   local host, how far down is that rabbit hole?
  I am thinking about using the local host IP, for bouncing Inter Process Comm. off of. The problem is I am not sure how much overhead that adds to the communication, and I dont know if it actually goes to the adapter, and then back up through all the abstraction layers (OSI). I will be using winsock, but hope to one day port to  the unix variety.There are other ways to do IPC but I kinda like the local host / IP socket variety.   
  The socket overhead is minimal over loopback adapters. I don't know for sure about Windows, but I do know that the standard Unix way to implement loopback is with a special driver, so your data never goes to hardware - it just shuffles around in the socket layer a bit. However, I've done a fair bit of IPC via sockets on Windows, and I know the overhead is trivial/minimal - so there is a very good chance that a similar strategy is used on Windows.   ;  First: nobody actually uses OSI, although some of the layers defined by OSI are useful to talk about as a reference point.Second: everybody who implements a TCP/IP stack implements a special device for localhost, that doesn't touch hardware. The reason for this has to do with a TCP/IP stack having to figure out what to do WRT routing to multiple interfaces anyway, so it comes "for free".