[SATLUG] Network+ question collision domains
bruce.dubbs at gmail.com
Sun Jan 10 20:27:12 CST 2010
Todd W. Bucy wrote:
>> 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.
> If a bridge holds the data until the line is free wouldn't that make it
> CSMA/CA rather then CSMA/CD?
No. There is only 2 devices on the physical line -- the bridge and the
nic. Both know what is going on and no collisions occur. You need a
third device to cause a collision and there are none present.
CSMA/CA lowers the probability of a collision by listening to a line for
traffic and waiting a random amount of time to start transmitting, but
doesn't prevent them completely.
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