Hi,
I resolved this issue. After I had run udhcp client, My board got IP address,
udhcpc is part of the very light busybox, a replacement for coreutils, often used on embedded platforms.It's used to get an ip address from a dhcp server.
Run DHCP client(for embedded Board -udhcpc)
root@mx28evk ~$ udhcpc –b –i eth0