Lantronix
x4120 User Guide
33551 Rev. C
Page
31
of
142
Displaying Auto Negotiation
The auto negotiate feature is defined on a port basis, letting you set the capabilities that will be advertised
for a device over a specific port.
Auto negotiation is a feature that can be used by devices that are capable of different transmission rates
(such as 10 Mbit/sec and 100 Mbit/sec), different duplex modes (half-duplex and full duplex), and/or
different standards at the same speed. Every device declares its possible modes of operation when
attempting to connect to another device. The two devices then choose the best possible modes of
operation that are shared by the two devices. These modes of operation include speed and duplex.
When one device supports auto negotiation and the other does not, the device that has auto negotiation
abilities can determine the speed of the other device, and then select the same speed for itself. However,
this procedure cannot determine the duplex setting of the other device, so half-duplex is always assumed.
If one device is using full duplex while the other one is using half-duplex, a duplex mismatch occurs.
The usual effect of this mismatch is that the connection works but at a very low speed. Disabling the auto
negotiate feature allows you to force the connection to the desired speed and duplex mode of operation
as long as both devices can support the operation.
Note
: The auto negotiate feature is always enabled for gigabit devices/ports.
