RE: Clause 49 /A/ /K/ /R/ on XGMII question
When there is no error on the XAUI, ||A||, ||K|| and ||R|| are translated by
the XGXS to a column of /I/ on the XGMII. I think that it is simpler to do
the same when an error occures in one of the bytes of such a column, except
that the specific erronous byte has to be translated to /E/ on the XGMII.
In the case of 10GBASE-R, the erronous byte is handled like /E/ and the rest
like /I/ on the XGMII.
Boaz
> -----Original Message-----
> From: pat_thaler@xxxxxxxxxxx [mailto:pat_thaler@xxxxxxxxxxx]
> Sent: Thursday, February 15, 2001 12:52 AM
> To: jgaither@xxxxxxxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
> Subject: RE: Clause 49 /A/ /K/ /R/ on XGMII question
>
>
>
> Justin,
>
> The XGXS only converts /A/, /K/, and /R/ to /I/ when they
> occur in a whole
> column: an ||A||, ||K||, or ||R|| ordered set. Therefore, one
> type of error
> that would cause /A/, /K/, or /R/ on the XGMII output from an
> XGXS would be
> a bit error that changed the value of one or more bytes in an
> ordered set.
> If such an error happens, there is no particular reason for a
> 10GBASE-R PCS
> to change the remaining /A/, /K/ and /R/ symbols to an /E/.
> We have code
> table entries for them and replacing them with something else would
> complicate implementation.
>
> The primary purposes of sending an /E/ are:
> to avoid changing an unencodeable input into something that
> might produce
> an undetectable error.
> to propogate special error detection that preserves
> delimiter Hamming
> distance so that code dependent 0- to 3-bit errors don't produce
> undetectable errors.
>
> Neither of those purposes would be served by changing a
> spurious /A/, /K/ or
> /R/ into an /E/. Furthermore, the RS has to handle receiving
> these /A/, /K/
> and /R/ code groups because an XGXS might be directly
> connected to the RS.
> If one believes that /A/, /K/ and /R/ should not be allowed
> to exist at the
> XGMII interface, than it is the 10GBASE-X/XGXS coding rules
> that should be
> changed and not 10GBASE-R.
>
> Regards,
> Pat
>
> -----Original Message-----
> From: Justin Gaither [mailto:jgaither@xxxxxxxxxxxxxxx]
> Sent: Wednesday, February 14, 2001 11:29 AM
> To: 802.3ae
> Subject: Clause 49 /A/ /K/ /R/ on XGMII question
>
>
> Hello,
> Page 345 line 30-31 says "The codes for /A/ /K/ and /R/
> are used on
> the
> XAUI interface to signal idle. They are not present on the XGMII when
> no errorrs have occurred, but certain bit errors cause the
> XGXS to send
> them on the XGMII."
>
> What types of errors would this be? and why would we want
> allow them to
> continue through the 10GBase-R, into the optional WIS and
> onto the link?
>
> Should these be replaced by /E/?
>
>
> --
> 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
>