3Com 3031 Command Reference Manual page 164

164 C 3: I M C
HAPTER NTERFACE ANAGEMENT OMMANDS
Parameter
None
Description
Using the loopback command, you can enable a serial interface to perform
loopback. Using the undo loopback command, you can disable the serial interface
to perform loopback.
By default, loopback of the serial interface is disabled.
It is necessary for you to enable the serial interface to perform loopback only for
the purpose of testing some special functions.
Example
Enable the serial interface to perform loopback.
[3com-Serial0/0/0]loopback
mtu
Syntax
mtu size
undo mtu
View
Serial interface view
Parameter
size: MTU size on the serial interface, which is in the range of 128 to 1500 bytes
and defaults to 1500.
Description
Using the mtu command, you can set the MTU of a serial interface. Using the
undo mtu command, you can restore the default setting.
The MTU setting of a serial interface can affect the assembly and fragmentation of
IP packets on the interface.
Example
Set MTU of the serial interface to 1200.
[3com-Serial0/0/0]mtu 1200
physical-mode
Syntax
physical-mode { sync | async }