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Re: Going the distance

     I believe that the WWDM approach that we have presented, when used 
     with uncooled, unisolated, reduced spec (on SMSR, linearity, RIN) DFBs 
     will cost equal or less than the serial 10G FP laser approach that 
     Lucent has proposed for 2km, and significantly less than the isolated 
     DFB approach that they have proposed for 15km.  This would support 
     ~300m on 62.5 micron fiber, and ~10km on SMF.  To push this approach 
     to 15km may involve tightening the SMSR or RIN spec which will 
     significantly increase the cost (since much of the low-cost nature of 
     the approach depends upon using low-cost DFBs).  
     I realize that there is an ongoing debate about relative cost, but it 
     would be a shame to set the objectives at 2km and 15km, when there is 
     a potentially very low-cost solution that can go 10km. I have no 
     problem with a 2km and 10km objective, since I believe we can satisfy 
     both with a single cost-competitive solution.
     I realize that Rich Taborek and others have criticized PMD suppliers 
     (such as HP and Lucent) on this reflector for suggesting objectives, 
     based on what each of our solutions can handle, but I don't think we 
     can afford to ignore it either.  I don't deny that I favor 300m on 
     installed base MMF and 10km on SMF in large part because that is what 
     our WWDM module can support.  I have no problem backing off on these 
     (say to 200m and 5km) if it allows alternative PMDs to be considered.  
     Lucent wants 2km (not 3km) to be an objective so that their serial FP 
     laser module is not excluded.  I'd like 10km (and not 15km) for the 
     same reason (although I believe we're still competitive at 2km).
     Distance objectives should reflect what the customers need, but should 
     be influenced by what the available technologies can achieve.
     -Brian Lemoff
      HP Labs

______________________________ Reply Separator _________________________________
Subject: Re: Going the distance
Author:  Non-HP-pbottorf (pbottorf@xxxxxxxxxxxxxxxxxx) at HP-PaloAlto,mimegw2
Date:    6/30/99 3:24 PM


I support your outlook. We already have 5-10 km with gigabit. Supporting
these distances is necessary to support the installed base. Since the
technology cut-off point is around 20 km and since a standard MAN distance
is 15 km I'd prefer a slightly more aggressive objective of 15 km. This
would still give reasonable design margin. I also believe lower cost
technology exits below 2.5 km motivating a 2 km specification. We could
either specify a single 15 km objective which covers all the applications
with a higher component cost or 2 km and 15 km each with a different price

I would like to see further extension into the MAN. GigE is selling day
with reaches over 50 km. The next standard distance is 40 km. I've heard
this distance was chosen to match the spacing of microwave towers. With the
40 km distance I believe we would have all that is necessary to build Metro

The three standard distances on SMF would be 2, 15, and 40 km. Each of
these ranges I believe falls into a different technology with a different
price point. If anyone has a technology which can do all three at the 2 km
price then all the better.


At 09:13 AM 6/30/99 -0700, Bruce_Tolley@xxxxxxxx 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
>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
>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    
>Palo Alto, CA 94303-4305    Alt email: rtaborek@xxxxxxxxxxxxx
Paul A. Bottorff, Director Switching Architecture
Bay Architecture Laboratory
Nortel Networks, Inc.
4401 Great America Parkway
Santa Clara, CA 95052-8185
Tel: 408 495 3365 Fax: 408 495 1299 ESN: 265 3365
email: pbottorf@xxxxxxxxxxxxxxxxxx