Delayed TCP ACK Transmission Method to Achieve Target RTT in Optical Packet Switching Networks
Toshiaki Hirai, Yosuke Tanigawa, Yusuke Hirota, Hideki Tode · 2025
Practical optical buffers have not yet been implemented in optical packet switching (OPS) networks, where packet-by-packet switching is performed using optical signals at optical switches. As a result, packet collisions occur when multiple optical packets simultaneously reach the same output port of optical switches. This leads to significant communication performance degradation, particularly when Transmission Control Protocol (TCP) is used. In this paper, we propose a method that the receiver host adaptively delays the transmission of TCP acknowledgment (ACK) to achieve a predefined target round-trip time (RTT) for the sender host. This target RTT is determined based on real-time pure RTT measurements obtained during data transmission and reception. By dynamically adjusting the RTT of data packets traversing optical paths of various lengths in an OPS network to one of a limited set of fixed values, we can reduce the likelihood of such collisions.