RE: Clock Tolerance and WAN PHY
Luigi,
Would it be also possible to map the LAN PHY directly into the OTN ( i.e.
a 10.3125 Gbit/s nominal frequency client signal)?
Regards,
Gary Nicholl .....
At 09:49 AM 1/23/01, Luigi.Ronchetti@xxxxxxxxxxxxxxxx wrote:
>Dave, Tom, James and all,
>
>I apologize but it was not my intention to suggest you to directly
>interface the WAN PHY to standard SONET/SDH network (I completely
>agree with you all, ELTE is needed).
>
>My intention was to make you aware of the new emerging standard that
>defines OTN (Optical Transport Network) in ITU-T (G.709).
>OTN is a "server layer" also for SONET/SDH services (i.e. for the
>first time, SONET/SDH is a "client layer").
>OTN is a "networking solution": it comprises its own performance
>monitor, path provision, ... functions.
>A CBR10G client signal (see my previous mail) is seen from OTN as a
>constant bit rate stream.
>
>I know that one 802.3 "philosophy" is to increase bandwidth by 10
>with a cost increasing of only 3 or 4, for each new generation; I
>wander if (for WAN interfaces only, not for LAN ones) it is convenient
>to make today a "little" exception, to gain advantage from the above
>mentioned new ITU-T standard.
>
>Best regards,
>Luigi
>
> > -----Original Message-----
> > From: dwmartin@xxxxxxxxxxxxxxxxxx [mailto:dwmartin@xxxxxxxxxxxxxxxxxx]
> > Sent: Monday, January 22, 2001 11:11 PM
> > To: james_colin_j@xxxxxxxxx; Ronchetti, Luigi /itah32;
> > tripathi@xxxxxxxxxxxx
> > Cc: dwmartin@xxxxxxxxxxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
> > Subject: RE: Clock Tolerance and WAN PHY
> >
> >
> >
> > James, Luigi,
> >
> > The 'ELTE' is also necessary to fill in the remaining SONET
> > overhead.
> >
> > ...Dave
> >
> > David W. Martin
> > Nortel Networks
> > +1 613 765-2901
> > +1 613 765-0769 (fax)
> > dwmartin@xxxxxxxxxxxxxxxxxx <mailto:dwmartin@xxxxxxxxxxxxxxxxxx>
> >
> > -----Original Message-----
> > From: Tom_Alexander@xxxxxxxxxxxxxx
> > [mailto:Tom_Alexander@xxxxxxxxxxxxxx]
> > Sent: Monday, January 22, 2001 11:12 PM
> > To: james_colin_j@xxxxxxxxx; Ronchetti, Luigi /itah32;
> > tripathi@xxxxxxxxxxxx
> > Cc: Tom_Alexander@xxxxxxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
> > Subject: RE: Clock Tolerance and WAN PHY
> >
> >
> >
> > James,
> >
> > There is no intent or support for directly interfacing the
> > WAN PHY to standard
> > SONET gear, especially in outside plant applications. Off
> > hand, I can think of
> > the following obstacles, even if you did match the clocks:
> >
> > - The optics are completely different
> > - Most of the overhead bytes are not supported (for instance, it
> > would not be possible to provision the ring)
> > - Much of the defects and alarm reporting is missing
> >
> > While it is certainly possible for someone to put back the
> > missing overhead
> > and defects and also use SONET optics rather than Ethernet
> > optics, all this
> > is totally outside the scope of the 802.3ae standard.
> >
> > Best regards,
> >
> > - Tom
> >
> > -----Original Message-----
> > From: James Colin [mailto:james_colin_j@xxxxxxxxx]
> > Sent: Sunday, January 21, 2001 12:54 AM
> > To: Luigi.Ronchetti@xxxxxxxxxxxxxxxx; tripathi@xxxxxxxxxxxx
> > Cc: stds-802-3-hssg@xxxxxxxx
> > Subject: Clock Tolerance and WAN PHY
> >
> >
> > Luigi,
> > I think that the motto in the WAN PHY standard is the
> > introduction of a new framing scheme (As opposed to
> > POS), rather than being gluelessly connectable to the
> > SONET network. The WAN PHY is supposed to be connected
> > to a SONET LTE (ELTE) that is doing clock drift and
> > jitter adjustments.
> >
> > Even if the WAN PHY Clock requirements were identical
> > to those of SONET, I'm not sure if the ELTE is still
> > needed or the WAN PHY can be directly interface to the
> > SONET ring. Can anybody comment on that?
> >
> > James
> >
> > --- Luigi.Ronchetti@xxxxxxxxxxxxxxxx wrote:
> > > Hi Devendra and all,
> > >
> > > I think that is not enough to reduce the clock
> > > tolerance to 50ppm.
> > >
> > > As far as I know, ITU-T is going to approve
> > > (February 2001) a new
> > > recommendation (G.709) that defines OTN (Optical
> > > Transport Network).
> > > Future optical backbones over long distances will
> > > likely to be realized
> > > using G.709 and this will happen before 10 GbE final
> > > approval.
> > >
> > > In G.709, among the others, a CBR10G client signal
> > > is defined as "a
> > > constant bit rate signal of 9953280 kbit/s +/-20
> > > ppm" (for example an
> > > OC-192/STM-64 signal and then, in principle, also a
> > > 10 GbE WAN signal).
> > >
> > > So, in my opinion, at least for a 10 GbE WAN signal,
> > > the clock
> > > tolerance should be 20ppm.
> > >
> > > Best regards,
> > > Luigi
> > > __
> > > \/ Luigi Ronchetti
> > > A L C A T E L via Trento, 30 - 20059 Vimercate (MI)
> > > Italy
> > > TND R&D phone: +39-039-686.4793 (Alcanet
> > > 2-210-(3)4793)
> > > fax: +39-039-686.3590 (Alcanet
> > > 2-210-(3)3590)
> > >
> > > mailto:luigi.ronchetti@xxxxxxxxxxxxxxxx
> > >
> > > > -----Original Message-----
> > > > From: tripathi@xxxxxxxxxxxx
> > > [mailto:tripathi@xxxxxxxxxxxx]
> > > > Sent: Tuesday, January 09, 2001 10:50 PM
> > > > To: stds-802-3-hssg@xxxxxxxx
> > > > Cc: tripathi@xxxxxxxxxxxx
> > > > Subject: Clock tolerance
> > > >
> > > >
> > > >
> > > > Hi,
> > > >
> > > > Right now we are specifying the clock tolerance of
> > > 100 ppm. Currently
> > > > in-expensive
> > > > oscillators are available with tolerance value
> > > less than 50
> > > > ppm. Just like
> > > > we are moving
> > > > voltage levels, it is time we revise the tolerance
> > > value too.
> > > > The elastic
> > > > buffer
> > > > requirements get simplified by this assumption. I
> > > propose
> > > > that we reduce it
> > > > to 50 ppm.
> > > >
> > > > Regards,
> > > > Devendra Tripathi
> > > > VidyaWeb, Inc
> > > >
> > >
> >
> >
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