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Re: [EFM] flow control in 802.3 - HPNA 1.0

HPNA 1.0 did this in the past.  The period of the TX_CLK was changed to
accomodate the additional physical layer time required.  It is described
(albeit in somewhat sparse detail) in section 3 of the 1M8 HPNA

charlie raasch
conexant systems.

                    "Vladimir Oksman"                                                                                              
                    <oksman@xxxxxxxxxxxx>                To:     "Hugh Barrass" <hbarrass@xxxxxxxxx>                               
                    Sent by:                             cc:     "MARC KIMPE" <>,     
                    owner-stds-802-3-efm@majordom        Subject:     Re: [EFM] flow control in 802.3                              
                    11/01/01 07:27 AM                                                                                              


     I also have the same feeling - an artificial collision signal is
something we can use. It doesn't seems good from the first glance to add
new signals.


Hugh Barrass wrote:

> Marc,
> What a good question!
> This is a problem that we (almost certainly) have to solve in the copper
track. We are looking for suggestions, the ones that immediately come to
mind are:
> MII clock adjustment
> IPG stretching
> .3x pause frames
> half-duplex back pressure (force collision)
> new signal for pause/continue
> The matter was discussed at length during .3ae - take a look at 10G
> There are various other discussions of this on 10G. It's not clear that
the arguments and conclusions are valid for .3ah in the same way as .3ae -
but it's always worth taking a look.
> Hugh.
> PS - Any of the 10G'ers care to comment?
> MARC KIMPE wrote:
> > All,
> >
> > Is there a way to transmit flow control information across an MII
interface from the PHY direction to the MAC ? If yes could someone point me
to the pertaining clause of 802.3 ?
> >
> > In other words, let's assume that a PHY for some reason or other can
only transmit at 3Mbps while information to that PHY flows at 10Mbps. How
can the PHY tell the MAC to stop sending ? I saw some presentations related
to 10 Gigabit Ethernet that proposed various mechanisms but I do not know
if anything was adopted.
> >
> > Any help would be appreciated.
> >
> > Thanks,
> > Marc Kimpe
> > Adtran