[ns] with wired and wireless links on, sending data on own desired link for over layered application routing protocol

I am working on overlayered application layer routing protocol...with
wired as well as wireless links working between them...but data is
sent on both interfaces at same time, i want that a parameter should
be passed within cc code not from tcl script that could control all
this process.....how to switch between these two interfaces, so that i
could send on my own desire
thnx :)