The implementation required a few data structures to be modified or added, a lot of new functions to be written... and all this new code to be inserted in the proper places in the voluminous files that make up the Tierra project.
Note: All the network related code is under #ifdef NET, except for the file netfunc.c, which is specific to the network version. This way the network version can be evolved (and released) along with the non network-related code.