nanog mailing list archives

Re: Protecting 1Gb Ethernet From Lightning Strikes


From: Eric Kuhnke <eric.kuhnke () gmail com>
Date: Wed, 14 Aug 2019 18:54:03 -0700

Another copper cable considered a "gold standard" for outdoor shielded +
9th ESD drain and ground wire, intended for long term rooftop and tower
installation is Shireen. There's a variety of types.

https://www.shireeninc.com/osc/cables/cat6



On Wed, Aug 14, 2019 at 6:30 PM Brandon Martin <lists.nanog () monmotha net>
wrote:

On 8/13/19 2:32 PM, Warren Kumari wrote:
This probably won't fully solve your problem, but I run a bunch of
Ubiquiti access points and similar -- I suffered a number of lightning
related outages, and then started using their TOUGHcable -
https://www.ui.com/accessories/toughcable/

While ToughCable isn't bad (especially for the price), if you want
something REALLY durable both physically and against electrical
transients, I've been very happy with Primus C6CMXFS-1864BK.  It costs
quite a bit more than the ToughCable but has real water blocking (which
means you had better be prepared to deal with "Icky Pic"), heavy
shielding with drain, meets or exceeds CAT6 (which means you can push
gigE a bit beyond 100m pretty reliably if you've got a tall tower or a
hut far away from a tower base), and has 23AWG wire so PoE, especially
Ubnt's crummy 24V passive POE, can go farther, too.

Be warned it's a bear to terminate.  In addition to the waterblock, the
cable diameter is too large for typical crimp-on RJ45 ends.  You have to
either use special ends (which Primus sells, among others) or terminate
it to a punch block which, while not usually a problem in a hut, is
often problematic up on a tower.

Ubnt also makes an outdoor fiber media converter I've found useful for
"small cell" style wISP deployments where I can drag my own fiber to the
tower/pole and don't want/need a hut or enclosure at the base.  Part
number is F-POE-G2.  That'll let you get your power and signal
separated.  I do wish they'd just put SFP slots in their radios, but at
the price they sell them for, I guess I can't complain too much.  I'd
put real 802.3af/at PoE higher on the list of wants, honestly.

As to actual surge protectors, I see there have been some other
suggestions in the list, and I'll defer to them.  I've personally had
decent luck with just making sure the Ubnt passive POE injectors (which
I need since I don't usually use their switches) are well grounded to be
mostly sufficient (along with the tower and hut having proper grounding
infrastructure).  I've not lost any radios, though I've had some lockups
requiring power cycle after nearby lightning strikes on some of the
lower end WA based platforms.  The XC based platforms seem hardier.  My
sample size isn't huge, though.

I'm usually of the impression that, unless you've got carrier (cellular
or committed-rate microwave) class wireless gear on the tower or
aggressive SLAs you have to meet from a wireless PoP, it's probably
cheaper overall to just take reasonable precautions against lightning
than it is to try to make things handle a "direct" strike.  Figure in
the wISP world, tech moves so fast that you're having to put new things
on the tower at least every 3-5 years anyway, so as long as an
unscheduled trip up to the tower doesn't cost you $ARM+$LEG, it's
probably easier to just take a lightning strike that fries everything
due to extreme proximity as an unscheduled upgrade than the try to
handle it electrically.

"Nearby" strikes, static, electrical transients on your utility line,
etc. are a different matter.  Those you can economically protect against
i.e. the protection will not cost as much or more than the gear and
service you're protecting.
--
Brandon Martin


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