Re: Equalization and benefits of Parallel Optics.
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. 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
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 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
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?
NetWorth Technologies, inc.
> 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
> 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
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?
> > 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
> including parallel optics to the data center with 100 m radius.
> Ali Ghiasi
> Sun Microsytems
> > Sharam Hakimi
> > Lucent Technologies