Command Reference Guide

3Com Router 3000 Ethernet Family
Command Reference Guide
Chapter 2 Fundamental Ethernet Interface
Configuration Commands
3Com Corporation
2-7
Description
Use the loopback command to enable local loopback on the Ethernet interface.
Use the undo loopback command to disable local loopback on the Ethernet interface.
By default, local loopback is disabled on the Ethernet interface.
You need to enable local loopback on the Ethernet interface only when testing some
special functions.
 Note:
The Ethernet interface works in full duplex mode after you enable loopback. The
original mode resumes after loopback is disabled.
Example
# Enable local loopback on the FE interface.
[3Com -Ethernet0/0/0]loopback
2.1.6 mtu (Ethernet/GE Interface)
Syntax
mtu size
undo mtu
View
Ethernet interface view
Parameter
size: Maximum transmission unit (MTU) size of the Ethernet interface, which is in bytes.
It is in the range 46 to 1500 for the frame formats of both Ethernet_II and GE.
Description
Use the mtu command to set the MTU size of the Ethernet interface.
Use the undo mtu command to restore the default or 1500 bytes.
The MTU setting of an Ethernet interface can affect the assembly and fragmentation of
IP packets on the interface.
Related command: display interface.
Example
# Set MTU of the FE interface 0/0/0 to 1492.