Joerg Schilling: This is done on a UNIX implementation that uses STREAMS. SVr4 is such a UNIX. ====== I know that SVr4 has STREAMS (somewhat more elaborate than the original stream I/O system, but the same principles), and knew (though I'd forgotten) that Ethernet devices are stream-capable. I did an implementation of the late lamented Coraid's AoE protocol that took advantage of that. Somewhat like the Research IP implementation, in fact: there was an AoE line discipline to be pushed onto an Ethernet device, coupled to devices in /dev/dsk and /dev/rdsk. But is IP done that way in SVr4 (or at least in Solaris, its most-visible descendant)? I had the impression that the IP stack was more like the BSD one, with everything coupled together within the kernel and a fundamentally socket interface. I've never actually looked at the code, though. Norman Wilson Toronto ON