RE: [RPRWG] 802.17 Outline: Stratum Clock distribution?
Hello everybody,
I would like to add my point of view in this discussion.
Circuit emulation is a functionality that is outside the scope of a
MAC. It is the responsability of the MAC client to perform it. Thus
also synchronization should be performed by such MAC client by using
the transport facilities provided by the RPR MAC client.
All these issues are outside the scope of the IEEE 802.17 standard so I
would propose to remove the section, not because unuseful but because
it is out of our scope.
Best regards, Italo
> -----Original Message-----
> From: timt@xxxxxxxxxxx [mailto:timt@xxxxxxxxxxx]
> Sent: Wednesday, November 28, 2001 6:34 AM
> To: stds-802-17@xxxxxxxx
> Cc: timt@xxxxxxxxxxx
> Subject: Re: [RPRWG] 802.17 Outline: Stratum Clock distribution?
>
>
>
> Somehow, the synchronization issue needs to be addressed in a
> standardized
> and most efficient way. For now, I would suggest leaving the
> placeholder for
> it until it is ultimately resolved. From a standardization
> perspective,
> failure to address the issue may lead to a lack of
> interoperability across
> vendor product offerings. From an efficiency perspective, failure to
> properly incorporate the best method may result in a
> proliferation of more
> efficient, incompatible approaches to the issue that, again,
> diverge across
> vendors. If RPR, by virtue of the standard, does not
> accomodate the *full*
> extensions and capabilities of converged services, it may not
> present itself
> as a viable alternative to existing technologies, even though
> they may offer
> these attributes in a less efficient manner overall.
>
> Tim
>
>
> ----- Original Message -----
> From: <jean-pierre.burvenich@xxxxxxxxxxx>
> To: <Jeanne.De_Jaegher@xxxxxxxxxx>
> Cc: <stds-802-17@xxxxxxxx>
> Sent: Tuesday, November 27, 2001 7:35 AM
> Subject: RE: [RPRWG] 802.17 Outline: Stratum Clock distribution?
>
>
> >
> > Alright,
> >
> > Here we go for a long one ... :
> >
> > I understand the PSTN/ISDN networks at both ends (if any)
> should be synced
> > (as they are today). This was not my point though. I am
> concerned about
> the
> > possible use of RPR networks to either:
> >
> > - convey information content emulating/carrying circuit
> based services
> (hard
> > to avoid in the telecom environment for the medium term;
> > - convey synchronisation information used itself to
> synchronize remote
> > clocks (SSU's etc) to a PRC (Primary Reference Clock).
> >
> > The latter application does not seem critical to me (there are good
> > aternatives: GPS receivers, other network layers etc).
> >
> > But about the former I would like to clarufy my point by a
> comparison with
> a
> > non-suspect because "synchronous" technology, SDH:
> >
> > In the SDH network (despite the S in the name) it is not
> necessary to
> > synchronize the SDH engine clocks either. However not doing
> so degrades
> the
> > timing quality of the transported signals considerably
> (jitter, wander).
> In
> > principle this could be corrected at the boundary of the
> SDH network by
> > adequate buffering and retiming.
> >
> > However, the preferred approach (by far) is simply to keep the SDH
> switching
> > core in sync with ref. clocks and minimize the accumulation
> of jitter.
> This
> > requires the availability of sync functions to certain
> standards in the
> > equipment used. Ref. ITU rec G.813.
> >
> > Why would this be different with RPR over whatever PHY as
> technology? Is
> > there evidence that the timing behaviour of synchronous
> services carried
> > over RPR rings would not be adversely affected? Once again:
> I agree that
> > there is no genuine sync requirement for the RPR to
> guarantee the RPR will
> > work. The question is: will it be good enough to support
> circuit based
> > services. If not that would be a seriuous limitation which
> may jeopardize
> > its chances for deployment in the telecom environment.
> >
> > JP.
> >
> > -----Original Message-----
> > From: Jeanne.De_Jaegher@xxxxxxxxxx
> [mailto:Jeanne.De_Jaegher@xxxxxxxxxx]
> > Sent: 26 November 2001 11:38
> > To: BURVENICH Jean-Pierre (ANS/NIS)
> > Subject: RE: [RPRWG] 802.17 Outline: Stratum Clock distribution?
> >
> >
> >
> >
> > Circuit emulation over a packet technology does not require
> synchronization
> > in the packet network.
> > The two PSTN end networks should be synchronized. There
> are different
> ways
> > of doing this but these are independant of the packet
> network in between.
> >
> >
> > Jeanne
> >
> >
> >
> >
> >
> > "BURVENICH Jean-Pierre (ANS/NIS)"
> <jean-pierre.burvenich@xxxxxxxxxxx> on
> > 26/11/2001 10:59:38
> >
> >
> >
> > To: "'Chan, James'" <jchan@xxxxxxxxxxxxxxxxx>
> >
> > cc: "'stds-802-17@xxxxxxxx'"
> > <stds-802-17@xxxxxxxx>(bcc: Jeanne DE
> > JAEGHER/BE/ALCATEL)
> >
> >
> >
> > Subject: RE: [RPRWG] 802.17 Outline: Stratum Clock
> > distribution?
> >
> >
> >
> >
> >
> >
> >
> > I share James' opinion in terms of the requirement. As a
> telecom operator
> > person I do not have the same opinion as to the requirement
> for it to be
> > part of the standard. If the industry's intention for RPR
> is to provide a
> > universal standard useful for telecom purposes I believe
> operators will
> > highly value the support of sync requirements. In a
> standardized way. Sync
> > requirements heve a tendency to be underestimated in most technology
> > developments until they are to be deployed in real life.
> > Though I can at this stage not contribute to the actual
> content of such
> > requirement I strongly believe it would be useful to be examined.
> >
> > JP.
> >
> > Jean-Pierre Burvenich
> > Manager Strategy, Architecture and Economics of the Core Network
> > Belgacom WBU/ANS/NIS
> > K. Albert II laan 27
> > B-1030 Brussel
> > Tel+32 2 202 7001
> > Fax +32 2 202 7425
> > Mob +32 477 666 746
> > EMail jean-pierre.burvenich@xxxxxxxxxxx
> >
> > -----Original Message-----
> > From: Chan, James [mailto:jchan@xxxxxxxxxxxxxxxxx]
> > Sent: 21 November 2001 22:33
> > To: 'djz@xxxxxxxxxxx'; Jeanne.De_Jaegher@xxxxxxxxxx
> > Cc:
> > 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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