Allied Telesis AT-S62 - Manual (Page 104)

Chapter 6: Port Parameters
Section I: Basic Operations 104
The options in the Flow Control menu are described below:
1 - Flow Control
Disabled - No flow control on the port. This is the default setting.
Enabled - Flow control is activated. This setting is appropriate only
when the end node connected to the port is also using flow
control.
Auto - The port uses flow control only if it detects that the end
node is using it.
2 - Flow Control (Cell Limit)
Specifies the number of cells. A cell represents 64 bytes. The range
is 1 to 57,344 cells. The default is 8192.
B -Back Pressure
Sets backpressure on a port. This option only applies for ports
operating in half-duplex mode.
Backpressure performs much the same function as flow control.
Both are used by a port to control the flow of ingress packets from
the end node.
Where they differ is that while flow control applies to ports
operating in full-duplex, backpressure applies to ports operating
in half-duplex mode.
When a twisted pair port on the switch operating in half-duplex
mode needs to stop an end node from transmitting data, it forces
a collision. A collision on an Ethernet network occurs when two
end nodes attempt to transmit data using the same data link at
the same time. A collision causes the end nodes to stop sending
data. This is called backpressure.
When a switch port needs to stop a half-duplex end node from
transmitting data, it forces a collision on the data link, which stops
the end node. Once the port is ready to receive data again, it stops
forcing collisions.
The default setting for backpressure on a switch port is disabled.