FDDI, was: Re: [rescue] u2 drive trays

Bjorn Ramqvist v53278 at g.haggve.se
Wed Aug 20 02:38:36 CDT 2003

Dave McGuire wrote:
>    But what *else* are you running over fiber?  The only applications
> I've seen for fiber in recent years are GigE, FibreChannel, and FDDI.
> (I'm not a telecom guy)

(Not me either)
We're running 100Base-FX too, but that's over single-mode, so it doesn't

Anyway, my point is that you SHOULD use 50 micron for FC, but it can
live with 62.5 too up to a certain distance. I don't know about GbE or
even less about FDDI.
>    So based on what you said, I assume you're using 62.5/125 for GigE?
> I've not seen much GigE, but what I have seen was all 50/125.

Every fiber distribution box we have is installed with 62.5 micron
fiber, between the various buildings, and every fiber-patch we have is
62.5, even with GbE. Mind you that we have equipment reaching as far as
simple 10Base-FL links on those screw-connectors. (the newer patch
panels are SC-connectors, but still 62.5 everywhere)
FibreChannel can live with 62.5 micron too, but as I said, the
preferable is 50. That said, it's likely to complicate things a little
bit for our upcoming backuprobotics move, since we must install new 50
micron fiber to that location. FC-related documents clearly states that
you should use either 50 or 62.5 *all*the*way* from point to point.

This has been tested by mistake on GbE when my boss (also network admin)
took a 50 micron orange FC fiber-patch for his GbE-gear. It worked, so
he didn't notice it until I told him about it. It worked even though we
mixed the core-sizes along the way, but I'm sure there was probably not
a healthy link, noise-wise.


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