[e2e] Lost Layer?

Noel Chiappa jnc at mercury.lcs.mit.edu
Tue Feb 11 08:09:29 PST 2014

    > From: Joe Touch <touch at isi.edu>

    >> IPvN = 'internetwork layer'.

    > Which is what ISO calls the network layer, which is why I map the two
    > as equal.

There are (at least) three layers there. If you persist in trying to name
them with only two names, you will of course run into insuperable Procustean

    > From: Jon Crowcroft <Jon.Crowcroft at cl.cam.ac.uk>

    > MOST things now have a net later as well as a link layer in fact,
    > because most the world is either in a data center or on a cellular data
    > net, and both have topology that is manged by routing that runs below
    > the IP layer and is tech specific

I'd forgotten all about mobile!

Amazing how the world has come full circle and we once again have complex
(subnetwork-wide) network layers underneath the internetwork layer. (To me, a
sign that the internetwork layer architecture is lacking in
functionality/capability/flexibility... but I digress.)

I'm not sure I'd go so far as to say 'most' as I think a lot of home links
don't have a complex network layer, since they are often via CATV (and, in
more advance plant, fiber to the home) - but then again, a lot of home links
are via DSL, and I don't know how that's carried inside the ISPs these days
(it used to be ATM), so perhaps your 'most' is correct.


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