3Com 9000 SX User Manual page 35

5 Assign an IP address and subnetwork mask for VLAN default. The
example below assigns an IP address of 123.45.67.8 and a subnetwork
mask of 255.255.255.0.
config vlan default ipaddress 123.45.67.8 255.255.255.0
Your changes take effect immediately.
6 Save your configuration changes so that they will be in effect after the
next Switch reboot, by typing
save
For more information on saving configuration changes, refer to
Chapter 10.
7 When you are finished using the facility, logout of the Switch by typing
logout
Logging on for the First Time 2-7