Allied Telesis AT-S24 - Manual (Page 70)

Configuring the Ports
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performance settings. If a connected device is not compliant, it
should only be configured for half-duplex. Auto-negotiate is the
default for all ports.
If you select the half-duplex or full-duplex setting on an AT-8224XL
switch or one of the twisted pair ports on an AT-8288XL switch, the
prompts in Figure 27 are displayed. You can use these prompts to
select the port speed.
Figure 27 Port Speed Setting for an AT-8224XL Switch or AT-8288XL
Switch
Note
Setting the port speed applies only to the twisted pair ports on an
AT-8224XL switch or an AT-8288XL switch.
Backpressure enabled (half-duplex)
No backpressure
Backpressure applies only to ports operating in half-duplex mode.
Backpressure is useful when the port input buffer is running low on
memory resources. In the switch, outbound packets are traversing a
single uplink port. When a switch detects that a port input buffer is
nearly full, it simulates a collision so that the sending node will defer
transmission. The sending node will retry transmissions according to
the Ethernet back-off algorithm. Once switch resources are available
again, the switch stops sending the collision signal and the sending
nodes can freely transmit packets.
Flow control (full-duplex)
No flow control
Flow control applies only to ports operating in full-duplex mode. It
works for full duplex ports the same way as backpressure does for
half-duplex ports except that the switch uses a special pause packet
instead of a jam signal. The pause packet notifies the other node to
stop transmitting for a specified period of time.
Global configuration
This option saves you from having to enter the same configurations
on every port. If you select this option, any settings you entered on a
port are copied to all the station ports on the switch (but not ports on
optional expansion modules).