Hari
Roy,
Three things should be clear to everyone from my presentation.
1. I was the one who was contacted by an large number of individuals asking
how the industry could possibly begin 10 Gig design work (at all levels)
without knowing what the common interfaces that would be used in practical
implementations would be.
2. I was the one who was contacted by Fibre Channel, NGIO, FIO, and SIO
companies asking if Ethernet could define a common PMD that would be usable
across different platforms.
3. I was the one who called the various individuals (primarily representing
systems companies) together for the discussion which spawned Hari.
If you are implying that all the vendors of the world are bowing to the
interests of a little (but highly sophisticated) start-up in Colorado called
Picolight, I hope you tell that to all the VC's.
Regarding some specific comments:
> "The HSSG is not the correct forum to be doing ...standards."
Correct. The HSSG is a study group. It creates no standards. The task force,
which we asked the IEEE to create, will do that job. If you were implying
that the task force would not be the correct forum to do standards.... Well,
I have no comment.
> "While I did not actively support it, as a XGMII it did not preclude the
existence of other PHYs. It could be modified to
incorporate a pacing mechanism between a PHY and the MAC. The PHY would
still implement the PCS/PMA/PMD for what ever standard the Task Force
decided on, even the one from Korea."
I see no reason why this is not still true.
> "There is enough disparity between the PHYs to cause a major rift if a PHY
implementation standard is decided on before the PHYs are even defined.
...there is no need to decide on implementation practices before the PHYs
are fully defined."
The PHYs are not fully defined until the standard is complete. We have a
requirement that all PHYs need to be proven technically feasible before we
go to vote (while the standard is still incomplete). I can't solve those two
equations simultaneously.
So, let me assume that you did not mean what you said. Let me assume you
mean: there is only one defined interface for doing 10 gig that can possibly
be used to prove feasibility, the one proposed for SONET in the OIF.
Anything else would be too late to permit the standard to move forward, too
late for companies to implement early hardware to validate designs and too
late to create the marketplace for 10 Gigabit Ethernet. In short, anything
other than this interface would be the work of "a particular vendor... doing
their best to back door a PHY standard before the Task Force is even in
place." Which is clearly in contrast to the up-front, honest work being
proposed by the SONET-inclined vendors.
You really couldn't mean that, could you? No, I don't think so.
So, what exactly are you saying? That you don't like Hari? That you have a
better idea?
OK.
What is the better idea? What are the advantages (bullet points on a
presentation would be nice)? What are the assumptions, goals, objectives?
Now you may think that the Hari advocates didn't do this. Perhaps not. But
we certainly tried! And frankly, they worked very long and hard at it.
jonathan
> -----Original Message-----
> From: Roy Bynum [mailto:rabynum@xxxxxxxxxxx]
> Sent: Tuesday, November 23, 1999 11:15 PM
> To: rtaborek@xxxxxxxxxx; rtaborek@xxxxxxxxxxxxx
> Cc: HSSG
> Subject: Re: Hari
>
>
>
> Rich,
>
> I saw a lot of confusion in the presentations of what Hari is intended
> for. One presentation used Hari as a backplane interconnect.
> There is
> confusion on the reflector. There IS a lot of "support" for Hari from
> vendors that want to stay on the good side of a particular vendor.
> Otherwise, I suspect that there is a lot of concern about the way that
> Hari has been brought to the HSSG.
>
> When Hari was first introduced at York, I thought that it was
> a proposal
> for a an XGMII. While I did not actively support it, as a
> XGMII it did
> not preclude the existence of other PHYs. It could be modified to
> incorporate a pacing mechanism between a PHY and the MAC.
> The PHY would
> still implement the PCS/PMA/PMD for what ever standard the Task Force
> decided on, even the one from Korea.
>
> As far as I am concerned, any chip maker/system designer that wants to
> use Hari can. I just don't want to see it standardized as the PCS to
> PMD interconnect, even as an optional. The HSSG is not the correct
> forum to be doing implementation practices or standards. That was one
> of the things that was impressed on me at the June meeting. There is
> enough disparity between the PHYs to cause a major rift if a PHY
> implementation standard is decided on before the PHYs are
> even defined.
> Unless a particular vendor is doing their best to back door a PHY
> standard before the Task Force is even in place, there is no need to
> decide on implementation practices before the PHYs are fully defined.
>
> Thank you,
> Roy Bynum
>
> Rich Taborek wrote:
>
> > Roy,
> >
> > Multiple proposals aired in Kauai and I have already explained that
> > Hari is simply a "better" interface for attaching a MAC/PCS/PMA to a
> > PMD. As Dan Dove of HP has explained, Hari would at most be an
> > optional interface as was the case with both the TBI (closest Hari
> > equivalent in GbE) and GbE's GMII. Hari is a serial-based interface,
> > and as such requires a transmission code. 8B/10B was deemed
> to be the
> > best choice for Hari. That's it! I encourage you to propose a better
> > interface than Hari for its intended purpose or a better
> transmission
> > code for Hari. In the absence of either, I saw an awful lot
> of support
> > for Hari in Kauai and will continue to do my best to
> improve upon the
> > current proposal.
> >
> > Roy Bynum wrote:
> >
> >> Rich,
> >>
> >> I'm not sure what gave you the idea that Hari was favorable to
> >> serial PHYs. I do know that
> >> it is not favorable to anything other than the legacy fiber channel
> >> 8B10B LAN PHY. Hari is
> >> NOT a PHY neutral device interconnect. Some LAN vendors have very
> >> huge boards and they want
> >> something that will support their 8B10B encoding over the distance
> >> of their board, and also
> >> the back plane if needed. By introducing Hari as the standard for
> >> device interconnect
> >> between the PMA and the PMD, they are specifically, and possibly
> >> knowingly, hampering the
> >> development of the agreed on WAN PHY. There is no mechanism for
> >> rate controlling over
> >> Hari. This is in violation of the agreed objective in this regard.
> >> Hari is an attempt by a
> >> specific camp to control the development of 10GbE and limit
> >> development of anything other
> >> than the 10.0 only rate PHY.
> >
> > On the rate control issue: 8B/10B encoding, with it's special
> > code-group support provides a means to support a myriad of
> out-of-band
> > functions such as rate control. In fact, the Insert/Remove protocol
> > proposed for Hari provides one very simple rate control signaling
> > method. I encourage you and other WAN PHY proponents to take a good
> > look at the Kauai Hari presentation material.
> >
> >> As you will remember, I called the presenters and floor on
> the issue
> >> of what Hari really
> >> was. It was admitted that it was a LAN extension interconnect by
> >> the individual that
> >> responded. For those of us that are attempting to bring 802.3 into
> >> the 20th century by
> >> making a truly ubiquitous MAC, we have been astounded by the brazen
> >> push of this
> >> "interconnect". Chip makers will confirm that Hari specifically
> >> makes the WAN PHY
> >> extremely difficult to implement. Since Hari truly is not
> common to
> >> all of the PHYs as
> >> specified in the objectives, I suggest that it be withdrawn from
> >> consideration as part of
> >> the 10GbE standard.
> >
> > Once again, I've pointed out that LAN Serial PMDs including
> binary and
> > multi-level signaling benefit from stripping off 8B/10B code and
> > recoding the serial stream with a considerably different
> transmission
> > code. Henning Lysdal of Giga did a great job illustrating in his
> > Kauai presentation entitled: "Serial LAN PMD Architecture Options"
> >
> http://grouper.ieee.org/groups/802/3/10G_study/public/nov99/ly
> sdal_1_1199.pdf.
> > The WAN PHY can do the same if it chooses to use the optional Hari
> > interface. If you don't like this optional interface, please suggest
> > an alternate optional interface for the WAN PHY.
> >
> > Best regards,
> > Rich
> >
> > --
> >
> >> Thank you,
> >> Roy Bynum
> >>
> >> Rich Taborek wrote:
> >>
> >> > Roy,
> >> >
> >> > I thought that Hari was clearly presented in at least
> half a dozen
> >> presentations by at
> >> > least the same number of presenters who all explained it in the
> >> same way in Kauai. I'll
> >> > try one more time here.
> >> >
> >> > Hari is the same as the Serial interface of the 10 GMII as
> >> presented to the HSSG by
> >> > Howard Frazier of Cisco in Montreal, York and Kauai. A group of
> >> Ethernet, Fibre Channel,
> >> > InfiniBand and even OIF folks have gotten together over the past
> >> several months to try
> >> > and arrive at a common interface for passing 10 Gbps of data
> >> continuously in each
> >> > direction between a PCS/PMA element (which may be integrated with
> >> the MAC and the PMD
> >> > (i.e. transceiver module).
> >> >
> >> > Note that a typical Ethernet PHY, like 1000BASE-X contains the
> >> PCS, PMA and PMD
> >> > sublayers. Hari is NOT a PHY nor is it a PHY sublayer. Hari is an
> >> interface between
> >> > sublayers and is very similar in nature to the Ten-Bit Interface
> >> (TBI) of 1000BASE-X,
> >> > which is fully described in Clause 36 of that standard.
> >> >
> >> > Hari has nothing at all to do with WWDM although it
> clearly may be
> >> used to attach a WWDM
> >> > PMD to its MAC/PCS/PMA.
> >> >
> >> > Hari may be used to attach a Parallel Optical PMD to its
> >> MAC/PCS/PMA in much the same
> >> > fashion as for WWDM
> >> >
> >> > Hari usage to attach a MAS PMD to its MAC/PCS/PMA has been
> >> described in all my MAS
> >> > proposals to the HSSG including the latest update presented in
> >> Kauai:
> >> >
> >>
> http://grouper.ieee.org/groups/802/3/10G_study/public/nov99/ta
> borek_2_1199.pdf
> >>
> >> >
> >> > Hari usage to attach a Serial PMD to its MAC/PCS/PMA along with a
> >> proposed coding to
> >> > maintain a line rate of ~10 Gbaud has been described in the Kauai
> >> proposal by Rick
> >> > Walker and Richard Dugan of Agilent:
> >> >
> >>
http://grouper.ieee.org/groups/802/3/10G_study/public/nov99/walker_1_1199.pd
f
>>
>> >
>> > Therefore, Hari provides a common interface for all major classes
>> of PMDs proposed to
>> > the HSSG to date in addition to being strongly considered as a
>> common interface for
>> > other ~10 Gbps standard and industry interfaces.
>> >
>> > The principal strengths of Hari are:
>> > 1) Low pin count
>> > 2) Self-timed (doesn't need a clock with data)
>> > 3) Supports reasonable distances over inexpensive medium (e.g. 20"
>> of FR4 traces)
>> > 4) Good synergy with traditional Ethernet MAC/PHY framing
>> > 5) Sufficient robustness to not compromise a 10E-12 link BER
>> >
>> > 8B/10B encoding has been proposed for Hari since it has been
>> proven time and time again
>> > in multiple forums that 8B/10B is a very robust serial link
>> transmission code. However,
>> > Hari is not a PCS and an alternate code could have been proposed
>> for Hari. I consider
>> > the Hari usage of 8B/10B to be analogous to a parity bit for a
>> traditional parallel
>> > interface. The "parity bit" can be generated at the source and
>> discarded after checking
>> > at the destination. The MAS and Serial PMD proposals referenced
>> above use Hari in
>> > exactly this fashion and result in the lower line rate possible
>> for those respective
>> > interfaces when compared to a PMD coding which would carry forward
>> the 8B/10B overhead.
>> >
>> > Hari is being proposed for inclusion into the 802.3ae standard as
>> an interface as
>> > described above. However, Hari does not dictate the encoding of
>> data transported over
>> > the Medium. Hari simply enables the transport of that data over
>> the medium in a manner
>> > commensurate with the 5 criteria of 802.3ae.
>> >
>> > As such, I would also recommend that Hari be considered for the
>> WAN PHY.
>> >
>> > Best regards,
>> > Rich
>
> ----------------------------------------------------------
>
> Richard Taborek Sr. 1441 Walnut Dr. Campbell, CA 95008 USA
> Tel: 408-330-0488 or 408-370-9233 Cell: 408-832-3957
> Email: rtaborek@xxxxxxxxxx or rtaborek@xxxxxxxxxxxxx
>