Re: XAUI and 64b/66b
Roy,
Please go ahead and put together a proposal for the Serial PHY based on SDLC or
HDLC. The complete proposal on the table for an 8B/10B-based XAUI/XGXS is backed
by at least 24 companies. The complete proposal on the table for a Serial LAN
PHY based on XAUI/XGXS and 64B/66B encoding is backed by at least 27 companies.
I don't see any other complete XAUI/XGXS or Serial LAN PHY proposals based on
SLP, HDLC, SDLC, SUPI or otherwise anywhere.
I'd be very happy to compare proposals.
P.S. XAUI is optional.
Best Regards,
Rich
--
Roy Bynum wrote:
>
> Rich,
>
> What several people is saying that making the 8B10B codes a required
> precursor to the 64B/66B encoding removes the "optional" label that has been
> put on XAUI. You can have your cake and eat it too. Either XAUI is an
> optional XGMII extender and 8B10B is not part of the 64B/66B encoding, or
> 8B10B is part of 64B/66B and XAUI is a requirement for all implementations.
>
> While I laud your work and experience with 8B10B, there are other solutions
> that are just as elegant. I recognize that you have wanted 8B10B to be part
> of the requirements for 10GbE from day one. This has perhaps clouded your
> ability to be pragmatic.
>
> If I were not pragmatic about the uses of protocols, I would be proposing
> that we use HDLC, but I am not. SDLC and HDLC have been around longer than
> 8B10B as communications protocols. I have been working with SDLC and HDLC
> as long if not longer than you have with 8B10B. The first protocol that I
> used to any extent other than SDLC was BiSync (1968). Do you see me
> suggesting these? I am pragmatic and unlike the IETF, recognize that HDLC
> has some major flaws and should not be part of the requirements for 10GbE.
>
> Again, is XAUI going to be optional or not? If it is not optional, then I
> think that you are going to have a hard time getting 75% of the people to
> include it in the standard. If XAUI is optional, then 8B10B encoding can
> not be a required precursor to any PCS. Which is it?
>
> With respects,
> Thank you,
> Roy Bynum
>
> ----- Original Message -----
> From: Rich Taborek <rtaborek@xxxxxxxxxxx>
> To: HSSG <stds-802-3-hssg@xxxxxxxx>
> Sent: Thursday, March 16, 2000 4:22 PM
> Subject: Re: XAUI and 64b/66b
>
> >
> > Ben,
> >
> > I disagree with your direction on this issue for the same reason that I
> have
> > trouble with the lack of specification of an optional interface in
> 1000BASE-X
> > which is implemented in 100% of Ethernet products implementing 1000BASE-X.
> I may
> > be being politically incorrect in stating this, but I typically like
> products to
> > match specs.
> >
> > I view XAUI as being a very prevalent 10 GbE interface, perhaps not as
> prevalent
> > as the serial side of the GbE Ten-Bit-Interface. Barring no other complete
> and
> > workable XAUI/XGXS proposals that meet the requirements of an optional
> XGMII
> > extender, my view is that the PCS should accommodate the optional XGMII
> extender
> > as well as operate properly without one. Since we'll have multiple PCS's
> > probably corresponding to PMA/PMDs, and one of the heavily backed (27
> companies)
> > Serial PHY proposals endorse a 64B/66B PCS, I believe that this PCS should
> > support the optional XGMII extender which is specified to be PHY/PMD
> > independent. The Serial PHY proposal already does this and I see no
> benefit or
> > savings in cost, complexity, etc. in removing it.
> >
> > I also see no significant difference in complexity between converting
> between
> > XGMII and PCS 64B/66B codes whether or not the IPG includes only /I/ or
> /A/K/R/.
> >
> > Best Regards,
> > Rich
> >
> > --
> >
> > "Benjamin J. Brown" wrote:
> > >
> > > Rich,
> > >
> > > Jonathan just sent me a note saying that I was even confusing
> > > him right now so I want to stop and ask my question again. I'll
> > > try to make this as clear as possible.
> > >
> > > In the layer diagram that Brad showed in Albuquerque, the XAUI
> > > was shown as an XGMII extender. To me this means that the
> > > reconcilation sub-layer speaks using XGMII language and the PCS
> > > listens using XGMII language. The XAUI can extend this interface
> > > by translating from XGMII to XAUI but it must translate back
> > > again before it gets to the PCS. The XGXS block is the translator.
> > >
> > > The 64b/66b proposal as written ignores the XGXS block between
> > > XAUI and the PCS. It is my contention that, though this would
> > > work, it is unnecessary and even burdensome to those implementors
> > > that choose to not use XAUI. 64b/66b would work equally as well
> > > without the XAUI specific control codes as they add nothing to
> > > the efficiencies of 64b/66b (that I can tell). The XGMII specific
> > > control codes are completely adequate for 64b/66b. In my opinion,
> > > a serial PCS should be specified as if XAUI didn't exist.
> > >
> > > I'll even go so far as to state that, in my opinion, even a
> > > parallel/CWDM PCS should be specified as if XAUI didn't exist.
> > > If this PCS turns out to be identical to the XGXS block then some
> > > implementors may choose to avoid the encode/decode/encode as
> > > specified in the standard, but I believe that is how it should
> > > be specified.
> > >
> > > Is the question/comment still confusing or do you merely disagree?
> > >
> > > Ben
-------------------------------------------------------
Richard Taborek Sr. Phone: 408-845-6102
Chief Technology Officer Cell: 408-832-3957
nSerial Corporation Fax: 408-845-6114
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