[ih] Hourglass model question

[David Walden]

I drew the diagram which Craig mentions and included it in the 1977 Telnet paper (walden-family.com/public/telnet-overview.pdf).  I believe my original use of the diagram was for a 197? presentation and following 1975 paper for Infocom (walden-family.com/public/infotech-host-protocols.pdf , page 298). I thought it was a good way to illustrate the layering which the Arpanet protocol development people were creating, including that other things could come in at any place. 

On July 5, 2019, at 5:30 PM, Craig Partridge <craig at tereschau.net> wrote:

>Related but not quite on target.
>
>The hourglass/margarita glass is a representation of layering.  And back in 1988 I tried to figure out the origins of the layered model for a collection of networking papers I edited.  At the time, the best answer I found was that layering, from a networking perspective, originated with a paper by Davidson et al. on the ARPANET TELNET protocol from the DATACOM conference in 1977.  It portrays layering as a fan, in which different protocols layer on each other as needed.  But it clearly articulates the notion of layering and how layers interact.  (And there's a narrow window between the 1977 paper and the Cerf/Kahn 1974 paper on TCP/IP, which presumably would have mentioned layering if the concept was in wide use).
>
>Craig

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