[ethmac] Re: TxMAC-DeferCounter

[Maik Boden <maik.boden@gmx.net>]

Hi,

> If DeferCounter is removed, how this TxEthMAC gets timeout to stop
> attempt process for transmiting a new packet of data ?
This is done indirectly via counting the number of collisions. The 16th
collision causes rejection of the current frame. Because we know about maximum
backoff times and so on, we can calculate the maxmimum possible time until the
TxMAC will stop transmission of a frame. It's about 4.000.000 bit-times what's
equal to 40 ms at 100 Mbps. In respect to the usage of random numbers for
backoff time calculation the "timeout" would ever be less than this value. But
it's sure that the MAC would never try to send a frame for a longer time than
40 ms.

If we want to stop transmission attempts within a constant time, we need a
real-timer interrupt because DeferCounter depends on network speed. So I think
it's better to use collision counting only because the standard does not require
a timeout at all. But that's what we are looking for!


Regards
Maik Boden