1 00:00:00,012 --> 00:00:04,298 Hello, and welcome back. I just wanted to give you sort of a sense 2 00:00:04,298 --> 00:00:09,956 of the actual physical experience of connecting and communicating and computing 3 00:00:09,956 --> 00:00:14,267 in the 60's and the 70's. The 70's was when I got my start and the 4 00:00:14,267 --> 00:00:19,649 lucky people go to use teletype, like was being used in that video, and other people 5 00:00:19,649 --> 00:00:23,933 used punch cards. You also heard the squealing sound of the 6 00:00:23,933 --> 00:00:27,584 data being converted into sound and back and forth. 7 00:00:27,585 --> 00:00:32,956 You know it's the key goal was there would be, if you were lucky, one computer within 8 00:00:32,956 --> 00:00:37,701 a 20 mile radius of where you were sitting so you could use a local phone call and 9 00:00:37,701 --> 00:00:42,519 you could be on all day and do things all day long and that was really exciting and 10 00:00:42,519 --> 00:00:45,965 a lot of fun. And this was sort of a, a common if you 11 00:00:45,965 --> 00:00:50,856 were sort of, you know, today you have a $2,000 laptop, the fancy people had these 12 00:00:50,856 --> 00:00:55,747 teletypes right in their office because then they could conveniently sort of do 13 00:00:55,747 --> 00:01:00,143 computation and, and not have to go somewhere to do that computation. 14 00:01:00,143 --> 00:01:04,507 So that's pretty exciting. So dial up was kind of like the way the 15 00:01:04,507 --> 00:01:08,033 campus operated. But you could also do data transfer with 16 00:01:08,033 --> 00:01:12,104 leased lines. And the typical thing about lease line is 17 00:01:12,104 --> 00:01:18,000 there the, the phone company is going between 2 cities digs a hole and put a 18 00:01:18,000 --> 00:01:23,232 cable in and has some numbers of copper wires in between those cities. 19 00:01:23,233 --> 00:01:28,168 This is back then of course it's fiber optic now, but back then it was copper. 20 00:01:28,168 --> 00:01:32,700 And every time you would make a call between those 2 cities, it would have to 21 00:01:32,700 --> 00:01:37,299 find a free piece of wire and connect it up so that your call, the audio of your 22 00:01:37,299 --> 00:01:41,833 call would go through that wire. And if you wanted to, you could pay them 23 00:01:41,833 --> 00:01:46,332 to lease one of those pieces of wire. It meant that people couldn't use that 24 00:01:46,332 --> 00:01:49,541 wire for phone calls. So you would sort of take it out of 25 00:01:49,541 --> 00:01:52,239 service. And if they had 500 wires between two 26 00:01:52,239 --> 00:01:55,675 cities and you leased one of them, then they had 499 wires. 27 00:01:55,675 --> 00:02:00,507 And so it was rather expensive. And really very importantly, the cost was 28 00:02:00,507 --> 00:02:04,896 based on distance, right? A mile versus 5 miles, versus 20 miles 29 00:02:04,896 --> 00:02:09,712 versus 100 miles, the cost would go up kind of linear based on distance. 30 00:02:09,712 --> 00:02:14,884 And so that's, that's a key thing that distance is important in these very 31 00:02:14,884 --> 00:02:20,296 limited resource copper wires where you had to dedicate a wire either to a phone 32 00:02:20,296 --> 00:02:23,629 call or to data. And so, we ended up evolving, in the 33 00:02:23,629 --> 00:02:28,735 academic world what we called store and forward networking, with the sole purpose 34 00:02:28,735 --> 00:02:33,471 of compromising everything so that we would keep our cost that we paid for our 35 00:02:33,471 --> 00:02:37,642 phone lines to a minimum. We wanted to communicate in Academia with 36 00:02:37,642 --> 00:02:42,230 people all around the country and all around the world so, we had to keep the 37 00:02:42,230 --> 00:02:46,676 costs low. And so we would lease a lease line, you 38 00:02:46,676 --> 00:02:53,000 know, so, so, so here would be us sitting with terminals in our offices and we would 39 00:02:53,000 --> 00:02:58,859 use dial up to get connected and so this might be a few miles, like 1 to 2 miles, 40 00:02:58,859 --> 00:03:03,253 or, 1 to 2 kilometers. And that's what you had to, you had to 41 00:03:03,253 --> 00:03:08,583 live near a computer or have an office near a computer and then you would use the 42 00:03:08,583 --> 00:03:12,041 local telephone network to dial in to do your work. 43 00:03:12,041 --> 00:03:17,087 And then there would be 1 connection out the back of that computer to another 44 00:03:17,087 --> 00:03:20,423 computer. They would also have users on it and then 45 00:03:20,423 --> 00:03:24,699 other computers with users on it, other computer with users on it. 46 00:03:24,699 --> 00:03:28,716 So this might for example be Michigan, this might be Stanford. 47 00:03:28,716 --> 00:03:32,779 Stanford would have a computer, Michigan will have a computer. 48 00:03:32,779 --> 00:03:36,650 Stanford people will be connected to the Stanford computer. 49 00:03:36,650 --> 00:03:41,584 Stanford will have one little connection on its back end and to the rest of the 50 00:03:41,584 --> 00:03:44,566 world. So you sitting here want to talk to 51 00:03:44,566 --> 00:03:48,132 somebody sitting here, so this is how it worked. 52 00:03:48,132 --> 00:03:53,154 You're sort of always connected so your data would be inside, you know, you type 53 00:03:53,154 --> 00:03:58,094 an email into the computer and then you would say, send that out to my colleague 54 00:03:58,094 --> 00:04:02,882 at Stanford, and so the problem is everyone else was sending and so let's say 55 00:04:02,882 --> 00:04:06,194 for example that somebody send it pretty big thing. 56 00:04:06,194 --> 00:04:11,096 Big purple circle is what they're sending, and then somebody next to you an office 57 00:04:11,096 --> 00:04:15,632 down sends a kind of medium size orange circle and there sitting there being 58 00:04:15,632 --> 00:04:20,168 stored in local computer and then you finally, finally finished typing your 59 00:04:20,168 --> 00:04:23,396 email messages and its kind of a small green circle. 60 00:04:23,396 --> 00:04:26,319 And now, the problem is, is you're in a line. 61 00:04:26,319 --> 00:04:30,485 The way this worked is the software would keep a queue or a line of those who were 62 00:04:30,485 --> 00:04:34,773 going to use the, the line and then, it would sort of start streaming this stuff 63 00:04:34,773 --> 00:04:37,100 out. And once it started, it just kept doing 64 00:04:37,100 --> 00:04:41,134 the same file, over and over and over. Now if it died, it would just start from 65 00:04:41,134 --> 00:04:44,397 the beginning again. And so, it takes some time for that thing 66 00:04:44,397 --> 00:04:48,387 to move across the network. And that would move across the network, 67 00:04:48,387 --> 00:04:51,978 the next message in line would start to be sent across the network. 68 00:04:51,978 --> 00:04:55,378 And it would use that link come on, finish up, there we go. 69 00:04:55,378 --> 00:04:57,874 Okay. It takes a while for these things to move 70 00:04:57,874 --> 00:05:00,907 across the link. And then finally, and this could be ten 71 00:05:00,907 --> 00:05:05,381 minutes later, finally it was your turn. And your stuff would work its way through 72 00:05:05,381 --> 00:05:09,809 the network, and get to the next computer. The problem is, is once it's in that 73 00:05:09,809 --> 00:05:14,481 computer, you face the same problem, because if all these messages are going 74 00:05:14,481 --> 00:05:19,664 from Michigan oop, forgot to hit the button thing from Michigan to Stanford and 75 00:05:19,664 --> 00:05:23,898 they are on the way, they got to go through all these linked, because it 76 00:05:23,898 --> 00:05:28,716 wasn't a direct connection because the direct connection to Stanford would be 77 00:05:28,716 --> 00:05:33,680 very expensive and so you're in, whereas you find yourself in a situation where it 78 00:05:33,680 --> 00:05:38,548 your stored, you sat on these computers. And if there was an outage of a network, 79 00:05:38,548 --> 00:05:42,292 or say this one, this might be hours. You might be sitting on this computer for 80 00:05:42,292 --> 00:05:45,759 hours, on their disk drive, right? Not even in their memory, you would be 81 00:05:45,759 --> 00:05:49,521 sitting on their disk drive for an hour, and then finally this would come back or 82 00:05:49,521 --> 00:05:53,324 maybe this computer was down. They would come back up and then the data 83 00:05:53,324 --> 00:05:57,500 would start flowing again. So it was our pass word, I keeping telling 84 00:05:57,500 --> 00:06:01,399 you, it was awesome, it was just slow, it was awesome but slow. 85 00:06:01,399 --> 00:06:06,355 So don't, don't, don't feel sorry for us, we loved it, we enjoyed it, it was great 86 00:06:06,355 --> 00:06:10,898 talking to colleagues all over the world. So we ended up with the network 87 00:06:10,898 --> 00:06:16,127 architecture that encouraged more hops, which means it encouraged more latency. 88 00:06:16,127 --> 00:06:21,101 It encouraged the likelihood of getting stuck behind something large as it worked 89 00:06:21,101 --> 00:06:25,452 its way through the network. So, for example, we were going to send a 90 00:06:25,452 --> 00:06:30,276 message from East Lansing to say, the East Coast somewhere, and we would have two 91 00:06:30,276 --> 00:06:33,676 connections maybe. We would have a connection between 92 00:06:33,676 --> 00:06:38,470 Michigan State University in East Lansing and Anne Arbor, and then we'd have a, the 93 00:06:38,470 --> 00:06:43,094 data would get stored and forwarded in Anne Arbor and then it would get further 94 00:06:43,094 --> 00:06:46,426 sent to Cleveland. And i-, if you think about it, the, the 95 00:06:46,426 --> 00:06:49,622 wire between Anne Arbor and Cleveland goes like this. 96 00:06:49,622 --> 00:06:55,678 Right, they probably buried wires under the ground, and if we could actually 97 00:06:55,678 --> 00:07:01,788 convince Toledo the cost of the big wire versus the cost of the 2 shorter wires, 98 00:07:01,788 --> 00:07:07,710 the cost of the 2 shorter wires is almost exactly the cost of the big wire, because 99 00:07:07,710 --> 00:07:12,471 it's not really a big wire. And so if we can convince Toledo to join 100 00:07:12,471 --> 00:07:17,817 our little club, then we don't increase the cost of our communications because 101 00:07:17,817 --> 00:07:22,869 we're, it's about the same right? The, the wire length is about the same but 102 00:07:22,869 --> 00:07:28,021 we've got 1 more school for the same cost. And if you keep doing that and you keep 103 00:07:28,021 --> 00:07:33,472 saying oh, well let's put a school here and put a school here, and put a school 104 00:07:33,472 --> 00:07:38,395 here in the middle of a lake and put a school here, in the middle of a forest. 105 00:07:38,395 --> 00:07:43,219 The economics dro-, said that you could connect more schools with effectively 106 00:07:43,219 --> 00:07:47,707 fixed cost by shortening the distance every time you made a connection. 107 00:07:47,707 --> 00:07:51,125 And sometimes they would sort of make 2 connections. 108 00:07:51,125 --> 00:07:56,639 But the way it often worked was from the perspective of this whole thing is, the 109 00:07:56,639 --> 00:08:01,985 data would sort of tend to go you know, up to some central location and then kind of 110 00:08:01,985 --> 00:08:07,692 fan back out from the central location. And, and so these, it, there wasn't a lot 111 00:08:07,692 --> 00:08:10,741 of redundant links in this whole situation. 112 00:08:10,741 --> 00:08:16,093 So we find ourselves in a situation where we can save more money, saving money by 113 00:08:16,093 --> 00:08:20,273 just simply adding hops. So in this environment we, had a lot of 114 00:08:20,273 --> 00:08:23,050 email. Back in those days we didn't have a lot of 115 00:08:23,050 --> 00:08:27,542 images, computers you know, barely could do upper and lowercase sometimes. 116 00:08:27,542 --> 00:08:31,949 It was impressive when we finally got to upper lowercase, let alone images. 117 00:08:31,949 --> 00:08:35,893 And so for the longest time everything we did was very text Oriented. 118 00:08:35,893 --> 00:08:39,970 Some times, we would send small files like programs to each other, but it was either 119 00:08:39,970 --> 00:08:42,121 text. And these days, those are tiny, it's 120 00:08:42,121 --> 00:08:44,998 almost like SMS, right? It's almost like the size of an SMS 121 00:08:44,998 --> 00:08:48,236 message was the size of a typical mail message back in those days. 122 00:08:48,236 --> 00:08:52,012 Images, we didn't have computers that could even display them and so it hardly 123 00:08:52,012 --> 00:08:54,509 mattered. So, you focused your life on this one 124 00:08:54,509 --> 00:08:58,797 computer within a 20 mile radius and it had this connection to like, a snake-like 125 00:08:58,797 --> 00:09:03,277 connection that sort of went over hill and dale and through somewhere and it finally 126 00:09:03,277 --> 00:09:05,834 got to Stanford or wherever your mail had to go. 127 00:09:05,834 --> 00:09:10,187 But again, it was awesome to be able to sit at a keyboard and talk to people all 128 00:09:10,187 --> 00:09:12,722 over the world, even though it took 4 hours. 129 00:09:12,722 --> 00:09:17,414 We didn't, we didn't send as much email back then and a number of networks came up 130 00:09:17,414 --> 00:09:21,816 one of them that would, became sort of pretty widely used was a thing called 131 00:09:21,816 --> 00:09:26,857 Bitnet, and it was where everything kind of came back to Princeton was one of the 132 00:09:26,857 --> 00:09:30,764 main hubs of Bitnet. And it worked really well, and, and there 133 00:09:30,764 --> 00:09:35,042 was a way to say, oh, I need one more school, and we'd go find the ones that are 134 00:09:35,042 --> 00:09:40,015 closest and we'd make the connection. And so that's pretty much how the average 135 00:09:40,015 --> 00:09:44,608 academic saw networking. One common campus computer and sort of 136 00:09:44,608 --> 00:09:49,991 this weird, slow, store and forward networking that worked well enough. 137 00:09:49,991 --> 00:09:56,138 But during that exact same time, from the 1960's to the 1980's, the US Department of 138 00:09:56,138 --> 00:10:00,770 Defense was investing in a research network called ARPANET. 139 00:10:00,770 --> 00:10:05,512 And ARPANET was funded by the military, the ARPA, Defense Advanced Research 140 00:10:05,512 --> 00:10:09,216 Projects Agency. And when we, and later in the lecture, 141 00:10:09,216 --> 00:10:14,166 we'll meet Vince Serf, who will tell the story much better that I can tell it, but 142 00:10:14,166 --> 00:10:17,001 I'll just tell you a short version right now. 143 00:10:17,001 --> 00:10:22,379 A lot of people wonder why the Department of Defense started this project and a lot 144 00:10:22,379 --> 00:10:26,159 of people say, oh it's because of the fear of nuclear war. 145 00:10:26,159 --> 00:10:31,469 And the project was very long, and there were various motivations throughout the 146 00:10:31,469 --> 00:10:35,830 various phases of the effort. But, if, based on what I've been told and 147 00:10:35,830 --> 00:10:40,726 what I've read, I think it's safe to say that the primary motivation Was to improve 148 00:10:40,726 --> 00:10:45,633 the use of their computing equipment that they were used for military purposes. 149 00:10:45,633 --> 00:10:49,889 Make it easier to access them, make it so people didn't have to travel as much. 150 00:10:49,890 --> 00:10:54,433 Made it so that people could work from their office on many different computers. 151 00:10:54,434 --> 00:10:59,015 And also so that people could actually talk more effectively so they could send 152 00:10:59,015 --> 00:11:03,134 email real fast so that the email would move faster for military people. 153 00:11:03,134 --> 00:11:07,424 So the first thing is really kind of end user focus to make them more useful to 154 00:11:07,424 --> 00:11:10,128 people and get people working together more. 155 00:11:10,129 --> 00:11:13,435 More effectively. That was the first kind of heavy 156 00:11:13,435 --> 00:11:17,043 motivation. The 2nd motivation was, actually had to do 157 00:11:17,043 --> 00:11:22,547 with reliably, reliability and redundancy and resistance to partial failure. 158 00:11:22,547 --> 00:11:27,233 And that really wasn't so much about nuclear attack, that was more about 159 00:11:27,233 --> 00:11:31,052 battlefield attack. So, the notion that once you start having 160 00:11:31,052 --> 00:11:35,322 all these links and you make them wireless, and you put them in trailers on 161 00:11:35,322 --> 00:11:39,872 a battlefield, and, you know, you got a few hundred miles and the data's moving 162 00:11:39,872 --> 00:11:42,543 back and forth. Then we have to worry about, in a 163 00:11:42,543 --> 00:11:45,941 battlefield situation, one of those trailers might get hit. 164 00:11:45,941 --> 00:11:50,061 And how would you keep the network running if one of those trailers got hit? 165 00:11:50,061 --> 00:11:54,327 So, the notion that we have sort of a whole nation and we are worried about 166 00:11:54,327 --> 00:11:59,155 communications I'm sure there was some worry about that, but it wasn't really the 167 00:11:59,155 --> 00:12:02,459 main reason. I, I mean, the, the exciting thing to me 168 00:12:02,459 --> 00:12:07,475 is the mean reason, was a ver-, very people-centered reason, of people working 169 00:12:07,475 --> 00:12:11,146 more effectively. But this was a rather exclusive club. 170 00:12:11,146 --> 00:12:16,542 Ra-, rather exclusive network because it was only for the people who were either 171 00:12:16,542 --> 00:12:21,054 military, or funded to build it. So in 1969 there were four hosts on it. 172 00:12:21,054 --> 00:12:25,129 Again, that's research. And these were lease lines, the same ones 173 00:12:25,129 --> 00:12:29,853 we were all using to do our e-mail, and they were expensive, very expensive. 174 00:12:29,853 --> 00:12:34,875 But, because it was a large grant, they just paid it because the research was not 175 00:12:34,875 --> 00:12:37,950 about the money. The research was if you had these 176 00:12:37,950 --> 00:12:42,184 connections, what would be the best way to use them and how to deal with 177 00:12:42,184 --> 00:12:46,361 redundancies, and how to deal with multiple paths to the same place. 178 00:12:46,361 --> 00:12:50,497 All of that stuff is, is interesting research questions that computer 179 00:12:50,497 --> 00:12:55,317 scientists spent many years conceiving of. And so by 1972, looks like we got about 180 00:12:55,317 --> 00:12:57,857 20. We got a couple of cross-country links and 181 00:12:57,857 --> 00:13:02,345 multiple connections, and, and this looks like a great testbed to see, y'know, so 182 00:13:02,345 --> 00:13:06,841 all of a sudden this part goes down, how quickly can we reroute around the outage. 183 00:13:06,841 --> 00:13:11,202 And literally, these things these days reroute around outages in far less than a 184 00:13:11,202 --> 00:13:17,062 second, and so that's really impressive. Our current internet can ooze its history 185 00:13:17,062 --> 00:13:22,514 to the research that was done in the 1960's and the 1970's, but what was 186 00:13:22,514 --> 00:13:29,094 fundamentally different between the store and forward networks of Bitnet and this 187 00:13:29,094 --> 00:13:34,173 ARPANET research network was the notion of packet switching. 188 00:13:34,174 --> 00:13:38,123 So the, it's a real simple concept. It just takes a little more s, complex 189 00:13:38,123 --> 00:13:41,430 software to solve. The store and forward network would start 190 00:13:41,430 --> 00:13:45,846 the, sending data across the link and then keep sending it until it was done that was 191 00:13:45,846 --> 00:13:49,542 seen to be very efficient. You didn't want to like, you wanted to use 192 00:13:49,542 --> 00:13:53,634 it as fast as you can and then put the next 1 out, and put the next 1 out, and 193 00:13:53,634 --> 00:13:56,875 put the next 1 out. It was really simple and it dealt with 194 00:13:56,875 --> 00:14:00,751 outages in a simple manner by storing them all locally on the disc. 195 00:14:00,751 --> 00:14:04,286 But what if instead, you made it so you broke every message. 196 00:14:04,286 --> 00:14:08,766 Let me see if I can even draw this. I should probably make a slide about this. 197 00:14:08,766 --> 00:14:14,310 So, if there's a network here, and here's her'es my computer and it's got a network 198 00:14:14,310 --> 00:14:19,380 connection, and it's got 1 really big message, broken into pieces Many pieces 199 00:14:19,380 --> 00:14:25,282 and it sends the pieces one at a time. If you show up with a really short message 200 00:14:25,282 --> 00:14:31,682 with only three pieces, all you have to do is wait for 1 piece to go and then your 201 00:14:31,682 --> 00:14:35,347 piece goes in and then you share for a while. 202 00:14:35,347 --> 00:14:41,227 Right you share for a while and then your, have made it through because you only have 203 00:14:41,227 --> 00:14:45,024 3 packets. This has like 1,000 packets, and then once 204 00:14:45,024 --> 00:14:49,624 your message is through, they resume sending this data in order. 205 00:14:49,624 --> 00:14:55,124 And so you were able to sneak and bypass the traffic jam that was This large amount 206 00:14:55,124 --> 00:14:57,733 of data. And so, that's the idea of packets. 207 00:14:57,733 --> 00:15:02,091 And packets are these chunks that say, what we're going to send is a piece, and 208 00:15:02,091 --> 00:15:06,569 then, at the end of that we're going to maybe send a piece of a different message. 209 00:15:06,569 --> 00:15:11,129 It was allowing simultaneously multiple message to be in-flight at the same time, 210 00:15:11,129 --> 00:15:15,115 that's packet switching. And what happened then is we also ended up 211 00:15:15,115 --> 00:15:18,511 with these special purpose computers called routers. 212 00:15:18,511 --> 00:15:23,347 They're still computers, but they weren't doing storing in the same way, they were 213 00:15:23,347 --> 00:15:28,107 just forwarding, they weren't store and forward they were merely forwarding, so 214 00:15:28,107 --> 00:15:32,527 we'll get back to that in a second. So my favorite analogy to talk about how 215 00:15:32,527 --> 00:15:36,099 packets work is postcards. So let's say that I want to send a 30 216 00:15:36,099 --> 00:15:40,856 character message to my friend Daphne at Stanford, but all I have is 10 character 217 00:15:40,856 --> 00:15:42,726 postcards. So, off I go. 218 00:15:42,726 --> 00:15:46,316 I break my message into 3 bits of 10 characters. 219 00:15:46,316 --> 00:15:49,601 I write each piece on a different postcard. 220 00:15:49,601 --> 00:15:54,885 I address with a from and a to address, from Chuck to Daphne, and I give a 221 00:15:54,885 --> 00:16:01,073 sequence number so that when she gets the postcard she knows what order to put them 222 00:16:01,073 --> 00:16:04,561 back together. So I have to label each of these. 223 00:16:04,561 --> 00:16:07,861 And these are fixed width and, fixed length. 224 00:16:07,861 --> 00:16:13,580 They, you know, it's like a packet, right? I'm breaking a long message that might be 225 00:16:13,580 --> 00:16:18,828 very long into, nothing, so that each piece is a certain size so that we can all 226 00:16:18,828 --> 00:16:22,582 share it, right? And so then what I do is I send these, I 227 00:16:22,582 --> 00:16:27,844 put them all in my mailbox. And then I wait and this magical thing 228 00:16:27,844 --> 00:16:34,613 called the post office picks them up, puts them in buildings, people sort them. 229 00:16:34,613 --> 00:16:41,175 They end up on trucks, they end up on planes, on trains, on donkeys, by hand. 230 00:16:41,175 --> 00:16:45,590 And each of my postcards might take a different route. 231 00:16:45,590 --> 00:16:51,996 I mean one of my postcards, I'll show you on a map here, now one of my postcards, 232 00:16:51,996 --> 00:16:58,018 nope not that one, let's do that. One of my postcards, you know, goes from 233 00:16:58,018 --> 00:17:02,481 Michigan to Chicago to Kansas City to San Francisco. 234 00:17:02,481 --> 00:17:07,881 Another of my postcards goes from Michigan, to Chicago, to Dallas, to 235 00:17:07,881 --> 00:17:12,453 Denver, to Kansas City, to Chicago, to San Francisco. 236 00:17:12,453 --> 00:17:18,411 And my third postcard goes really crazy, it goes to Cleveland, then it goes to 237 00:17:18,411 --> 00:17:24,135 Atlanta, then it goes to Washington D.C. And then it goes to Chicago, and then it 238 00:17:24,135 --> 00:17:27,625 goes to Kansas City, and then it makes it to San Francisco. 239 00:17:27,625 --> 00:17:32,104 Now the fact that they took different paths and they might not even arrive in 240 00:17:32,104 --> 00:17:36,305 order, some might get past each other, they might get stuck somewhere. 241 00:17:36,305 --> 00:17:41,001 It doesn't matter, because each one of these has been labelled Both with the from 242 00:17:41,001 --> 00:17:44,676 and the to destination. So each of these intermediate locations 243 00:17:44,676 --> 00:17:48,570 doesn't have to get it to the final destination, they just have to get it 244 00:17:48,570 --> 00:17:51,308 closer. They make choices and even if they make 245 00:17:51,308 --> 00:17:55,352 the wrong choice, it can be sort of dealt with one way or the other, okay? 246 00:17:55,352 --> 00:17:58,630 So, this is some big mystery, it's called the Post Office. 247 00:17:58,630 --> 00:18:03,259 It just takes these little cards and moves them, it doesn't know If that's a Youtuve 248 00:18:03,259 --> 00:18:07,346 video or if it's an email, it doesn't really care, it just has these little 249 00:18:07,346 --> 00:18:10,414 chunks to move around that have from and to addresses. 250 00:18:10,414 --> 00:18:13,891 And that's the essence of the network, the internet, the cloud. 251 00:18:13,891 --> 00:18:18,118 That's why draw this picture, you'll see like, ooh, it's a cloud, and that's 252 00:18:18,118 --> 00:18:22,741 because it's, don't worry about what's inside here, it's all super mysterious and 253 00:18:22,741 --> 00:18:27,359 don't worry about it, it just comes out. So after all that happens, Daphne who 254 00:18:27,359 --> 00:18:30,896 happens to have the exact same mailbox as I do, kind of rare. 255 00:18:30,896 --> 00:18:34,396 We both have a mailbox that's copyright creative comments. 256 00:18:34,396 --> 00:18:39,187 That's what's cool about this mailbox. At some point later these things start 257 00:18:39,187 --> 00:18:42,298 appearing. She goes like, whoa, looks like Chuck is 258 00:18:42,298 --> 00:18:46,045 sending me a note. But because of his limitation of postcards 259 00:18:46,045 --> 00:18:49,349 he's only sent me 1. I know who it's from and I know who it's 260 00:18:49,349 --> 00:18:52,486 to, and I know that's the 1st of some number of messages. 261 00:18:52,486 --> 00:18:56,713 And then the next day out comes another 1, because that was the 1 that sort of, went 262 00:18:56,713 --> 00:19:00,461 the more southerly route. And she goes well I'm missing something, 263 00:19:00,461 --> 00:19:02,861 I'll just sit and wait and see what happens. 264 00:19:02,861 --> 00:19:07,899 And then finally, many, many days later, the, the one that took the circuitous, 265 00:19:07,899 --> 00:19:11,463 cir-, most circuitous more s, most roundabout route. 266 00:19:11,464 --> 00:19:18,295 Comes and now Daphne can reassemble the messages because she has the sequences. 267 00:19:18,295 --> 00:19:22,737 So she simply puts them back together. 1, 2, 3, boom. 268 00:19:22,737 --> 00:19:29,211 So she puts them back together, she has it, she sort of throws the post cards away 269 00:19:29,211 --> 00:19:33,750 and she has The ultimate final message. That's packets. 270 00:19:33,750 --> 00:19:39,300 Packets are breaking a big message into small parts, labeling each 1 of them 271 00:19:39,300 --> 00:19:44,028 individually, and then throwing them into the shared network. 272 00:19:44,028 --> 00:19:48,992 And so this is what it looks like. The post office in this is called a 273 00:19:48,992 --> 00:19:50,556 gateway. Okay. 274 00:19:50,556 --> 00:19:52,361 Come on. Gateway. 275 00:19:52,361 --> 00:19:55,137 Okay. So, that's a gateway. 276 00:19:55,137 --> 00:20:02,865 So, here's Michigan, here's Stanford, Stanford has a gateway too, that's like 277 00:20:02,865 --> 00:20:08,451 their post office. In the middle is the post office box. 278 00:20:08,451 --> 00:20:12,588 Right. And the Post Office box basic, the Post 279 00:20:12,588 --> 00:20:18,863 Office has intermediate locations. And it has trucks and locations. 280 00:20:18,863 --> 00:20:24,955 These are links and routers. And messages can take different paths 281 00:20:24,955 --> 00:20:26,154 This. Right? 282 00:20:26,154 --> 00:20:30,176 And then they arrive and they're reassembled. 283 00:20:30,176 --> 00:20:35,966 And we have, like their ability to hook from home, stuff like that. 284 00:20:35,966 --> 00:20:42,940 So there's a local area network, LAN, LAN and there's this sort of like internet, 285 00:20:42,940 --> 00:20:47,186 the network of networks. It's like the post office. 286 00:20:47,186 --> 00:20:52,887 And it still breaks things into packets, they still come out as packets, and then 287 00:20:52,887 --> 00:20:57,856 Daphne has to reassemble them on her computer to create the message. 288 00:20:57,856 --> 00:21:03,710 So, it, so the research network ARPANET solved a lot of engineering problems, and 289 00:21:03,710 --> 00:21:08,801 that was sort of what they did. So here is an example problem to solve. 290 00:21:08,801 --> 00:21:13,322 Now, none of the mailbox, none of the routers, none of the post office offices, 291 00:21:13,322 --> 00:21:17,802 know exactly where the thing is going. And they don't transport it to the final 292 00:21:17,802 --> 00:21:20,739 destination. All they do is they transport it to the 293 00:21:20,739 --> 00:21:25,004 future to further down destination. But what if they get it wrong? 294 00:21:25,004 --> 00:21:29,137 What if one, this is like Michigan, this is Chicago, this is Dallas. 295 00:21:29,137 --> 00:21:32,640 And what if Michigan thinks sending to Chicago is a good idea? 296 00:21:32,640 --> 00:21:35,415 Chicago thinks sending to Dallas is a good idea. 297 00:21:35,415 --> 00:21:38,801 And then Dallas thinks sending it to Michigan is a good idea. 298 00:21:38,801 --> 00:21:42,536 Well, and Michigan's going to get it again and send it back to Chicago. 299 00:21:42,536 --> 00:21:47,031 And so, then what you end up with is this situation where your packet, your data is 300 00:21:47,031 --> 00:21:50,271 in a loop, right? This wouldn't be good for the post office 301 00:21:50,271 --> 00:21:54,319 and it's not good for the Internet. So, you have to say, how do we solve this 302 00:21:54,319 --> 00:21:56,700 problem when something's wrong? Right. 303 00:21:56,700 --> 00:21:59,469 It's, you, you wish it were perfect, but it's not. 304 00:21:59,469 --> 00:22:03,501 And so this is the kind of research question, as to how to solve this kind of 305 00:22:03,501 --> 00:22:07,857 problem, and we'll talk more about this in a bit when we get into a little more 306 00:22:07,857 --> 00:22:11,049 technical detail. But I just wanted to sort of say, that's 307 00:22:11,049 --> 00:22:15,207 the kind of research and engineering that took literally 20 years, and four 308 00:22:15,207 --> 00:22:18,272 different versions of it, of the ARPANET to get right. 309 00:22:18,273 --> 00:22:23,633 And so, by the end of the 1970's there was quite a sophisticated network. 310 00:22:23,633 --> 00:22:26,954 Like I said, they'd rewritten it four times. 311 00:22:26,954 --> 00:22:32,143 It had gotten to be very sophisticated, it had been a good investment. 312 00:22:32,143 --> 00:22:38,221 They had been careful about understanding how to improve it each time they rebuilt 313 00:22:38,221 --> 00:22:40,932 it. And do it was that it really a fine 314 00:22:40,932 --> 00:22:46,470 working piece of software, and the people who used it at these research universities 315 00:22:46,470 --> 00:22:51,852 and at the military, it, it was kind of like a futuristic world, right, you could 316 00:22:51,852 --> 00:22:56,766 send email and a second later it would appear, Right, it was really quick and 317 00:22:56,766 --> 00:23:01,836 everything was nice and you could even have instant message like your actions 318 00:23:01,836 --> 00:23:06,688 where when right then and. The problem is this was a small group of 319 00:23:06,688 --> 00:23:09,885 people. This is maybe, looks like 60 or so. 320 00:23:09,885 --> 00:23:14,121 That was all the computers on the entire internet, right? 321 00:23:14,121 --> 00:23:19,138 I mean now we have our cell phones and we have billions of them, right? 322 00:23:19,138 --> 00:23:23,861 But this is like 60. And so a real question is how did this go 323 00:23:23,861 --> 00:23:28,766 from 60 computers of a very narrow group to A much larger group. 324 00:23:28,766 --> 00:23:34,196 And the answer to that question is at Urbana Champaign, Illinois. 325 00:23:34,196 --> 00:23:40,464 And so, at the same time that, this kind of goes back to Blechley Park, right, 326 00:23:40,464 --> 00:23:46,169 where the computers were part of science. Throughout the 50's and 60's and 70's 327 00:23:46,169 --> 00:23:50,926 scientists, much like the military, were realizing computers were mighty useful to 328 00:23:50,926 --> 00:23:54,545 advance scientific research. And so the National Science Foundation 329 00:23:54,545 --> 00:23:58,465 would fund universities to buy computers, and they'd say gimme ten million dollars 330 00:23:58,465 --> 00:24:01,412 to buy a computer. And another university would be like, give 331 00:24:01,412 --> 00:24:05,312 me ten million dollars to buy a computer. And then three years later the first 332 00:24:05,312 --> 00:24:09,468 University says, my computer is obsolete, I need another ten million dollars. 333 00:24:09,468 --> 00:24:12,486 Now the research questions were good research questions. 334 00:24:12,486 --> 00:24:16,485 And they were important to society. But the National Science Foundation got 335 00:24:16,485 --> 00:24:19,666 tired of giving ten million dollars to every, everybody who. 336 00:24:19,666 --> 00:24:23,096 Wait, hold on a sec, let me. As a matter of fact, I was part of this 337 00:24:23,096 --> 00:24:25,938 because I used to be a high performance computer guy. 338 00:24:25,938 --> 00:24:31,997 This is a Convex C3800 super computer. I would be about this tall on this super 339 00:24:31,997 --> 00:24:37,515 computer, this is a lovely and very expensive model that I was given after, 340 00:24:37,515 --> 00:24:42,826 afterwards, and wouldn't throw it away because this was from, like, 1987. 341 00:24:42,827 --> 00:24:46,707 And, and basically I wanted one of these terribly badly. 342 00:24:46,707 --> 00:24:50,997 Each one of these is about 2,000,000 dollars, so this is like two, four, six, 343 00:24:50,997 --> 00:24:54,823 eight, ten million dollars. And I so badly wanted this, and I thought 344 00:24:54,823 --> 00:24:59,047 that I, I deserved a ten million dollar toy, and I could do such great research 345 00:24:59,047 --> 00:25:02,677 but unfortunately everybody else wanted the exact same thing. 346 00:25:02,677 --> 00:25:06,933 And they were important, too. So National Science Foundation said to 347 00:25:06,933 --> 00:25:11,373 themselves hey, this isn't going to work very well if I can't find my pen. 348 00:25:11,374 --> 00:25:15,567 You know, we're not going to be able to, we're going to make a network. 349 00:25:15,567 --> 00:25:20,193 How about we put a few of these things in, and then make a network and connect them 350 00:25:20,193 --> 00:25:23,543 together. Of course it's never as simple as that, so 351 00:25:23,543 --> 00:25:28,691 now we're going to meet Larry Smarr, at the National Center for Supercomputing 352 00:25:28,691 --> 00:25:33,848 Applications, N-C-S-A, at the University of Illinois Urbana-Champaign. 353 00:25:33,848 --> 00:25:39,482 And Larry was the director of NCSA and one of the, one of the many people, but one of 354 00:25:39,482 --> 00:25:45,614 the most instrumental people in creating the national network, that we now think of 355 00:25:45,614 --> 00:25:51,242 as the Internet, and getting it moving it from being a research project to being a 356 00:25:51,242 --> 00:25:57,038 project that we all, both academics and regular people that we all can, can make 357 00:25:57,038 --> 00:26:01,155 really good use of, and so let's take a look at Larry Smarr.