[ih] Arpanet raw messages, voice, and TCP

[Matthias Bärwolff]

Hi all,

I was wondering if anyone here knows closely of the precise history of
how the raw message facility of the Arpanet came about and in which ways
it relates to early voice (NVP) and TCP experiments in the mid-1970s. I
gather from the 1822 report (and a couple of other BBN reports from
around 1974 to 1978) that hosts could send uncontrolled messages (one
packet messages at that) that would be delivered without paranoid error
control IMP-to-IMP and without RFNMs and retransmissions. However (!),
BBN would control whether or not hosts could use that facility in the
first place. From the 1822 report (as of 1976,
http://www.bitsavers.org/pdf/bbn/imp/BBN1822_Jan1976.pdf):

"Uncontrolled use of these messages will degrade the
performance of the network for all users.  Therefore,
ability to use these messages will be regulated by the
Network Control Center and will require prior arrange-
ment for each experiment."
(p. 3-36)

My questions are:

1. What experiments or actual applications did people do with the raw
messages? The papers on early network voice stuff indicate that three or
four host sites where playing around with that. What about TCP?

2. How does this Arpanet feature relate to TCP and the ARPA agenda from
around 1973/1974 of pushing development of TCP? Am I right in thinking
that the first TCP experiments must have involved using the raw messages
facility?

3. How did BBN actually control sites' use of the feature? And, what
were the experiences with congestion (as in congesting intermediary
nodes, as well as in overwhelming the destination IMP/host)?

4. How did those experiments (provided the link that I am here assuming
exists) feed into actual TCP developments?

5. Last, the TCP/IP split is often ascribed somewhat to common sense
(proper modularization, see e.g. IEN 2), and particularly the canonical
example of interactive voice. But how does the actual availability of a
"best effort" transport facility at Arpanet (the raw message facility)
relate to the later notion of an IP protocol (which, too, provides an
effective service guarantee of zero; and comes with all the congestion
problems that will require the hosts to well behave)?

Thanks for any suggestions, pointers and accounts on this. Also, I am
told Bob Kahn would be a good person to ask on this, maybe someone here
can reach out to him on this.

Best,
Matthias

-- 
Matthias Bärwolff
www.bärwolff.de