All numbers in u-boot are considered in HEX format, unless it is an ip address. No matter if you write the leading 0x or not
First of all you need to configure your LAN controller
If MAC address is not set by default then do it manually (you are free to give any numbers here):
setenv ethaddr 00:11:22:33:44:55
Give IP address to your board:
setenv ipaddr 192.168.1.10
Specify a TFTP server ip:
setenv serverip 192.168.1.36
nfs ADDR_IN_MEMORY host_ip:/export_dir/name_of_file
All files loaded by net must be placed in a free RAM region. You need to specify this address in HEX with or without leading “0x”.
tftp ADDR_IN_MEMORY name_of_file
for example to boot linux kernel:
tftp 82000000 uImage