[SATLUG] Network+ question collision domains

Bruce Dubbs bruce.dubbs at gmail.com
Sun Jan 10 20:04:19 CST 2010


Todd W. Bucy wrote:
> situation:
> 
> I have a virtual server running with three nic cards.  each nick card is 
> bridged.  One bridged nic is connected to the the DMZ router/switch, 
> another one is connected to my private router, and a third is connected 
> to a separate experimental network.  the virtual server itself lies 
> behind the private router and hosts a 2 webservers and a mail server 
> inside of the DMZ and a LTSP sever on my experimental switch.  finally 
> each bridge nic can accomidate up to 10 hosts.
> 
> question:
> 
> given that the nics are bridged do the hosts connected to that bridged 
> nic constitute a collision domain?

I don't know about your setup, but if it were HW, a collision domain is 
where frames being sent out can collide.  Bridges do a Carrier Sense 
with Multiple Acesss and Collision Detection CSMA/CD.  Hubs do not and 
the collision detection has to be at the NIC.   That is fairly old 
technology with Thick-net or Thin-net.  10*-BaseT is generally hooked up 
to a bridge or a router that inherently prevents collisions.

A bridge receives a frame and can hold it until the destination is free.

My conclusion is that what you have is probably free of collisions.

   -- Bruce


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