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Command Reference Guide Ethernet Interface Configuration Command Set
61200510L1-35E Copyright © 2005 ADTRAN 625
half-duplex
Use the half-duplex command to configure the Ethernet interface for half-duplex operation. This setting
allows the Ethernet interface to either send or receive at any given moment, but not simultaneously. Use
the no form of this command to disable half-duplex operation.
Syntax Description
No subcommands.
Default Values
By default, all Ethernet interfaces are configured for half-duplex operation.
Applicable Platforms
This command applies to the NetVanta 300, 1000, 1000R, 2000, 3000, 4000, and 5000
and Total Access 900 Series units.
Command History
Release 1.1 Command was introduced.
Functional Notes
Half-duplex Ethernet is the traditional form of Ethernet that employs the Carrier Sense Multiple
Access/Collision Detect (CSMA/CD) protocol to allow two or more hosts to share a common transmission
medium while providing mechanisms to avoid collisions. A host on a half-duplex link must “listen” on the
link and only transmit when there is an idle period. Packets transmitted on the link are broadcast (so it will
be “heard” by all hosts on the network). In the event of a collision (two hosts transmitting at once), a
message is sent to inform all hosts of the collision and a backoff algorithm is implemented. The backoff
algorithm requires the station to remain silent for a random period of time before attempting another
transmission. This sequence is repeated until a successful data transmission occurs.
Usage Examples
The following example configures the Ethernet interface for half-duplex operation:
(config)#interface ethernet 0/1
(config-eth 0/1)#half-duplex
If the speed is manually set to 10 or 100, the duplex must be manually configured as
full-duplex or half-duplex. Refer to speed [10 | 100 | auto | nonegotiate] on page 645
for more information.