Décès à 84 ans d'un des inventeurs des réseaux à commutation de paquets: Paul Baran - Wikipedia

(dernière mise à jour: 19:01 29/03/2011)
Eh oui, si le nucléaire est tant décrié maintenant, il faut bien avouer que, après deux guerres mondiales, la peur du nucléaire militaire a probablement évité la guerre entre le bloc soviétique et le bloc occidental [voir ***]. D'un autre côté, le monde d'alors a vécu dans l'angoisse d'une destruction totale par le nucléaire.

Le même nucléaire militaire a permis à la France des années 60/70 de rester indépendante (plus ou moins) de ces deux blocs grâce à sa stratégie dite de dissuasion nucléaire.

Le nucléaire civil issu en grande partie de ce monde militaire a hélas amené avec lui une lourde tradition de secrets qui nous a amené à ce triste nuage de Tchernobyl qui "contournait la France" . Insidieusement, il y eu une augmentation statistiquement visible du nombre de cancers de la thyroïde suite à l'explosion du réacteur de Tchernobyl. Une partie de ces cancers aurait certainement pu être évitée si cette tradition du secret n'avait pas été maintenue par le lobby du nucléaire.

C'est probablement cette même tradition du secret qui fait que la CRIIRAD hurle tant et plus contre les dissimulations et autres désinformations de cette période de liquidation de la centrale de Fukushima japonaise.

Dans les années 60, Paul Baran inventa un réseau
destiné a résister à une guerre nucléaire
afin de rendre le monde plus sûr

Indirectement et presque en opposition, les réseaux à commutation de paquets (par exemple TCP/IP que nous utilisons dans Internet, héritier direct de ces recherches d'alors) ont été développés de manière ouverte et quasiment sans secret par des chercheurs comme Paul Baran avec un but avoué: rendre le réseau résistant à une attaque nucléaire .

Il s'agissait alors et très sérieusement de rendre le monde plus sûr et moins prompt à une guerre nucléaire: En effet, vu la puissance des bombes nucléaires, si un agresseur détruisait le centre de commandement de son ennemi alors ce premier agresseur avait probablement gagné. Il devenait alors tentant d'interpréter les signaux "au plus juste" et d'attaquer le premier quitte à avoir attaqué à tort afin de garantir la victoire. Nous étions alors dans un monde extrêmement dangereux où chacun était très proche d'appuyer sur le bouton nucléaire et cela dans une complète paranoïa. C'est ce monde là que les réseaux de communication résistants aux attaques nucléaires nous ont permis de quitter.

En effet savoir résister à une première attaque nucléaire permet de réinterpréter les signaux, de réengager le dialogue avec l'opposant au cas où il s'agirait d'une manœuvre malencontreuse et ainsi d'avoir une réponse beaucoup plus flexible.

Paul Baran a démontré dans les années 1960 que la redondance des nœuds du réseau était la clé à la survie de celui-ci. La découpe du flux de transport en paquets devenant nécessaire pour facilement rerouter le flux dynamiquement si les nœuds du réseau étaient détruits. Ce fût un long et périlleux parcours...

Plus d'infos dans cet article en anglais de NetworkWorld.com

et dans cette interview en anglais datant de 1990 (date de la naissance du web ;-)

_______________________________

*** extracts from An Interview with Paul Baran (1990):

P13 About network resilience & cold war : " BARAN: Yes. It may be helpful to understand that time period.

• 1. The US and the USSR distrusted one another.

• 2. Each superpower regarded the other as a potential enemy having the capability of mounting a surprise attack.

• 3. The physical vulnerability of the strategic weapons systems at that time created a doctrine in which the counter attack would be launched immediately on detection of an attack.

• 4. Humans and defense systems are highly prone to errors.

• 5. It's too easy to accidentally misread the signals in an environment of mutual distrust and paranoia.

• 6. If we could wait until after attack rather than having to respond too quickly under pressure then the world would be a more stable place. This meant that enough strategic forces would have to survive the first attack to return the unfriendly act.

• 7. This meant as a minimum hardening missile sites and dispersing aircraft, both of which can be done.

• 8. To coordinate the response, to surrender or to accept a surrender to stop a bloody war required a survivable network. But we didn't know how to build survivable networks.

• 9. Our hypothesis was that somehow it should be possible to build a survivable system. Learning how this objective could be accomplished was my personal motivating interest. Almost all my work in this field was completed in the1960-62 time period. It was not done out of intellectual curiosity or a desire to write papers. It was not done in response to a work statement. It was done in response to a most dangerous situation that existed. After 1962 it took another year or two more to respond to the many objections raised, first orally and then in writing.
  

The major defense objective for the last 40 years has been to prevent the world's superpowers from stumbling into World War III. It was an extremely expensive standoff. But, in retrospect, it worked.

The threat of an attack by the USSR today is no longer regarded as a realistic concern.
...
"
P16 About packet switching: "...And then you had to tell them that each packet will find its own route on a statistical basis to get where it wants to go.
After I heard the melodic refrain of "bullshit" often enough I was motivated to go away and write papers to show that algorithms were possible that did in fact allow a short message to contain all the information it needs to know where to go..."

P16:"... O'NEILL: How did the eleven volume report as such start to develop?
BARAN: Where do they come from? Why produce so damn much paper? Good question. Why would anybody in their right mind voluntarily grind out so much paper? I did it only with great reluctance, and in piecemeal fashion.

Here is how it happened. I had this set of briefing charts and would present the concepts throughout the relevant military and R&D community. The responses were mixed. Some thought it great. Many others said something like, "Since it hasn't been done, it probably won't work." More useful were comments like, "It probably won't work because ..." and then would give me a reason. Most times I could answer the question with confidence. And sometimes I was less sure of myself. I would have to go away and think about whether the objection was in fact valid. And, if so, how one would circumvent the problem noted. This made for a lot of detail paper.

It is easy to propose a global concept. It is far more difficult to provide enough details to overcome the hurdles raised by those that say "It ain't gonna work."

The basic network configuration was simple. Avoid any central node. Build a distributed network of nodes, each connected to its neighbor. How much redundancy of connections are needed for survivability? ..."

P17 about Numeric Voice over network: "... O'NEILL: So, at that time, you were trying to include voice along with these other things and make allowances for that all the way through?

BARAN: Yes, why not? I mentioned that at that time there was work going on in Bell Labs, on what is now T-1 digital voice transmission. This proved that high digital data rates were feasible over existing copper pairs of the telephone system. ...

...The most outspoken of the "it ain't gonna work" school were the most senior AT&T technical management people. AT&T at that time held a total monopoly of all long distance communications within the US."

P19 about AT&T: "... AT&T was in an awkward position here as the workability of such a network constituted a multifaceted threat. AT&T had long denied that there were any vulnerability problems with their network. They even blocked the military from the data needed for proper analyses. Their claims of invincibility were based upon distortions of fact, concealed weaknesses, and statements phrased in the common public relations style of the 1950s and '60s. Deny that any problem of any sort exists. Keep it all positive...back in the early '60s denial and concealment of problems at all costs were considered as proper corporate policy. ..."

P20 about AT&T: " ... I think that AT&T's views were most honestly summarized by AT&T's Jack Osterman after an exasperating session with me. "First, it can't possibly work, and if it did, damned if we are going to allow creation of a competitor to ourselves."
In the early days, anything that AT&T didn't make couldn't be connected to the telephone system. A company that made a plastic mouthpiece cover called HushaPhone, to allow voice privacy in large offices, was sued in each state of the Union in the 1950s. An undertaker who gave out free plastic phone book covers was sued by the telephone company. ..."

P21 about AT&T: "... Trying to stop technical innovation is like trying to stop a river. You can dam it up, but as the water gets higher and higher, watch out when the dam breaks. It was this attitude of arrogance, I believe, that lead to the unfortunate later fracturing of AT&T. It might not have occurred if AT&T had allowed a modicum of freedom to others to use their network as is now commonplace. ..."

P21 Trying to convince: ".. I recall walking into a room of AT&T engineers and started to describe how the network would work.

One of the older analog transmission guys said, "Wait a minute son, let's try that again. You mean you open the switch here before the traffic has emerged from the end of the cross country circuit."

I would say, "Yes."

He raised his eyebrows, looked at the others shaking their heads and said, "Son, this is how a telephone works."

It was pretty patronizing from time to time, until I learned to use Western Electric part numbers. This greatly improved the interaction. At least I didn't start out with an image of complete stupidity.

Nevertheless, I don't think we were ever really taken seriously by AT&T during that time..."

P23 About telecom switches : "... "Why are these things so big?" "Why do these switching systems require rooms and rooms of stuff?"
Answer: much of the capacity is journalling and storing traffic that passed through the node.

"Well, why do you want to store all these transactions?"
"Well, we always have in the past."

It seems that the real reason that every communications center office was built with that burdensome capability was to be able to prove that lost traffic was someone else's fault.

"I can prove it left here okay." I learned that these and similar antiquated requirements could be thrown out if we were able to operate in real time. The big switches were implicitly designed for an era where bandwidth was very scarce..."

P25 About publishing :"... -- the average technical paper is read by about six people. At first you laugh. Then you say wait a minute, how could that possibly be so? And, if you think what reading a paper really entails; not skimming it, but sitting down and reading it from beginning to end, including the references ...

... O'NEILL: Were the reports classified? There is conflicting information in the literature about the status of the reports.

BARAN: Eleven reports of the series were not classified. Two were classified. So, instead of eleven reports there really were thirteen reports. Two of them came out later and were classified. ..."

P26:"... BARAN: We chose not to classify this work and also chose not to patent the work. We felt that it properly belonged in the public domain.

Not only would the US be safer with a survivable command and control system, the US would be even safer if the USSR also had a survivable command and control system as well!

There was never any desire for classification of this work ..."

P30:"... O'NEILL: I just want to be sure I get the dates right. Is that all part of this long review process you were talking about, once the reports got written?

BARAN: Yes. The drafts were essentially compiled in 1962. Almost everything was done. It was a matter of finishing the loose details for publication. ..."

P40 About Donald Davies: "... O'NEILL: Did you know Donald Davies over in England?
BARAN: I met him after the fact, many years later. I did not know him at the time.

He had a nice way of putting it, he said, "Well, you may have got there first, but I got the name first."

He is correct. Packet switching is a far more graceful name than Distributed Adaptive Message Block Switching. Precise, economic, and very British.

I take my hat off to him for coming up with such a wonderful name. ..."

P41 About ARPANet: "... The first period, you should pardon the expression, was the "Baran Era... or pre-ARPANET." Everything beyond that date is the ARPANET Era. And, as I said at that meeting, "Hey fellas, I didn't do the ARPANET. That was Larry Roberts." (I am from time to time unfortunately given credit for things I haven't done, and conversely, I lived only in the period 1960 to about 1967 at the latest ..."