Allied Telesis AT-GS924GB - Manual (Page 20)

Product Description
8
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-GS924GB switch 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 the AT-GS924GB switch,
the end-nodes connected to the switch 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 switch port. A port on the AT-GS924GB
switch 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.
Store and
Forward
This Gigabit Ethernet Switch uses store and forward as the method for
receiving and transmitting frames. When a Ethernet frame is received on
a switch port, the switch does not retransmit the frame out the
destination port until it has received the entire frame and stored the
frame in a port buffer. It then examines the frame to determine if it is a
valid frame. Invalid frames, such as fragments or runts, are discarded by
the switch. This ensures that only valid frames are transmitted out the
switch ports and that damaged frames are not propagated on your
network.