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Re: 64/66 control code mapping




Roy,

Architecturally, the proposed layering of 10 GbE requires a MAC and
Reconciliation sublayer and a PCS. It requires neither a XGMII nor XAUI/XGXS and
both these interfaces are proposed as optional interfaces. The Reconciliation
sublayer maps data and control signals to PLS service primitives defined in
Clause 6 of the 802.3 standard.

In the case that the PCS is 64B/66B in support of a Serial PHY type, I see no
requirement for 8B/10B encoding/decoding to be performed. The fact that both the
XGMII and 64B/66B support special codes to simplify synchronization,
delineation, error checking, parallel lane deskew, jitter control, clock
tolerance compensation, etc. and that these codes are similar to those used by
8B/10B are a credit to the elegant and timeless nature of the 8B/10B
transmission code developed by Widmer, et. al.

Best Regards,
Rich

--

Roy Bynum wrote:
> 
> Rich,
> 
> It was my impression that I got from the 64B/66B presentations, that an
> 8B10B precoding was a requirement for the 64B/66B in order for detection of
> errored codes.  In every presentation that I have seen so far, 8B10B
> precoding was included.  This makes XAUI not optionional, but a requirement
> for the 64B/66B encoder, regardless of whether the XAUI is optional in the
> standard.  So, unlike other proposals, a unifed PHY that uses 64B/66B has
> XAUI as a requirement, or at least some other 8B10B precoder is required.
> 
> Thank you,
> Roy Bynum
> 
> ----- Original Message -----
> From: Rich Taborek <rtaborek@xxxxxxxxxxx>
> To: HSSG <stds-802-3-hssg@xxxxxxxx>
> Sent: Monday, March 13, 2000 5:40 AM
> Subject: Re: 64/66 control code mapping
> 
> >
> > Ben,
> >
> > 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 translation.
> >
> > 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,
> > Rich
> >
> > --
> >
> > "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
> > > XGMII.
> > >
> > > Thanks,
> > > Ben Brown
> > >
> > > --
> > > -----------------------------------------
> > > Benjamin Brown
> > > Router Products Division
> > > Nortel Networks
> > > 1 Bedford Farms,
> > > Kilton Road
> > > Bedford, NH 03110
> > > 603-629-3027 - Work
> > > 603-629-3070 - Fax
> > > 603-798-4115 - Home
> > > bebrown@xxxxxxxxxxxxxxxxxx
> > > -----------------------------------------
                                      
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Richard Taborek Sr.               Phone: 408-845-6102       
Chief Technology Officer           Cell: 408-832-3957
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