3 ms·

"not sure the author realizes TCP is a virtual circuit protocol" That struck me too -- kind of undermining the simple narrative of "connection-full telecom big

by mturmon 13y ago

"not sure the author realizes TCP is a virtual circuit protocol" That struck me too -- kind of undermining the simple narrative of "connection-full telecom biggies vs. connection-less insurgents". It would have been worth a note in the article, because it's in IEEE Spectrum after all. Not a networking pro, but I believe the converse is also true, that OSI has specifically connection-less protocol elements (e.g., CLNS) that are at a lower level in its own hierarchy, and more equivalent to IP in TCP/IP. I just saw part of an interview with Cerf (http://www.internet-history.info/media-library/mediaitem/1003-vint-cerf-on-the-history-of-packets.html http://www.internet-history.info/media-library/mediaitem/100...), in which he said that part of the motivation for packet switching is to maintain command and control in the chaos of a post-nuclear-strike world. That explains why the person connected with packet switching (Paul Baran) was at RAND, which was not a networking place, but very much a "let's plan for the apocalypse" place.

hga 13y ago
Well, there was a big controversy over basing your protocols on datagrams with stateless nodes in the middle. The CCITT's X.25 didn't. When I was working for Lisp Machines Inc. (LMI) in 1982-3, when TCP/IP was being mandated for the Arpanet (and therefore Lisp Machines, sometime I worked on at LMI), I can remember the father of the Lisp Machine, Richard Greenblatt, arguing that it wouldn't work because too many packets would get lost in the middle. With stateless nodes---a necessary virtue for the small memory minicomputers the Arpanet was built on---re-transmission has to come from the endpoints, and if the error rate was too high it would have failed to be practical. Look at TCP over ATM for a modern example of this sort of lossage. I assume Vint Cerf et. al. did the math based on observed error rates, then tested it to make sure (TCP/IP and NCP ran side by side for some time on the Arpanet) and Greenblatt, who was rather distracted designing his 3rd generation Lisp Machine, was going by general principles.
derleth 13y ago
Actually, it seems ARPANET was not designed to survive nuclear war: http://www.internetsociety.org/internet/what-internet/history-internet/brief-history-internet http://www.internetsociety.org/internet/what-internet/histor... > It was from the RAND study that the false rumor started claiming that the ARPANET was somehow related to building a network resistant to nuclear war. This was never true of the ARPANET, only the unrelated RAND study on secure voice considered nuclear war. However, the later work on Internetting did emphasize robustness and survivability, including the capability to withstand losses of large portions of the underlying networks. Charles Herzfeld, ARPA Director (1965–1967), said: http://inventors.about.com/library/inventors/bl_Charles_Herzfeld.htm http://inventors.about.com/library/inventors/bl_Charles_Herz... > The ARPANET was not started to create a Command and Control System that would survive a nuclear attack, as many now claim. To build such a system was, clearly, a major military need, but it was not ARPA's mission to do this; in fact, we would have been severely criticized had we tried. Rather, the ARPANET came out of our frustration that there were only a limited number of large, powerful research computers in the country, and that many research investigators, who should have access to them, were geographically separated from them. Paul Baran: http://www.wired.com/wired/archive/9.03/baran.html http://www.wired.com/wired/archive/9.03/baran.html > Wired: The myth of the Arpanet - which still persists - is that it was developed to withstand nuclear strikes. That's wrong, isn't it? > Paul Baran: Yes. Bob Taylor had a couple of computer terminals speaking to different machines, and his idea was to have some way of having a terminal speak to any of them and have a network. That's really the origin of the ARPANET. The method used to connect things together was an open issue for a time.
- mturmon 13y ago
  Cerf does say that part of the reasoning behind packet switching was robust command and control in the event of nuclear war. Cerf doesn't say that ARPANET, in itself, was designed for that (and neither did I). This is also consistent with the following quote in the Baran interview you cite: Baran: But the origin of packet switching itself is very much Cold War. The argument was: To have a credible defense, you had to be able to withstand an attack and at least be able to show you had the capability to return the favor in kind. So there is no disagreement on that point, and your corrective "Actually, ..." is misplaced.

by mturmon 13y ago

hga 13y ago

Well, there was a big controversy over basing your protocols on datagrams with stateless nodes in the middle. The CCITT's X.25 didn't. When I was working for Lisp Machines Inc. (LMI) in 1982-3, when TCP/IP was being mandated for the Arpanet (and therefore Lisp Machines, sometime I worked on at LMI), I can remember the father of the Lisp Machine, Richard Greenblatt, arguing that it wouldn't work because too many packets would get lost in the middle. With stateless nodes---a necessary virtue for the small memory minicomputers the Arpanet was built on---re-transmission has to come from the endpoints, and if the error rate was too high it would have failed to be practical. Look at TCP over ATM for a modern example of this sort of lossage. I assume Vint Cerf et. al. did the math based on observed error rates, then tested it to make sure (TCP/IP and NCP ran side by side for some time on the Arpanet) and Greenblatt, who was rather distracted designing his 3rd generation Lisp Machine, was going by general principles.

derleth 13y ago

Actually, it seems ARPANET was not designed to survive nuclear war: http://www.internetsociety.org/internet/what-internet/history-internet/brief-history-internet http://www.internetsociety.org/internet/what-internet/histor... > It was from the RAND study that the false rumor started claiming that the ARPANET was somehow related to building a network resistant to nuclear war. This was never true of the ARPANET, only the unrelated RAND study on secure voice considered nuclear war. However, the later work on Internetting did emphasize robustness and survivability, including the capability to withstand losses of large portions of the underlying networks. Charles Herzfeld, ARPA Director (1965–1967), said: http://inventors.about.com/library/inventors/bl_Charles_Herzfeld.htm http://inventors.about.com/library/inventors/bl_Charles_Herz... > The ARPANET was not started to create a Command and Control System that would survive a nuclear attack, as many now claim. To build such a system was, clearly, a major military need, but it was not ARPA's mission to do this; in fact, we would have been severely criticized had we tried. Rather, the ARPANET came out of our frustration that there were only a limited number of large, powerful research computers in the country, and that many research investigators, who should have access to them, were geographically separated from them. Paul Baran: http://www.wired.com/wired/archive/9.03/baran.html http://www.wired.com/wired/archive/9.03/baran.html > Wired: The myth of the Arpanet - which still persists - is that it was developed to withstand nuclear strikes. That's wrong, isn't it? > Paul Baran: Yes. Bob Taylor had a couple of computer terminals speaking to different machines, and his idea was to have some way of having a terminal speak to any of them and have a network. That's really the origin of the ARPANET. The method used to connect things together was an open issue for a time.

mturmon 13y ago
Cerf does say that part of the reasoning behind packet switching was robust command and control in the event of nuclear war. Cerf doesn't say that ARPANET, in itself, was designed for that (and neither did I). This is also consistent with the following quote in the Baran interview you cite: Baran: But the origin of packet switching itself is very much Cold War. The argument was: To have a credible defense, you had to be able to withstand an attack and at least be able to show you had the capability to return the favor in kind. So there is no disagreement on that point, and your corrective "Actually, ..." is misplaced.