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RE: RS minimum IPG

I believe Sanjeev was close on his description below.

Basically, because of the way the 64/66 start-codes are declared compared to
the possible modulo ending conditions, IPG has the window of 9-15 bytes
between packets.  Column stripping for clock compensation is required to
preserve alignment, thus stripping is allowed in 4 byte increments (comes
from having 4 lanes).  And, because there's only so many there to strip, and
we need to leave some there for alignment corrections when the data arrives
at the end point, we say you must preserve at least 5 (9-4).  The added "oh
by the way" here is one must have enough buffer in order to handle skipping
a column strip and waiting for the next IPG to do it, between two packets
that only have an IPG of 5 because someone upstream already did a column
strip here.



-----Original Message-----
From: pat_thaler@xxxxxxxxxxx [mailto:pat_thaler@xxxxxxxxxxx]
Sent: Tuesday, February 20, 2001 9:48 AM
To: sanjeev@xxxxxxxxx; stds-802-3-hssg@xxxxxxxx; yariv@xxxxxxxxxxxxx
Subject: RE: RS minimum IPG


Where do you find such a definition in the standard? I don't know of
anyplace a minimum receive IPG of 5 is stated. Further, that is a parameter
that has varied based on speed so what it was at 100/1000 Mb/s does not
limit our choice at 10 Gig. 


-----Original Message-----
From: Sanjeev Mahalawat [mailto:sanjeev@xxxxxxxxx]
Sent: Monday, February 19, 2001 11:25 AM
To: stds-802-3-hssg@xxxxxxxx; yariv@xxxxxxxxxxxxx
Subject: Re: RS minimum IPG

The min IPG varies from 9 bytes to 15 bytes
based on the packet size and due to clock compensation
the PHY may delete a column that will lead to min
IPG of 5 Bytes. So, thoeritically it should not be
less than 5 bytes but the spec. always defines it
to be 4 bytes as this was in the 100/1000 mbps