Re: [ethmac] New volunteer

[nbase <nbase@nbase.com>]

Hi,

   I would be EXTREMLY carefull in changing ANY of the spec definition like
the collition you suggested as most spec defineition are not coming "out of
the blue" but rather have some importent aspect behind them, which you
might not be aware of.

a small exmaple is the prevantion of constat head to head collision, not
only for any two or more shared port but also what if two of those ports
are your own design since the random is the same in both port and since
both will start immidiatly than you will never get out of this collision
until you reach the 16'th repeteted collision and than both port might want
to discard the packet and will continue so until one of them don't have any
more packet to transmite. and this is of course a beahve we would not want
to happen.

I notice you gave a probability but if it is 0-1 than is it like the
traditional as the traditional will random a number after the first
collision between 0-1 slot times.

and the point of saving slot time is also danger as after collision BY
DEFINITON each station need to continue transmiting so ALL station will
"hear" it for at least extra 32BT (jam), and after this there must be an
IPG and so we get back to the traditional

or did I missed something.

I would also think that any change from the standard should be (if at all)
only as an option.

about the fifo in the Rx Machine I agree with the comment and you can see
more about it in previus Email I send in respect to the clock's and width
issue.

another thing that need to be consider is are we to support RMII as it will
save lot's of pins but it will also need additional module to interface to
it as well as the clock is now all source from same crystal which is 50M so
the clocking issue will need to be sort out differently.

have a nice day

   Illan

At 08:35 PM 07/24/2000 +0400, you wrote:
>>
>> And we don't have IEEE standard, because it's too expensive for us.
>> We obtain MAC-regarded data from several datasheets.
>> About the specifications, any comments or advices ?
>>
>> - novan hartadi -
>
>Ok.
>1. Why do you use clocked from cable scheme of Rx, instantiating FIFO after
>the Rx block? Why not to put dual-port FIFO right after MII? I think system
>clock is much more accurate and predictable than cable-driven.
>
>2. I have some consideration about collision prevention technique.
>"Traditional" ethernet cores wait for a random time after a collision
occured.
>There's other algorithm: core starts transmit immediately after collision
with
>some probability (p), or waits traffic-adjustable time with (1-p)
probability.
>2nd algorithm increases brandwith of a network, although requires more gates
>to be implemented.
>
>3. For a new members, I think it'll be comfortable to read old mail archive
>off-line.  Please if it possible put all messages from an archive  in 1
>downloadable txt or html file.
>
> With best regards, Alex Shayda.
>
>