> I.e., layering is, IMO at least, a model. Fine for describing
> things, but not necessarily a good blueprint for an implementation.
Yes, but this is hardly news in the IETF - or at least, it *ought not* to
be news. See RFC-817, "Modularity and Efficiency in Protocol
Implementation", July 1982 - about 20 years ago.
I also wonder why the notion that the functional modularization of the
architecture/specification might differ from that of particular
implementations is something some people seem not to have internalized -
this idea dates all the way back to the IBM 360 line of the early 1960's.
Noel