RE: [EFM] 100 Mbps Proposals
Geoff,
thanks
for correcting me the two cases. I was actually thinking the two proposals
earlier at EFM. Specifically there were some proposals at EFM regarding 100
meg, one was on single pair (TDD-combined up/down) and one on 4-pairs of
cat-5/3.
What I
am suggesting is regarding any telephone copper pair and spectrally compatible
with services in the bundle which is different from what was discussed on those
proposals.
I guess I was hoping to hear "is this something
of interest to ieee?" since we
brought up the 100 meg fiber discussion.
that is all
Behrooz
Behrooz
At 01:39 PM 2/14/02 -0800,
Behrooz Rezvani wrote:
Sorry just got of a meeting did not realize
that I have created some
confusion:
You are right Geoff.
100BASE-T4 was 100 Meg combined on a single pair.
No, it was
100 Mb/s on 3 pair. There was one pair dedicated to each direction and 2 pair
that were used in the direction of data transmission. It only takes one pair
to easily handle the carrier sense information. So the CSMA/CD was done on 1
pair each direction. The data transmission was done on 3 pairs with 8B/6T
encoding. See Figs 23-3, 23-4, 23-23. That is why you can't do full duplex on
100BASE-T4.
So this is not that. I am suggesting just like
100BASE-T put 25Meg full duplex on each pair
100BASE-T does
not put 25Meg full duplex on each pair.
I assume that you mean that
1000BASE-T puts 25Meg full duplex on each pair. That is not true either. There
is no pair specific coding in 1000BASE-T. The coding is spread over all 4 pair
at once. The decoder looks at 5 levels on 4 pairs (which yields a code space
of 625 points) and derives 1 byte from it (256 code points plus control
codes). The excess code space is used to provide more than one possible code
target for the subsequent code. Choosing the one that provides the greatest
voltage swing generates extra noise immunity.
And,
Barry
you are correct Spectrum
compatibility should be dealt with I think it can
be dealt with on
400-500 meter reaches
If the team thinks that there is interest for
100 Meg I'll be happy to send
a short presentation off line to people who
are interested
Thanks
Behrooz
-----Original
Message-----
From: Geoff Thompson [mailto:gthompso@xxxxxxxxxxxxxxxxxx]
Sent: Thursday,
February 14, 2002 1:09 PM
To: O'Mahony, Barry
Cc: 'larry rennie';
Behrooz Rezvani; Bruce Tolley;
stds-802-3-efm@ieee.org; Roy
Bynum
Subject: RE: [EFM] 100 Mbps Proposals
In addition,
100BASE-T4 does not support full duplex
Geoff
At 12:04
PM 2/14/02 -0800, O'Mahony, Barry wrote:
>As was brought up in
Raleigh, it has not been demonstrated that 100BASE-T4
>meets the
spectrum compatibility objective (and it is unlikely that
it
>does). Leaving aside the discussion as to how close
installed POTS wiring
>is to CAT3.
>
>There may be MxU
instances where spectrum compatibility is not
required,
and
>instances where it would be. It is an adopted
EFM objective, however.
>
>~~~~~~~~~~~~~~~~~~~~~~~
>Barry
O'Mahony
>Intel Labs
>Hillsboro, OR, USA
>tel: +1 (503)
264-8579
>barry.omahony@xxxxxxxxx
>barry.omahony@xxxxxxxxxxxx
>~~~~~~~~~~~~~~~~~~~~~~~
>
>
>-----Original
Message-----
>From: larry rennie [mailto:Larry.Rennie@xxxxxxx]
>Sent: Thursday,
February 14, 2002 11:28 AM
>To: Behrooz Rezvani
>Cc: Bruce
Tolley; stds-802-3-efm@ieee.org; Roy Bynum
>Subject: Re: [EFM] 100
Mbps Proposals
>
>
>
>Behrooz,
>
>Is not
100BASE-T4 100Mbits/sec over 4, Cu
pairs?
>
>Larry
>
>Behrooz Rezvani
wrote:
>
> > Bruce,
> >
> > if there is a
success in starting such an effort, I would very much to
> >
encourage you and other people to consider 100 mbps over 4 copper
pairs
>for
> > reach <xyz> meters. That has a lot more
practical applications in MxU.
> >
> > Thanks
> >
Behrooz
> > ----- Original Message -----
> > From: "Roy
Bynum" <rabynum@xxxxxxxxxxxxxx>
> > To: "Bruce Tolley"
<btolley@cisco.com>; <stds-802-3-efm@ieee.org>
> >
Sent: Wednesday, February 13, 2002 7:59 PM
> > Subject: Re: [EFM]
100 Mbps Proposals
> >
> > >
> > >
Bruce,
> > >
> > > I am concerned about putting
effort into developing a standard for
> > > technology that
already exists for a market that is current, not
greatly
> >
in
> > > the future.
> > >
> > > Thank
you,
> > > Roy Bynum
> > >
> > > At
07:48 PM 2/13/2002 -0800, Bruce Tolley wrote:
> > >
> >
> >Colleagues:
> > > >
> > > >Those of
you who are also on the 802.3 reflector saw that there is
call
>
> > >for interest on the agenda of the March meeting in St Louis
to
discuss
> > > >starting a 100 Mbps dual fiber SM fiber
project outside of 802.3ah
task
> > force.
> > >
>
> > > >While I have not yet decided where I stand on 100
Mbps solutions for
>EFM,
> > > >I wanted to communicate
that I think this call for interest is
>premature,
> > >
>I would strongly encourage the proponents of 100 Mbps on SM fiber
to
> > > >converge on one strong proposal for the March IEEE
802.3ah meeting.
> > > >
> > > >We are already
facing the challenge of perhaps too many EFM PHYs. To
> >
> >specify an additional PHY for EFM outside of the 802.3ah TF
only
makes
> > > >life more difficult.
> > >
>
> > > >Bruce
> > >