The OSN3500 Ethernet port self-negotiation flow control negotiation feature allows a network device to communicate information about its own supported operating modes to the opposite end device on the network, and to receive the corresponding information that the other side may pass over. The operating modes of the docking ports of the devices on both ends must be the same, or the service will not work. If the working mode of the port of the opposite-end device is full-duplex and the port of the local device is set to self-negotiation, the result of self-negotiation at this time is that the local device is working in half-duplex mode, which does not realize the matching of the working modes of the two ends, and may cause packet loss. Therefore, when the working mode of the port of the opposite-end device is full-duplex, the local device should be set to the same working mode as the opposite-end. When the docking ports of both end devices work in self-negotiation mode, both devices can also negotiate the flow control function through the self-negotiation function. The self-negotiation feature conveys the negotiation information for the operating mode through fast link pulses and normal link pulses without using dedicated packets or incurring any high-level protocol overhead. Self-negotiation flow control method (Ethernet port attribute) - refers to the flow control method used when an Ethernet port is operating in self-negotiation mode. Impact on the system: if the result of the negotiation is flow control enabled, a PAUSE frame is sent to the upstream port during network congestion.