[e2e] Lost Layer?

[Greg Skinner]

On Mon, Feb 10, 2014 at 11:11:57PM -0500, Noel Chiappa wrote:
>     > From: Joe Touch <touch at ISI.EDU>
> 
>     > I don't at all understand the difference between a "network layer" and
>     > an "internetwork layer".
> 
> ATM stuff, etc = 'network layer'. (Or, reaching further back, ARPANET stuff.)
> 
> IPvN = 'internetwork layer'.
> 
>     > I have no idea what a 'network' layer is that is different from what we
>     > currently call the link layer.
> 
> The thing is that for more complex networks (like ATM, ARPANET, etc) you have
> 'link' layers which are lower/more-local than the system-wide 'network' layer.
> 
> For example, in the ARPANET example, ISTR that one of the interface modes
> involved using an HDLC link to talk to the IMP. On top of that one ran 1822
> headers (with the destination IMP/port, etc); the latter being the 'network'
> layer.

Correct.  It was called HDH.  There's a short description of it in
http://www.rfc-editor.org/rfc/museum/ddn-news/ddn-news.n9.1.

--gregbo