Duplex Mode - Allied Telesis AT-8516F/SC Installation Manual

Overview

Duplex Mode

Duplex mode refers to the manner in which 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-8500 Series switches can operate in
either half- or full-duplex mode. The twisted pair ports are IEEE 802.3u-
compliant and will Auto-Negotiate the duplex mode setting for you.
By allowing the switch to configure the duplex mode for each port, you
will not need to change the setting for a port on the switch should you
replace an end node with an end node that has a different duplex mode
capability. With Auto-Negotiation, the switch automatically resets the
port to a new duplex mode setting.
If desired, you can disable Auto-Negotiation on the switch ports so that
you can set the duplex mode manually through the switch's
management software.
Note
In order for a switch port to successfully Auto-Negotiate its duplex
mode with an end node, the end node should also be using Auto-
Negotiation. Otherwise, a duplex mode mismatch can occur. A
switch port, using Auto-Negotiation, defaults to half-duplex if it
detects that the end node is not using Auto-Negotiation. This
results in a mismatch if the end node is operating at a fixed duplex
mode of full-duplex.
Consequently, when you connect an end node with a fixed duplex
mode of full-duplex to a switch port, you should use the AT-S62
management software to disable Auto-Negotiation on the port and
set the port speed and duplex mode manually.
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