[ih] Installed base momentum (was Re: Design choices in SMTP)

[Craig Partridge]

On Sat, Feb 11, 2023 at 7:48 AM Noel Chiappa via Internet-history <
internet-history at elists.isoc.org> wrote:

>
>
>     > From: Craig Partridge
>
>     > We figured out congestion collapse well enough for the time
>
> It should be remembered that the ARPANET people (hi!) had perhaps solved
> this
> problem a long time before. I'm trying to remember how explicitly they saw
> this as a separate problem from the issue of running out of buffer space
> for
> message re-assembly at the destination IMP, but I seem to recall that RFNMs
> were seen as a needed throttle to prevent the network as a whole from being
> overrun (i.e. what we now think of as 'congestion', although IIRC that term
> wasn't used then), as well as flow control to the source host (as we would
> now call it).
>
> I don't recall exactly where I saw that, but I'd try the BBN proposal to
> DARPA's RFP, and the first JFIPS paper ("The interface message processor
> for
> the ARPA computer network").
>

I don't recall the details either, though I remember stories of Bob Kahn
going to LA to beat up on the first few ARPANET nodes
because he anticipated various issues, I think including congestion.  And
he found them and fixes were made.

But remember ARPANET was homogeneous -- same speed for each link and a
single control mechanism.  I think John Nagle was
the first to point out ("On packet switches with infinite storage") that
connecting very different networks had its own challenges.
And to my point, not something that a person working with X.25 would have
understood terribly well (yes X.75 gateways existed but
they typically throttled the window size to 2 packets, which hid a lot of
issues).

Craig
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