1 00:00:00,000 --> 00:00:04,079 So, welcome back. Now the purpose, of course, of all this stuff that you had in 2 00:00:04,079 --> 00:00:09,091 your office, and all that banging, and all the sqweeee squealing noise where we're 3 00:00:09,091 --> 00:00:15,046 sending the data across the across the phone using sound. All the purpose was the 4 00:00:15,046 --> 00:00:21,010 fact that computation was rare and extremely valuable. And for scientists who 5 00:00:21,010 --> 00:00:27,005 were trying to solve research problems, access to computers was essential. And you 6 00:00:27,005 --> 00:00:33,021 couldn't all sit, sort of in a little ring around the computer. It's so we would have 7 00:00:33,021 --> 00:00:38,089 phones in our offices and we would, you know, work in our office, just like I'm 8 00:00:38,089 --> 00:00:45,024 working in my office right now. But there wasn't enough computation [inaudible], any 9 00:00:45,024 --> 00:00:51,058 work in my office so I had to connect to something outside. And so this was the way 10 00:00:51,058 --> 00:00:57,078 of science. And, it, it, it was the fact that comp-, computing was rare, and access 11 00:00:57,078 --> 00:01:03,066 to computing was a critical enabler of scientific research. Now, I'd mentioned 12 00:01:03,066 --> 00:01:09,075 earlier, data transfer with leased lines. And so, while it. You tended to interact 13 00:01:09,075 --> 00:01:14,045 with the computer that was rather local, geographically to you because you could 14 00:01:14,045 --> 00:01:19,009 have this permanent dial up connection all day long without paying a permanent 15 00:01:19,009 --> 00:01:23,096 charge. If you were a bank, or you had some really critical need you would lease 16 00:01:23,096 --> 00:01:28,656 some line from the phone company 24 hours a day, seven days a week so you could send 17 00:01:28,656 --> 00:01:33,044 data across that anytime that you wanted. No dialing, it's always connected and, 18 00:01:33,044 --> 00:01:38,618 after while, I mean you can send data, we academics wanted to communicate with each 19 00:01:38,618 --> 00:01:43,938 other. It would be nice to be able to use each other's computers, but we tended to 20 00:01:43,938 --> 00:01:47,898 have too much, but sometimes we don't want to send a file, or some email, or 21 00:01:47,898 --> 00:01:52,623 something like that. And so this led to the invention and the creation of store 22 00:01:52,623 --> 00:01:57,772 and forward networking. And how this would work is we would sort of, you would sort 23 00:01:57,772 --> 00:02:03,796 of have some thing and you would use a modem to do all your dialing, like that. I 24 00:02:03,796 --> 00:02:08,957 mean maybe they had paper and, and didn't. That looks a little too advanced, but you 25 00:02:08,957 --> 00:02:13,175 would have some geographically local computer that was your, sort of the compu 26 00:02:13,175 --> 00:02:17,237 ter that did most of your work. You didn't have a computer in your office, you just 27 00:02:17,237 --> 00:02:21,242 had a connection to the single campus computer or on a few campus computers. And 28 00:02:21,242 --> 00:02:25,753 then what universities would do is they would lease a line. And then we could 29 00:02:25,753 --> 00:02:31,183 send, write a mail program that would run on this computer and then would send mail 30 00:02:31,183 --> 00:02:36,320 and then everyone else would read it. And what happened was is we sort of started 31 00:02:36,320 --> 00:02:41,835 stringing them together in these snakelike structures and so, we could share this. 32 00:02:41,835 --> 00:02:47,545 And so let me just show you kind of how the store and forward networking works. So 33 00:02:47,545 --> 00:02:52,316 somebody sends a mail message in. Now let's say, let's say we are this bottom 34 00:02:52,316 --> 00:02:56,982 person down here, okay. And so someone else has sent a mail message in, they're 35 00:02:56,982 --> 00:03:01,460 sitting in there. And now the next person sends a mail message in and now ten 36 00:03:01,460 --> 00:03:05,794 seconds later, you send a mail message in. Those mail messengers are sitting in a 37 00:03:05,794 --> 00:03:10,665 cue. They're waiting just like waiting in line at the bus stop or waiting in line in 38 00:03:10,665 --> 00:03:15,269 a train station. Waiting in line for a cup of coffee at Starbucks. They're waiting in 39 00:03:15,269 --> 00:03:19,498 line, and what would happen is the computer that was our local computer would 40 00:03:19,498 --> 00:03:24,498 then start sending that data across the line. Okay, and slowly but surely it would 41 00:03:24,498 --> 00:03:29,686 take awhile. And everyone else had to sit and wait. Your poor message is last in 42 00:03:29,686 --> 00:03:34,199 line so you have to wait. So finally this message gets across the closest link. And 43 00:03:34,199 --> 00:03:38,878 then the, the next message starts being sent and you have to wait for that message 44 00:03:38,878 --> 00:03:43,495 and wait and wait and wait and wait and wait. Wait and wait and wait! Hey wait. 45 00:03:43,495 --> 00:03:48,807 Okay. Now its finally your turn. So your message finally gets to use the one 46 00:03:48,807 --> 00:03:53,162 connected line. So they, they are sought of stand in line until your turn 47 00:03:53,162 --> 00:03:57,736 [inaudible] runs acrossed. And they all, these messages aren't destined for just 48 00:03:57,736 --> 00:04:02,932 one computer away, then they got to go through the whole thing again, move across 49 00:04:02,932 --> 00:04:07,748 the next link until you know eventually you move across one link over here and 50 00:04:07,748 --> 00:04:12,396 then go another, and then finally talks to the people who get their email. So its a 51 00:04:12,396 --> 00:04:17,415 sought of dedicat ed line and you had to stand in line to get your chance. And the 52 00:04:17,415 --> 00:04:23,138 key thing here is each of these lease lines has a fixed cost 24 hours a day 53 00:04:23,138 --> 00:04:28,940 seven days a week, and it's very dependent on the distance, so we saw a weird 54 00:04:28,940 --> 00:04:33,464 phenomena. ≫> And that is. ≫> If we could add hops, it would slow our 55 00:04:33,464 --> 00:04:38,491 message down, but it would reduce our cost greatly. And so let's just say we have 56 00:04:38,491 --> 00:04:43,985 Michigan State University, which is where I got all my degrees from. University of 57 00:04:43,985 --> 00:04:48,944 Michigan here in Ann Arbor, which is where I work. And let's say, you know, we're 58 00:04:48,944 --> 00:04:54,081 connecting to the rest of the world, and we're going through Cleveland, where Case 59 00:04:54,081 --> 00:04:59,566 Western Reserve is. Case Western Reserve was the early innovator in, in networking, 60 00:04:59,566 --> 00:05:04,019 and so we have two leased lines with a certain distance, right? One from East 61 00:05:04,019 --> 00:05:08,646 Lansing to Ann Arbor and one from Ann Arbor to Cleveland and so we're sharing 62 00:05:08,646 --> 00:05:14,112 the cost of these lines between three schools and we can all kind of connect to 63 00:05:14,112 --> 00:05:19,427 the rest of the internet, all connect to the rest of the internet out here and, and 64 00:05:19,427 --> 00:05:24,029 we just, some of us have, are farther away, and so we take longer. The folks in 65 00:05:24,029 --> 00:05:28,921 Cleveland are closer. Like all the rest of the connection to like the East Coast and 66 00:05:28,921 --> 00:05:34,955 the West Coast come through, say like here Cleveland, but if we can simply convince 67 00:05:34,955 --> 00:05:43,118 somebody in between us like say Toledo to add a connection. Now of course. Of 68 00:05:43,118 --> 00:05:51,095 course, this, [inaudible] Give me green. There we go.'Course this line probably 69 00:05:51,095 --> 00:05:56,312 goes, probably went around when we just went straight to Cleveland, here. But 70 00:05:56,312 --> 00:06:01,815 basically if we can convince Toledo to sort of put in their computer and hold 71 00:06:01,815 --> 00:06:06,892 onto our messages for a while, we could send now one hop, two hops, three hops. 72 00:06:06,892 --> 00:06:12,171 But the cost now is not that different, because the original long line between Ann 73 00:06:12,171 --> 00:06:16,645 Arbor and Cleveland was distance sensitive. And, so, you can think of this 74 00:06:16,645 --> 00:06:21,800 as, you can get this almost for free. And now we have a whole additional university. 75 00:06:21,800 --> 00:06:26,711 Both to send stuff to, and they can send to the whole world as well. And so this 76 00:06:26,711 --> 00:06:31,872 motivation to effectively take the same c ost, and now basically we're taking this 77 00:06:31,872 --> 00:06:36,784 cost, and dividing it by four schools. And if you start thinking about it, it doesn't 78 00:06:36,784 --> 00:06:40,857 take long to say, "You know what, let's put one here, one here, one here, one 79 00:06:40,857 --> 00:06:45,588 here, and one here." Because the cost of the phone company isn't that different. 80 00:06:45,588 --> 00:06:50,177 You can think of each of these as adding some delay to your message. You know, and 81 00:06:50,177 --> 00:06:54,868 given the fact that each of these represents an outbound queue of messages 82 00:06:54,868 --> 00:07:00,478 that are waiting to be sent, there's some delay. There's some cost adding this, but 83 00:07:00,478 --> 00:07:05,929 It's so much cheaper. So our faculty have to wait another twenty minutes to get 84 00:07:05,929 --> 00:07:11,126 their mail through if we can bring that many more universities on. And so this 85 00:07:11,126 --> 00:07:15,881 just works out. There's this sorta motivation that if you can find an 86 00:07:15,881 --> 00:07:19,992 intermediate person, geographically intermediate school or university or 87 00:07:19,992 --> 00:07:25,133 company, and you can add them in, you can replace one long link with two short 88 00:07:25,133 --> 00:07:30,801 links. And this led to long chains of mail. And so from the mid 70s to the late 89 00:07:30,801 --> 00:07:37,095 80s most academics were communicating through a network that was like this. It 90 00:07:37,095 --> 00:07:43,450 typically was email and I recall when I first started to use national email. It 91 00:07:43,450 --> 00:07:49,510 took a long time for mail to go back and forth but it was actually quite magical I 92 00:07:49,510 --> 00:07:54,102 mean who cares if it took an hour. Now we expect it in three seconds. We send an 93 00:07:54,102 --> 00:07:58,243 email and hit the refresh buttons, hurry up, hurry up. You know, it could be hours, 94 00:07:58,243 --> 00:08:02,293 it could be days if you were going far enough and your message was long enough 95 00:08:02,293 --> 00:08:06,276 and you end up behind too many queues. And so you had this one computer locally and 96 00:08:06,276 --> 00:08:09,856 every once in a while you'd do most of your communication computation locally. 97 00:08:09,856 --> 00:08:14,303 And every once in a while you would fire a note off and that would kind of fight its 98 00:08:14,303 --> 00:08:18,571 way through all those successive connections. This is sort of the life in 99 00:08:18,571 --> 00:08:24,093 the early 1980s. One of the, most widely distributed networks of this kind was a 100 00:08:24,093 --> 00:08:29,024 thing called Bitnet. And Princeton was kinda the hub of this and these tendrils 101 00:08:29,024 --> 00:08:33,657 of connections ran out from Princeton. And by connecting to a, a network with lots of 102 00:08:33,657 --> 00:08:38,479 oth er folks, then you had more people to talk to. And the more people that you, 103 00:08:38,479 --> 00:08:43,540 that were connected the cheaper that it was for everybody. So it was a pretty, it 104 00:08:43,540 --> 00:08:48,407 was the perfect kinda thing that caused people and com-, universities to want to 105 00:08:48,407 --> 00:08:52,841 work together, because together their shared cost was much, much lower than to, 106 00:08:52,841 --> 00:08:58,002 to provide this uniform connectivity and email. So at the same time, during that 107 00:08:58,002 --> 00:09:04,275 same period, where most of us were using store and forward network, with our one on 108 00:09:04,275 --> 00:09:09,557 campus computer, a bunch of computer scientists were funded by DARPA. The 109 00:09:09,557 --> 00:09:14,482 Defense Advanced Research Projects Administration, to imagine a different 110 00:09:14,482 --> 00:09:20,559 kind of network. And the idea was direct connections are expensive. The long trails 111 00:09:20,559 --> 00:09:26,166 of store and forward networks, they're very slow, and if you had a giant message 112 00:09:26,166 --> 00:09:32,062 that you got behind, then what, how do you get past that. It could clog the system up 113 00:09:32,062 --> 00:09:37,318 for, for hours, if not days. And, and how do you keep from failures breaking the 114 00:09:37,318 --> 00:09:42,443 entire system? If you think about a store and forward network, one computer going 115 00:09:42,443 --> 00:09:47,515 down would cause data to back up on both sides of that computer until it's done. 116 00:09:47,515 --> 00:09:52,391 And so, you don't really wanna have one outage and, and how if we have sort of 117 00:09:52,391 --> 00:09:57,460 instead, instead of just a few messages, what if we just wanted all the messages to 118 00:09:57,460 --> 00:10:03,214 go simultaneously, so that there's more of a fair allocation of the network, rather 119 00:10:03,214 --> 00:10:09,124 than whoever gets there first gets it all until they're done with it. And, and so 120 00:10:09,124 --> 00:10:14,951 Darpa wanted to solve the problem of outages. You know, many will say that it 121 00:10:14,951 --> 00:10:21,549 had to do with, battlefield conditions, which is probably true They expected that 122 00:10:21,549 --> 00:10:27,784 various connections would go out in, in, in dynamic situations. Maybe it was that 123 00:10:27,784 --> 00:10:34,027 stuff was moving. But also how to be more efficient. And so, in effect, you can kind 124 00:10:34,027 --> 00:10:40,393 of think of this as all a game, where the phone companies own the wire. So everyone, 125 00:10:40,393 --> 00:10:45,558 even government, even military has to lease the wire from the phone companies. 126 00:10:45,558 --> 00:10:51,274 And so everyone is like doing research to figure out or creating systems to figure 127 00:10:51,274 --> 00:10:56,625 how not to pay t he phone company so much money, okay. So these research networks, 128 00:10:56,625 --> 00:11:02,799 and so if we look for example at this one down here by 1972 they had this network. I 129 00:11:02,799 --> 00:11:08,396 have my, I, yes I got a caller. So they have this network by 1972 and it's got, 130 00:11:08,396 --> 00:11:14,076 like some [inaudible] right around twelve, fourteen, fifteen hosts in it, and it goes 131 00:11:14,076 --> 00:11:19,028 cross-country. Now, now, the, the key about this is in 1972 to have leased lines 132 00:11:19,028 --> 00:11:24,428 that were up 24 hours a day, seven days a week, all the way across the country? Very 133 00:11:24,428 --> 00:11:29,258 expensive. But hey, it's a government project, and the government says this is 134 00:11:29,258 --> 00:11:34,169 important so we're gonna spend the money because, so we're imagining battlefield 135 00:11:34,169 --> 00:11:39,379 communications of the future and our own ability to do computations so they could 136 00:11:39,379 --> 00:11:44,098 have comp-, computational equipment all over the place. So this was very 137 00:11:44,098 --> 00:11:49,365 expensive, but research dollars were being flooded into it, because the q, they were 138 00:11:49,365 --> 00:11:54,291 solving a research question. If you just think about this as a network, it was not 139 00:11:54,291 --> 00:11:58,636 all [laugh], it wasn't sorta like, it was so costly that the average person wouldn't 140 00:11:58,636 --> 00:12:03,343 like, pay $fifteen a month to use it. It would just be that costly. But it's okay. 141 00:12:03,343 --> 00:12:08,455 Now if you look at this, you see that across the United States, there was always 142 00:12:08,455 --> 00:12:12,436 at least one connection. They had three cross country links with totally 143 00:12:12,436 --> 00:12:17,381 independent cross country links, with the ideas that you could take one of these 144 00:12:17,381 --> 00:12:21,894 things out, and you could still be functioning. So they, they were able to 145 00:12:21,894 --> 00:12:26,797 research all these things right, as well as the efficiency problem, which they 146 00:12:26,797 --> 00:12:32,501 solved using packet switching. So, by the mid 70's there was quite a few folks on 147 00:12:32,501 --> 00:12:37,751 this. And for a group of people they just started using it in production. It was 148 00:12:37,751 --> 00:12:42,649 pretty cool, right? If you were, if you were one of these universities or 149 00:12:42,649 --> 00:12:47,801 companies, you had a pretty cool, futuristic world. You could, you could 150 00:12:47,801 --> 00:12:53,300 send email and get an answer back in two minutes, or a minute, or 30 seconds, even. 151 00:12:53,300 --> 00:12:58,520 And so it was kind of this futuristic world that was heavily subsidized by the 152 00:12:58,520 --> 00:13:04,564 government in the name of researching. And so there are two essential things that 153 00:13:04,564 --> 00:13:10,747 really came out of this research. And one is the notion of what was called Packet 154 00:13:10,747 --> 00:13:16,222 Switching. Packet Switching basically eliminates the problem where once the 155 00:13:16,222 --> 00:13:22,066 message starts using that leased line wire, you have to wait till they're done. 156 00:13:22,066 --> 00:13:27,933 As, as I showed in that in that store and forward. What you want is to be able to 157 00:13:27,933 --> 00:13:33,101 send little pieces. Break the messages up into little pieces, and then they, they 158 00:13:33,101 --> 00:13:37,745 Each, each message has a little bit of the network connectivity and then the next one 159 00:13:37,745 --> 00:13:42,302 comes after it. And so you could have many messages going at the same time. And a 160 00:13:42,302 --> 00:13:46,462 real long message won't fill up the network, fill up the connection forever 161 00:13:46,462 --> 00:13:50,783 and ever and ever. So it and it also allows, if you to break the message up 162 00:13:50,783 --> 00:13:55,530 into small parts, they can flow over different paths. The other thing that they 163 00:13:55,530 --> 00:13:59,989 figured out was this notion of instead of oop, oop, oop come back here, come back 164 00:13:59,989 --> 00:14:04,233 here. Instead of using computers as the intermediate stop points, because in store 165 00:14:04,233 --> 00:14:08,482 and forward you could have a lot of messages so you tend to store them on 166 00:14:08,482 --> 00:14:13,413 disks. Whereas routers, these packets were smaller individually than the entire 167 00:14:13,413 --> 00:14:18,515 message and so they didn't need to store them nearly as long and they didn't need 168 00:14:18,515 --> 00:14:22,953 as much storage. So these are, routers are just a form of computer, right? But they 169 00:14:22,953 --> 00:14:27,563 were specialized for moving just data from one connection to the other without long 170 00:14:27,563 --> 00:14:33,404 term, without storing that data for a long time. So, I like to think of packets as 171 00:14:33,404 --> 00:14:40,781 postcards, letters and think of the Packet Switching Network as the postal system. So 172 00:14:40,781 --> 00:14:47,226 let's say, for example, I had a friend, and his name is Glen, and I want to send 173 00:14:47,226 --> 00:14:52,645 him a message. I want to send him a message that's hello there, have a nice 174 00:14:52,645 --> 00:14:57,543 day. But I have a limitation. I have limitation. All I have is postcards that 175 00:14:57,543 --> 00:15:02,963 it can, that can store ten characters on them, and I have to send my message to 176 00:15:02,963 --> 00:15:08,530 Glenn using only 10-character postcards. And so, before Glenn and I part ways, we 177 00:15:08,530 --> 00:15:14,073 agree on the following protocol: that I will take the first ten characters of the 178 00:15:14,073 --> 00:15:19,586 me ssage and put them on one postcard, and then I will put an address from Chuck to 179 00:15:19,586 --> 00:15:25,075 Glenn, and I'll put a sequence number. So that says that hey, hey Glenn, here comes 180 00:15:25,075 --> 00:15:31,067 a message, this is part one. Then we take the next ten characters. And I mark that 181 00:15:31,067 --> 00:15:37,203 as part two, from Chuck to Glen. And then here's the third part, it's marked as part 182 00:15:37,203 --> 00:15:42,532 three, from Chuck to Glenn. And, so, what can I do now? Well, I walk out to my post 183 00:15:42,532 --> 00:15:48,047 office box, and I send'em, I just stack'em in. I might stack them neatly in order. 184 00:15:48,047 --> 00:15:53,545 Now, they go through the postal system. Like, they get dropped, some get dropped 185 00:15:53,545 --> 00:15:59,288 on the ground. A couple of them get lost. Or they end up on the wrong truck. They go 186 00:15:59,288 --> 00:16:04,513 through Kansas City by mistake. Blah, blah, blah, blah, blah, blah, blah. Blah, 187 00:16:04,513 --> 00:16:09,612 blah, blah, blah, blah, blah, blah, blah, blah, blah, blah. But, you know, some days 188 00:16:09,612 --> 00:16:14,653 later. They start arriving at Glen's house. And so, Glenn goes out to his post 189 00:16:14,653 --> 00:16:19,834 office box, and he gets a message. It's hello ther-, and it's sequence number one. 190 00:16:19,835 --> 00:16:25,074 So it looks like Chuck is going to send me a message, and I've got the first part of 191 00:16:25,074 --> 00:16:29,785 it. That's pretty cool. So then he goes out the next day, and out comes, nice day. 192 00:16:29,785 --> 00:16:34,602 But this is #three. So, because I've numbered them, Glenn knows that there's 193 00:16:34,602 --> 00:16:39,569 some missing bits, right? So Glenn just can hold on to them, and leave a little 194 00:16:39,569 --> 00:16:44,311 space on his kitchen table for what he hopes to be message number two. And so 195 00:16:44,311 --> 00:16:49,007 message two finally comes out. And now Glen is capable of saying, "Looks like I 196 00:16:49,007 --> 00:16:53,922 got the whole message and I can reassemble them. And, surprise, surprise. I have just 197 00:16:53,922 --> 00:16:58,363 sent him. With a lot of effort in three packets. Hello there! Have a nice day." 198 00:16:58,363 --> 00:17:03,561 And so this notion of breaking the message into packets, labeling each packet with a 199 00:17:03,561 --> 00:17:08,750 sequence number, and then sending them to this network that can take multiple paths, 200 00:17:08,750 --> 00:17:13,173 You can even have a situation where the you know, the message would go across one 201 00:17:13,173 --> 00:17:17,975 link, it would get lost and then it would, you know go across a different link. So 202 00:17:17,975 --> 00:17:21,961 you have ways of recovering. You can recover the messages. We'll talk about 203 00:17:21,961 --> 00:17:28,275 that later as well. So this ends up with a sort of a structure that has these 204 00:17:28,275 --> 00:17:36,238 computers that are specialized routers in the middle. And the routers have multiple 205 00:17:36,238 --> 00:17:43,091 connections. And if we take a campus, for example, and the campus has some computers 206 00:17:43,091 --> 00:17:47,484 and we have high-speed networking on this campus. We have some, you know, stuff in 207 00:17:47,484 --> 00:17:52,213 our offices on the campus, and then we have some stuff in the machine room and we 208 00:17:52,213 --> 00:17:56,461 talk to these things. And then, somehow, our entire campus has a little spicket to 209 00:17:56,461 --> 00:18:01,420 the outside world and this is our, sort of, campus router and we get this router, 210 00:18:01,420 --> 00:18:05,672 and then there are, sort of, intermediate routers that are inside the network. And 211 00:18:05,672 --> 00:18:09,688 if you sort of look at a router, a router sort of simply forwards traffic and the 212 00:18:09,688 --> 00:18:14,706 traffic now is these small packets, rather than whole messages, so you don't need a 213 00:18:14,706 --> 00:18:18,797 disk drive on these, on these routers. There's no disk drive on these routers, so 214 00:18:18,797 --> 00:18:22,689 that they just kind of grab a packet and they forward it. And the systems are 215 00:18:22,689 --> 00:18:27,084 trained. And the software does not overflow the network. We'll talk about 216 00:18:27,084 --> 00:18:31,968 that later, much later. And so these routers have these real simple view of the 217 00:18:31,968 --> 00:18:36,594 world, they've got some incoming traffic, they've got some outgoing traffic, 218 00:18:36,594 --> 00:18:41,537 outgoing traffic. And so they just grab and forward. It's like a intermediate 219 00:18:41,537 --> 00:18:47,240 postal spot, right? They, they grab big thing of. Postcards and books. Send them 220 00:18:47,240 --> 00:18:53,696 to the right place and, and they get where they do and so eventually the data gets. 221 00:18:53,696 --> 00:18:58,385 Getting a little sloppy, getting a little messy, here. Eventually, the data sort of 222 00:18:58,385 --> 00:19:03,304 is broken up, finds its way to the other end, and then dumps out in some campus 223 00:19:03,304 --> 00:19:07,743 local area network and then somebody sees the data on the far end, okay? And so it 224 00:19:07,743 --> 00:19:12,658 might different, take different routes, you know? It might get lost that might 225 00:19:12,658 --> 00:19:17,089 crash and then it has to get sent again on a different route. And so these things, 226 00:19:17,089 --> 00:19:21,097 these little pieces, these little postcards, find their way through the 227 00:19:21,097 --> 00:19:26,086 series of routers. And we can, we both can see sort of like a, a whole campus being 228 00:19:26,086 --> 00:19:32,006 connected. We can see individual folks who are, buying, buying some dial up through 229 00:19:32,006 --> 00:19:37,030 cable or DSL, and at some point we like to represent this whole thing. Here is this 230 00:19:37,030 --> 00:19:42,034 big cloud, this you don't worry about the detail inside here. Call that the cloud. 231 00:19:42,034 --> 00:19:45,757 We'll see it in the future slides it`s just a cloud, a white, fluffy cloud. That 232 00:19:45,757 --> 00:19:49,498 means that we are trying to hide the detail. But in there it`s just a bunch of 233 00:19:49,498 --> 00:19:53,265 things that are connected. In a way it`s not that different in the store and 234 00:19:53,265 --> 00:19:57,974 forward network, except for the fact that every message is tiny, so it doesn't clog 235 00:19:57,974 --> 00:20:01,665 the whole network up, which means that routers don`t have to have a lot of 236 00:20:01,665 --> 00:20:06,470 intermediate storage to hold on to these packets in flight. And it also means that 237 00:20:06,470 --> 00:20:10,747 every packet can take a different path and if things get loaded up, they can 238 00:20:10,747 --> 00:20:14,941 dynamically move. And so. Here's just sort of an example problem to solve. If you 239 00:20:14,941 --> 00:20:19,706 think about it, these routers have a very limited view of the world. And there are 240 00:20:19,706 --> 00:20:24,795 hundreds of thousands of routers around this world right now. And they don't know 241 00:20:24,795 --> 00:20:29,210 the entire network, they kind of know the lines that come in to them and the lines 242 00:20:29,210 --> 00:20:33,866 that go out, just like a post office in Kansas city doesn't know every address, 243 00:20:33,866 --> 00:20:38,583 every house in the world. It just knows the trucks that are coming in and the 244 00:20:38,583 --> 00:20:44,556 trucks going out. And so these packets that have to and from addresses can get a 245 00:20:44,556 --> 00:20:51,133 little confused at times. So we won't solve this but if, if we had a situation 246 00:20:51,133 --> 00:20:55,981 where This particular packet would come into a router, and it would route it here, 247 00:20:55,981 --> 00:20:59,426 and then this packet would see it and then it would route it this way, this packet 248 00:20:59,426 --> 00:21:03,228 would see it and route it this way, this packet would see that this router would 249 00:21:03,228 --> 00:21:06,864 see it again and say, oh, I gotta route it that way. And so we end up in this 250 00:21:06,864 --> 00:21:11,938 situation where we would create a loop. Okay. So this is the kind of technical 251 00:21:11,938 --> 00:21:17,157 things they had to solve to keep these things from going round and round and 252 00:21:17,157 --> 00:21:22,954 round and sort of melting the network. We'll talk more about that in a bit. So. 253 00:21:22,954 --> 00:21:28,364 This was DARPANET. It was doing research on these kin ds of problems. The kinds of 254 00:21:28,364 --> 00:21:32,988 problems of, you know what's the best way to do this? How big should packets be? 255 00:21:32,988 --> 00:21:38,392 What should, how long should we wait until we send a packet again? You know, this 256 00:21:38,392 --> 00:21:43,428 kind of thing. And so that was our research network. And the, that could've 257 00:21:43,428 --> 00:21:49,654 gone on forever, it might've been a purely military project, but. At the University 258 00:21:49,654 --> 00:21:57,237 of Illinois - Urbana Champagne - folks started to think about super computers and 259 00:21:57,237 --> 00:22:03,506 starting all the way back to Bletchley Park, science was enhanced by the use of 260 00:22:03,506 --> 00:22:08,802 computations. And so as the 70's and 80's were happening, all these scientists were 261 00:22:08,802 --> 00:22:13,037 sort of like, "Wow, I can do better physics. I can do better chemistry. I can 262 00:22:13,037 --> 00:22:17,607 do better material science. I can invent new plastics. I can do pharmacy. I can do 263 00:22:17,607 --> 00:22:22,741 all kinds of things. With computers. And so what happened was is everyone started 264 00:22:22,741 --> 00:22:27,448 asking the government. For money. For computers. It's like, "I need a bigger 265 00:22:27,448 --> 00:22:32,077 computer. And if I, if I had this bigger computer. I could do research." Matter of 266 00:22:32,077 --> 00:22:35,972 fact. I was part of all this. Matter of fact I wrote a book. High Performance 267 00:22:35,972 --> 00:22:40,569 Computing. Here's the book. That's kind of what I did before I became an internet 268 00:22:40,569 --> 00:22:45,606 guy. These are beautiful things. Here's, this isn't, was my baby, I never got this. 269 00:22:45,606 --> 00:22:50,965 This is like about $8,000,000, it's not small like this, this is a model of a 270 00:22:50,965 --> 00:22:56,575 Convex C3800 supercomputer. And each of these was the size of a refrigerator, it's 271 00:22:56,575 --> 00:23:02,109 slightly taller than me. I would be about this tall, right here. And each of these, 272 00:23:02,109 --> 00:23:08,160 I think this is like, like I said, like $8,000,000 or something. And I wanted one 273 00:23:08,160 --> 00:23:13,164 just for me. And so the problem is, is that, you know, I'm a nice guy, and I'm 274 00:23:13,164 --> 00:23:17,093 probably worth $8,000,000 of the governments money without a doubt, but not 275 00:23:17,093 --> 00:23:21,451 that the government didn't always think about that. So we couldn't all have out 276 00:23:21,451 --> 00:23:26,994 own personal computer, or at least our own personal supercomputers. Today, of course. 277 00:23:26,994 --> 00:23:32,807 This has about as much power as this, but this is not a history of computers. 278 00:23:32,807 --> 00:23:38,542 Computation. The iPhone is as powerful as this thing, it literally with abou t as 279 00:23:38,542 --> 00:23:42,625 much storage, But what happened was, is, all these scientists would say give me, 280 00:23:42,625 --> 00:23:45,860 give me this supercomputer. I need a supercomputer to do this, I need a 281 00:23:45,860 --> 00:23:50,216 supercomputer to do that. And the National Science Foundation said oh, hmm, well, why 282 00:23:50,216 --> 00:23:53,446 don't we just buy a few of these supercomputers and put them in these 283 00:23:53,446 --> 00:23:57,081 supercomputer centers and then let people connect to them. And then make people, and 284 00:23:57,081 --> 00:24:01,700 make it so they could share, so we didn't have to give every single scientist one of 285 00:24:01,700 --> 00:24:08,181 these things. And so. The notion that we would create a network to connect these 286 00:24:08,181 --> 00:24:16,069 things, again, seems completely logical today, but in 1981, 1982, 1983, it wasn't 287 00:24:16,069 --> 00:24:23,154 entirely the most logical idea. And of course, the telephone companies might have 288 00:24:23,154 --> 00:24:28,523 something to say about that and so the next person that you're going to meet is 289 00:24:28,523 --> 00:24:34,029 Larry Smarr from NCSA, the National Center for Supercomputing Applications. And Larry 290 00:24:34,029 --> 00:24:39,440 Smarr was one of the early innovators that sort of realized that we had to build 291 00:24:39,440 --> 00:24:44,684 computational infrastructure and internet computational infrastructure. And did a 292 00:24:44,684 --> 00:24:50,098 lot of work to convince the federal government that this is something that we 293 00:24:50,098 --> 00:24:54,020 should do. And so let's go ahead and meet Larry Smarr.