Flow control configuration. Flow control is used to throttle the throughput rate of an end station to avoid dropping packets during network congestion. If flow control mode is not set and if there is no packet buffer space available, the incoming packets are discarded. Symmetric Flow Control stops and restarts packet transmission by transmitting and receiving pause frames. When a port's free buffer space is almost empty, the device send out a Pause frame to stop the remove node from sending more frames into the switch. When congestion on the port is relieved, the device send out a Pause frame with pause time equal to zero, making the remove node resume transmission.