RE: [EFM] Network timing?
Roy,
Actually what I think is needed is the reverse of ITU X 86 i.e. E1/T1 over
Ethernet. The ietf have some rfcs on this with an IP layer of course. I have
a proposal for E1/T1 over Ethernet / 802.3 only, but I am not sure which
forum would be interested (if any). As I said in an earlier email today, it
is much easier to carry T1/E1 over a side band than it is to packetise and
de-packetise it. However, one benefit of packetising it is that it can be
carried through a layer two or an IP metro / core network, all the way to
the switch (given constant latanct of course, I think we went round that
loop about six weeks ago).
Bob
> -----Original Message-----
> From: owner-stds-802-3-efm@majordomo.ieee.org
> [mailto:owner-stds-802-3-efm@majordomo.ieee.org]On Behalf Of Roy Bynum
> Sent: 26 September 2001 17:51
> To: Frank Coluccio; Matthew.Beanland@xxxxxxxxxxxxxx
> Cc: stds-802-3-efm@ieee.org
> Subject: Re: [EFM] Network timing?
>
>
>
> Framk,
>
> One of the interesting side features of a "side band" type of OAM, is the
> simplistic ability to support "network timing" if the service requires
> it. Personally, I do not think that E1/T1 interfaces at the CPE Demark
> will be much of an issue. There is already a simple standard for mapping
> Ethernet frames into T1/E1 payloads, ITU X.86.
>
> Thank you,
> Roy Bynum
>
> At 08:10 AM 9/26/01 +0000, Frank Coluccio wrote:
>
> >Hi Mathhew,
> >
> >It sounds like you're desribing a variant of FDDI II's "guaranteed" T1
> >capabilities, or some form of T1 emulation _a_la_ ATM. I've
> discussed this
> >possibility with others here in the past. At what "super rate"
> (minimum entry
> >level) of Ethernet would you propose, first, before such an isochronous
> >approach
> >should be considered? [Or, should it be considered at all?]
> >
> >In 10 Mb/s or lower, I don't think so. At 100 Mb/s or higher, a
> >possibility, imo.
> >What say?
> >
> >Frank
> >
> > >
> > > Hi EFMers,
> > >
> > > I guess this is a question for the service providers out there.
> > Imagining an
> > > EFM ONU supporting bearer emulation (say, in order to provide E1/T1
> > interfaces
> > > for connection to a legacy PABX), is there any interest in
> having the OLT
> > > propagate network timing (usually 8kHz, traceable back to some
> > reference) to
> > > the ONUs by some method?
> > >
> > > Propagation of network timing is allowed for in the xDSL standards.
> > >
> > > Should we require propagation of network timing in EFM it could be
> > propagated
> > > by either the Ethernet symbol rate itself or via some coding
> method. Some
> > > physical layer schemes (ATM25 comes to mind) use a low spec
> oscillator
> > for the
> > > line rate and insert special line tokens at 8kHz to allow user side
> > equipment
> > > to recover network timing if required. It would be possible
> to use one
> > of the
> > > non-data 8B/10B tokens as a timing marker and send at 8kHz,
> > alternatively if
> > > there is an OAM block it could be sent at 8kHz rate.
> > >
> > > Best Regards,
> > >
> > > Matt
> > >
> > > Matt Beanland, Project Manager/Principal Architect
> > > Telecommunications Research and Development, Fujitsu Australia Ltd
> > > 5 Lakeside Drive, Burwood East 3151, Victoria, Australia
> > > e-mail: matthew.beanland@xxxxxxxxxxxxxx Phone: (613) 9845 4313
> > >
> > >
>