[57708] in North American Network Operators' Group
RE: DS3 Coax..
daemon@ATHENA.MIT.EDU (McBurnett, Jim)
Sat Apr 19 23:12:21 2003
Date: Sat, 19 Apr 2003 23:11:47 -0400
From: "McBurnett, Jim" <jmcburnett@msmgmt.com>
To: "nanog list" <nanog@merit.edu>
Errors-To: owner-nanog-outgoing@merit.edu
I not only agree with these guys but I can give you an example..
One upon a time in a job a long long time ago, I worked on a
data differential passing system based on Frequency Multiplexed=20
microwave signaling to send information up to 1000 feet.
We had a special interface on both ends, and a ground potential=20
leveling circuit. The coax was very similiar to what is used for
a DS3. In addition to the "data" coax we also ran a "grounding"
strap.=20
A number of times in the service of this equipment we had lightning=20
strikes, power surges, and grounding failures.
Everytime we had one of these events, there were major system failures.
Now this system was quite a bit more expensive than a DS3 mux, and=20
as I recall, none of our failures were under a solid 5 figure level.
We finally retired this old animal in 1993 after 21 years of faithful
headches. Thank you Uncle Sam..... That is a different story...
It was replaced with a fiber system and a backup high-freq RF system.
So with that thought of nostalga, I would defiantely go with a fiber =
link.
Even if you have to put a DS3 router on the COLO side of the park and =
run=20
Ethernet fiber across the parking lot.....
If you do this, it will be a much better idea. and much more expanable.
DS3 to a router- 100 Meg fiber...
This will even allow some monitoring for errors across the pipe...
Anyway...
Jim
> -----Original Message-----
> From: David Lesher [mailto:wb8foz@nrk.com]
> Sent: Saturday, April 19, 2003 9:20 PM
> To: nanog list
> Subject: Re: DS3 Coax..
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> Speaking on Deep Background, the Press Secretary whispered:
> >=20
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> > Definately.
> >=20
> > You most emphatically do NOT want copper going across your=20
> parking lot.
> > Besides the danger from lightning strikes and other=20
> electrostatic discharges
> > you run the risk of ground potentials differing=20
> significantly. You could
> > wind up with a significant amount of current flowing across=20
> the coax just to
> > balance building grounds. (This is why telcos insist on a=20
> single ground
> > point and have that point connected to an array of ground=20
> rods driven deep
> > in the ground.)
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> Agreed.
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> Fiber is Your Friend [tm].=20
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> Ground loops and potential differences will not only have you
> ripping your hair out, but you stand to lose DS-3 ports. Now
> some guy told me that such costs a bit more than the RS-232 &
> Ethernet ports I regularly see die, but that's likely just a rumor.
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> --=20
> A host is a host from coast to coast.................wb8foz@nrk.com
> & no one will talk to a host that's close........[v].(301) 56-LINUX
> Unless the host (that isn't close).........................pob 1433
> is busy, hung or dead....................................20915-1433
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