1
00:00:00,030 --> 00:00:02,149
{\an1}so we're just going to talk for a moment

2
00:00:02,149 --> 00:00:02,159
{\an1}so we're just going to talk for a moment

3
00:00:02,159 --> 00:00:07,010
{\an1}so we're just going to talk for a moment
about peer-to-peer architectures and how

4
00:00:07,010 --> 00:00:07,020
{\an1}about peer-to-peer architectures and how

5
00:00:07,020 --> 00:00:08,810
{\an1}about peer-to-peer architectures and how
they're different and some advantages

6
00:00:08,810 --> 00:00:08,820
{\an1}they're different and some advantages

7
00:00:08,820 --> 00:00:13,190
{\an1}they're different and some advantages
that they have the one of the main

8
00:00:13,190 --> 00:00:13,200
{\an1}that they have the one of the main

9
00:00:13,200 --> 00:00:14,509
{\an1}that they have the one of the main
differences in a peer-to-peer

10
00:00:14,509 --> 00:00:14,519
{\an1}differences in a peer-to-peer

11
00:00:14,519 --> 00:00:16,609
{\an1}differences in a peer-to-peer
architecture is that there's no always

12
00:00:16,609 --> 00:00:16,619
{\an1}architecture is that there's no always

13
00:00:16,619 --> 00:00:18,710
{\an1}architecture is that there's no always
on uber fast

14
00:00:18,710 --> 00:00:18,720
{\an1}on uber fast

15
00:00:18,720 --> 00:00:22,820
{\an1}on uber fast
uber uber ha storage server it's kind of

16
00:00:22,820 --> 00:00:22,830
{\an1}uber uber ha storage server it's kind of

17
00:00:22,830 --> 00:00:24,830
{\an1}uber uber ha storage server it's kind of
like everybody's a server and so

18
00:00:24,830 --> 00:00:24,840
{\an1}like everybody's a server and so

19
00:00:24,840 --> 00:00:26,390
{\an1}like everybody's a server and so
everybody's the server and everybody's a

20
00:00:26,390 --> 00:00:26,400
{\an1}everybody's the server and everybody's a

21
00:00:26,400 --> 00:00:30,290
{\an1}everybody's the server and everybody's a
client in the end system can communicate

22
00:00:30,290 --> 00:00:30,300
{\an1}client in the end system can communicate

23
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{\an1}client in the end system can communicate
with any other end system arbitrarily

24
00:00:32,420 --> 00:00:32,430
{\an1}with any other end system arbitrarily

25
00:00:32,430 --> 00:00:34,060
{\an1}with any other end system arbitrarily
they can connect will bring in a

26
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{\an1}they can connect will bring in a

27
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{\an1}they can connect will bring in a
client-server scenario the in the end

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{\an1}client-server scenario the in the end

29
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{\an1}client-server scenario the in the end
systems only connect to a server which

30
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{\an1}systems only connect to a server which

31
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{\an1}systems only connect to a server which
is usually just in one spot it has a lot

32
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{\an1}is usually just in one spot it has a lot

33
00:00:44,460 --> 00:00:47,770
{\an1}is usually just in one spot it has a lot
greater resources in terms of speed and

34
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{\an1}greater resources in terms of speed and

35
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{\an1}greater resources in terms of speed and
capacity one of the challenges that and

36
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{\an1}capacity one of the challenges that and

37
00:00:52,370 --> 00:00:54,680
{\an1}capacity one of the challenges that and
properties of this p2p architecture is

38
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{\an1}properties of this p2p architecture is

39
00:00:54,690 --> 00:00:59,290
{\an1}properties of this p2p architecture is
that there may be changes in the

40
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{\an1}that there may be changes in the

41
00:00:59,300 --> 00:01:01,760
{\an1}that there may be changes in the
connectivity of the devices right where

42
00:01:01,760 --> 00:01:01,770
{\an1}connectivity of the devices right where

43
00:01:01,770 --> 00:01:03,529
{\an1}connectivity of the devices right where
if you you might move your computer from

44
00:01:03,529 --> 00:01:03,539
{\an1}if you you might move your computer from

45
00:01:03,539 --> 00:01:05,119
{\an1}if you you might move your computer from
one place to another place and get a

46
00:01:05,119 --> 00:01:05,129
{\an1}one place to another place and get a

47
00:01:05,129 --> 00:01:06,440
{\an1}one place to another place and get a
different IP address when you go to a

48
00:01:06,440 --> 00:01:06,450
{\an1}different IP address when you go to a

49
00:01:06,450 --> 00:01:08,570
{\an1}different IP address when you go to a
different network that doesn't happen to

50
00:01:08,570 --> 00:01:08,580
{\an1}different network that doesn't happen to

51
00:01:08,580 --> 00:01:09,980
{\an1}different network that doesn't happen to
a server because the server always stays

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{\an1}a server because the server always stays

53
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{\an1}a server because the server always stays
though hmm one thought we're going to

54
00:01:14,600 --> 00:01:14,610
{\an1}though hmm one thought we're going to

55
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{\an1}though hmm one thought we're going to
consider what's that's a file one

56
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{\an1}consider what's that's a file one

57
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{\an1}consider what's that's a file one
problem that we're going to consider is

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{\an1}problem that we're going to consider is

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{\an1}problem that we're going to consider is
file distribution and that means how do

60
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{\an1}file distribution and that means how do

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{\an1}file distribution and that means how do
we get this file from this computer to

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{\an1}we get this file from this computer to

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{\an1}we get this file from this computer to
all the other computers so how do we

64
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{\an1}all the other computers so how do we

65
00:01:29,640 --> 00:01:33,890
{\an1}all the other computers so how do we
download a file and get it our one copy

66
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{\an1}download a file and get it our one copy

67
00:01:33,900 --> 00:01:35,810
{\an1}download a file and get it our one copy
on my computer to all the computers in

68
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{\an1}on my computer to all the computers in

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00:01:35,820 --> 00:01:38,660
{\an1}on my computer to all the computers in
this system so what we're going to do is

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{\an1}this system so what we're going to do is

71
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{\an1}this system so what we're going to do is
we're going to see we're going to

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{\an1}we're going to see we're going to

73
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{\an1}we're going to see we're going to
mathematically model that in a

74
00:01:42,889 --> 00:01:42,899
{\an1}mathematically model that in a

75
00:01:42,899 --> 00:01:44,870
{\an1}mathematically model that in a
client-server scenario and in a

76
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{\an1}client-server scenario and in a

77
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{\an1}client-server scenario and in a
peer-to-peer scenario and see how they

78
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{\an1}peer-to-peer scenario and see how they

79
00:01:47,970 --> 00:01:50,780
{\an1}peer-to-peer scenario and see how they
compare based on some different factors

80
00:01:50,780 --> 00:01:50,790
{\an1}compare based on some different factors

81
00:01:50,790 --> 00:01:53,539
{\an1}compare based on some different factors
so we're going to call you sub s the

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00:01:53,539 --> 00:01:53,549
{\an1}so we're going to call you sub s the

83
00:01:53,549 --> 00:01:57,560
{\an1}so we're going to call you sub s the
server upload speed we're going to call

84
00:01:57,560 --> 00:01:57,570
{\an1}server upload speed we're going to call

85
00:01:57,570 --> 00:02:01,969
{\an1}server upload speed we're going to call
you so by the upload bandwidth of each

86
00:02:01,969 --> 00:02:01,979
{\an1}you so by the upload bandwidth of each

87
00:02:01,979 --> 00:02:04,249
{\an1}you so by the upload bandwidth of each
of the peers with each of the hosts

88
00:02:04,249 --> 00:02:04,259
{\an1}of the peers with each of the hosts

89
00:02:04,259 --> 00:02:06,319
{\an1}of the peers with each of the hosts
those regular computers and we're going

90
00:02:06,319 --> 00:02:06,329
{\an1}those regular computers and we're going

91
00:02:06,329 --> 00:02:09,050
{\an1}those regular computers and we're going
to call D sub I the download speed for

92
00:02:09,050 --> 00:02:09,060
{\an1}to call D sub I the download speed for

93
00:02:09,060 --> 00:02:13,320
{\an1}to call D sub I the download speed for
each of the computers

94
00:02:13,320 --> 00:02:13,330
{\an1}

95
00:02:13,330 --> 00:02:16,089
{\an1}do these make sense well we're going to

96
00:02:16,089 --> 00:02:16,099
{\an1}do these make sense well we're going to

97
00:02:16,099 --> 00:02:20,199
{\an1}do these make sense well we're going to
sell you out in big in total clients in

98
00:02:20,199 --> 00:02:20,209
{\an1}sell you out in big in total clients in

99
00:02:20,209 --> 00:02:31,410
{\an1}sell you out in big in total clients in
the system okay so given this set up

100
00:02:31,410 --> 00:02:31,420
{\an1}the system okay so given this set up

101
00:02:31,420 --> 00:02:35,140
{\an1}the system okay so given this set up
what are the limiting factors so

102
00:02:35,140 --> 00:02:35,150
{\an1}what are the limiting factors so

103
00:02:35,150 --> 00:02:36,850
{\an1}what are the limiting factors so
depending on what these values are we're

104
00:02:36,850 --> 00:02:36,860
{\an1}depending on what these values are we're

105
00:02:36,860 --> 00:02:38,259
{\an1}depending on what these values are we're
gonna have different things that could

106
00:02:38,259 --> 00:02:38,269
{\an1}gonna have different things that could

107
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{\an1}gonna have different things that could
occur um

108
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{\an1}occur um

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00:02:39,470 --> 00:02:44,020
{\an1}occur um
one situation is that kind of the

110
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{\an1}one situation is that kind of the

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00:02:44,030 --> 00:02:46,420
{\an1}one situation is that kind of the
bottleneck what could be the bottlenecks

112
00:02:46,420 --> 00:02:46,430
{\an1}bottleneck what could be the bottlenecks

113
00:02:46,430 --> 00:02:48,610
{\an1}bottleneck what could be the bottlenecks
in this situation can you think about it

114
00:02:48,610 --> 00:02:48,620
{\an1}in this situation can you think about it

115
00:02:48,620 --> 00:02:54,720
{\an1}in this situation can you think about it
like that

116
00:02:54,720 --> 00:02:54,730
{\an1}

117
00:02:54,730 --> 00:03:00,910
{\an1}well actually what we're just talking

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00:03:00,910 --> 00:03:00,920
{\an1}well actually what we're just talking

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00:03:00,920 --> 00:03:02,470
{\an1}well actually what we're just talking
about client server did I say that

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00:03:02,470 --> 00:03:02,480
{\an1}about client server did I say that

121
00:03:02,480 --> 00:03:04,660
{\an1}about client server did I say that
sorry okay so that's a great response

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00:03:04,660 --> 00:03:04,670
{\an1}sorry okay so that's a great response

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00:03:04,670 --> 00:03:06,550
{\an1}sorry okay so that's a great response
because I didn't clear so let's just

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{\an1}because I didn't clear so let's just

125
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{\an1}because I didn't clear so let's just
consider client server first all right

126
00:03:08,259 --> 00:03:08,269
{\an1}consider client server first all right

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{\an1}consider client server first all right
client server should be the simple

128
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{\an1}client server should be the simple

129
00:03:09,709 --> 00:03:13,150
{\an1}client server should be the simple
scenario there's clients and servers so

130
00:03:13,150 --> 00:03:13,160
{\an1}scenario there's clients and servers so

131
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{\an1}scenario there's clients and servers so
what factors would in a client-server

132
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{\an1}what factors would in a client-server

133
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{\an1}what factors would in a client-server
setup cause the system to be

134
00:03:22,030 --> 00:03:22,040
{\an1}setup cause the system to be

135
00:03:22,040 --> 00:03:28,870
{\an1}setup cause the system to be
bottlenecked well we're only sending the

136
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{\an1}bottlenecked well we're only sending the

137
00:03:28,880 --> 00:03:33,750
{\an1}bottlenecked well we're only sending the
file from the server to all the clients

138
00:03:33,750 --> 00:03:33,760
{\an1}

139
00:03:33,760 --> 00:03:38,349
{\an1}the client download speeds may be a

140
00:03:38,349 --> 00:03:38,359
{\an1}the client download speeds may be a

141
00:03:38,359 --> 00:03:43,449
{\an1}the client download speeds may be a
factor so what's that and how fast the

142
00:03:43,449 --> 00:03:43,459
{\an1}factor so what's that and how fast the

143
00:03:43,459 --> 00:03:45,370
{\an1}factor so what's that and how fast the
server so if we had really fast clients

144
00:03:45,370 --> 00:03:45,380
{\an1}server so if we had really fast clients

145
00:03:45,380 --> 00:03:47,830
{\an1}server so if we had really fast clients
but the server has a slow upload speed

146
00:03:47,830 --> 00:03:47,840
{\an1}but the server has a slow upload speed

147
00:03:47,840 --> 00:03:50,020
{\an1}but the server has a slow upload speed
the server's can't get out the upper

148
00:03:50,020 --> 00:03:50,030
{\an1}the server's can't get out the upper

149
00:03:50,030 --> 00:03:51,309
{\an1}the server's can't get out the upper
body so we kind of have two different

150
00:03:51,309 --> 00:03:51,319
{\an1}body so we kind of have two different

151
00:03:51,319 --> 00:03:53,309
{\an1}body so we kind of have two different
scenarios and that's what this equation

152
00:03:53,309 --> 00:03:53,319
{\an1}scenarios and that's what this equation

153
00:03:53,319 --> 00:03:58,479
{\an1}scenarios and that's what this equation
represents so the distribution time in a

154
00:03:58,479 --> 00:03:58,489
{\an1}represents so the distribution time in a

155
00:03:58,489 --> 00:04:02,080
{\an1}represents so the distribution time in a
client-server scenario is whichever one

156
00:04:02,080 --> 00:04:02,090
{\an1}client-server scenario is whichever one

157
00:04:02,090 --> 00:04:03,550
{\an1}client-server scenario is whichever one
of these is bigger we've got these two

158
00:04:03,550 --> 00:04:03,560
{\an1}of these is bigger we've got these two

159
00:04:03,560 --> 00:04:07,000
{\an1}of these is bigger we've got these two
quantities okay the first quantity these

160
00:04:07,000 --> 00:04:07,010
{\an1}quantities okay the first quantity these

161
00:04:07,010 --> 00:04:08,080
{\an1}quantities okay the first quantity these
are easy to understand the first

162
00:04:08,080 --> 00:04:08,090
{\an1}are easy to understand the first

163
00:04:08,090 --> 00:04:10,000
{\an1}are easy to understand the first
quantity is related to the server how

164
00:04:10,000 --> 00:04:10,010
{\an1}quantity is related to the server how

165
00:04:10,010 --> 00:04:12,550
{\an1}quantity is related to the server how
many bits does the server have to put

166
00:04:12,550 --> 00:04:12,560
{\an1}many bits does the server have to put

167
00:04:12,560 --> 00:04:15,970
{\an1}many bits does the server have to put
out there well it has to put out the

168
00:04:15,970 --> 00:04:15,980
{\an1}out there well it has to put out the

169
00:04:15,980 --> 00:04:19,659
{\an1}out there well it has to put out the
whole file that's F in Tom's because

170
00:04:19,659 --> 00:04:19,669
{\an1}whole file that's F in Tom's because

171
00:04:19,669 --> 00:04:21,399
{\an1}whole file that's F in Tom's because
it's got to send a complete copy of the

172
00:04:21,399 --> 00:04:21,409
{\an1}it's got to send a complete copy of the

173
00:04:21,409 --> 00:04:26,100
{\an1}it's got to send a complete copy of the
file to every single

174
00:04:26,100 --> 00:04:26,110
{\an1}

175
00:04:26,110 --> 00:04:28,750
{\an1}client but the server has to send the

176
00:04:28,750 --> 00:04:28,760
{\an1}client but the server has to send the

177
00:04:28,760 --> 00:04:31,330
{\an1}client but the server has to send the
file the whole file in Tom's so this is

178
00:04:31,330 --> 00:04:31,340
{\an1}file the whole file in Tom's so this is

179
00:04:31,340 --> 00:04:34,270
{\an1}file the whole file in Tom's so this is
how many bits and s to send in F and how

180
00:04:34,270 --> 00:04:34,280
{\an1}how many bits and s to send in F and how

181
00:04:34,280 --> 00:04:36,340
{\an1}how many bits and s to send in F and how
fast is this and it sends at a speed it

182
00:04:36,340 --> 00:04:36,350
{\an1}fast is this and it sends at a speed it

183
00:04:36,350 --> 00:04:41,910
{\an1}fast is this and it sends at a speed it
up close at a speed of us so in F us is

184
00:04:41,910 --> 00:04:41,920
{\an1}up close at a speed of us so in F us is

185
00:04:41,920 --> 00:04:44,770
{\an1}up close at a speed of us so in F us is
the speed that at the time that's going

186
00:04:44,770 --> 00:04:44,780
{\an1}the speed that at the time that's going

187
00:04:44,780 --> 00:04:47,590
{\an1}the speed that at the time that's going
to take the server to send that file out

188
00:04:47,590 --> 00:04:47,600
{\an1}to take the server to send that file out

189
00:04:47,600 --> 00:04:51,220
{\an1}to take the server to send that file out
that many times does that make sense so

190
00:04:51,220 --> 00:04:51,230
{\an1}that many times does that make sense so

191
00:04:51,230 --> 00:04:54,430
{\an1}that many times does that make sense so
if the server is the slow part then this

192
00:04:54,430 --> 00:04:54,440
{\an1}if the server is the slow part then this

193
00:04:54,440 --> 00:04:56,260
{\an1}if the server is the slow part then this
is going to be the bigger time and it's

194
00:04:56,260 --> 00:04:56,270
{\an1}is going to be the bigger time and it's

195
00:04:56,270 --> 00:04:57,580
{\an1}is going to be the bigger time and it's
that's going to determine how much time

196
00:04:57,580 --> 00:04:57,590
{\an1}that's going to determine how much time

197
00:04:57,590 --> 00:05:00,520
{\an1}that's going to determine how much time
it takes to get the file distributed the

198
00:05:00,520 --> 00:05:00,530
{\an1}it takes to get the file distributed the

199
00:05:00,530 --> 00:05:02,050
{\an1}it takes to get the file distributed the
other hand on the other hand it might be

200
00:05:02,050 --> 00:05:02,060
{\an1}other hand on the other hand it might be

201
00:05:02,060 --> 00:05:04,180
{\an1}other hand on the other hand it might be
that we just have a super slow client

202
00:05:04,180 --> 00:05:04,190
{\an1}that we just have a super slow client

203
00:05:04,190 --> 00:05:08,170
{\an1}that we just have a super slow client
and he's holding everybody back it makes

204
00:05:08,170 --> 00:05:08,180
{\an1}and he's holding everybody back it makes

205
00:05:08,180 --> 00:05:09,880
{\an1}and he's holding everybody back it makes
sense if you've got one got out here

206
00:05:09,880 --> 00:05:09,890
{\an1}sense if you've got one got out here

207
00:05:09,890 --> 00:05:11,920
{\an1}sense if you've got one got out here
that can only download it you know a 56k

208
00:05:11,920 --> 00:05:11,930
{\an1}that can only download it you know a 56k

209
00:05:11,930 --> 00:05:15,580
{\an1}that can only download it you know a 56k
modem then the server can send it out to

210
00:05:15,580 --> 00:05:15,590
{\an1}modem then the server can send it out to

211
00:05:15,590 --> 00:05:17,140
{\an1}modem then the server can send it out to
everybody but this guy's he's just still

212
00:05:17,140 --> 00:05:17,150
{\an1}everybody but this guy's he's just still

213
00:05:17,150 --> 00:05:19,060
{\an1}everybody but this guy's he's just still
waiting on this guy to finish that makes

214
00:05:19,060 --> 00:05:19,070
{\an1}waiting on this guy to finish that makes

215
00:05:19,070 --> 00:05:22,720
{\an1}waiting on this guy to finish that makes
sense so we found the minimum di that's

216
00:05:22,720 --> 00:05:22,730
{\an1}sense so we found the minimum di that's

217
00:05:22,730 --> 00:05:24,730
{\an1}sense so we found the minimum di that's
the minimum download speed of all of the

218
00:05:24,730 --> 00:05:24,740
{\an1}the minimum download speed of all of the

219
00:05:24,740 --> 00:05:27,190
{\an1}the minimum download speed of all of the
clients and we take the file size

220
00:05:27,190 --> 00:05:27,200
{\an1}clients and we take the file size

221
00:05:27,200 --> 00:05:29,140
{\an1}clients and we take the file size
divided by that speed so this is the

222
00:05:29,140 --> 00:05:29,150
{\an1}divided by that speed so this is the

223
00:05:29,150 --> 00:05:30,550
{\an1}divided by that speed so this is the
time that takes the slowest client to

224
00:05:30,550 --> 00:05:30,560
{\an1}time that takes the slowest client to

225
00:05:30,560 --> 00:05:33,010
{\an1}time that takes the slowest client to
download the file once hmm

226
00:05:33,010 --> 00:05:33,020
{\an1}download the file once hmm

227
00:05:33,020 --> 00:05:34,590
{\an1}download the file once hmm
so those are two potential bottlenecks

228
00:05:34,590 --> 00:05:34,600
{\an1}so those are two potential bottlenecks

229
00:05:34,600 --> 00:05:37,840
{\an1}so those are two potential bottlenecks
whichever one of those is bigger is what

230
00:05:37,840 --> 00:05:37,850
{\an1}whichever one of those is bigger is what

231
00:05:37,850 --> 00:05:40,090
{\an1}whichever one of those is bigger is what
the time to distribute the file is in a

232
00:05:40,090 --> 00:05:40,100
{\an1}the time to distribute the file is in a

233
00:05:40,100 --> 00:05:42,760
{\an1}the time to distribute the file is in a
client-server scenario does that math

234
00:05:42,760 --> 00:05:42,770
{\an1}client-server scenario does that math

235
00:05:42,770 --> 00:05:45,390
{\an1}client-server scenario does that math
make sense it's pretty straightforward

236
00:05:45,390 --> 00:05:45,400
{\an1}make sense it's pretty straightforward

237
00:05:45,400 --> 00:05:47,650
{\an1}make sense it's pretty straightforward
I'm so depending on what these values

238
00:05:47,650 --> 00:05:47,660
{\an1}I'm so depending on what these values

239
00:05:47,660 --> 00:05:48,850
{\an1}I'm so depending on what these values
are that could be it could look very

240
00:05:48,850 --> 00:05:48,860
{\an1}are that could be it could look very

241
00:05:48,860 --> 00:05:51,040
{\an1}are that could be it could look very
different but this is a scenario that

242
00:05:51,040 --> 00:05:51,050
{\an1}different but this is a scenario that

243
00:05:51,050 --> 00:05:52,720
{\an1}different but this is a scenario that
models it so now we're going to do the

244
00:05:52,720 --> 00:05:52,730
{\an1}models it so now we're going to do the

245
00:05:52,730 --> 00:05:56,700
{\an1}models it so now we're going to do the
same thing in client in and peer-to-peer

246
00:05:56,700 --> 00:05:56,710
{\an1}same thing in client in and peer-to-peer

247
00:05:56,710 --> 00:05:58,810
{\an1}same thing in client in and peer-to-peer
so we're gonna have these two

248
00:05:58,810 --> 00:05:58,820
{\an1}so we're gonna have these two

249
00:05:58,820 --> 00:06:00,340
{\an1}so we're gonna have these two
constraints and peer to peer which is

250
00:06:00,340 --> 00:06:00,350
{\an1}constraints and peer to peer which is

251
00:06:00,350 --> 00:06:02,770
{\an1}constraints and peer to peer which is
how long does it take to upload the file

252
00:06:02,770 --> 00:06:02,780
{\an1}how long does it take to upload the file

253
00:06:02,780 --> 00:06:05,140
{\an1}how long does it take to upload the file
to everybody and how long does it take

254
00:06:05,140 --> 00:06:05,150
{\an1}to everybody and how long does it take

255
00:06:05,150 --> 00:06:07,570
{\an1}to everybody and how long does it take
this slowest got to download it but we

256
00:06:07,570 --> 00:06:07,580
{\an1}this slowest got to download it but we

257
00:06:07,580 --> 00:06:10,930
{\an1}this slowest got to download it but we
have one more scenario right because in

258
00:06:10,930 --> 00:06:10,940
{\an1}have one more scenario right because in

259
00:06:10,940 --> 00:06:19,360
{\an1}have one more scenario right because in
peer to peer everybody's a server clear

260
00:06:19,360 --> 00:06:19,370
{\an1}peer to peer everybody's a server clear

261
00:06:19,370 --> 00:06:27,159
{\an1}peer to peer everybody's a server clear
what that is No

262
00:06:27,159 --> 00:06:27,169
{\an1}

263
00:06:27,169 --> 00:06:31,540
{\an1}let's look at it like this so if

264
00:06:31,540 --> 00:06:31,550
{\an1}let's look at it like this so if

265
00:06:31,550 --> 00:06:33,309
{\an1}let's look at it like this so if
everybody can be a client and a server

266
00:06:33,309 --> 00:06:33,319
{\an1}everybody can be a client and a server

267
00:06:33,319 --> 00:06:35,619
{\an1}everybody can be a client and a server
then the server just has to upload it

268
00:06:35,619 --> 00:06:35,629
{\an1}then the server just has to upload it

269
00:06:35,629 --> 00:06:39,010
{\an1}then the server just has to upload it
once so that somebody else gets a copy

270
00:06:39,010 --> 00:06:39,020
{\an1}once so that somebody else gets a copy

271
00:06:39,020 --> 00:06:41,950
{\an1}once so that somebody else gets a copy
of it and then that guy can upload it to

272
00:06:41,950 --> 00:06:41,960
{\an1}of it and then that guy can upload it to

273
00:06:41,960 --> 00:06:46,209
{\an1}of it and then that guy can upload it to
somebody else makes sense this whole

274
00:06:46,209 --> 00:06:46,219
{\an1}somebody else makes sense this whole

275
00:06:46,219 --> 00:06:49,929
{\an1}somebody else makes sense this whole
setup does assume that all the computers

276
00:06:49,929 --> 00:06:49,939
{\an1}setup does assume that all the computers

277
00:06:49,939 --> 00:06:52,480
{\an1}setup does assume that all the computers
just magically know who to connect to

278
00:06:52,480 --> 00:06:52,490
{\an1}just magically know who to connect to

279
00:06:52,490 --> 00:06:54,820
{\an1}just magically know who to connect to
and in actuality that couldn't happen

280
00:06:54,820 --> 00:06:54,830
{\an1}and in actuality that couldn't happen

281
00:06:54,830 --> 00:06:56,559
{\an1}and in actuality that couldn't happen
right they'd have to know I need to talk

282
00:06:56,559 --> 00:06:56,569
{\an1}right they'd have to know I need to talk

283
00:06:56,569 --> 00:06:58,209
{\an1}right they'd have to know I need to talk
to this guy to get this part of the file

284
00:06:58,209 --> 00:06:58,219
{\an1}to this guy to get this part of the file

285
00:06:58,219 --> 00:06:59,950
{\an1}to this guy to get this part of the file
but we're going to kind of assume it in

286
00:06:59,950 --> 00:06:59,960
{\an1}but we're going to kind of assume it in

287
00:06:59,960 --> 00:07:01,959
{\an1}but we're going to kind of assume it in
an ideal case so now we have three

288
00:07:01,959 --> 00:07:01,969
{\an1}an ideal case so now we have three

289
00:07:01,969 --> 00:07:04,600
{\an1}an ideal case so now we have three
quantities the first quantity is this is

290
00:07:04,600 --> 00:07:04,610
{\an1}quantities the first quantity is this is

291
00:07:04,610 --> 00:07:06,519
{\an1}quantities the first quantity is this is
how long it takes the server to upload

292
00:07:06,519 --> 00:07:06,529
{\an1}how long it takes the server to upload

293
00:07:06,529 --> 00:07:09,189
{\an1}how long it takes the server to upload
the file once so that's the full file F

294
00:07:09,189 --> 00:07:09,199
{\an1}the file once so that's the full file F

295
00:07:09,199 --> 00:07:11,170
{\an1}the file once so that's the full file F
mints divided by the server's upload

296
00:07:11,170 --> 00:07:11,180
{\an1}mints divided by the server's upload

297
00:07:11,180 --> 00:07:13,360
{\an1}mints divided by the server's upload
speed so this is an improvement from

298
00:07:13,360 --> 00:07:13,370
{\an1}speed so this is an improvement from

299
00:07:13,370 --> 00:07:15,279
{\an1}speed so this is an improvement from
before because the server doesn't have

300
00:07:15,279 --> 00:07:15,289
{\an1}before because the server doesn't have

301
00:07:15,289 --> 00:07:17,019
{\an1}before because the server doesn't have
to upload it in Tom's just has to do it

302
00:07:17,019 --> 00:07:17,029
{\an1}to upload it in Tom's just has to do it

303
00:07:17,029 --> 00:07:19,300
{\an1}to upload it in Tom's just has to do it
once and then sharing the load of the

304
00:07:19,300 --> 00:07:19,310
{\an1}once and then sharing the load of the

305
00:07:19,310 --> 00:07:20,769
{\an1}once and then sharing the load of the
additional distributions to other

306
00:07:20,769 --> 00:07:20,779
{\an1}additional distributions to other

307
00:07:20,779 --> 00:07:23,350
{\an1}additional distributions to other
clients we've got the same one which is

308
00:07:23,350 --> 00:07:23,360
{\an1}clients we've got the same one which is

309
00:07:23,360 --> 00:07:26,260
{\an1}clients we've got the same one which is
whoever the slowest client is the has to

310
00:07:26,260 --> 00:07:26,270
{\an1}whoever the slowest client is the has to

311
00:07:26,270 --> 00:07:27,670
{\an1}whoever the slowest client is the has to
download the file once so that's F

312
00:07:27,670 --> 00:07:27,680
{\an1}download the file once so that's F

313
00:07:27,680 --> 00:07:30,489
{\an1}download the file once so that's F
divided by the minimum di and the new

314
00:07:30,489 --> 00:07:30,499
{\an1}divided by the minimum di and the new

315
00:07:30,499 --> 00:07:32,950
{\an1}divided by the minimum di and the new
one that's interesting to us is we know

316
00:07:32,950 --> 00:07:32,960
{\an1}one that's interesting to us is we know

317
00:07:32,960 --> 00:07:35,170
{\an1}one that's interesting to us is we know
that the file has to be distributed from

318
00:07:35,170 --> 00:07:35,180
{\an1}that the file has to be distributed from

319
00:07:35,180 --> 00:07:39,879
{\an1}that the file has to be distributed from
every person to all the bits have to be

320
00:07:39,879 --> 00:07:39,889
{\an1}every person to all the bits have to be

321
00:07:39,889 --> 00:07:42,010
{\an1}every person to all the bits have to be
distributed to everyone so the total

322
00:07:42,010 --> 00:07:42,020
{\an1}distributed to everyone so the total

323
00:07:42,020 --> 00:07:45,670
{\an1}distributed to everyone so the total
number of bits is in F but we get to

324
00:07:45,670 --> 00:07:45,680
{\an1}number of bits is in F but we get to

325
00:07:45,680 --> 00:07:48,219
{\an1}number of bits is in F but we get to
share the upload capacity of the whole

326
00:07:48,219 --> 00:07:48,229
{\an1}share the upload capacity of the whole

327
00:07:48,229 --> 00:07:50,079
{\an1}share the upload capacity of the whole
network and the upload capacity of the

328
00:07:50,079 --> 00:07:50,089
{\an1}network and the upload capacity of the

329
00:07:50,089 --> 00:07:52,149
{\an1}network and the upload capacity of the
network is the server's upload speed

330
00:07:52,149 --> 00:07:52,159
{\an1}network is the server's upload speed

331
00:07:52,159 --> 00:07:55,389
{\an1}network is the server's upload speed
plus a sum of all the upload speeds of

332
00:07:55,389 --> 00:07:55,399
{\an1}plus a sum of all the upload speeds of

333
00:07:55,399 --> 00:07:58,059
{\an1}plus a sum of all the upload speeds of
all the clients so this is what makes it

334
00:07:58,059 --> 00:07:58,069
{\an1}all the clients so this is what makes it

335
00:07:58,069 --> 00:07:59,800
{\an1}all the clients so this is what makes it
peer-to-peer is that we don't just have

336
00:07:59,800 --> 00:07:59,810
{\an1}peer-to-peer is that we don't just have

337
00:07:59,810 --> 00:08:01,389
{\an1}peer-to-peer is that we don't just have
to upload it from the server and that's

338
00:08:01,389 --> 00:08:01,399
{\an1}to upload it from the server and that's

339
00:08:01,399 --> 00:08:03,100
{\an1}to upload it from the server and that's
the only choice but everybody can upload

340
00:08:03,100 --> 00:08:03,110
{\an1}the only choice but everybody can upload

341
00:08:03,110 --> 00:08:04,629
{\an1}the only choice but everybody can upload
and that means other people could

342
00:08:04,629 --> 00:08:04,639
{\an1}and that means other people could

343
00:08:04,639 --> 00:08:06,730
{\an1}and that means other people could
download from that other sort of other

344
00:08:06,730 --> 00:08:06,740
{\an1}download from that other sort of other

345
00:08:06,740 --> 00:08:09,429
{\an1}download from that other sort of other
clients other people could download from

346
00:08:09,429 --> 00:08:09,439
{\an1}clients other people could download from

347
00:08:09,439 --> 00:08:11,769
{\an1}clients other people could download from
that other clients upload and in that

348
00:08:11,769 --> 00:08:11,779
{\an1}that other clients upload and in that

349
00:08:11,779 --> 00:08:14,079
{\an1}that other clients upload and in that
case where that client is acting like a

350
00:08:14,079 --> 00:08:14,089
{\an1}case where that client is acting like a

351
00:08:14,089 --> 00:08:20,110
{\an1}case where that client is acting like a
server that's peer-to-peer so this is

352
00:08:20,110 --> 00:08:20,120
{\an1}server that's peer-to-peer so this is

353
00:08:20,120 --> 00:08:22,420
{\an1}server that's peer-to-peer so this is
the interesting part is that we are as

354
00:08:22,420 --> 00:08:22,430
{\an1}the interesting part is that we are as

355
00:08:22,430 --> 00:08:27,070
{\an1}the interesting part is that we are as
we add more computers to the network in

356
00:08:27,070 --> 00:08:27,080
{\an1}we add more computers to the network in

357
00:08:27,080 --> 00:08:28,540
{\an1}we add more computers to the network in
the client-server scenario that just

358
00:08:28,540 --> 00:08:28,550
{\an1}the client-server scenario that just

359
00:08:28,550 --> 00:08:30,459
{\an1}the client-server scenario that just
gets works right because the more you

360
00:08:30,459 --> 00:08:30,469
{\an1}gets works right because the more you

361
00:08:30,469 --> 00:08:31,570
{\an1}gets works right because the more you
have the more times you have to

362
00:08:31,570 --> 00:08:31,580
{\an1}have the more times you have to

363
00:08:31,580 --> 00:08:32,769
{\an1}have the more times you have to
distribute that's more load on the

364
00:08:32,769 --> 00:08:32,779
{\an1}distribute that's more load on the

365
00:08:32,779 --> 00:08:35,740
{\an1}distribute that's more load on the
server whereas in a p2p scenario the

366
00:08:35,740 --> 00:08:35,750
{\an1}server whereas in a p2p scenario the

367
00:08:35,750 --> 00:08:38,139
{\an1}server whereas in a p2p scenario the
more servers that the more clients that

368
00:08:38,139 --> 00:08:38,149
{\an1}more servers that the more clients that

369
00:08:38,149 --> 00:08:40,120
{\an1}more servers that the more clients that
you add yeah you have to distribute

370
00:08:40,120 --> 00:08:40,130
{\an1}you add yeah you have to distribute

371
00:08:40,130 --> 00:08:42,100
{\an1}you add yeah you have to distribute
more but you get their capacity also

372
00:08:42,100 --> 00:08:42,110
{\an1}more but you get their capacity also

373
00:08:42,110 --> 00:08:44,140
{\an1}more but you get their capacity also
added in there upload capacity that

374
00:08:44,140 --> 00:08:44,150
{\an1}added in there upload capacity that

375
00:08:44,150 --> 00:08:46,210
{\an1}added in there upload capacity that
makes sense so kind of you get this

376
00:08:46,210 --> 00:08:46,220
{\an1}makes sense so kind of you get this

377
00:08:46,220 --> 00:08:48,490
{\an1}makes sense so kind of you get this
trade-off effect so now I'm going to

378
00:08:48,490 --> 00:08:48,500
{\an1}trade-off effect so now I'm going to

379
00:08:48,500 --> 00:08:51,640
{\an1}trade-off effect so now I'm going to
show you this graph which they authors

380
00:08:51,640 --> 00:08:51,650
{\an1}show you this graph which they authors

381
00:08:51,650 --> 00:08:56,140
{\an1}show you this graph which they authors
chose some reasonable amounts for F

382
00:08:56,140 --> 00:08:56,150
{\an1}chose some reasonable amounts for F

383
00:08:56,150 --> 00:08:57,940
{\an1}chose some reasonable amounts for F
divided by U so that's the time that

384
00:08:57,940 --> 00:08:57,950
{\an1}divided by U so that's the time that

385
00:08:57,950 --> 00:09:04,230
{\an1}divided by U so that's the time that
takes the the download time for a client

386
00:09:04,230 --> 00:09:04,240
{\an1}takes the the download time for a client

387
00:09:04,240 --> 00:09:06,730
{\an1}takes the the download time for a client
they're gonna assume for this that all

388
00:09:06,730 --> 00:09:06,740
{\an1}they're gonna assume for this that all

389
00:09:06,740 --> 00:09:08,770
{\an1}they're gonna assume for this that all
clients have the same download speed so

390
00:09:08,770 --> 00:09:08,780
{\an1}clients have the same download speed so

391
00:09:08,780 --> 00:09:12,550
{\an1}clients have the same download speed so
all the D is and all that you learn all

392
00:09:12,550 --> 00:09:12,560
{\an1}all the D is and all that you learn all

393
00:09:12,560 --> 00:09:16,720
{\an1}all the D is and all that you learn all
the UI's are the same so it takes if

394
00:09:16,720 --> 00:09:16,730
{\an1}the UI's are the same so it takes if

395
00:09:16,730 --> 00:09:18,700
{\an1}the UI's are the same so it takes if
after about about you is one hour and us

396
00:09:18,700 --> 00:09:18,710
{\an1}after about about you is one hour and us

397
00:09:18,710 --> 00:09:23,320
{\an1}after about about you is one hour and us
is ten use so that the server has 10

398
00:09:23,320 --> 00:09:23,330
{\an1}is ten use so that the server has 10

399
00:09:23,330 --> 00:09:25,060
{\an1}is ten use so that the server has 10
times the upload speed of the clients

400
00:09:25,060 --> 00:09:25,070
{\an1}times the upload speed of the clients

401
00:09:25,070 --> 00:09:27,930
{\an1}times the upload speed of the clients
and we're assuming that the minimum

402
00:09:27,930 --> 00:09:27,940
{\an1}and we're assuming that the minimum

403
00:09:27,940 --> 00:09:32,230
{\an1}and we're assuming that the minimum
download speed is greater than the

404
00:09:32,230 --> 00:09:32,240
{\an1}download speed is greater than the

405
00:09:32,240 --> 00:09:35,230
{\an1}download speed is greater than the
upload speed of the server which that's

406
00:09:35,230 --> 00:09:35,240
{\an1}upload speed of the server which that's

407
00:09:35,240 --> 00:09:38,440
{\an1}upload speed of the server which that's
probably reasonable too then this is the

408
00:09:38,440 --> 00:09:38,450
{\an1}probably reasonable too then this is the

409
00:09:38,450 --> 00:09:40,150
{\an1}probably reasonable too then this is the
graph that we get which should make

410
00:09:40,150 --> 00:09:40,160
{\an1}graph that we get which should make

411
00:09:40,160 --> 00:09:43,440
{\an1}graph that we get which should make
sense that as we add more and more

412
00:09:43,440 --> 00:09:43,450
{\an1}sense that as we add more and more

413
00:09:43,450 --> 00:09:46,840
{\an1}sense that as we add more and more
devices to the system right the client

414
00:09:46,840 --> 00:09:46,850
{\an1}devices to the system right the client

415
00:09:46,850 --> 00:09:50,140
{\an1}devices to the system right the client
server continues up linearly all right

416
00:09:50,140 --> 00:09:50,150
{\an1}server continues up linearly all right

417
00:09:50,150 --> 00:09:51,130
{\an1}server continues up linearly all right
let's go back and look at that equation

418
00:09:51,130 --> 00:09:51,140
{\an1}let's go back and look at that equation

419
00:09:51,140 --> 00:09:53,350
{\an1}let's go back and look at that equation
to make sense of that but as this gets

420
00:09:53,350 --> 00:09:53,360
{\an1}to make sense of that but as this gets

421
00:09:53,360 --> 00:09:55,180
{\an1}to make sense of that but as this gets
as we had more and more clients which

422
00:09:55,180 --> 00:09:55,190
{\an1}as we had more and more clients which

423
00:09:55,190 --> 00:10:02,020
{\an1}as we had more and more clients which
one of these terms dominates in M right

424
00:10:02,020 --> 00:10:02,030
{\an1}one of these terms dominates in M right

425
00:10:02,030 --> 00:10:04,450
{\an1}one of these terms dominates in M right
there's no end in this so it's gonna be

426
00:10:04,450 --> 00:10:04,460
{\an1}there's no end in this so it's gonna be

427
00:10:04,460 --> 00:10:07,510
{\an1}there's no end in this so it's gonna be
kind of fixed with respect to n so as we

428
00:10:07,510 --> 00:10:07,520
{\an1}kind of fixed with respect to n so as we

429
00:10:07,520 --> 00:10:09,160
{\an1}kind of fixed with respect to n so as we
add more and more clients this thing

430
00:10:09,160 --> 00:10:09,170
{\an1}add more and more clients this thing

431
00:10:09,170 --> 00:10:10,930
{\an1}add more and more clients this thing
just blows up right it just increases

432
00:10:10,930 --> 00:10:10,940
{\an1}just blows up right it just increases

433
00:10:10,940 --> 00:10:13,240
{\an1}just blows up right it just increases
linearly because there's a in there what

434
00:10:13,240 --> 00:10:13,250
{\an1}linearly because there's a in there what

435
00:10:13,250 --> 00:10:16,090
{\an1}linearly because there's a in there what
do we see here linear increase make

436
00:10:16,090 --> 00:10:16,100
{\an1}do we see here linear increase make

437
00:10:16,100 --> 00:10:18,100
{\an1}do we see here linear increase make
sense right so in a client-server

438
00:10:18,100 --> 00:10:18,110
{\an1}sense right so in a client-server

439
00:10:18,110 --> 00:10:20,350
{\an1}sense right so in a client-server
scenario the time to distribute this

440
00:10:20,350 --> 00:10:20,360
{\an1}scenario the time to distribute this

441
00:10:20,360 --> 00:10:22,060
{\an1}scenario the time to distribute this
file that's the minimum distribution

442
00:10:22,060 --> 00:10:22,070
{\an1}file that's the minimum distribution

443
00:10:22,070 --> 00:10:25,420
{\an1}file that's the minimum distribution
time increases linearly in the number of

444
00:10:25,420 --> 00:10:25,430
{\an1}time increases linearly in the number of

445
00:10:25,430 --> 00:10:28,780
{\an1}time increases linearly in the number of
computers in the network however we get

446
00:10:28,780 --> 00:10:28,790
{\an1}computers in the network however we get

447
00:10:28,790 --> 00:10:31,360
{\an1}computers in the network however we get
this nice looking chart here for

448
00:10:31,360 --> 00:10:31,370
{\an1}this nice looking chart here for

449
00:10:31,370 --> 00:10:34,560
{\an1}this nice looking chart here for
peer-to-peer where as we add more

450
00:10:34,560 --> 00:10:34,570
{\an1}peer-to-peer where as we add more

451
00:10:34,570 --> 00:10:37,930
{\an1}peer-to-peer where as we add more
systems to the network the minimum

452
00:10:37,930 --> 00:10:37,940
{\an1}systems to the network the minimum

453
00:10:37,940 --> 00:10:40,260
{\an1}systems to the network the minimum
distribution time doesn't go up linearly

454
00:10:40,260 --> 00:10:40,270
{\an1}distribution time doesn't go up linearly

455
00:10:40,270 --> 00:10:46,030
{\an1}distribution time doesn't go up linearly
and why does it not go up linearly and

456
00:10:46,030 --> 00:10:46,040
{\an1}and why does it not go up linearly and

457
00:10:46,040 --> 00:10:49,049
{\an1}and why does it not go up linearly and
kind of sum up we said hmm

458
00:10:49,049 --> 00:10:49,059
{\an1}kind of sum up we said hmm

459
00:10:49,059 --> 00:10:50,369
{\an1}kind of sum up we said hmm
sharing the bandwidth of sharing that

460
00:10:50,369 --> 00:10:50,379
{\an1}sharing the bandwidth of sharing that

461
00:10:50,379 --> 00:10:52,859
{\an1}sharing the bandwidth of sharing that
upload responsibility

462
00:10:52,859 --> 00:10:52,869
{\an1}upload responsibility

463
00:10:52,869 --> 00:10:54,719
{\an1}upload responsibility
so that's peer-to-peer and you see how

464
00:10:54,719 --> 00:10:54,729
{\an1}so that's peer-to-peer and you see how

465
00:10:54,729 --> 00:10:57,959
{\an1}so that's peer-to-peer and you see how
with a large number of n we get a nice

466
00:10:57,959 --> 00:10:57,969
{\an1}with a large number of n we get a nice

467
00:10:57,969 --> 00:10:59,789
{\an1}with a large number of n we get a nice
payoff well and with these particular

468
00:10:59,789 --> 00:10:59,799
{\an1}payoff well and with these particular

469
00:10:59,799 --> 00:11:04,769
{\an1}payoff well and with these particular
value stud does that make sense so this

470
00:11:04,769 --> 00:11:04,779
{\an1}value stud does that make sense so this

471
00:11:04,779 --> 00:11:06,769
{\an1}value stud does that make sense so this
kind of shared responsibility and

472
00:11:06,769 --> 00:11:06,779
{\an1}kind of shared responsibility and

473
00:11:06,779 --> 00:11:11,269
{\an1}kind of shared responsibility and
sharing the bandwidth and often saving

474
00:11:11,269 --> 00:11:11,279
{\an1}sharing the bandwidth and often saving

475
00:11:11,279 --> 00:11:14,429
{\an1}sharing the bandwidth and often saving
time right making it more efficient to

476
00:11:14,429 --> 00:11:14,439
{\an1}time right making it more efficient to

477
00:11:14,439 --> 00:11:18,329
{\an1}time right making it more efficient to
distribute this file is why p2p has been

478
00:11:18,329 --> 00:11:18,339
{\an1}distribute this file is why p2p has been

479
00:11:18,339 --> 00:11:20,969
{\an1}distribute this file is why p2p has been
popular