Allied Telesis AT-FS238a/2 - Manual (Page 19)

AT-FS238a/x and AT-FS238b/x Series Installation Guide
7
Twisted Pair Port
The AT-FS238a/x and AT-FS238b/x Series Bridging Converters have one
10Base-T/100Base-TX twisted pair port. The twisted pair port features a
RJ-45 connector.
Port Speed
The twisted pair port is compliant with the 10Base-T and 100Base-TX
standards and is capable of either 10 Mbps or 100 Mbps operation. You can set
the port speed manually or, since the port is IEEE 802.3u auto-negotiation
compliant, you can allow the bridging converter to set the port speed
automatically. With auto-negotiation, the speed of the port is set
automatically by the bridging converter after it determines the speed of the
end-node connected to the port. Auto-negotiation is designed to ensure that
the port on the bridging converter and the end-node are operating at the same
speed and that they are communicating at the highest possible common speed
of the devices.
Duplex Mode
Duplex mode refers to how an end-node receives and transmits data. If an
end-node can receive or transmit data, but not both simultaneously, the end-
node is operating in what is referred to as half-duplex mode. If an end-node
can both receive and transmit data simultaneously, the end-node is said to be
operating in full-duplex mode. Naturally, an end-node capable of operating in
full-duplex can handle data much faster than an end-node that can only
operate in half-duplex mode.
The twisted pair ports on the AT-FS238a/x and AT-FS238b/x Series Bridging
Converter can operate in either half-or full-duplex mode. They are IEEE
802.3u-compliant and use Auto-Negotiation to set the duplex mode setting for
you automatically.
For Auto-Negotiation to operate properly on a bridging converter, the end-
nodes connected to the converter should also use Auto-Negotiation. If an end-
node does not have this feature and has a fixed duplex mode of full-duplex, the
result will be a duplex mode mismatch between the end-node and a converter
port. A port on the bridging converter connected to an end-node with a fixed
duplex mode of full-duplex will operate at only half-duplex. This results in the
end node using full-duplex and the switch port using half-duplex. This can
produce network performance problems. Should you encounter this situation,
you must configure the port on the end-node to use Auto-Negotiation or, if it
lacks that feature, to half-duplex.