[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:04.08,Default,,0000,0000,0000,,So, welcome back. Now the purpose, of\Ncourse, of all this stuff that you had in
Dialogue: 0,0:00:04.08,0:00:09.09,Default,,0000,0000,0000,,your office, and all that banging, and all\Nthe sqweeee squealing noise where we're
Dialogue: 0,0:00:09.09,0:00:15.05,Default,,0000,0000,0000,,sending the data across the across the\Nphone using sound. All the purpose was the
Dialogue: 0,0:00:15.05,0:00:21.01,Default,,0000,0000,0000,,fact that computation was rare and\Nextremely valuable. And for scientists who
Dialogue: 0,0:00:21.01,0:00:27.00,Default,,0000,0000,0000,,were trying to solve research problems,\Naccess to computers was essential. And you
Dialogue: 0,0:00:27.00,0:00:33.02,Default,,0000,0000,0000,,couldn't all sit, sort of in a little ring\Naround the computer. It's so we would have
Dialogue: 0,0:00:33.02,0:00:38.09,Default,,0000,0000,0000,,phones in our offices and we would, you\Nknow, work in our office, just like I'm
Dialogue: 0,0:00:38.09,0:00:45.02,Default,,0000,0000,0000,,working in my office right now. But there\Nwasn't enough computation [inaudible], any
Dialogue: 0,0:00:45.02,0:00:51.06,Default,,0000,0000,0000,,work in my office so I had to connect to\Nsomething outside. And so this was the way
Dialogue: 0,0:00:51.06,0:00:57.08,Default,,0000,0000,0000,,of science. And, it, it, it was the fact\Nthat comp-, computing was rare, and access
Dialogue: 0,0:00:57.08,0:01:03.07,Default,,0000,0000,0000,,to computing was a critical enabler of\Nscientific research. Now, I'd mentioned
Dialogue: 0,0:01:03.07,0:01:09.08,Default,,0000,0000,0000,,earlier, data transfer with leased lines.\NAnd so, while it. You tended to interact
Dialogue: 0,0:01:09.08,0:01:14.04,Default,,0000,0000,0000,,with the computer that was rather local,\Ngeographically to you because you could
Dialogue: 0,0:01:14.04,0:01:19.01,Default,,0000,0000,0000,,have this permanent dial up connection all\Nday long without paying a permanent
Dialogue: 0,0:01:19.01,0:01:23.10,Default,,0000,0000,0000,,charge. If you were a bank, or you had\Nsome really critical need you would lease
Dialogue: 0,0:01:23.10,0:01:28.66,Default,,0000,0000,0000,,some line from the phone company 24 hours\Na day, seven days a week so you could send
Dialogue: 0,0:01:28.66,0:01:33.04,Default,,0000,0000,0000,,data across that anytime that you wanted.\NNo dialing, it's always connected and,
Dialogue: 0,0:01:33.04,0:01:38.62,Default,,0000,0000,0000,,after while, I mean you can send data, we\Nacademics wanted to communicate with each
Dialogue: 0,0:01:38.62,0:01:43.94,Default,,0000,0000,0000,,other. It would be nice to be able to use\Neach other's computers, but we tended to
Dialogue: 0,0:01:43.94,0:01:47.90,Default,,0000,0000,0000,,have too much, but sometimes we don't want\Nto send a file, or some email, or
Dialogue: 0,0:01:47.90,0:01:52.62,Default,,0000,0000,0000,,something like that. And so this led to\Nthe invention and the creation of store
Dialogue: 0,0:01:52.62,0:01:57.77,Default,,0000,0000,0000,,and forward networking. And how this would\Nwork is we would sort of, you would sort
Dialogue: 0,0:01:57.77,0:02:03.80,Default,,0000,0000,0000,,of have some thing and you would use a\Nmodem to do all your dialing, like that. I
Dialogue: 0,0:02:03.80,0:02:08.96,Default,,0000,0000,0000,,mean maybe they had paper and, and didn't.\NThat looks a little too advanced, but you
Dialogue: 0,0:02:08.96,0:02:13.18,Default,,0000,0000,0000,,would have some geographically local\Ncomputer that was your, sort of the compu
Dialogue: 0,0:02:13.18,0:02:17.24,Default,,0000,0000,0000,,ter that did most of your work. You didn't\Nhave a computer in your office, you just
Dialogue: 0,0:02:17.24,0:02:21.24,Default,,0000,0000,0000,,had a connection to the single campus\Ncomputer or on a few campus computers. And
Dialogue: 0,0:02:21.24,0:02:25.75,Default,,0000,0000,0000,,then what universities would do is they\Nwould lease a line. And then we could
Dialogue: 0,0:02:25.75,0:02:31.18,Default,,0000,0000,0000,,send, write a mail program that would run\Non this computer and then would send mail
Dialogue: 0,0:02:31.18,0:02:36.32,Default,,0000,0000,0000,,and then everyone else would read it. And\Nwhat happened was is we sort of started
Dialogue: 0,0:02:36.32,0:02:41.84,Default,,0000,0000,0000,,stringing them together in these snakelike\Nstructures and so, we could share this.
Dialogue: 0,0:02:41.84,0:02:47.54,Default,,0000,0000,0000,,And so let me just show you kind of how\Nthe store and forward networking works. So
Dialogue: 0,0:02:47.54,0:02:52.32,Default,,0000,0000,0000,,somebody sends a mail message in. Now\Nlet's say, let's say we are this bottom
Dialogue: 0,0:02:52.32,0:02:56.98,Default,,0000,0000,0000,,person down here, okay. And so someone\Nelse has sent a mail message in, they're
Dialogue: 0,0:02:56.98,0:03:01.46,Default,,0000,0000,0000,,sitting in there. And now the next person\Nsends a mail message in and now ten
Dialogue: 0,0:03:01.46,0:03:05.79,Default,,0000,0000,0000,,seconds later, you send a mail message in.\NThose mail messengers are sitting in a
Dialogue: 0,0:03:05.79,0:03:10.66,Default,,0000,0000,0000,,cue. They're waiting just like waiting in\Nline at the bus stop or waiting in line in
Dialogue: 0,0:03:10.66,0:03:15.27,Default,,0000,0000,0000,,a train station. Waiting in line for a cup\Nof coffee at Starbucks. They're waiting in
Dialogue: 0,0:03:15.27,0:03:19.50,Default,,0000,0000,0000,,line, and what would happen is the\Ncomputer that was our local computer would
Dialogue: 0,0:03:19.50,0:03:24.50,Default,,0000,0000,0000,,then start sending that data across the\Nline. Okay, and slowly but surely it would
Dialogue: 0,0:03:24.50,0:03:29.69,Default,,0000,0000,0000,,take awhile. And everyone else had to sit\Nand wait. Your poor message is last in
Dialogue: 0,0:03:29.69,0:03:34.20,Default,,0000,0000,0000,,line so you have to wait. So finally this\Nmessage gets across the closest link. And
Dialogue: 0,0:03:34.20,0:03:38.88,Default,,0000,0000,0000,,then the, the next message starts being\Nsent and you have to wait for that message
Dialogue: 0,0:03:38.88,0:03:43.50,Default,,0000,0000,0000,,and wait and wait and wait and wait and\Nwait. Wait and wait and wait! Hey wait.
Dialogue: 0,0:03:43.50,0:03:48.81,Default,,0000,0000,0000,,Okay. Now its finally your turn. So your\Nmessage finally gets to use the one
Dialogue: 0,0:03:48.81,0:03:53.16,Default,,0000,0000,0000,,connected line. So they, they are sought\Nof stand in line until your turn
Dialogue: 0,0:03:53.16,0:03:57.74,Default,,0000,0000,0000,,[inaudible] runs acrossed. And they all,\Nthese messages aren't destined for just
Dialogue: 0,0:03:57.74,0:04:02.93,Default,,0000,0000,0000,,one computer away, then they got to go\Nthrough the whole thing again, move across
Dialogue: 0,0:04:02.93,0:04:07.75,Default,,0000,0000,0000,,the next link until you know eventually\Nyou move across one link over here and
Dialogue: 0,0:04:07.75,0:04:12.40,Default,,0000,0000,0000,,then go another, and then finally talks to\Nthe people who get their email. So its a
Dialogue: 0,0:04:12.40,0:04:17.42,Default,,0000,0000,0000,,sought of dedicat ed line and you had to\Nstand in line to get your chance. And the
Dialogue: 0,0:04:17.42,0:04:23.14,Default,,0000,0000,0000,,key thing here is each of these lease\Nlines has a fixed cost 24 hours a day
Dialogue: 0,0:04:23.14,0:04:28.94,Default,,0000,0000,0000,,seven days a week, and it's very dependent\Non the distance, so we saw a weird
Dialogue: 0,0:04:28.94,0:04:33.46,Default,,0000,0000,0000,,phenomena. ≫> And that is. ≫>\NIf we could add hops, it would slow our
Dialogue: 0,0:04:33.46,0:04:38.49,Default,,0000,0000,0000,,message down, but it would reduce our cost\Ngreatly. And so let's just say we have
Dialogue: 0,0:04:38.49,0:04:43.98,Default,,0000,0000,0000,,Michigan State University, which is where\NI got all my degrees from. University of
Dialogue: 0,0:04:43.98,0:04:48.94,Default,,0000,0000,0000,,Michigan here in Ann Arbor, which is where\NI work. And let's say, you know, we're
Dialogue: 0,0:04:48.94,0:04:54.08,Default,,0000,0000,0000,,connecting to the rest of the world, and\Nwe're going through Cleveland, where Case
Dialogue: 0,0:04:54.08,0:04:59.57,Default,,0000,0000,0000,,Western Reserve is. Case Western Reserve\Nwas the early innovator in, in networking,
Dialogue: 0,0:04:59.57,0:05:04.02,Default,,0000,0000,0000,,and so we have two leased lines with a\Ncertain distance, right? One from East
Dialogue: 0,0:05:04.02,0:05:08.65,Default,,0000,0000,0000,,Lansing to Ann Arbor and one from Ann\NArbor to Cleveland and so we're sharing
Dialogue: 0,0:05:08.65,0:05:14.11,Default,,0000,0000,0000,,the cost of these lines between three\Nschools and we can all kind of connect to
Dialogue: 0,0:05:14.11,0:05:19.43,Default,,0000,0000,0000,,the rest of the internet, all connect to\Nthe rest of the internet out here and, and
Dialogue: 0,0:05:19.43,0:05:24.03,Default,,0000,0000,0000,,we just, some of us have, are farther\Naway, and so we take longer. The folks in
Dialogue: 0,0:05:24.03,0:05:28.92,Default,,0000,0000,0000,,Cleveland are closer. Like all the rest of\Nthe connection to like the East Coast and
Dialogue: 0,0:05:28.92,0:05:34.96,Default,,0000,0000,0000,,the West Coast come through, say like here\NCleveland, but if we can simply convince
Dialogue: 0,0:05:34.96,0:05:43.12,Default,,0000,0000,0000,,somebody in between us like say Toledo to\Nadd a connection. Now of course. Of
Dialogue: 0,0:05:43.12,0:05:51.10,Default,,0000,0000,0000,,course, this, [inaudible] Give me green.\NThere we go.'Course this line probably
Dialogue: 0,0:05:51.10,0:05:56.31,Default,,0000,0000,0000,,goes, probably went around when we just\Nwent straight to Cleveland, here. But
Dialogue: 0,0:05:56.31,0:06:01.82,Default,,0000,0000,0000,,basically if we can convince Toledo to\Nsort of put in their computer and hold
Dialogue: 0,0:06:01.82,0:06:06.89,Default,,0000,0000,0000,,onto our messages for a while, we could\Nsend now one hop, two hops, three hops.
Dialogue: 0,0:06:06.89,0:06:12.17,Default,,0000,0000,0000,,But the cost now is not that different,\Nbecause the original long line between Ann
Dialogue: 0,0:06:12.17,0:06:16.64,Default,,0000,0000,0000,,Arbor and Cleveland was distance\Nsensitive. And, so, you can think of this
Dialogue: 0,0:06:16.64,0:06:21.80,Default,,0000,0000,0000,,as, you can get this almost for free. And\Nnow we have a whole additional university.
Dialogue: 0,0:06:21.80,0:06:26.71,Default,,0000,0000,0000,,Both to send stuff to, and they can send\Nto the whole world as well. And so this
Dialogue: 0,0:06:26.71,0:06:31.87,Default,,0000,0000,0000,,motivation to effectively take the same c\Nost, and now basically we're taking this
Dialogue: 0,0:06:31.87,0:06:36.78,Default,,0000,0000,0000,,cost, and dividing it by four schools. And\Nif you start thinking about it, it doesn't
Dialogue: 0,0:06:36.78,0:06:40.86,Default,,0000,0000,0000,,take long to say, "You know what, let's\Nput one here, one here, one here, one
Dialogue: 0,0:06:40.86,0:06:45.59,Default,,0000,0000,0000,,here, and one here." Because the cost of\Nthe phone company isn't that different.
Dialogue: 0,0:06:45.59,0:06:50.18,Default,,0000,0000,0000,,You can think of each of these as adding\Nsome delay to your message. You know, and
Dialogue: 0,0:06:50.18,0:06:54.87,Default,,0000,0000,0000,,given the fact that each of these\Nrepresents an outbound queue of messages
Dialogue: 0,0:06:54.87,0:07:00.48,Default,,0000,0000,0000,,that are waiting to be sent, there's some\Ndelay. There's some cost adding this, but
Dialogue: 0,0:07:00.48,0:07:05.93,Default,,0000,0000,0000,,It's so much cheaper. So our faculty have\Nto wait another twenty minutes to get
Dialogue: 0,0:07:05.93,0:07:11.13,Default,,0000,0000,0000,,their mail through if we can bring that\Nmany more universities on. And so this
Dialogue: 0,0:07:11.13,0:07:15.88,Default,,0000,0000,0000,,just works out. There's this sorta\Nmotivation that if you can find an
Dialogue: 0,0:07:15.88,0:07:19.99,Default,,0000,0000,0000,,intermediate person, geographically\Nintermediate school or university or
Dialogue: 0,0:07:19.99,0:07:25.13,Default,,0000,0000,0000,,company, and you can add them in, you can\Nreplace one long link with two short
Dialogue: 0,0:07:25.13,0:07:30.80,Default,,0000,0000,0000,,links. And this led to long chains of\Nmail. And so from the mid 70s to the late
Dialogue: 0,0:07:30.80,0:07:37.10,Default,,0000,0000,0000,,80s most academics were communicating\Nthrough a network that was like this. It
Dialogue: 0,0:07:37.10,0:07:43.45,Default,,0000,0000,0000,,typically was email and I recall when I\Nfirst started to use national email. It
Dialogue: 0,0:07:43.45,0:07:49.51,Default,,0000,0000,0000,,took a long time for mail to go back and\Nforth but it was actually quite magical I
Dialogue: 0,0:07:49.51,0:07:54.10,Default,,0000,0000,0000,,mean who cares if it took an hour. Now we\Nexpect it in three seconds. We send an
Dialogue: 0,0:07:54.10,0:07:58.24,Default,,0000,0000,0000,,email and hit the refresh buttons, hurry\Nup, hurry up. You know, it could be hours,
Dialogue: 0,0:07:58.24,0:08:02.29,Default,,0000,0000,0000,,it could be days if you were going far\Nenough and your message was long enough
Dialogue: 0,0:08:02.29,0:08:06.28,Default,,0000,0000,0000,,and you end up behind too many queues. And\Nso you had this one computer locally and
Dialogue: 0,0:08:06.28,0:08:09.86,Default,,0000,0000,0000,,every once in a while you'd do most of\Nyour communication computation locally.
Dialogue: 0,0:08:09.86,0:08:14.30,Default,,0000,0000,0000,,And every once in a while you would fire a\Nnote off and that would kind of fight its
Dialogue: 0,0:08:14.30,0:08:18.57,Default,,0000,0000,0000,,way through all those successive\Nconnections. This is sort of the life in
Dialogue: 0,0:08:18.57,0:08:24.09,Default,,0000,0000,0000,,the early 1980s. One of the, most widely\Ndistributed networks of this kind was a
Dialogue: 0,0:08:24.09,0:08:29.02,Default,,0000,0000,0000,,thing called Bitnet. And Princeton was\Nkinda the hub of this and these tendrils
Dialogue: 0,0:08:29.02,0:08:33.66,Default,,0000,0000,0000,,of connections ran out from Princeton. And\Nby connecting to a, a network with lots of
Dialogue: 0,0:08:33.66,0:08:38.48,Default,,0000,0000,0000,,oth er folks, then you had more people to\Ntalk to. And the more people that you,
Dialogue: 0,0:08:38.48,0:08:43.54,Default,,0000,0000,0000,,that were connected the cheaper that it\Nwas for everybody. So it was a pretty, it
Dialogue: 0,0:08:43.54,0:08:48.41,Default,,0000,0000,0000,,was the perfect kinda thing that caused\Npeople and com-, universities to want to
Dialogue: 0,0:08:48.41,0:08:52.84,Default,,0000,0000,0000,,work together, because together their\Nshared cost was much, much lower than to,
Dialogue: 0,0:08:52.84,0:08:58.00,Default,,0000,0000,0000,,to provide this uniform connectivity and\Nemail. So at the same time, during that
Dialogue: 0,0:08:58.00,0:09:04.28,Default,,0000,0000,0000,,same period, where most of us were using\Nstore and forward network, with our one on
Dialogue: 0,0:09:04.28,0:09:09.56,Default,,0000,0000,0000,,campus computer, a bunch of computer\Nscientists were funded by DARPA. The
Dialogue: 0,0:09:09.56,0:09:14.48,Default,,0000,0000,0000,,Defense Advanced Research Projects\NAdministration, to imagine a different
Dialogue: 0,0:09:14.48,0:09:20.56,Default,,0000,0000,0000,,kind of network. And the idea was direct\Nconnections are expensive. The long trails
Dialogue: 0,0:09:20.56,0:09:26.17,Default,,0000,0000,0000,,of store and forward networks, they're\Nvery slow, and if you had a giant message
Dialogue: 0,0:09:26.17,0:09:32.06,Default,,0000,0000,0000,,that you got behind, then what, how do you\Nget past that. It could clog the system up
Dialogue: 0,0:09:32.06,0:09:37.32,Default,,0000,0000,0000,,for, for hours, if not days. And, and how\Ndo you keep from failures breaking the
Dialogue: 0,0:09:37.32,0:09:42.44,Default,,0000,0000,0000,,entire system? If you think about a store\Nand forward network, one computer going
Dialogue: 0,0:09:42.44,0:09:47.52,Default,,0000,0000,0000,,down would cause data to back up on both\Nsides of that computer until it's done.
Dialogue: 0,0:09:47.52,0:09:52.39,Default,,0000,0000,0000,,And so, you don't really wanna have one\Noutage and, and how if we have sort of
Dialogue: 0,0:09:52.39,0:09:57.46,Default,,0000,0000,0000,,instead, instead of just a few messages,\Nwhat if we just wanted all the messages to
Dialogue: 0,0:09:57.46,0:10:03.21,Default,,0000,0000,0000,,go simultaneously, so that there's more of\Na fair allocation of the network, rather
Dialogue: 0,0:10:03.21,0:10:09.12,Default,,0000,0000,0000,,than whoever gets there first gets it all\Nuntil they're done with it. And, and so
Dialogue: 0,0:10:09.12,0:10:14.95,Default,,0000,0000,0000,,Darpa wanted to solve the problem of\Noutages. You know, many will say that it
Dialogue: 0,0:10:14.95,0:10:21.55,Default,,0000,0000,0000,,had to do with, battlefield conditions,\Nwhich is probably true They expected that
Dialogue: 0,0:10:21.55,0:10:27.78,Default,,0000,0000,0000,,various connections would go out in, in,\Nin dynamic situations. Maybe it was that
Dialogue: 0,0:10:27.78,0:10:34.03,Default,,0000,0000,0000,,stuff was moving. But also how to be more\Nefficient. And so, in effect, you can kind
Dialogue: 0,0:10:34.03,0:10:40.39,Default,,0000,0000,0000,,of think of this as all a game, where the\Nphone companies own the wire. So everyone,
Dialogue: 0,0:10:40.39,0:10:45.56,Default,,0000,0000,0000,,even government, even military has to\Nlease the wire from the phone companies.
Dialogue: 0,0:10:45.56,0:10:51.27,Default,,0000,0000,0000,,And so everyone is like doing research to\Nfigure out or creating systems to figure
Dialogue: 0,0:10:51.27,0:10:56.62,Default,,0000,0000,0000,,how not to pay t he phone company so much\Nmoney, okay. So these research networks,
Dialogue: 0,0:10:56.62,0:11:02.80,Default,,0000,0000,0000,,and so if we look for example at this one\Ndown here by 1972 they had this network. I
Dialogue: 0,0:11:02.80,0:11:08.40,Default,,0000,0000,0000,,have my, I, yes I got a caller. So they\Nhave this network by 1972 and it's got,
Dialogue: 0,0:11:08.40,0:11:14.08,Default,,0000,0000,0000,,like some [inaudible] right around twelve,\Nfourteen, fifteen hosts in it, and it goes
Dialogue: 0,0:11:14.08,0:11:19.03,Default,,0000,0000,0000,,cross-country. Now, now, the, the key\Nabout this is in 1972 to have leased lines
Dialogue: 0,0:11:19.03,0:11:24.43,Default,,0000,0000,0000,,that were up 24 hours a day, seven days a\Nweek, all the way across the country? Very
Dialogue: 0,0:11:24.43,0:11:29.26,Default,,0000,0000,0000,,expensive. But hey, it's a government\Nproject, and the government says this is
Dialogue: 0,0:11:29.26,0:11:34.17,Default,,0000,0000,0000,,important so we're gonna spend the money\Nbecause, so we're imagining battlefield
Dialogue: 0,0:11:34.17,0:11:39.38,Default,,0000,0000,0000,,communications of the future and our own\Nability to do computations so they could
Dialogue: 0,0:11:39.38,0:11:44.10,Default,,0000,0000,0000,,have comp-, computational equipment all\Nover the place. So this was very
Dialogue: 0,0:11:44.10,0:11:49.36,Default,,0000,0000,0000,,expensive, but research dollars were being\Nflooded into it, because the q, they were
Dialogue: 0,0:11:49.36,0:11:54.29,Default,,0000,0000,0000,,solving a research question. If you just\Nthink about this as a network, it was not
Dialogue: 0,0:11:54.29,0:11:58.64,Default,,0000,0000,0000,,all [laugh], it wasn't sorta like, it was\Nso costly that the average person wouldn't
Dialogue: 0,0:11:58.64,0:12:03.34,Default,,0000,0000,0000,,like, pay $fifteen a month to use it. It\Nwould just be that costly. But it's okay.
Dialogue: 0,0:12:03.34,0:12:08.46,Default,,0000,0000,0000,,Now if you look at this, you see that\Nacross the United States, there was always
Dialogue: 0,0:12:08.46,0:12:12.44,Default,,0000,0000,0000,,at least one connection. They had three\Ncross country links with totally
Dialogue: 0,0:12:12.44,0:12:17.38,Default,,0000,0000,0000,,independent cross country links, with the\Nideas that you could take one of these
Dialogue: 0,0:12:17.38,0:12:21.89,Default,,0000,0000,0000,,things out, and you could still be\Nfunctioning. So they, they were able to
Dialogue: 0,0:12:21.89,0:12:26.80,Default,,0000,0000,0000,,research all these things right, as well\Nas the efficiency problem, which they
Dialogue: 0,0:12:26.80,0:12:32.50,Default,,0000,0000,0000,,solved using packet switching. So, by the\Nmid 70's there was quite a few folks on
Dialogue: 0,0:12:32.50,0:12:37.75,Default,,0000,0000,0000,,this. And for a group of people they just\Nstarted using it in production. It was
Dialogue: 0,0:12:37.75,0:12:42.65,Default,,0000,0000,0000,,pretty cool, right? If you were, if you\Nwere one of these universities or
Dialogue: 0,0:12:42.65,0:12:47.80,Default,,0000,0000,0000,,companies, you had a pretty cool,\Nfuturistic world. You could, you could
Dialogue: 0,0:12:47.80,0:12:53.30,Default,,0000,0000,0000,,send email and get an answer back in two\Nminutes, or a minute, or 30 seconds, even.
Dialogue: 0,0:12:53.30,0:12:58.52,Default,,0000,0000,0000,,And so it was kind of this futuristic\Nworld that was heavily subsidized by the
Dialogue: 0,0:12:58.52,0:13:04.56,Default,,0000,0000,0000,,government in the name of researching. And\Nso there are two essential things that
Dialogue: 0,0:13:04.56,0:13:10.75,Default,,0000,0000,0000,,really came out of this research. And one\Nis the notion of what was called Packet
Dialogue: 0,0:13:10.75,0:13:16.22,Default,,0000,0000,0000,,Switching. Packet Switching basically\Neliminates the problem where once the
Dialogue: 0,0:13:16.22,0:13:22.07,Default,,0000,0000,0000,,message starts using that leased line\Nwire, you have to wait till they're done.
Dialogue: 0,0:13:22.07,0:13:27.93,Default,,0000,0000,0000,,As, as I showed in that in that store and\Nforward. What you want is to be able to
Dialogue: 0,0:13:27.93,0:13:33.10,Default,,0000,0000,0000,,send little pieces. Break the messages up\Ninto little pieces, and then they, they
Dialogue: 0,0:13:33.10,0:13:37.74,Default,,0000,0000,0000,,Each, each message has a little bit of the\Nnetwork connectivity and then the next one
Dialogue: 0,0:13:37.74,0:13:42.30,Default,,0000,0000,0000,,comes after it. And so you could have many\Nmessages going at the same time. And a
Dialogue: 0,0:13:42.30,0:13:46.46,Default,,0000,0000,0000,,real long message won't fill up the\Nnetwork, fill up the connection forever
Dialogue: 0,0:13:46.46,0:13:50.78,Default,,0000,0000,0000,,and ever and ever. So it and it also\Nallows, if you to break the message up
Dialogue: 0,0:13:50.78,0:13:55.53,Default,,0000,0000,0000,,into small parts, they can flow over\Ndifferent paths. The other thing that they
Dialogue: 0,0:13:55.53,0:13:59.99,Default,,0000,0000,0000,,figured out was this notion of instead of\Noop, oop, oop come back here, come back
Dialogue: 0,0:13:59.99,0:14:04.23,Default,,0000,0000,0000,,here. Instead of using computers as the\Nintermediate stop points, because in store
Dialogue: 0,0:14:04.23,0:14:08.48,Default,,0000,0000,0000,,and forward you could have a lot of\Nmessages so you tend to store them on
Dialogue: 0,0:14:08.48,0:14:13.41,Default,,0000,0000,0000,,disks. Whereas routers, these packets were\Nsmaller individually than the entire
Dialogue: 0,0:14:13.41,0:14:18.52,Default,,0000,0000,0000,,message and so they didn't need to store\Nthem nearly as long and they didn't need
Dialogue: 0,0:14:18.52,0:14:22.95,Default,,0000,0000,0000,,as much storage. So these are, routers are\Njust a form of computer, right? But they
Dialogue: 0,0:14:22.95,0:14:27.56,Default,,0000,0000,0000,,were specialized for moving just data from\None connection to the other without long
Dialogue: 0,0:14:27.56,0:14:33.40,Default,,0000,0000,0000,,term, without storing that data for a long\Ntime. So, I like to think of packets as
Dialogue: 0,0:14:33.40,0:14:40.78,Default,,0000,0000,0000,,postcards, letters and think of the Packet\NSwitching Network as the postal system. So
Dialogue: 0,0:14:40.78,0:14:47.23,Default,,0000,0000,0000,,let's say, for example, I had a friend,\Nand his name is Glen, and I want to send
Dialogue: 0,0:14:47.23,0:14:52.64,Default,,0000,0000,0000,,him a message. I want to send him a\Nmessage that's hello there, have a nice
Dialogue: 0,0:14:52.64,0:14:57.54,Default,,0000,0000,0000,,day. But I have a limitation. I have\Nlimitation. All I have is postcards that
Dialogue: 0,0:14:57.54,0:15:02.96,Default,,0000,0000,0000,,it can, that can store ten characters on\Nthem, and I have to send my message to
Dialogue: 0,0:15:02.96,0:15:08.53,Default,,0000,0000,0000,,Glenn using only 10-character postcards.\NAnd so, before Glenn and I part ways, we
Dialogue: 0,0:15:08.53,0:15:14.07,Default,,0000,0000,0000,,agree on the following protocol: that I\Nwill take the first ten characters of the
Dialogue: 0,0:15:14.07,0:15:19.59,Default,,0000,0000,0000,,me ssage and put them on one postcard, and\Nthen I will put an address from Chuck to
Dialogue: 0,0:15:19.59,0:15:25.08,Default,,0000,0000,0000,,Glenn, and I'll put a sequence number. So\Nthat says that hey, hey Glenn, here comes
Dialogue: 0,0:15:25.08,0:15:31.07,Default,,0000,0000,0000,,a message, this is part one. Then we take\Nthe next ten characters. And I mark that
Dialogue: 0,0:15:31.07,0:15:37.20,Default,,0000,0000,0000,,as part two, from Chuck to Glen. And then\Nhere's the third part, it's marked as part
Dialogue: 0,0:15:37.20,0:15:42.53,Default,,0000,0000,0000,,three, from Chuck to Glenn. And, so, what\Ncan I do now? Well, I walk out to my post
Dialogue: 0,0:15:42.53,0:15:48.05,Default,,0000,0000,0000,,office box, and I send'em, I just stack'em\Nin. I might stack them neatly in order.
Dialogue: 0,0:15:48.05,0:15:53.54,Default,,0000,0000,0000,,Now, they go through the postal system.\NLike, they get dropped, some get dropped
Dialogue: 0,0:15:53.54,0:15:59.29,Default,,0000,0000,0000,,on the ground. A couple of them get lost.\NOr they end up on the wrong truck. They go
Dialogue: 0,0:15:59.29,0:16:04.51,Default,,0000,0000,0000,,through Kansas City by mistake. Blah,\Nblah, blah, blah, blah, blah, blah. Blah,
Dialogue: 0,0:16:04.51,0:16:09.61,Default,,0000,0000,0000,,blah, blah, blah, blah, blah, blah, blah,\Nblah, blah, blah. But, you know, some days
Dialogue: 0,0:16:09.61,0:16:14.65,Default,,0000,0000,0000,,later. They start arriving at Glen's\Nhouse. And so, Glenn goes out to his post
Dialogue: 0,0:16:14.65,0:16:19.83,Default,,0000,0000,0000,,office box, and he gets a message. It's\Nhello ther-, and it's sequence number one.
Dialogue: 0,0:16:19.84,0:16:25.07,Default,,0000,0000,0000,,So it looks like Chuck is going to send me\Na message, and I've got the first part of
Dialogue: 0,0:16:25.07,0:16:29.78,Default,,0000,0000,0000,,it. That's pretty cool. So then he goes\Nout the next day, and out comes, nice day.
Dialogue: 0,0:16:29.78,0:16:34.60,Default,,0000,0000,0000,,But this is #three. So, because I've\Nnumbered them, Glenn knows that there's
Dialogue: 0,0:16:34.60,0:16:39.57,Default,,0000,0000,0000,,some missing bits, right? So Glenn just\Ncan hold on to them, and leave a little
Dialogue: 0,0:16:39.57,0:16:44.31,Default,,0000,0000,0000,,space on his kitchen table for what he\Nhopes to be message number two. And so
Dialogue: 0,0:16:44.31,0:16:49.01,Default,,0000,0000,0000,,message two finally comes out. And now\NGlen is capable of saying, "Looks like I
Dialogue: 0,0:16:49.01,0:16:53.92,Default,,0000,0000,0000,,got the whole message and I can reassemble\Nthem. And, surprise, surprise. I have just
Dialogue: 0,0:16:53.92,0:16:58.36,Default,,0000,0000,0000,,sent him. With a lot of effort in three\Npackets. Hello there! Have a nice day."
Dialogue: 0,0:16:58.36,0:17:03.56,Default,,0000,0000,0000,,And so this notion of breaking the message\Ninto packets, labeling each packet with a
Dialogue: 0,0:17:03.56,0:17:08.75,Default,,0000,0000,0000,,sequence number, and then sending them to\Nthis network that can take multiple paths,
Dialogue: 0,0:17:08.75,0:17:13.17,Default,,0000,0000,0000,,You can even have a situation where the\Nyou know, the message would go across one
Dialogue: 0,0:17:13.17,0:17:17.98,Default,,0000,0000,0000,,link, it would get lost and then it would,\Nyou know go across a different link. So
Dialogue: 0,0:17:17.98,0:17:21.96,Default,,0000,0000,0000,,you have ways of recovering. You can\Nrecover the messages. We'll talk about
Dialogue: 0,0:17:21.96,0:17:28.28,Default,,0000,0000,0000,,that later as well. So this ends up with a\Nsort of a structure that has these
Dialogue: 0,0:17:28.28,0:17:36.24,Default,,0000,0000,0000,,computers that are specialized routers in\Nthe middle. And the routers have multiple
Dialogue: 0,0:17:36.24,0:17:43.09,Default,,0000,0000,0000,,connections. And if we take a campus, for\Nexample, and the campus has some computers
Dialogue: 0,0:17:43.09,0:17:47.48,Default,,0000,0000,0000,,and we have high-speed networking on this\Ncampus. We have some, you know, stuff in
Dialogue: 0,0:17:47.48,0:17:52.21,Default,,0000,0000,0000,,our offices on the campus, and then we\Nhave some stuff in the machine room and we
Dialogue: 0,0:17:52.21,0:17:56.46,Default,,0000,0000,0000,,talk to these things. And then, somehow,\Nour entire campus has a little spicket to
Dialogue: 0,0:17:56.46,0:18:01.42,Default,,0000,0000,0000,,the outside world and this is our, sort\Nof, campus router and we get this router,
Dialogue: 0,0:18:01.42,0:18:05.67,Default,,0000,0000,0000,,and then there are, sort of, intermediate\Nrouters that are inside the network. And
Dialogue: 0,0:18:05.67,0:18:09.69,Default,,0000,0000,0000,,if you sort of look at a router, a router\Nsort of simply forwards traffic and the
Dialogue: 0,0:18:09.69,0:18:14.71,Default,,0000,0000,0000,,traffic now is these small packets, rather\Nthan whole messages, so you don't need a
Dialogue: 0,0:18:14.71,0:18:18.80,Default,,0000,0000,0000,,disk drive on these, on these routers.\NThere's no disk drive on these routers, so
Dialogue: 0,0:18:18.80,0:18:22.69,Default,,0000,0000,0000,,that they just kind of grab a packet and\Nthey forward it. And the systems are
Dialogue: 0,0:18:22.69,0:18:27.08,Default,,0000,0000,0000,,trained. And the software does not\Noverflow the network. We'll talk about
Dialogue: 0,0:18:27.08,0:18:31.97,Default,,0000,0000,0000,,that later, much later. And so these\Nrouters have these real simple view of the
Dialogue: 0,0:18:31.97,0:18:36.59,Default,,0000,0000,0000,,world, they've got some incoming traffic,\Nthey've got some outgoing traffic,
Dialogue: 0,0:18:36.59,0:18:41.54,Default,,0000,0000,0000,,outgoing traffic. And so they just grab\Nand forward. It's like a intermediate
Dialogue: 0,0:18:41.54,0:18:47.24,Default,,0000,0000,0000,,postal spot, right? They, they grab big\Nthing of. Postcards and books. Send them
Dialogue: 0,0:18:47.24,0:18:53.70,Default,,0000,0000,0000,,to the right place and, and they get where\Nthey do and so eventually the data gets.
Dialogue: 0,0:18:53.70,0:18:58.38,Default,,0000,0000,0000,,Getting a little sloppy, getting a little\Nmessy, here. Eventually, the data sort of
Dialogue: 0,0:18:58.38,0:19:03.30,Default,,0000,0000,0000,,is broken up, finds its way to the other\Nend, and then dumps out in some campus
Dialogue: 0,0:19:03.30,0:19:07.74,Default,,0000,0000,0000,,local area network and then somebody sees\Nthe data on the far end, okay? And so it
Dialogue: 0,0:19:07.74,0:19:12.66,Default,,0000,0000,0000,,might different, take different routes,\Nyou know? It might get lost that might
Dialogue: 0,0:19:12.66,0:19:17.09,Default,,0000,0000,0000,,crash and then it has to get sent again on\Na different route. And so these things,
Dialogue: 0,0:19:17.09,0:19:21.10,Default,,0000,0000,0000,,these little pieces, these little\Npostcards, find their way through the
Dialogue: 0,0:19:21.10,0:19:26.09,Default,,0000,0000,0000,,series of routers. And we can, we both can\Nsee sort of like a, a whole campus being
Dialogue: 0,0:19:26.09,0:19:32.01,Default,,0000,0000,0000,,connected. We can see individual folks who\Nare, buying, buying some dial up through
Dialogue: 0,0:19:32.01,0:19:37.03,Default,,0000,0000,0000,,cable or DSL, and at some point we like to\Nrepresent this whole thing. Here is this
Dialogue: 0,0:19:37.03,0:19:42.03,Default,,0000,0000,0000,,big cloud, this you don't worry about the\Ndetail inside here. Call that the cloud.
Dialogue: 0,0:19:42.03,0:19:45.76,Default,,0000,0000,0000,,We'll see it in the future slides it`s\Njust a cloud, a white, fluffy cloud. That
Dialogue: 0,0:19:45.76,0:19:49.50,Default,,0000,0000,0000,,means that we are trying to hide the\Ndetail. But in there it`s just a bunch of
Dialogue: 0,0:19:49.50,0:19:53.26,Default,,0000,0000,0000,,things that are connected. In a way it`s\Nnot that different in the store and
Dialogue: 0,0:19:53.26,0:19:57.97,Default,,0000,0000,0000,,forward network, except for the fact that\Nevery message is tiny, so it doesn't clog
Dialogue: 0,0:19:57.97,0:20:01.66,Default,,0000,0000,0000,,the whole network up, which means that\Nrouters don`t have to have a lot of
Dialogue: 0,0:20:01.66,0:20:06.47,Default,,0000,0000,0000,,intermediate storage to hold on to these\Npackets in flight. And it also means that
Dialogue: 0,0:20:06.47,0:20:10.75,Default,,0000,0000,0000,,every packet can take a different path and\Nif things get loaded up, they can
Dialogue: 0,0:20:10.75,0:20:14.94,Default,,0000,0000,0000,,dynamically move. And so. Here's just sort\Nof an example problem to solve. If you
Dialogue: 0,0:20:14.94,0:20:19.71,Default,,0000,0000,0000,,think about it, these routers have a very\Nlimited view of the world. And there are
Dialogue: 0,0:20:19.71,0:20:24.80,Default,,0000,0000,0000,,hundreds of thousands of routers around\Nthis world right now. And they don't know
Dialogue: 0,0:20:24.80,0:20:29.21,Default,,0000,0000,0000,,the entire network, they kind of know the\Nlines that come in to them and the lines
Dialogue: 0,0:20:29.21,0:20:33.87,Default,,0000,0000,0000,,that go out, just like a post office in\NKansas city doesn't know every address,
Dialogue: 0,0:20:33.87,0:20:38.58,Default,,0000,0000,0000,,every house in the world. It just knows\Nthe trucks that are coming in and the
Dialogue: 0,0:20:38.58,0:20:44.56,Default,,0000,0000,0000,,trucks going out. And so these packets\Nthat have to and from addresses can get a
Dialogue: 0,0:20:44.56,0:20:51.13,Default,,0000,0000,0000,,little confused at times. So we won't\Nsolve this but if, if we had a situation
Dialogue: 0,0:20:51.13,0:20:55.98,Default,,0000,0000,0000,,where This particular packet would come\Ninto a router, and it would route it here,
Dialogue: 0,0:20:55.98,0:20:59.43,Default,,0000,0000,0000,,and then this packet would see it and then\Nit would route it this way, this packet
Dialogue: 0,0:20:59.43,0:21:03.23,Default,,0000,0000,0000,,would see it and route it this way, this\Npacket would see that this router would
Dialogue: 0,0:21:03.23,0:21:06.86,Default,,0000,0000,0000,,see it again and say, oh, I gotta route it\Nthat way. And so we end up in this
Dialogue: 0,0:21:06.86,0:21:11.94,Default,,0000,0000,0000,,situation where we would create a loop.\NOkay. So this is the kind of technical
Dialogue: 0,0:21:11.94,0:21:17.16,Default,,0000,0000,0000,,things they had to solve to keep these\Nthings from going round and round and
Dialogue: 0,0:21:17.16,0:21:22.95,Default,,0000,0000,0000,,round and sort of melting the network.\NWe'll talk more about that in a bit. So.
Dialogue: 0,0:21:22.95,0:21:28.36,Default,,0000,0000,0000,,This was DARPANET. It was doing research\Non these kin ds of problems. The kinds of
Dialogue: 0,0:21:28.36,0:21:32.99,Default,,0000,0000,0000,,problems of, you know what's the best way\Nto do this? How big should packets be?
Dialogue: 0,0:21:32.99,0:21:38.39,Default,,0000,0000,0000,,What should, how long should we wait until\Nwe send a packet again? You know, this
Dialogue: 0,0:21:38.39,0:21:43.43,Default,,0000,0000,0000,,kind of thing. And so that was our\Nresearch network. And the, that could've
Dialogue: 0,0:21:43.43,0:21:49.65,Default,,0000,0000,0000,,gone on forever, it might've been a purely\Nmilitary project, but. At the University
Dialogue: 0,0:21:49.65,0:21:57.24,Default,,0000,0000,0000,,of Illinois - Urbana Champagne - folks\Nstarted to think about super computers and
Dialogue: 0,0:21:57.24,0:22:03.51,Default,,0000,0000,0000,,starting all the way back to Bletchley\NPark, science was enhanced by the use of
Dialogue: 0,0:22:03.51,0:22:08.80,Default,,0000,0000,0000,,computations. And so as the 70's and 80's\Nwere happening, all these scientists were
Dialogue: 0,0:22:08.80,0:22:13.04,Default,,0000,0000,0000,,sort of like, "Wow, I can do better\Nphysics. I can do better chemistry. I can
Dialogue: 0,0:22:13.04,0:22:17.61,Default,,0000,0000,0000,,do better material science. I can invent\Nnew plastics. I can do pharmacy. I can do
Dialogue: 0,0:22:17.61,0:22:22.74,Default,,0000,0000,0000,,all kinds of things. With computers. And\Nso what happened was is everyone started
Dialogue: 0,0:22:22.74,0:22:27.45,Default,,0000,0000,0000,,asking the government. For money. For\Ncomputers. It's like, "I need a bigger
Dialogue: 0,0:22:27.45,0:22:32.08,Default,,0000,0000,0000,,computer. And if I, if I had this bigger\Ncomputer. I could do research." Matter of
Dialogue: 0,0:22:32.08,0:22:35.97,Default,,0000,0000,0000,,fact. I was part of all this. Matter of\Nfact I wrote a book. High Performance
Dialogue: 0,0:22:35.97,0:22:40.57,Default,,0000,0000,0000,,Computing. Here's the book. That's kind of\Nwhat I did before I became an internet
Dialogue: 0,0:22:40.57,0:22:45.61,Default,,0000,0000,0000,,guy. These are beautiful things. Here's,\Nthis isn't, was my baby, I never got this.
Dialogue: 0,0:22:45.61,0:22:50.96,Default,,0000,0000,0000,,This is like about $8,000,000, it's not\Nsmall like this, this is a model of a
Dialogue: 0,0:22:50.96,0:22:56.58,Default,,0000,0000,0000,,Convex C3800 supercomputer. And each of\Nthese was the size of a refrigerator, it's
Dialogue: 0,0:22:56.58,0:23:02.11,Default,,0000,0000,0000,,slightly taller than me. I would be about\Nthis tall, right here. And each of these,
Dialogue: 0,0:23:02.11,0:23:08.16,Default,,0000,0000,0000,,I think this is like, like I said, like\N$8,000,000 or something. And I wanted one
Dialogue: 0,0:23:08.16,0:23:13.16,Default,,0000,0000,0000,,just for me. And so the problem is, is\Nthat, you know, I'm a nice guy, and I'm
Dialogue: 0,0:23:13.16,0:23:17.09,Default,,0000,0000,0000,,probably worth $8,000,000 of the\Ngovernments money without a doubt, but not
Dialogue: 0,0:23:17.09,0:23:21.45,Default,,0000,0000,0000,,that the government didn't always think\Nabout that. So we couldn't all have out
Dialogue: 0,0:23:21.45,0:23:26.99,Default,,0000,0000,0000,,own personal computer, or at least our own\Npersonal supercomputers. Today, of course.
Dialogue: 0,0:23:26.99,0:23:32.81,Default,,0000,0000,0000,,This has about as much power as this, but\Nthis is not a history of computers.
Dialogue: 0,0:23:32.81,0:23:38.54,Default,,0000,0000,0000,,Computation. The iPhone is as powerful as\Nthis thing, it literally with abou t as
Dialogue: 0,0:23:38.54,0:23:42.62,Default,,0000,0000,0000,,much storage, But what happened was, is,\Nall these scientists would say give me,
Dialogue: 0,0:23:42.62,0:23:45.86,Default,,0000,0000,0000,,give me this supercomputer. I need a\Nsupercomputer to do this, I need a
Dialogue: 0,0:23:45.86,0:23:50.22,Default,,0000,0000,0000,,supercomputer to do that. And the National\NScience Foundation said oh, hmm, well, why
Dialogue: 0,0:23:50.22,0:23:53.45,Default,,0000,0000,0000,,don't we just buy a few of these\Nsupercomputers and put them in these
Dialogue: 0,0:23:53.45,0:23:57.08,Default,,0000,0000,0000,,supercomputer centers and then let people\Nconnect to them. And then make people, and
Dialogue: 0,0:23:57.08,0:24:01.70,Default,,0000,0000,0000,,make it so they could share, so we didn't\Nhave to give every single scientist one of
Dialogue: 0,0:24:01.70,0:24:08.18,Default,,0000,0000,0000,,these things. And so. The notion that we\Nwould create a network to connect these
Dialogue: 0,0:24:08.18,0:24:16.07,Default,,0000,0000,0000,,things, again, seems completely logical\Ntoday, but in 1981, 1982, 1983, it wasn't
Dialogue: 0,0:24:16.07,0:24:23.15,Default,,0000,0000,0000,,entirely the most logical idea. And of\Ncourse, the telephone companies might have
Dialogue: 0,0:24:23.15,0:24:28.52,Default,,0000,0000,0000,,something to say about that and so the\Nnext person that you're going to meet is
Dialogue: 0,0:24:28.52,0:24:34.03,Default,,0000,0000,0000,,Larry Smarr from NCSA, the National Center\Nfor Supercomputing Applications. And Larry
Dialogue: 0,0:24:34.03,0:24:39.44,Default,,0000,0000,0000,,Smarr was one of the early innovators that\Nsort of realized that we had to build
Dialogue: 0,0:24:39.44,0:24:44.68,Default,,0000,0000,0000,,computational infrastructure and internet\Ncomputational infrastructure. And did a
Dialogue: 0,0:24:44.68,0:24:50.10,Default,,0000,0000,0000,,lot of work to convince the federal\Ngovernment that this is something that we
Dialogue: 0,0:24:50.10,0:24:54.02,Default,,0000,0000,0000,,should do. And so let's go ahead and meet\NLarry Smarr.