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Re: 64/66 control code mapping


The proposed XGMII is an encoded interface which can be directly mapped to
either XAUI/XGXS and/or 64B/66B. The "and/or" indicates that XAUI/XGXS need not
be present. 

I believe that you are correct in stating that the spec should provide the
proper translation between XGMII codes and 64B/66B codes regardless of whether
XAUI/XGXS is present. The PCS is the specific part of the spec documenting this

Therefore, if 64B/66B coding is accepted as the Serial PHY code of choice, the
PCS should specify the translation of information between the XGMII and PMA and
operate correctly in the presence or absence of XAUI/XGXS.  

Best Regards,

"Benjamin J. Brown" wrote:
> Rick Walker,
> I've been looking at your 64b/66b presentation and, in
> particular, looking at your control code mapping. The
> 7-bit line code is specific to encodings from the 8b10b
> XAUI interface. This is an optional interface and may
> not exist between all MAC and PCS layers. When the XAUI
> doesn't exist, what 7-bit line codes should be used?
> Given the protocol stack shown by Brad Booth, I would
> expect that this PCS layer be specified to an XGMII
> and not to an XAUI. Implementations may choose to short-
> cut the conversion from XAUI to XGMII to 64b/66b but
> the specification should assume it communicates to the
> Thanks,
> Ben Brown
> --
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> Benjamin Brown
> Router Products Division
> Nortel Networks
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