I do think the upper layers are reasonable as long as you condense them down into transport and application layers. Transport has historically been either UDP o

I do think the upper layers are reasonable as long as you condense them down into transport and application layers. Transport has historically been either UDP or TCP, but I think a better definition is a layer which provides "meta" level guarantees. Under that definition TLS is also a transport technology (providing encryption) and even HTTP could be part of the transport layer since it can provide automatic caching and the ability to be used from the browser (kind of a tautology, but significant since the browser has become so important).