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Re: 3PMD Proposal




I have to agree with Larry's thoughts 'Arghhhh!!!'.  I would opt to
scrap the 1300 nm wwdm solution if a patch cord is required.

Joel
------------------------

Larry Miller wrote:

>
>
> Arghhhh!!! Are we really back to that, David? The offset patchcord has
> been terribly unpopular with us, adding so much cost that it nearly
> doubles the cost of 1 Gb MM LX links.
>
> Is the Agilent 4X WWDM going to work with SMF? I will be wanting to
> know that.....
>
> Larry Miller
>
>      -----Original Message-----
>      From:   david_cunningham@xxxxxxxxxxx
>      [SMTP:david_cunningham@xxxxxxxxxxx]
>      Sent:   Monday, June 12, 2000 9:04 PM
>      To:     Bernd.Prediger@xxxxxxxxxxxx; piers_dawe@xxxxxxxxxxx
>      Cc:     Stds-802-3-Hssg@xxxxxxxx
>      Subject:        RE: 3PMD Proposal
>
>      Bernd,
>            the offset launch patchcord is assumed for the 1300 nm WWDM
>      case for
>      10 Gigabit Ethernet.  As was documented in IEEE 802.3z
>      1000BASE-LX the
>      offset launch patchcord ensures a worst-case minimum bandwidth of
>      500
>      MHz.km.  For 1300 nm links the inclusion of the offset launch
>      patchcord
>      obsoleted the 385 Mhz.km modal bandwidth value that was present
>      in some
>      older drafts of the 1000BASE-LX clause.
>
>      In conclusion, since the offset launch patchcord is part of the
>      1300 nm WWDM
>      proposal 500 MHz.km is the correct modal bandwidth to use for the
>      multimode
>      links.
>
>      Best wishes,
>
>      David.
>
>      -----Original Message-----
>      From: Bernd.Prediger@xxxxxxxxxxxx
>      [mailto:Bernd.Prediger@xxxxxxxxxxxx]
>      Sent: Wednesday, June 07, 2000 9:49 AM
>      To: piers_dawe@xxxxxxxxxxx
>      Cc: Stds-802-3-Hssg@xxxxxxxx
>      Subject: 3PMD Proposal
>
>
>      Hello Piers,
>      I just got through Del's presentation from Ottawa again and
>      stumpled over
>      your calculation for the "Minimum Range" of CWDM over installed
>      MM-Fiber
>      (Slide 4).
>      You calculated 2-300m for all 500MHz*km fiber but I understood
>      that since
>      Gigabit Ethernet the worst case effective bandwidth everbody
>      agreed on is
>      375MHz*km. Our calculation with the latter value let to about
>      180m.
>      What am I missing here? (Of course we used your spreadsheet!)
>      Best wishes
>      Bernd
>
--
Joel Goergen
Force10 Networks
1440 McCarthy blvd
Milpitas, Ca, 95035

Email:  joel@xxxxxxxxxxxxxxxxxxx
Direct: (408) 571-3694
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