Re: PMD discussion
Roy,
I'm sorry about your confusion.
8B/10B has been the primary coding for used for WDM ever since the 802.3 Call
for Interest in March 1999 Call to consider the possibility of developing an
Ethernet Standard capable of 10 Gbps data transport. Please see slide #5 of the
presentation entitled "Low-Cost Wide Wavelength Division Multiplexing (WWDM) for
10 Gb Ethernet", Mr. David Dolfi, Hewlett-Packard,
http://grouper.ieee.org/groups/802/3/10G_study/public/march99/dolfi_1_0399.pdf.
It has now been 15 months since that initial direction, and 8B/10B is still
assumed to be the PCS code of choice for WDM. Multiple presentations at each
meeting reinforce this direction.
I'm not aware of any presentation to the HSSG or Task Force since the Call for
Interest that even suggested that 8B/10B be dropped as the transmission code for
the WDM PHY, are you?
64B/66B was first introduced to the HSSG eight months later. Please note that
this means that 8B/10B was understood to be the PCS for the WDM PHY, and stable,
for eight months since the Call for Interest. Mr. Rick Walker and Mr. Richard
Dugan, both of Agilent Labs, initially presented a proposal for a "Low overhead
coding proposal for 10G b/s serial links",
http://grouper.ieee.org/groups/802/3/10G_study/public/nov99/walker_1_1199.pdf,
at the November 1999 meeting. This proposal gained immediate and significant
momentum as a method to reduce the line rate of a 4-lane 8B/10B based Hari
(later renamed to XAUI) which when multiplexed to single serial lane resulted in
a line rate of 12.5 GBaud. The reduction resulted in a line rate of 10.3125
GBaud which was much more compatible with existing optics.
Separately, the 8B/10B-based XAUI/XGXS was developed as a PHY independent means
of extending the short PCB traces supported by the XGMII.
I am not aware of any HSSG, Task Force or 802.3 votes with respect to PCS
transmission codes and certainly none removing 8B/10B as the code for WDM, are
you? I haven't missed a single HSSG or Task Force meeting including the Call for
Interest.
The Uniphy proposal presented by Mr. Howard Frazier,
http://grouper.ieee.org/groups/802/3/ae/public/mar00/frazier_1_0300.pdf, is
applicable to the Serial PHY. This proposal clearly does not imply or indicate
how a WWDM PMD would be supported. What exactly are you claiming that I'm
deviating from?
The A WDM LAN PHY supporting a WIS at the remote end (e.g. in a transponder,
etc.) could simply locate a LAN PHY including a 64B/66B CODEC and WIS inside the
transponder as illustrated in slide 17 of Mr. Frazier's UniPHY proposal. Note
that in this scenario, both XAUI and the WDM PCS is proposed to be 8B/10B.
If you're still confused about the WDM PCS, please have a look at Mr. Paul
Bottorff's presentation from the recent May meeting, "10GE WAN PHY Overview",
http://grouper.ieee.org/groups/802/3/ae/public/may00/bottorff_1_0500.pdf, slide
3. See how simple it is to have the same 8B/10B transmission code (called XAUI
in this figure) for the entire vertical stack of the WDM PMD.
Best Regards,
Rich
--
Roy Bynum wrote:
>
> Rich,
>
> I was under the understanding that only one block coding PHY was being proposed, 64B66B. When 64B/66B was proposed, that 8B/10B as
> an external coding scheme was dropped. I thought that 8B/10B was for XAUI, internal only, transparent only copper extension.
>
> I was not aware that a separate coding scheme than the rest of P802.3ae was being proposed just for the WDM PMDs. If so, then the
> WDM solution is now a separate complete PHY not a PMD. I do not believe that this is what has been voted on.
>
> The presentation by Howard Frazier, that proposed the "WIS" based "UniPHY" has only 64B/66B out of the PCS. Please see
> http://grouper.ieee.org/groups/802/3/ae/public/mar00/frazier_1_0300.pdf. If you are now deviating from that, with WDM being a
> separate PHY, then what is the status of the "UniPHY"?
>
> Thank you,
> Roy Bynum
>
> ----- Original Message -----
> From: "Rich Taborek" <rtaborek@xxxxxxxxxxxxx>
> To: "HSSG" <stds-802-3-hssg@xxxxxxxx>
> Sent: Monday, June 05, 2000 3:25 AM
> Subject: Re: PMD discussion
>
> >
> > Roy,
> >
> > I'm not sure where your confusion is coming from, please explain.
> >
> > All initial LAN WDM PHY proposals as well as those currently in front of the
> > Task Force employ 8B/10B encoding. This coding choice has been essentially
> > stable for more than a year now. 64B/66B has never been formally proposed as a
> > PCS for LAN WDM PHYs.
> >
> > 64B/66B has been proposed as the PCS for the LAN Serial PHY since approximately
> > the November, 1999 meeting.
> >
> > Best Regards,
> > Rich
> >
> > --
> >
> > Roy Bynum wrote:
> > >
> > > Rich,
> > >
> > > Now I am confused. It was my understanding that the LAN only PHY would be using 64b/66b, just like what is being forced on the
> WAN
> > > compatible PHY. If so, then it was my understanding that the parallel/CWDM PMD would also be 64b/66b.
> > >
> > > Thank you,
> > > Roy Bynum
> > >
> > > ----- Original Message -----
> > > From: "Rich Taborek" <rtaborek@xxxxxxxxxxxxx>
> > > To: "HSSG" <stds-802-3-hssg@xxxxxxxx>
> > > Sent: Saturday, June 03, 2000 2:35 AM
> > > Subject: Re: PMD discussion
> > >
> > > >
> > > > Ed,
> > > >
> > > > Done! I completely agree to drop this tangent and focus on PMD issues.
> > > >
> > > > Best Regards,
> > > > Rich
> > > >
> > > > --
> > > >
> > > > NetWorthTK@xxxxxxx wrote:
> > > > >
> > > > > Rich:
> > > > >
> > > > > I believe you misunderstood my mail to conclude your comments too quickly.
> > > > >
> > > > > I never mentioned that I like the 12.5 Gbps 8B/10B coding to be replaced by
> > > > > 10.3125 Gbps 64b/66b.
> > > > >
> > > > > We are discussing serial vs parallel issues.
> > > > >
> > > > > We are too much involved in resolving PMD issues right now, and I believe no
> > > > > one is interested in bring the coding scheme back to reflector at this moment.
> > > > >
> > > > > Please do not intiate this one. let us focuse on PMD issues.
> > > > >
> > > > > Regards,
> > > > >
> > > > > Ed Chang
> >
> > -------------------------------------------------------
> > Richard Taborek Sr. Phone: 408-845-6102
> > Chief Technology Officer Cell: 408-832-3957
> > nSerial Corporation Fax: 408-845-6114
> > 2500-5 Augustine Dr. mailto:rtaborek@xxxxxxxxxxx
> > Santa Clara, CA 95054 http://www.nSerial.com
-------------------------------------------------------
Richard Taborek Sr. Phone: 408-845-6102
Chief Technology Officer Cell: 408-832-3957
nSerial Corporation Fax: 408-845-6114
2500-5 Augustine Dr. mailto:rtaborek@xxxxxxxxxxx
Santa Clara, CA 95054 http://www.nSerial.com