Pause frames are NOT exchanged between two end-stations connected through a switch.
Pause frames are only exchanged between two directly-connected link partners that is, between a switch and an end station, or between two end-stations when they are connected back-to-back. Upper layer protocols such as TCP should be preferably used instead of flow control, to control the flow of data. A pause frame can impact all hosts connected to that interface. Enabling flow control reduces the possibility that one interface will overrun the other interface.
The link partner will stop transmitting data packets until it receives a pause off (Xon) frame or a timeout expires. An interface that is receiving data packets and is almost out of receive buffers will send a pause on (Xoff) frame to its link partner.
