CSMA - are packets frames or signals colliding?

davidt · Joined: 05 Apr 2005 Posts: 1

with csma/cd, is it more correct to say that signals collide, packets collide, or frames collide? are any of those wrong?

The detection must occur at the physical layer, so it's signals there. But once there's a collission, i'd have thought it's frames. and all frames contain packets.

i know that cisco refers to signals colliding. But most other sources refer to packets colliding, and many - but fewer - refer to frames colliding. IF it is packets colliding then that's more specific than signals. But is it as correct?

lachesis · Joined: 03 Mar 2005 Posts: 4

mmmm

I would say frames. This is my understanding of it:

1. The NIC transmits the frame onto the medium via its 'transmit' pair.

2. The NIC loops the transmitted frame back to it's receive pair

3. It compares the two - if they are different then it detects a collision has taken place.