Disable Exponential Backoff (retry) on Ethernet?

[John-Mark Gurney]

Len Gross wrote this message on Wed, Oct 17, 2007 at 20:51 -0700:
> I'm doing some protocol development and it is convenient to start it on
> Ethernet.  I will need to send a packet to the Ethernet device and only have
> it be sent once, even if there is a colision.  (Higher levels in the
> protocol will detect the failure.)  I've searched quite a bit, and haven't
> found any place that talks about this.   Are there any hardware cards, or
> drivers, that let me turn off the backoff/retry behavior?

Are you even using hardware that does collisions?  Collisions pretty
much went out w/ 10Mbit ethernet...  Not completely as there are older
10/100mbit "switches" that only switched between the two segments (and
each of 10/100 segments was hubbed)...  All modern switches are
full-duplex and don't suffer from the old CD part of CDMA that was part
of the original ethernet specification..

For Gige, you can't even do half-duplex, as each side is transmitting
on all four pairs at the same time...  The physical layer handles the
fact that both sides may transmit at the same time, and knows how to
cancel their own interference out so they can hear the other side...

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."