Allied Telesis AT-S62 - Manual (Page 115)

AT-S62 Management Software Menus Interface User’s Guide
Section I: Basic Operations 115
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 57,344.
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.
Selecting this option displays the Back Pressure menu shown in
Figure 26.
Figure 26. Back Pressure Menu
Allied Telesyn Ethernet Switch AT-8524M - AT-S62
Production Switch
User: Manager 11:20:02 02-Jan-2006
Back Pressure
Configuring Port 11
1 - Back Pressure ................. Disabled
2 - Back Pressure Cell Limit ...... 8192
R - Return to Previous Menu
Enter your selection?