I worked on the STREAMS based TCP/IP stack (at the
time at Lachman
Associates but I think the code came from Convergent, not sure).
My memory of CTIX was that it was a native in-kernel BSD(-ish)
implementation. At least for the SVR2-derived CTIX kernels. I don't ever
recall a STREAMS-based implementation from Convergent, but I stopped using
CTIX in the fall of 1988.
--lyndon