Re: 850 nm solutions
All,
This note is along the same lines as Ms. Pat Thaler and Mr. Rick Walker's
comments regarding the suitability and economic benefit of providing a short
(e.g. to ~20 meters) coax-based copper solution at 10 Gbps.
At it's April meetings in San Diego, the Fibre Channel Copper Working Group
approved a work item to document a Hari/XAUI coax-based copper PMD for it's
approved 10 Gigabit Fibre Channel project. The specific 10 GFC objective calls
for a 15 meter support distance. A call for proposals is outstanding. The T11.2
Copper Working Group will next meet in Boise, ID on June 6, 2000.
I understand fully that this same solution has been voted down by the IEEE 802.3
HSSG and I am NOT trying to dredge it up again. The purpose of this note is
simply to present related industry activities for short-haul 10 Gbps
interconnects.
Best Regards,
Rich
--
"THALER,PAT (A-Roseville,ex1)" wrote:
>
> Infiniband will be using something very similar to the HARI interface over
> short copper links though the distance goal is, I think, 6 m. To travel over
> short copper cables, it may make sense to use a 4 wide signal from HARI
> rather than 10 Gbit/s serial.
>
> -----Original Message-----
> From: Rick Walker [mailto:walker@cutter.hpl.hp.com]
> Sent: Wednesday, April 19, 2000 4:58 PM
> To: stds-802-3-hssg@ieee.org
> Subject: Re: 850 nm solutions
>
> > Jim Tatum writes:
> > But why does it matter? Why limit the users? Why not put in the table. It
> > costs nothing. Just put in what the model and data tell us to. It is
> > my opinion that a large percentage of 10GB style links are going to be
> > very short, less than 10m. If you look at the way many fiber ports
> > are being used today, many are in the 10m range. Also, since copper
> > cables are going to be EXTREMELY challanged to go that distance at
> > 10GB, why not let the market choose the lowest cost solution using
> > 850nm VCSELs and 62.5um fiber?
>
> FWIW, I agree that 10G across CAT-6 or other twisted pair would be very
> difficult. However 10G across coaxial cable is fairly easy. It can be
> done with 0.1" diameter coaxial cable using simple NRZ data encoding. A
> simple FIR pre-equalizer can double this distance. Without a doubt
> copper would be the cheapest solution for links under 10M. I would
> estimate a mature chipset price of about $50 per end and $15 for the
> cable.
>
> This performance was demonstrated in 1998 using a 25GHz bipolar chipset.
> See: Walker, R. C., K. Hsieh, T. A. Knotts and C. Yen, "A 10Gb/s
> Si-Bipolar TX/RX Chipset for Computer Data Transmission" , ISSCC Digest
> of Technical Papers 41(February 1998), 302,303,450.
>
> A Copper PHY was voted down by the committee because it was thought that
> there was no market for this type of low-cost short distance link.
>
> kind regards,
> --
> Rick Walker
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