Re: Equalization and benefits of Parallel Optics.
Ed,
By any means I am not trying to replace Ali. Please see may
comments below.
Cheers,
Tad
----- Original Message -----
Sent: Friday, July 28, 2000 12:20 AM
Subject: Re: Equalization and benefits of Parallel
Optics.
>
> Ghiasi:
>
> If you have 75% support
for 6-PMDs to include parallel-interconnect, I will
> vote for parallel,
since I support all VCSEL technologies. Otherwise, 5-PMDs
> is
sufficient already.
>
> The Parallel approach is mainly for up to
20 meter connections. It is not
> designed for 100 meter to go
through ducked, or underfloor pipe
> installations, because a ribbon
fiber is not jacketed enough for those rough,
> punishing pulling
environment.
I strongly disagree with your statement. Ribbon
fiber cables are as rigid as one can think of being the
design of choice for the telco market. There is
no difference in cabling single, two or ribbon fiber structures.
Furthermore, at the patch panel connections,
> the
fibers are all single (duplex fibers) fibers, but not 4-parallel (duplex)
> fibers. For a parallel fiber to connect to an existing single
(duplex) fiber
> at the patch panel, one has to perform field
termination, to which a parallel
> fiber is not designed for due to the
tight tolerance of spacing between
> adjacent channels. Normally,
the parallel ribbon fiber cable is factory
> terminated only.
Sorry to correct you again. Ribbon fiber
is much easier and more cost effective to terminate than
single
fiber structures. Reason being is that the
cable preparation and cable management is much less
complicated. Connector termination is same
for both once ribbon is separated into individual fibers.
>
> However, if the parallel fibers are used just as a jumper cable to
> interconnect closely located nodes -- 5 meter, 10 meter,-- the ribbon
cable
> can do the job. Then, how about the serial 850 nm approach,
which is
> cheaper, and easier eventually to reach more than 20
meters?
I will not get into cost arguments. we've
seen enough of it over the past 12 months.
>
> I was a
member of OETC consortium in early 1991, which promoted the parallel
>
interconnect in industry with the blessing from ARPA. The project failed
> several years later due to the lack of interest from industry.
The reason
> was too expensive, difficult in termination and alignment,
and expensive
> ribbon cables.
>
> I was
a big fun for, the industry first commercial parallel interconnect,
>
OCTOBUS. I tried very hard to implement to my company's equipment.
After
> several years, the product never reach production stage, and was
canceled,
> due to the lack of interest from industry. The reason
was the same as OETC.
>
> There was only two ribbon cable suppliers
and was expensive that time. The
> factory only termination was
very inconvenient for users. It implies there
> is no flexibility
in modifying the cable lengths, when an equipment, or
> terminals are
rearranged to a different location. One has to go back to
> order
new set of cables?
>
> For last 10 years, parallel interconnect was
highly valued; however, it was
> never motorized as a contender for the
top interconnect solutions. I hope it
> will this
time?
Based on the amount of traffic on this
topic I'd say you're right on the money.
>
>
>
Regards,
> Ed Chang
>
> NetWorth Technologies, inc.
>
>
> l
>
> Brad
>
>
>>
> > I have one question:
> >
> > Which of our distance objectives is satisfied with parallel
fiber and
> > parallel optics?
>
> The
100 m data center applications.
> >
> > It has
been my interpretation that when we talked about f installed
> >
base of MMF, that we were referring to the MMF fiber currently available
> for
> > use by 802.3z. Parallel optics does not
operate over this installed base.
>
> You are correct
parallel optics would not operate over an installed two fiber
>
plant. Parallel optics would loose if you go in to an installed
fiber base.
> What I suggested was 100m data center applications,
where the fiber are not
> installed in the building wiring.
>
> Data center application are very significant as stated in
the last meeting
> about half the total market. Solutions
significantly lower cost targeted
> for sub 100 m is needed,
otherwise there will several proprietary solutions.
> Parallel
optics is the lowest cost, almost mature after 3 years, lowest
>
power,
> and smallest foot print. Parallel optics is ideal to
get bandwidth off the
> edge of your board.
>
>
Serial 850 or CWDM 850 can be another candidate for low cost data
center
> applications by having cable advantage over parallell
fiber. But you need
> to offset fiber advantage against
power, size, cost, testing, and maturity.
>
>
> >
> > Or am I missing the point
here?
> >
> > Cheers,
> >
Brad
>
> Thanks,
>
> Ali
Ghiasi
> Sun Microsystems
>
> >
>
> -
> >
> > Sharam
>
>
> > >
> > >
> > > Although parallel fiber is technically an easier
solution, the
> > major reason
> > > for
support of 850nm has been to consider the installed base, and
> >
cost. If
> > > users have to pull new fiber, IMHO,
parallel fiber would not be on
> > top of
>
> > the list and most of installed base is single
fiber.
> >
> > I did not suggest to pull
any new fiber. Limit the shortwave
> > variant
>
> including parallel optics to the data center with 100 m
radius.
> >
> > Thanks,
> >
> > Ali Ghiasi
> > Sun
Microsytems
> >
> > >
>
> > Sharam Hakimi
> > > Lucent
Technologies
> > >
> >
>
>
>
>
>
>
--
>