Re: Equalization and benefits of Parallel Optics.
> From: NetWorthTK@xxxxxxx
> Date: Fri, 28 Jul 2000 01:37:43 EDT
> Subject: Re: Equalization and benefits of Parallel Optics.
> To: NetWorthTK@xxxxxxx, Ali.Ghiasi@xxxxxxxxxxx, stds-802-3-hssg@xxxxxxxx,
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> Further Comment:
> The parallel technique will add more skew than a single fiber to further
> restrict the distance and cost.
Current base line proposal allocates 16 bit (5.12 ns) of skew to the fiber
media. Ribbon fiber worst case skew is 10 ps/m even at 300 m it address to
3 ns. Skew will not restrict the parallel optics distance at 300m.
> Ed Chang
> NetWorth Technologies, Inc.
> If you have 75% support for 6-PMDs to include parallel-interconnect, I will
> vote for parallel, since I support all VCSEL technologies. Otherwise,
> 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
> punishing pulling environment. Furthermore, at the patch panel connections,
> the fibers are all single (duplex fibers) fibers, but not 4-parallel
> fibers. For a parallel fiber to connect to an existing single (duplex)
> at the patch panel, one has to perform field termination, to which a
> 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
> will this time?
> Ed Chang
> NetWorth Technologies, inc.