Are you using a DE2 board with a DM9000A controller to Ethernet?
Quartus 7.2 has LWIP instead Nichestack.
Look that (terasic support):
I am afraid that the DM9000A does not support to be initialized in the Quartus II 9,0 or later version. So it is quite difficuilt to port the DE2_NET project from NIOS II 7.2 IDE to NIOS II SBT 11.1 directly.
In the Nios II v9.0 or later, the TCP/IP includes the networking stack of the Nichstack, however, the DE2_NET project was built on the LWIP. The driver for the DM9000A should be different in the Nichstack to the LWIP. Then, if you want to migrate the DE2_Net project to Nios II v11.1, you have to create a new driver for the DM9000A at first.