[K12OSN] 100Mbit switch vs. 100Mbit hub

Olivier Mugnier olivier.mugnier at laposte.net
Mon Mar 19 21:24:13 UTC 2007

On heavy traffic, the server talk a lot....


There communication from the client to the server as well...
Imagine that all your 20 client ask 1 questions to the servers...
You are (with a Hub) saying to them: Wait a second to the first....
Wait 2 second to the other one... and then wait 3,4,5,...
And, 1 second latter, the first one try again... you're again telling him 
a second....
1 Second latter, you have both 1 and 2 asking you... Since there are 2 at
the same time, collision appear... And they will try again a bit latter....

With a switch... You said nothing to them... you just take the packet in, 
for the server to listen... and send it to the server (queuing)

Much more efficient... (as in classroom, the first to ask, the first to 
the second one wait until the first have finish his question, than the third 

So has the server on it side.... It will send data as much as he can... but 
the switch
will wait until he as finished talking to ask him something new...

Slowing down the fill by queuing is more efficient than making all of them 
talking as
the same time...
(As for car jame... better slowing down speed and be regular than going fast 
on 30 feet
then stop)

----- Original Message ----- 
From: "Rob Owens" <rowens at ptd.net>
To: <k12osn at redhat.com>
Sent: Monday, March 19, 2007 10:06 PM
Subject: [K12OSN] 100Mbit switch vs. 100Mbit hub

> I've been on this list long enough that I've heard "use a switch, not a
> hub" about a hundred times.  But I have a question about the reasoning:
> The server has the most traffic going to/from it.  So if you were using
> a switch, the server port of the switch would be saturated first--as
> soon as 100Mbit/sec is going to/from the server.  If
> you instead used a hub, the only difference I see is that *all* of the
> ports would saturate at the same time--as soon as 100Mbit/sec is going
> to/from the server.
> Since there is no traffic going from one terminal
> to another, it seems like a 100Mbit/sec hub would become a bottleneck at
> the same time that a 100Mbit/sec switch would.  What am I missing?
> -Rob
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