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Re: AW: 1550nm Serial PMD Question


It might be noted that the jitter specification that the ITU is applying is 
to allow all signals to be multiplexed at the electrical level, not just 
the optical level.  No one in ITU has considered an "optical multiplexing 
only" jitter specification.  Using the "Class B" regenerator specification 
with a plezio-isosynchronous timing instead of a full isosynchronous and a 
relaxed timing specification would allow non-TDM multiplexed optical 
services and non-"digital wrapper" DWDM wavelength services.  The larger 
vendors are attempting to maintain their dominance and high margins for 
transmission equipment.  I expect that ITU is very upset about 802.3ae 
being a non-electrical multiplexable optical channel.

Thank you,
Roy Bynum

At 09:37 AM 5/4/01 +0200, Rahn, Juergen (Juergen) wrote:

>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@xxxxxxxxxxxxxx]
> > Gesendet:     Mittwoch, 2. Mai 2001 16:39
> > An:   stds-802-3-hssg@xxxxxxxx
> > 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
> >
> >