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[ih] Why did congestion happen at all? Re: why did CC happen at all?

Everyone  has been pointing out the technical 
points of how the ARPANET worked and they are 
correct.  There are two points that are worth 
taking into account:

1) No one had yet built a packet switching 
network, so BBN was kind of flying in the dark. 
It is amazing that it turned out as well as it 

2)  The ARPANET was never intended as a network 
for doing research on networks.  It was intended 
as a production network to facilitate other 
research.  BBN was very limited in how much 
experimentation was possible and in what it could 

CYCLADES on the other hand was built as a network 
for doing research on networking.  It was not 
intended to be a production network. There was no 
real attempt for the network to be operational 
for certain hours of the day. (BBN on the other 
hand could only try new IMPSYSs on Monday nights.)

It was partly because it was a research network 
that Pouzin and crew came up with datagrams. 
They wanted to have a very basic system that made 
as few assumptions about how the network should 
work as possible.  The datagram does this.  There 
was quite a lot of work (cited previously in this 
discussion) on what would be called 
connection-oriented flow and congestion control 
of the kind found in the ARPANET and the early 
X.25 networks.  In addition, Pouzin had more 
minimalist ideas to test alont the lines of what 
we call connectionless today.  And has been cited 
earlier, they started to look at the problems of 
congestion control in these minimalist 
architectures in the early 70s as did others on 
the project, such as Gerard LeLann and Erol 
Gelenbe.  This was for them a research problem, 
more than an engineering problem.

The decentralized, stochastic nature of a 
datagram-like approach and the use of an 
end-to-end transport protocol pioneered with 
CYCLADES that set the direction for most of the 
academic research on the 70s and early 80s.

As Noel as already described, some working on the 
Internet were lulled by the central role the 
ARPANET played in the early Internet to not 
realizing that the congestion control problem 
would arise as the ARPANET's role decreased as 
the Internet grew.  By the time this occurred, 
there were very few other datagram networks 
operating.  CYCLADES had been shut down.  The UK 
and EIN was operating primarily over X.25.

This had a lot to do with how we got where we are.


The Internet and the ARPANET have always been 
much more engineering problems than a platform 
for network research.  Remember (someone can 
provide the date) but by 74-75, ARPA declared the 
ARPANET project completed.

At 5:22 PM +0200 8/31/14, Detlef Bosau wrote:
>Am 31.08.2014 um 08:14 schrieb Miles Fidelman:
>>  So, you're saying that accidents, rush hours, and construction DON'T
>>  cause congestion on the A7/E45?  Or that people don't people don't
>>  adjust their schedules or routes based on traffic reports?
>>  Miles Fidelman
>At least in Germany, wie try (admittedly without sucess) to avoid
>traffic congestion by careful planning.
>It is always a pity to visit a widow only to tell her: "Unfortunately,
>your husband is not coming home today, he was dropped together with his
>car this afternoon due to traffic jam near to Frankfurt."
>Or, since today it was mentioned that our German secretary of defense,
>Ursula von der Leyen, has seven children. I'm not quite sure whether she
>is going to solve the problem in the Ukraine by "probing". Send four
>children to war, if some are dropped halve the window and send only two,
>now the next try is stop and wait....
>(Rumour says, that the US Air Force actually assesses traffic control by
>probing and drop,  I think the project is conducted near to Ramstein
>Particularly, the ARPANET in its original design offered the necessary
>equipment to get along without this nonsense.
>Or, if I may quote a sentence which John Day wrote me in a private
>communication: "A congestion control scheme, that causes congestion. Funny."
>When I started thinking about this issue, I hang on BIC and CUBIC and
>thought, why we do this nonsense only to tell a sender on a wireless
>link what he already knows, i.e. how fast he may send?
>The very reason is that we neglected scheduling. And when we got aware
>of this fact, we replaced scheduling by
>a) probing and
>b) Little's law.
>That's the whole story.
>And now, we are to overcome the consequences. And we do so for about 25
>years. (And we are going still to do so in 25 years, when we don't
>attack the basic problem: the lack of proper scheduling and proper flow
>And as the Internet is likely to grow, we will see even more buffers and
>even more buffer bloat and perhaps even more heterogeneous networks
>which suffer from loss differentiation caused problems and even more
>unfairness between mice and elephants and so on.
>And as we solve buffer utilization problems by adding more and more
>buffer (which can be probed and utilized) the hardware costs increase as
>do the round trip times as well.
>My only intention is to pursue a different way of thinking here. No
>more, no less. (However, we are that brainwashed by these nonsense PhD
>projects on "congestion control" who attempt to keep a dead mummy alive,
>that we rather sacrifice the world than our probing/dropping nonsense.)
>Detlef Bosau
>Galileistra?e 30  
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