This documentation is released under the Creative Commons licenseThe 802.3x standard supports PAUSE frames as a means of flow control. The frame contains a timer value, expressed as a multiple of 512 bit-times, that specifies how long the transmitter should remain quiet. If the receiver becomes uncongested before the transmitter's pause timer expires, the receiver may elect to send another PAUSE frame to the transmitter with a timer value of zero, allowing the transmitter to resume immediately.
EtherMAC will properly respond to PAUSE frames it receives (EtherPauseFrame class), but it will never send a PAUSE frame by itself. (For one thing, it doesn't have an input buffer that can overflow.)
EtherMAC, however, transmits PAUSE frames received by higher layers, and EtherLLC and EtherEncap can be instructed by a command to send a PAUSE frame to MAC.
IMACRelayUnit types (and thus EtherSwitch) currently implement a very simple scheme for sending PAUSE frames -- this can be refined if the need arises.
This documentation is released under the Creative Commons license