YOST wiring (was Re: Datacenter tools?)

Thu Jun 3 16:14:23 PDT 2004

chuck+baylisa at snew.com said:
> In the end, I use a flat "flip over" RJ45  wire at the patch to wire
> things together.  The YOST glory is that ALL The devices at the panel
> are the same.  I can wire a modem to another modem with the same wire
> that I do computer -> modem.  Key:  NO THINKING REQUIRED.

Fiber ought to be installed like that, too.

At a place I worked recently, their main campus datacenter was
remodeled and fiber went everywhere, in LC connectors.  Generally
(mostly true with FC-AL HBAs of the 2Gb variety) fiber gigabit can be
connected  face-to-face with a single cable, because it's crossover.
Unfortunately, the patch panels were wired straight, and until we
realized this we were blaming the cables when everything was solid and
still no link, and taking apart half of the SC duplexors (and even some
of the LC!) so we could connect them the other way and get link.
Thus, everything should be crossover so there's only one kind of cable
(modulo SC-LC conversion), and everything is an odd number of
connections so it's still net crossover.

I suppose nobody thought that the vendor could install things in the
pessimal way, or that the plans we made could have overlooked this
detail (I just don't know.).  Fixing it now, of course, means fixing
half the cable plant (since it's about 30% used), moving everything
over to it with lots and lots of tiny network outages (some triggering
failovers), and then doing the other half (moving back is optional).

Not My Problem anymore...

$job[-2] we wired up a small machine room with Cat-5 everywhere.  I had
the installers give me one row per IDF of just crossovers, so that they
would be there if we need them, and I could abolish actual crossover cables
and have only straight (since hubs and switches are, er, DCE, and computers
are all DTE, so to speak) ones.  

The Holy Grail is avoiding cases where equipment A and B work when connected
with one cable, and don't when using a physically-identical (i.e. it fits)
twin. USB and FireWire are different kettles of fish, lacking such twins.
If it connects, it works (but that dang symmetrical shell on the host-end of
USB drives me nuts).

-- 
Jeff Woolsey {woolsey,jlw}@{jlw,jxh}.com
"A toy robot!!!!" -unlucky Japanese scientist
"And Leon's getting laaaarrger!"  -Johnny
"Delete! Delete! OK!" -Dr. Bronner on disk space management
"I didn't get a 'Harrumph!' out of _that_ guy." -Gov Le Petomaine