Consider N Peers （ user ） distribute F=15Gb A file of . The server has us=30Mbps Upload rate of , Download rate per peer di=2Mbps, The upload rate is u. Please target customers separately - Server distribution mode and P2P There are two cases of distribution mode , about N=10,100 and 1000 as well as u=500kbps,1Mbps and 2Mbps Each combination of , Chart minimum distribution time .（ notes ：k=10^3,M=10^6,G=10^9）
answer ： For customers - Server distribution mode （C-S）, Minimum distribution time and upload rate u irrelevant , And N of . The minimum distribution time in each case is shown in the table below , Below , The unit is seconds .
N C-S P2P
500kbps 1Mbps 2Mbps
10 7500 7500 7500 7500
100 50000 18750 11539 7500
1000 500000 28302 14563 7500
It can be seen that , about C-S pattern , Minimum distribution time with N And linear growth .
about P2P pattern , Minimum distribution time with N The growth rate of the two groups has been slowed down , close to log function . And the higher the upload rate of the client , The minimum distribution time is affected by N The smaller the impact , It can transfer files to more users in a short time .
The specific steps are as follows ：
N
NF/us
F/min(di)
F/us
NF/(us+∑ui)
Minimum distribution time /s
10
C-S
5000
7500
7500
P2P
500kbps
7500
500
4286
7500
1Mbps
7500
500
3750
7500
2Mbps
7500
500
3000
7500
100
C-S
50000
7500
50000
P2P
500kbps
7500
500
18750
18750
1Mbps
7500
500
11539
11539
2Mbps
7500
500
6522
7500
1000
C-S
500000
7500
500000
P2P
500kbps
7500
500
28302
28302
1Mbps
7500
500
14563
14563
2Mbps
7500
500
7389
7500
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