free tcp/ip stack for nios

Quan,

For the plugs library, there are documented examples that will show up in your sdk/src/plugs folder ready to build. Plugs uses a non-standard API, but it is well documented in the Plugs Referene Manual (PDF doc, on Altera web site).

For LWIP (uCOS version), we provide two TCP servers and one UDP client as examples (go to make a new Nios II software design in the IDE and you should see these). The source code for these is *very* well documented (in my opinion anyways). A colleague of mine is also working on a tutorial document/design for LWIP (uCOS version) that will be publicly available soon. The API is Berkeley sockets... many good textbooks on this.

For LWIP (standalone version), I have not tried it yet, but I believe it includes a web server example design.