Loopback (Ethernet Interface) - 3Com 3C13618 Command Reference Manual

When the fast Ethernet interface is set to duplex negotiation, its remote end must
work in the same mode. If this could not be achieved, then use forced setting to
ensure consistency of the working mode.
The execution of speed negotiation after executing duplex full or duplex half at the
fast Ethernet interface will restore the working mode to duplex negotiation. This will
automatically start the duplex auto process and negotiate the speed and the working
mode.
For related commands, see speed, display interfaces.
Example
# Set the 100Base-T fast Ethernet interface to work in full duplex mode.
[3Com-Ethernet0]duplex full

2.1.2 loopback (Ethernet Interface)

Syntax
loopback
undo loopback
View
Ethernet interface view
Parameter
None
Description
Using the loopback command, you can enable the internal loopback and the
external loopback on the Ethernet interface. Using the undo loopback command,
you can disable the internal loopback and the external loopback on the Ethernet
interface.
By default, the internal loopback and the external loopback are disabled on the
Ethernet interface.
The internal loopback and the external loopback are enabled on the Ethernet
interface when some special functions are tested.
Interface Management
13