Disable Exponential Backoff (retry) on Ethernet?

[Julian Elischer]

Sten Daniel Soersdal wrote:
> Len Gross wrote:
>> Thanks so much for the response.  Here is some additional information.
>>
>> I'm trying to emulate an RF network where there are colisions (e.g. 
>> "Aloha"
>> type protocol) so I actually need collisions!  I had forgotten that 
>> modern
>> hardware
>> essentially eliminated them.  So, lets say I can find/use an "old hub",
>> can I control the number of retries?  Maybe I have to find some old 
>> NICs and
>> old drivers?
> 
> That would be very NIC specific. Retries are done in NIC hardware as far 
> as i know.
> 
> All you need to do to get some collisions is to set the rates to 
> half-duplex on both sides (hubs were half-duplex). Hubs with lot's of 
> traffic between other hosts would definitely produce more collisions.
> 
> Modern hardware didn't eliminate them. Full-Duplex medium did.
> There is a broad range of full-duplex RF systems too :)

one thing I'd like, that is related, is that if you disconnect a 
link for 3 hours it shouldn't sit there using 3000 Mbufs in its output 
queue..  how about discarding them....

currently they sit in the queue forwever as far as I can see.
certainly in the em or bce drivers they do..


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