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Discussion Starter · #1 ·
hi am new here and this is my first post ...
i have just started preparing for ccna .. and am confused about collision domain and broadcast domain ...

i was reading a book on ccna and in this pic below



it says the example in that pic has nine collision domains and three broadcast domains...

i cant understand .. how do i find the collision and broadcast domains from that pic ???:confused:

can somebody explain those in a simple way ??
 

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Look at the lines between the boxes. Collision domains include the NIC in a system. In a CSMA/CD network a system has to listen for a clear carrier before transmittal. The more devices in a collision domain the higher the propensity for two devices transmitting at the same time.

Hubs are simply repeaters. All traffic is repeated to every port.

Bridges look at layer 2 frames and only forward frames that are broadcast (everybody), or frames that are unicast that are in their FIB to destined MAC.

Switches are a bit like bridges, but keep their FIB table down to individual ports. In a given network broadcast traffic can still hit all ports..

Routers....

That make some sense?
 

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Discussion Starter · #3 ·
ok ... thanks

so that means pc-> switch (1 collison domain)
switch->switch (1 collision domain )
switch->router (1 collision domain )

different devices->hub (1 collision domain )

but i still dont understand how this layout here has 3 collision domain ??



especially the the two connection to the bridge from two different hubs?? is that a single collision domain ??:(
 

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PC 1 to bridge - collision
PC 2 to bridge - collision
bridge to router - collision
 
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