Re: Equalization and benefits of Parallel Optics.
> From: NetWorthTK@xxxxxxx
> Date: Fri, 28 Jul 2000 01:20:10 EDT
> Subject: Re: Equalization and benefits of Parallel Optics.
> To: Ali.Ghiasi@xxxxxxxxxxx, stds-802-3-hssg@xxxxxxxx, bradley.booth@xxxxxxxxx
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> 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.
Most of the large data center or high traffic buildings already use parallel
fiber to carry several dozen duplex traffic. Ribbon fibers are very well
reinforced and are laid today in the data center or in outdoor.
Below are several example of common form of ribbon cable you can get today:
- plenum and non-plenum simplex 12 fiber ribbon
- plenum and non-plenum ripcord 12 fiber ribbon
- reinforced cable with 4 to 12 ribbon.
>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.
> 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
> 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?
You certainly have stated some pitfall of the technology from the last 10
years. The biggest reason for failure of these early program was ignoring
copper capability. They were developing product more expensive and less
reliable than copper. Many of the complexity which made these early program
fail also applies to any of the variant in consideration in the 802.3ae.
Cable termination is more difficult with MT or MT-RJ, how come MT RJ are
implemented in the LAN?
> Ed Chang
> 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?
> > Cheers,
> > Brad
> 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
> > >