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Re: Equalization and benefits of Parallel Optics.

Hi Ed

> 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.



> Regards, 
> Ed Chang
> NetWorth Technologies, Inc.
> << 
>  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.  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?
>  Regards, 
>  Ed Chang
>  NetWorth Technologies, inc.
>   >>