[ih] On queueing from len

[Jack Haverty]

On 10/4/22 18:10, Dave Taht via Internet-history wrote: (apparently 
actually from Len Kleinrock)
> BUT, in 1975, our role was taken over by DCA and
> as far as I know, the did little, if any, further experimentation and so we
> lost track of what was going on in the net.  Of course, we continue to pay
> the price of not really knowing how the network is performing.

There was extensive experimentation and data collected during the many 
years that the ARPANET was in operation by DCA.  The NOC at BBN 
collected data about network operations, which was used by the NOC 
Operators to handle everyday issues.  Long-term data, showing operation 
over days to months, was also collected and analyzed by mathematicians 
in the BBN "Network Analysis" group.   Such data was used to make 
decisions about reconfiguring the ARPANET, both to accommodate its 
growth and to modify the topology to reflect changes observed in the 
user traffic loads and network performance.   The same data was used to 
motivate changes in the algorithms, which were designed, implemented, 
and tested experimentally before enabling them for operational use in 
the entire ARPANET.

For example, one such change was simply called "Routing Algorithm 
Improvements", and introduced new mechanisms and techniques for routing 
as well as congestion control and other such important issues.   All of 
that was based on the data collected from years of observing network 
behavior during live operations.

That work was documented, but IIRC largely in the form of technical 
reports submitted to DCA as "deliverables" for our contracts.  I believe 
DCA made many such reports public, but I don't recall that there were 
many publications of the work in traditional technical journals, student 
theses, or other such channels.   So the experimentation, results, and 
changes made were possibly not very visible in academic environments, 
unless students or their librarians figured out how to access the 
government reports, e.g., through the Defense Technical Information 
Center (DTIC).

Many of those old reports appear to be online now at the DTIC site. 
Here's one example, one of the volumes of a rather large report 
documenting some of the work done in one of the ARPANET Operations 
contracts in the early 1980s, to "improve the routing algorithm":

https://apps.dtic.mil/sti/citations/ADA121350

There are probably many more such documents, especially in the Quarterly 
Technical Reports where lots of detail was often captured from the 
operating ARPANET.   There's lots of information collected by Dave 
Walden (one of the original IMP programmers) online at 
https://walden-family.com/impcode/   That site includes links to 
listings of the 1970s IMP code itself, which was resurrected about 10 
years ago and the original 4-node ARPANET recreated, all operating 
within a simulator of the Honeywell 316 computer that was the IMP 
hardware.  So even today, it would be possible to run experiments using 
the old IMP code and its embedded algorithms and techniques.

So actually BBN, and DCA, did know a lot about how the ARPANET was 
performing through its lifetime, and used that data to drive changes in 
the underlying technical mechanisms to better provide service to ARPANET 
users.  IMHO, it's likely that operational experience was an important 
factor in the selection of a "clone" of ARPANET to create the DDN - 
Defense Data Network, which served all military users, and had to "just 
work."

The ARPANET research progressed from ARPA to DCA to pervasive use within 
all of DoD, with constant data collection employed to keep it running 
well and evolving.  During the 80s, the ARPANET was a vehicle for trying 
out new ideas, observing their performance in an operational 
environment, and only migrating the new technology to the more critical 
elements of the DDN (MILNET at al), when they had been proven successful 
in the ARPANET which served as a testbed for such experimentation.   
Research was motivated by data collected during operational experience, 
and only solutions proven by field experimentation, first in simulation, 
then in small laboratory networks, and then in the ARPANET were 
permitted to be deployed into the wider DDN environments.

I've often wondered how such technical evolution happens now in The 
Internet.

Jack Haverty
(BBN 1977-1990)