22
CHAPTER 2
Intel Express 10/100 Fast Ethernet Switch
Configuring a port for full duplex
Configuring a port for full duplex allows the switch to send and
receive packets simultaneously with the destination device. To
establish a full-duplex link, the switch and the destination device both
must be configured for full duplex.
Additionally, the link must be to a switch, workstation, or server. You
can’t establish a full-duplex link to a device that broadcasts incoming
packets to every port on the device. This excludes shared hubs,
repeaters, or concentrators from using full duplex.
Commands used
get-port-cfg
set-speed-sel <port> {asense|10|100}
set-port-dplex <port> {full|half}
Recommended environments
Full duplex is best when two devices exchange information to and
from each other (such as a file server). In the diagram on page 20, the
Payroll and Finance 100 Mbps workgroups frequently copy files to
and from the file server on port 5.
To configure a port for full duplex
1Configure the device on the other end for full duplex. In the
diagram on page 20, you’d configure the adapter in the file server
for full duplex.
2Get the current port settings using the get-port-cfg command. If
the port is set to autosense the speed (asense is the default) then
you must set the speed to either 10 or 100. This example sets
port 5 to 100 Mbps.
set-speed-sel 5 100
3Set the port to full duplex. (This command fails is you haven’t
manually changed the speed to 10 or 100).
set-port-dplex 5 full
4Check the Coll/Fdpx LED. It should be solid green, indicating full
duplex.
NOTE
You must have a point-to-
point connection to establish
a full-duplex connection
(shared hubs/repeaters/
concentrators aren’t capable
of full duplex). Additionally,
both points of the connection
must be configured for full
duplex.
NOTE
Setting a port to full duplex
automatically disables flow
control. Since collisions don’t
occur on a full-duplex link,
flow control isn’t possible.
One exception is between two
Express 10/100 switches.
Special information is added
to packets traveling between
switches to accomplish this.
The Coll/Fdpx LED is solid
green when the port is
configured for full duplex.