3Com 3031 Command Reference Manual page 157

Fundamental Ethernet Interface Configuration Commands 157
Parameter
size: MTU size on the Ethernet interface, which is in bytes. It is in the range of 46
to 1500 if the adopted frame format is Ethernet_II.
Description
Using the mtu command, you can set the maximum transmission unit (MTU) of
the Ethernet interface. Using the undo mtu command, you can restore the default
configuration.
MTU defaults to 1500 if the adopted frame format is Ethernet_II.
The MTU setting of an Ethernet interface can affect the assembly and
fragmentation of IP packets on the interface.
For a related command, see display interface.
Example
Set MTU of the Ethernet interface to 1492.
[3com-Ethernet0/0/0]mtu 1492
speed Syntax
speed { 10 | 100 | negotiation }
undo speed
View
Ethernet interface view
Parameter
10: Forces the FE interface to work in 10Base-T (at 10Mbps) mode.
100: Forces the FE interface to work in 100Base-TX (100Mbps) mode.
negotiation: Sets the FE interface to work in auto-negotiation mode.
Description
Using the speed command, you can set the operating speed of the FE interface.
Using the undo speed command, you can restore the default operating speed of
the FE interface.
By default, the FE interface operates in auto-negotiation mode.
Before setting the FE interface to work in auto-negotiation mode, you must make
sure that the connected remote end has been working in auto-negotiation mode.
If this cannot be guaranteed, the two parties should use the forced setting for
operating consistency.
For related commands, see duplex and display interface.