Allied Telesis AT-S39 - Manual (Page 73)

AT-S39 User’s Guide
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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.
5. Once you have set the port parameters, type S to select Save
Configuration Changes.
Configuration changes are immediately activated on a port.
The Port Configuration menu also features these selections:
F - Force Renegotiation
This selection appears in the menu only when a port is set to Auto-
Negotiation. You can use the option to prompt the port to re-Auto-
Negotiate with the end node. This can be helpful if you believe that a
port and end node are not operating at the same speed and duplex
mode.
X - Reset Port
You can use this option to reset the selected port. This can prove useful
in situations where a port is experiencing a problem establishing a valid
connection to the end node. The reset takes less than a second to
complete. The port’s current parameter settings are not changed by this
option.