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Re: Equalization and benefits of Parallel Optics.

Further Comment:

The parallel technique will add more skew than a single fiber to further 
restrict the distance and cost.


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.