Re: Going the distance

["Larry Miller" <l_d_miller@xxxxxxxxxxxxx>]

Ed,

In our case the huge majority of increased link length came from the fact
that the LX receivers are 6dB or more quieter than SX (or the standard), and
on SM fiber this translates into a much larger link budget. One of the
reasons we standardized on this is that transceivers with lower noise seem
to be more reliable as well.

It was not until we got into some custom 50 km links that we had to go to
"death ray" lasers of increased power.

This was a case of getting a 2X improvement over the standard "for free".
Obviously, this may not happen in the 10GbE world.

I suspect that if the Committee, in its wisdom, legislates under-achieving
link lengths to accommodate the simultaneous worst-case everything as was
done in 802.3z, then we will have a similar phenomenon as we have today: if
you cannot easily double the link lengths (at least) then you probably
bought some pretty cheesy equipment. Sales people, I think, would rather
have the standard reflect more closely what the technology will reliably do,
not some pruned-back number that they have to talk around.

Larry Miller
Nortel Networks

-----Original Message-----
From: Cornejo, Edward (Edward) <ecornejo@xxxxxxxxxx>
To: stds-802-3-hssg@xxxxxxxx <stds-802-3-hssg@xxxxxxxx>
Date: Thursday, July 01, 1999 8:32 AM
Subject: RE: Going the distance


>
>Bruce/Larry,
>
>Before deciding your minimum link distance requirements, consider the
>following.
>
>The 10km GE extension was possible with some minor spec modifications to
the
>laser characteristics. However, this will not be the case for 10GE serial
>approaches. To extend 10GE to 10km or 15km you will be going to a different
>laser technology, which will be higher in cost than the 2km laser source.
>This does not necessarily mean that the serial 10GE 15km solution will be
>higher in cost than the WWDM; this is still to be proven, but it does mean
>it will cost more than the 2km serial solution.
>
>Ed-Lucent
>
>> ----------
>> From:
>> ldmiller@xxxxxxxxxxxxxxxxxx[SMTP:ldmiller@xxxxxxxxxxxxxxxxxx]
>> Sent: Wednesday, June 30, 1999 8:35 PM
>> To: Bruce_Tolley@xxxxxxxx; Les Poltrack
>> Cc: Ed Grivna; rtaborek@xxxxxxxxxxxxxxxx; hfrazier@xxxxxxxxx;
>> stds-802-3-hssg@xxxxxxxx
>> Subject: Re: Going the distance
>>
>>
>> Bruce,
>>
>> Your percentage (30%) rings a bell here, and we are insisting that LX
>> transceivers be qualified for 10 km for EVERYTHING in the enterprise
>> space;
>> most vendors seem to be offering that as standard anyway now.
>>
>> Larry Miller
>> Nortel Networks
>>
>> At 05:02 PM 6/30/99 -0700, Bruce_Tolley@xxxxxxxx wrote:
>> >
>> >
>> >
>> >Les and Ed:
>> >
>> >We might be able to estimate the potential size of the 5 to 10 km
>> application
>> >segment by looking at shipments of LX ports today if the transceiver
>> vendors
>> >have the data and are willing to share it.
>> >
>> >But more important than the mix of LX to SX ports  is the fact that many
>> >customers today  have a requirement to go these kind of distances. The
>> number of
>> >LX ports sold might be small compared to SX but this kind of application
>> is
>> >pulling a lot of GbE business.  If you want me to quantify it, I'd say
of
>> the
>> >last ten customers I have been in meetings with, 3 of them were looking
>> to
>> use
>> >the 10 km LX solution to go 5 to 10 km.
>> >
>> >Also I am not all that comfortable with the unstated assumption in much
>> of
>> the
>> >previous debate that the short distances are in fact the major market
for
>> 10
>> >GbE.  The logical application for 10GbE in the LAN and Campus is to
>> aggregate
>> >lots of GbE segments, which means between buildings and between rather
>> large
>> >capacity switches that could be a long way apart (shall we call it a
>> MAN?).
>> >
>> >Bruce Tolley
>> >3Com Corporation
>> >
>> >
>> >
>> >
>> >
>> >
>> >Les Poltrack <lap@xxxxxxxxx> on 06/30/99 12:54:03 PM
>> >
>> >Sent by:  Les Poltrack <lap@xxxxxxxxx>
>> >
>> >
>> >To:   Ed Grivna <elg@xxxxxxxxxxx>, rtaborek@xxxxxxxxxxxxxxxx, Bruce
>> >      Tolley/HQ/3Com
>> >cc:   hfrazier@xxxxxxxxx, stds-802-3-hssg@xxxxxxxx
>> >Subject:  Re: Going the distance
>> >
>> >
>> >
>> >
>> >
>> >Ed, you raise a good point and I wish I could answer with an
>> >absolute percentage on the requirement.
>> >
>> >There was another point raised that this might be more of a
>> >marketing question than anything else.  For what it's worth,
>> >my subjective marketing perspective, based on talking to
>> >hundreds of users about Gigabit Ethernet and their expectations
>> >for Ethernet backbone technologies, is that Bruce Tolley's
>> >suggestion of 5 to 10 km is right on the mark.
>> >
>> >I don't have the incontrovertible quantitative data I'd like to
>> >have on the distribution of distances required, but I would say
>> >that a good point was raised earlier that the fact that most
>> >long wavelength Gigabit Ethernet devices support 10km has
>> >created somewhat of an expectation for backbone distances
>> >in customer's mind and support of 10km by 10 Gigabit Ethernet
>> >devices would materially enhance the adoption of the technology.
>> >
>> >My two cents is that 10km is the right goal for a volume singlemode
>> >high speed backbone technology.
>> >
>> >Thanks,
>> >
>> >Les Poltrack
>> >Cisco Systems, Inc.
>> >
>> >At 11:35 AM 6/30/99 -0500, Ed Grivna wrote:
>> >>
>> >>Bruce, while I do not dispute your facts, I do question your
>> >>conclusion.  Just because some small part of the populace is doing
>> >>something does not necessarily require that it be standarized.
>> >>
>> >>As is evident by the statement itself, for those small segments of
>> >>the market that have needs beyond those that are standardized, there
>> >>are often low-cost avenues that they can persue to fill those needs.
>> >>
>> >>The fact that they are using LX beyond the rated distances even
>> >>puts into question if what they have is really a 1000Base-LX link.
>> >>It may well be constructed with LX compatible components and be
>> >>running the proper protocols, but that doesn't necessarily make it
>> >>an LX link.
>> >>
>> >>The requirements for the standards committee are to standarized those
>> >>areas of the technology where such effort would benefit the overall
>> >>user community, not 1 or 2 users or potential users.  Unless this
>> >>market segment can be quantified into a reasonable percentage of
>> >>the overall market, I question whether a standarization effort is
>> >>appropriate.
>> >>
>> >>Are we talking 5%, 1%, 0.1%, or 0.001% of the market?   At some point
>> >>it is necessary to make a cut, and state that the user may create links
>> >>beyond these bounds, but that their implementation is beyond the scope
>> >>of the standard.
>> >>
>> >>-Ed Grivna
>> >>
>> >>
>> >>
>> >>Bruce Tolley wrote:
>> >>>
>> >>> The point has been made before that today customers are already going
>> >>> 5 to 10 Km with 1000BASE-LX.  There should be no debate that it is a
>> >>> market requirement to go 5 to 10 km with 10 GbE.
>> >>>
>> >>> While I am willing to consider accepting  a conservative 2 to 3 km
>> >>> goal as the official goal of the project,  we need to acknowledge
>> >>> that this is a conservative goal and, as we get on with the work
>> >>> of the project , we should investigate whether we can stretch this
>> goal..
>> >>>
>> >>> Bruce Tolley
>> >>> 3Com Corporation
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> Rich Taborek <rtaborek@xxxxxxxxxxxxxxxx> on 06/29/99 05:01:32 PM
>> >>>
>> >>> Please respond to rtaborek@xxxxxxxxxxxxxxxx
>> >>>
>> >>> Sent by:  Rich Taborek <rtaborek@xxxxxxxxxxxxxxxx>
>> >>>
>> >>>
>> >>> To:   Howard Frazier <hfrazier@xxxxxxxxx>, HSSG
>> <stds-802-3-hssg@xxxxxxxx>
>> >>> cc:    (Bruce Tolley/HQ/3Com)
>> >>> Subject:  Re: Going the distance
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> Howard,
>> >>>
>> >>> I will gladly accept your suggestion of removing the portion of the
>> >>> motion in parenthesis as a  friendly amendment post-haste given your
>> >>> support of this motion as a seconder.
>> >>>
>> >>> - Rich
>> >>>
>> >>> Howard Frazier wrote:
>> >>>
>> >>> > The more I think about it, the more I like the idea of adopting the
>> >>> > 802.3z link distance objectives for 10 Gig. We should remember that
>> >>> > we are still in the study group phase, trying to scope out a
>> project.
>> >>> > We can always adjust the objectives later.
>> >>> >
>> >>> > Let me therefore state my support for Rich's proposed motion:
>> >>> >
>> >>> > > "Support the premises cabling plant distances as specified in
>> >>> > > ISO/IEC 11801"
>> >>> > >
>> >>> > > The distances supported in ISO/IEC 11801 are:
>> >>> > >
>> >>> > > 100 m for horizontal cabling (applicable to copper, MMF, SMF)
>> >>> > >
>> >>> > > 550 m for vertical cabling: (applicable to SMF and possibly MMF)
>> >>> > >
>> >>> > > 2-3 km for campus cabling: (applicable to SMF)
>> >>> >
>> >>> > Rich, I would encourage you to drop the parenthesis.
>> >>> >
>> >>> > If we adopt this objective, we can make progress on the rest of the
>> >>> > work we need to do as a study group.  As was demonstrated in
802.3z,
>> >>> > we will need to review the objectives periodically, and revise them
>> >>> > if there is consensus to do so.
>> >>> >
>> >>> > Howard Frazier
>> >>> > Cisco Sytems, Inc.
>> >>>
>> >>> -------------------------------------------------------------
>> >>> Richard Taborek Sr.    Tel: 650 210 8800 x101 or 408 370 9233
>> >>> Principal Architect         Fax: 650 940 1898 or 408 374 3645
>> >>> Transcendata, Inc.           Email: rtaborek@xxxxxxxxxxxxxxxx
>> >>> 1029 Corporation Way              http://www.transcendata.com
>> >>> Palo Alto, CA 94303-4305    Alt email: rtaborek@xxxxxxxxxxxxx
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>>
>