If you are using FNET, I would suggest you refer to the FNET quick start guider.
You are able to change the default network parameters manually:
set address <default-if IPv4 address> set gateway <default-if IPv4 gateway address> set netmask <default-if IPv4 netmask address> set mac <default-if Ethernet address>
Thanx for ur quick response Daniel. Actually, I haven't used shell commands with microcontrollers. I've used them like initialize or setting up microcontroller through main() function. I am struggling with it since last week. If u can prove me any sample project then it would be a great help.