AW: AW: 1550nm Serial PMD Question
Hi,
I just try to answer a question that due to mixture of jitter and WDM
compliance I (as editor of the SDH WDM standard) could not completely
understand and so I tried to clarify some conditions:
See also a small remark I have on your answer:
> Juergen:
>
> The 1500 nm 10Ge is intended for dark fiber, not for WDM networks. There
> are no IEEE objectives to make the 1500 nm spec operate with WDM or even
> to
> make it operate over optical amplification. The 1500 nm interface allows
> 10
> Ge to operate over a 40 Km dark fiber which has a 10Ge PHY at both ends.
> If
> this signal were extended further it would require a switch or repeater
> before the next fiber segment. The 10 Ge specification can support a WDM
> optical network by using a 1300 nm interface into the edge of the WDM
> network where a transponder at the edge of the WDM network transforms the
> signal into the "ITU Grid" and reforms the clock to the requirements of
> the
> WDM network.
In case of "transponder use " you have at least two regenerators and
therefore an interworking and accumulation issue that not at al has been
considered.
The main issue in this respect I see is that the current spec contains a
high value of RJ where first I do not understand where it comes from but
more as important issue it has to be checked if normally "Sonet" type
regenerators (Transponders) can interwork and under which restrictions. This
means we can quickly say just use a transponder but this thing is nor
specified , so performance is unknown.
Regards Juergen
> Cheers,
>
> Paul
>
> At 09:37 AM 5/4/2001 +0200, Rahn, Juergen (Juergen) wrote:
>
> >Hi,
> >The spec is indeed not in line to the "ITU Grid". However it should be
> >noted that beside this small pree condition of supporting particular
> >wavelength there are a lot further specs required that are not at all in
> the
> >Ethernet document. This means this interface in the current spec is not
> >suited for direct WDM also. For WDM you would in this case require a real
> >SDH/SONET interface. In this respect it should also be noted that one
> reason
> >(beside the optical parameters that do not support effective
> transmission)
> >is the way the jitter is specified as this prevents the cascadability of
> 3 R
> >regens which are needed in WDM networks of larger dimensions.
> >Regards Juergen Rahn
> >
> > > ----------
> > > Von: Marshall Eisenberg[SMTP:marshall@foundrynet.com]
> > > Gesendet: Mittwoch, 2. Mai 2001 16:39
> > > An: stds-802-3-hssg@ieee.org
> > > Betreff: 1550nm Serial PMD Question
> > >
> > >
> > > All,
> > > A while back there were rumors that the 1550nm Serial PMD would be ITU
> > > Grid
> > > Spec compliant, making it DWDM 'ready' I've downloaded draft D3.0
> and
> > > cannot find any references or further notations. Can anyone shed any
> > > light
> > > on this or point out the relevant section in the draft?
> > >
> > > Regards,
> > >
> > > Marshall Eisenberg
> > > Director of product marketing
> > > Foundry Networks Inc.
> > > 2100 Gold Street
> > > P.O. Box 649100
> > > San Jose, CA 95164-9100
> > > (408) 586-1754 direct
> > > (408) 586-1900 fax
> > > (408) 398-0014 mobile
> > >
> > >
>
> Paul A. Bottorff, Director Switching Architecture
> Enterprise Solutions Technology Center
> 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@NortelNetworks.com
>