RE: Clause 48: Errors after T.
Justin and Howard,
I think there is a misunderstanding here of what happens when an error is
"pushed back". The character were the error was detected is still sent as an
/E/. Since it didn't obey the coding rules, the decoder doesn't know what
its "real" values was suppose to be. Therefore, the only thing the decoder
can send in the character's place is an /E/. When we push an error back, we
send an _additional_ /E/ in place of the character before the one where the
error was detected.
Justin also asked where the checking was put. The change was executed by
adding check_end to the DATA_MODE_START state and modifying the check_end
function to cover operation in that state.
The only reason I can see to not push all errors back is that it multiplies
the apparent errors. When it is only done on errors at the end of a packet,
the effect on anything collecting error statistics is minimal. As the
current check_end function is written, an error is at most doubled when it
occurs at the end of a packet. If we move all errors back, then all errors
can be doubled, tripled, or quadrupled (because a packet may go through 3
receive state machines on its path). This is a relatively minor failing, but
I can't think of any particular advantage to pushing all errors back.
Regards,
Pat
-----Original Message-----
From: Justin Gaither [mailto:jgaither@xxxxxxxxxxxxxxx]
Sent: Tuesday, March 27, 2001 8:46 AM
Cc: 802.3ae
Subject: Re: Clause 48: Errors after T.
Thanks Rich, Bob, and Howard.
This is the most compelling reason to NOT to push all errors back.
However, if a running disparity error occured in the ||S|| column, would
it not persist for quite a while until it encounterd a RD error
correcting code? Keeping the packet bad. However the check_end
function also looks for proper ||A|| and ||K|| placement after the
||T||. If we have todo this, we might as well limit the pushback during
this time as well.
Thanks
justin
"Howard A. Baumer" wrote:
>
> Justin,
> If we push all errors back one column then the error that was in
the
> ||S|| column could potentially get pushed out of the packet and a good
> packet that should be indicated as bad would be produced. This is a
> very low probability but, none the less, we should error on the side of
> caution.
>
> Howard
>
> Justin Gaither wrote:
> >
> > Everyone,
> > During the Plenary, it was determined that we need to push an error that
> > occurs after the /T/ back 1 column so that it is included inside the /S/
> > and /T/ delimeters. My question is, can we just push all errors back on
> > column, or must we determine if it is in the column following a //T//?
> >
> > I could not find this in D2.3, where did it get put?
> >
> > Thanks
> >
> > --
> > Justin Gaither Phone: 512-306-7292 x529
> > RocketChips a Division of Xilinx Fax: 512-306-7293
> > 500 N. Capital of TX Hwy.
> > Bldg 3 email: jgaither@xxxxxxxxxxxxxxx
> > Austin, TX 78746 WWW: www.rocketchips.com
> >
> >
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> > Name: jgaither.vcf
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--
Justin Gaither Phone: 512-306-7292 x529
RocketChips a Division of Xilinx Fax: 512-306-7293
500 N. Capital of TX Hwy.
Bldg 3 email: jgaither@xxxxxxxxxxxxxxx
Austin, TX 78746 WWW: www.rocketchips.com