RE: [RPRWG] 802.17 Outline: Stratum Clock distribution?
All,
A few comments that might help to clarify the intent.
> I am not saying that the standard should preclude the
> possibility of doing circuit emulation, ... but it is not the
> standard's role to impose whether and how to do synchronization
> at the MAC layer.
I agree with this statement, while believing in Stratum Clock distribution.
Providing a way of accurately synchronizing "time-of-day" clocks between
different stations is necessary to not "preclude" circuit emulation.
How that clock is used within stations, however, is beyond the
scope of the standard.
I'm more familiar with IEEE Std 1394, which distributes&synchronizes
timers so that the microphone data can be presented to the amplifier
without dropping/inserting samples. From what I have heard, the same
kind of thing is useful (for similar reasons) within telephony
applications...
If you think of RPR replacing other connections, providing similar
services is required. Telephony traffic can be tunneled and
reconstructed at the boundaries. However, without some hardware
support, I'm not sure that the same can be said for the synchronized
clock domains...
DVJ
David V. James, PhD
Chief Architect
Network Processing Solutions
Data Communications Division
Cypress Semiconductor
110 Nortech Parkway
San Jose, CA 95134
Work: +1.408.942.2010
Cell: +1.650.954.6906
Fax: +1.408.942.2099
Work: djz@xxxxxxxxxxx
Base: dvj@xxxxxxxxxxxx
> -----Original Message-----
> From: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
> [mailto:owner-stds-802-17@xxxxxxxxxxxxxxxxxx]On Behalf Of
> Jeanne.De_Jaegher@xxxxxxxxxx
> Sent: Thursday, November 22, 2001 3:41 AM
> To: jean-pierre.burvenich@xxxxxxxxxxx
> Cc: stds-802-17@xxxxxxxx
> Subject: RE: [RPRWG] 802.17 Outline: Stratum Clock distribution?
>
>
>
>
>
> Hello Jean-Pierre,
>
> I am not sure I understand exactly what you mean.
>
> Please remember also that there is no synchronization requirement
> for RPR. I am not saying that the standard should preclude the
> possibility of doing circuit emulation, that is why different
> insertion and transit path behaviors adapted to different
> applications should be allowed in the standard, but it is not the
> standard's role to impose whether and how to do synchronization
> at the MAC layer.
>
> regards,
>
> Jeanne
>
>
>
>
>
> jean-pierre.burvenich@xxxxxxxxxxx on 22/11/2001 12:30:44
>
>
>
> To: Jeanne DE JAEGHER/BE/ALCATEL@ALCATEL,
> stds-802-17@xxxxxxxx
>
> cc:
>
>
>
> Subject: RE: [RPRWG] 802.17 Outline: Stratum Clock
> distribution?
>
>
>
>
>
>
> As usual when it comes to this subject (synchronisation) in the context of
> introducing/defining a new technology, everybody is wondering what this is
> good for, and nobody remebers who put it on the agenda neither why he/she
> did it.
> -)
>
> I do not know it either.
> But I do believe it is a good idea to keet the item as a
> placeholderfor the
> time being.
> The question is: does the RPR concept have an impact on the possible
> requirement for synchronization of either
> something happenining within the RPR layer itself(in which case the item
> should preferably be dealt with in the standard)
> or
> happening in a different (i.c. PHY) but impacted by the presence
> of the RPR
> mechanism for some services supported.
>
> e.g. Timing quality required for emulated LL circuits routed across RPR
> could be hard to meet if PHY layer supporting RPR is not synchronized to a
> certain standard (does not mean I pretend this - just a hypothetical
> example).
>
> JP Burvenich
>
> -----Original Message-----
> From: Jeanne.De_Jaegher@xxxxxxxxxx [mailto:Jeanne.De_Jaegher@xxxxxxxxxx]
> Sent: 22 November 2001 10:18
> To: stds-802-17@xxxxxxxx
> Subject: RE: [RPRWG] 802.17 Outline: Stratum Clock distribution?
>
>
>
>
>
> It seems nobody really knows what it really means or why this section
> suddenly appeared in the outline for .17.
> If it's like James says, synchronization for circuit emulation this is
> indeed not something that should be part of the RPR standard.
> Also since we are not defining a PHY layer, I don't understand
> why we should
> bother with synchronization or lack of synchronization in the
> different PHY
> layers we are going to use.
>
> Can we momentarily remove this section from the outline. If in
> the future we
> all agree on content and purpose of this section, we can always add it
> again.
>
> jeanne
>
>
>
>
>
>
> "Chan, James" <jchan@xxxxxxxxxxxxxxxxx> on 21/11/2001 22:32:51
>
>
>
> To: "'djz@xxxxxxxxxxx'" <djz@xxxxxxxxxxx>, Jeanne DE
> JAEGHER/BE/ALCATEL@ALCATEL
>
> cc: stds-802-17@xxxxxxxx
>
>
>
> Subject: RE: [RPRWG] 802.17 Outline: Stratum Clock
> distribution?
>
>
>
>
>
>
>
>
> Stratum Clock Distribution to me means ANSI T1.101
> Synchronization hierarchy
> standard. This is very different to time-of-day clocks. Synchronization is
> necessary from PSTN (TDM voice) perspective. It may also be required for a
> RPR network supporting circuit emulation services (there may be other ways
> to do it without synchronization). However, this is an implementation
> specific issue which should not be part of the RPR standard. Individual
> vendors may choose to do it as their differentiator.
>
> I was not aware of stratum clock discussion in the last meeting. Can any
> else shed some light?
>
>
> Regards,
>
> James Chan
>
>
>
>
> -----Original Message-----
> From: David James [mailto:djz@xxxxxxxxxxx]
> Sent: Wednesday, November 21, 2001 10:14 AM
> To: Jeanne.De_Jaegher@xxxxxxxxxx
> Cc: stds-802-17@xxxxxxxx
> Subject: RE: [RPRWG] 802.17 Outline: Stratum Clock distribution?
>
>
>
> Jeanne,
>
> Some physical layers have no provisions for accurately
> synchronizing time-of-day clocks (GMT like clocks) of
> clock slave's to clock masters.
>
> For physical layers without such services, this clause
> describes how such time-of-day clocks can be accurately
> synchronized by MAC-level services.
>
> From IEEE Std 1394 Serial Bus experiences, as well as
> the telecom industry as a whole, the value of synchronous
> transfers is greatly increased if time-of-day clocks
> can also be synchronized.
>
> DVJ
>
>
> David V. James, PhD
> Chief Architect
> Network Processing Solutions
> Data Communications Division
> Cypress Semiconductor
> 110 Nortech Parkway
> San Jose, CA 95134
> Work: +1.408.942.2010
> Cell: +1.650.954.6906
> Fax: +1.408.942.2099
> Work: djz@xxxxxxxxxxx
> Base: dvj@xxxxxxxxxxxx
>
> > -----Original Message-----
> > From: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
> > [mailto:owner-stds-802-17@xxxxxxxxxxxxxxxxxx]On Behalf Of
> > Jeanne.De_Jaegher@xxxxxxxxxx
> > Sent: Wednesday, November 21, 2001 3:17 AM
> > To: stds-802-17@xxxxxxxx
> > Subject: [RPRWG] 802.17 Outline: Stratum Clock distribution?
> >
> >
> >
> >
> >
> > Good morning,
> >
> > Can someone tell me what the section over Stratum Clock
> > Distribution covers?
> >
> >
> > Thank's
> >
> > Jeanne
> >
> >
> >
>
>
>
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