Ethernet Flow Control

Ethernet is a best-effort protocol that does not guarantee reliable delivery or in-order packet arrival. Reliability mechanisms such as retransmission, sequencing, and error correction are implemented by upper-layer protocols like TCP or by the application itself.

The IEEE 802.3x standard added flow control to Ethernet protocol, enabling devices to regulate data transmission between full-duplex peers. If the sender transmits data faster than the receiver can accept it, the overwhelmed receiver can send a pause signal (Xoff or transmit off) to the sender, requesting that the sender stop transmitting data for a specified period of time. The sender resumes transmission either after the timeout period expires or if the receiver indicates that it is ready to accept more data by sending an Xon (transmit on) signal

Without flow control, data loss or retransmission may occur, impacting overall performance especially in high-throughput environments.