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RE: Minimum IPG w/ WIS ?

Hi Pat,

Thanks and sorry for asking such an elementary

However, the second part still remains. In the draft
for 10gigE, do we have any spec for how much IPG is
allowed at the Tx and how much is the minimum the
Receiver needs. I'm guessing the Rx needs at least 4
bytes so that it can be used in the parallel fiber
case. Is that correct?


--- "THALER,PAT (A-Roseville,ex1)"
<pat_thaler@xxxxxxxxxxx> wrote:
> Rohit,
> Transmitted IPG out of the MAC is 96 bit times
> regardless of speed. This is
> part of the MAC spec. A note in 4.4.2 indicates that
> the minimum IPG between
> two non-collided packets at 1000 Mb/s is 64 bits.
> There is no indication of
> the receive IPG for 100 Mb/s and even in the 1000
> Mb/s case, the gap between
> a collision fragment and a good packet is not
> covered. There are a number of
> sources of IPG shrinkage and repeaters are only one
> of them.
> I'm surprised receive IPG for 100 Mb/s isn't
> documented. I know calculations
> were done during the development, but I've been
> unable to find a number in
> the standard.
> Regards,
> Pat
> -----Original Message-----
> From: rohit mitt [mailto:ro_mittal@xxxxxxxxx]
> Sent: Wednesday, February 28, 2001 8:46 AM
> To: THALER,PAT (A-Roseville,ex1);
> stds-802-3-hssg@xxxxxxxx
> Subject: RE: Minimum IPG w/ WIS ?
> Pat,
> I believe in 100/1000 Mb/s ethernet standards there
> was a limitation that at the Receive end of an
> ethernet link, there had to be a minimum of 8 bytes
> of
> IFG. Do you recall if there was a minimum IFG at the
> Transmit end. I believe the difference between the
> Transmit and the Receive had to do with the fact
> that
> you could have a repeater in between which might,
> itself, add/drop idles to make up for clock
> tolerance.
> In the 10gigE, we do not have repeaters but we still
> might have a system to send ethernet over long
> distances, say 160km. (Don't want to confuse the
> topic
> but an example could be sending 10gigE over one
> wavelength in an optical network). 
> Looking at this application, do you think it makes
> sense to specify a minimum number of IFGs at the
> source itself
> thanks
> rohit
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