collisions

[carl_townshend]

Hi all, on a hub, when we have collisions, do we get that when 2 machines that are trying to talk to each other collide, or when ANY 2 machines transmit at the same time ?

cheers

[Joseph W. Doherty]

On shared media, such as a hub, when multiple NICs try to transmit at the same time (after checking the wire seems inactive). Could be more than two.

PS:

With switches running in half duplex, and with just one host directly connected to the switch, happens when host and switch both try to transmit on the shared link between them.

[purohit_810]

In HUB, Hub is bydefault HALF DUPLEX.

At a time it can be send or receive...NOT BOTH.

So, obvious only one machine can send at a time and one machine can receive. Upon one side communication finish it start to send-receive again.

Regards,

Dharmesh

[carl_townshend]

so how come we have collisions on a hun then ?

[avmabe]

you have collisions because you are using a hub. Don't try to figure out /why/ you have collisions. You have collisions because you are using a hub.

[carl_townshend]

Can anyone explain why we have collisions ?

[avmabe]

A collision is when two computers try to send data at the same time. I.e. when computer a sends data to computer B, and computer C sends data to computer A. Both computers listen to the wire, don't see any traffic on the wire and send. You then get a collision. Because a hub sends all data on all wires you would see a collision with a hub.

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