Approach 1:
The transmitting device sends a notification packet before actually transmitting data packets. This notification packet contains information about the data to be transmitted, allowing the receiving device to prepare in advance. By performing this preliminary action, the system can maintain higher transmission capacity without proportionally increasing delay, as the receiving device can start processing earlier.
Solution Approach 2:
The notification packet acts as an intermediary between the data transmission request and the actual data transmission. It carries metadata about the upcoming data packets, enabling the receiving device to prepare reception resources and reduce processing delay without requiring the actual data to wait for full acknowledgment of previous packets.
2Reliability
If response delay time is set for packet loss detection, then false retransmissions are reduced, but transmission efficiency decreases due to waiting periods
Solution Approach 1:
The receiving device sends an ACK packet as soon as it receives and validates data, without waiting for a response delay period. The transmitting device uses the notification packet mechanism to proactively manage retransmissions, eliminating the need for conservative delay waiting while maintaining accurate loss detection.
Solution Approach 2:
The system implements continuous feedback through ACK packets and notification packets. The receiving device immediately acknowledges received data, and the transmitting device uses this feedback combined with notification packet status to determine retransmission needs, eliminating arbitrary delay periods while maintaining detection accuracy.
3Reliability
If conventional ACK-based retransmission is used, then packet loss is detected, but wasteful retransmissions occur when packets are merely delayed not lost
Solution Approach 1:
The transmitting device sends a notification packet before transmitting actual data packets. If the notification packet itself is acknowledged and processed successfully, the transmitting device knows the communication path is functional and can avoid retransmitting the actual data packets even if ACKs are delayed, thereby preventing wasteful retransmissions.
Solution Approach 2:
The notification packet contains a copy or representation of the data transmission information without transmitting the actual data payload. This lightweight copy allows the system to verify transmission path status and manage retransmission logic without the overhead of retransmitting full data packets when unnecessary.
Data Source
AI summary
A transfer device increments a value of a phase ID at predetermined time intervals, and registers a packet ID of a transmitted data packet and a phase ID on a determination table in an associated manner. When having received a response packet from a receiving-side transfer device, the transfer device determines an unarrived packet on the basis of received packet IDs contained in the received response packet and packet IDs of transmitted data packets. Then, the transfer device determines whether a data packet corresponding to the unarrived packet is lost or on-the-fly from a relationship between a phase ID of the unarrived packet and the maximum phase contained in the received response packet, and retransmits the corresponding data packet only if it is lost.