[問答] hub & switch

[pop10353 (女乃 豆頁 單戈 示申)]

   Suppose there are five computers connected together to form a LAN.
The maximum data transport rate that the network cable can provide is 100Mbps,
ideally.
   If we use a hub to connect them,all computers in the network share the
100Mbps bandwidth. <<這句話是說所有電腦會分享總寬頻？
                     那麼分享的意思是共用、還是分割？
   If we use a switch,then any two of the computers can communicate with
each other without disturbing the other computers.
   Assume that the other four computers only communicate with each other,
and each has a constant data rate of 20Mbps.<<想問這句話確切的意思??
   Now,you want to download a 10MB file from a remote server,which is located
outside your local network.

Q1:How long will it take if using a hub?
Q2:How long will it take if using a switch?

Ans:1. (10*8)/ (100-20*4)= 4sec
    2. (10*8)/  100=0.8sec

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◆ From: 124.9.193.233
推 imiss0960:共用
如果是共用 那為什麼第一個問題100Mbps要扣掉80??
※ 編輯: pop10353        來自: 124.9.193.233        (07/28 20:09)
推 badctc252:共用是指共同使用頻寬如果一台PC使用了20%的頻寬剩下的
→ badctc252:PC只能用80%
推 kimi7918:那句話的意思是，四台電腦都占用20Mbps互相傳輸
→ kimi7918:使用HUB的話，剩下的那port就只剩下20M可以用
→ kimi7918:但Switch不會占用頻寬，剩下那Port還是有100M可對外溝通