Suggestions for a short building-to-building hop

I'm helping a downtown non-profit that operates a daycare center in
the building next door to its main offices. They would like to bridge
the Internet connection from the main building to the daycare so staff
can check e-mail, web, etc. -- general purpose communication, nothing
mission critical. [The daycare staff will have wifi cards on their
desktops and laptops.]

The two buildings are brick/stucco/steel and the distance between them
is 10 or 15 feet of open space. There is also a furnace/plumbing room
in the daycare building that seems to cause some attenuation.

I've tried a couple Linksys WRE54g network extenders (one in each
building) to bridge the distance, but the connection is weak and
unstable at best. (Not sure if this is a problem with the extenders,
or limits imposed by the architecture.)

Any suggestions on an inexpensive way to connect between the buildings
would be appreciated.

Thanks, in advance!

-Cloy

Cloy <(E-Mail Removed)> hath wroth:

>I'm helping a downtown non-profit that operates a daycare center in
>the building next door to its main offices.

I use to service a few non-profits. I don't any more. I now sleep 8
hours per day and don't cringe when the phone rings.

>They would like to bridge
>the Internet connection from the main building to the daycare so staff
>can check e-mail, web, etc. -- general purpose communication, nothing
>mission critical. [The daycare staff will have wifi cards on their
>desktops and laptops.]
>
>The two buildings are brick/stucco/steel and the distance between them
>is 10 or 15 feet of open space. There is also a furnace/plumbing room
>in the daycare building that seems to cause some attenuation.

All the material you've listed are impervious to RF. Even at 10-15
ft, the chicken wire under the stucco will block the signal. Do you
have any opposing windows? If you put the wireless in the window, and
there's no metal screen, it will pass nicely.

>I've tried a couple Linksys WRE54g network extenders (one in each
>building) to bridge the distance, but the connection is weak and
>unstable at best. (Not sure if this is a problem with the extenders,
>or limits imposed by the architecture.)

Two repeaters are two hops and probably won't work even if you had a
strong signal. One repeater maximum please.

>Any suggestions on an inexpensive way to connect between the buildings
>would be appreciated.

Over a distance of 10-15ft, you should be able to run CAT5 between the
buildings somehow, even if you have to do some underground horizontal
drilling, trenching, digging, or overhead building to building wiring.
There's also a possibility that they're both on the same power
xformer, in which case Power Line Networking (HomePlug) will work.

However, if the wired alternative is impossible, then I suggest a
simple dedicated wireless bridge between buildings. Get two identical
wireless bridges, one for each building. At 10-15ft, you won't need
any fancy antennas. Connect one bridge into the main office network.

The other bridge you have to make a decision. If you want to connect
via wireless, get a wireless access point and plug it into the
wireless bridge. Use a different RF channel (1, 6, 11) for these
radios to prevent mutual interference. Also, different SSID. Note
that this is now a total of 3 radios. You can install an ethernet
switch between the wireless bridge radio and the wireless access point
for nearby desktops. Everyone else connects wireless to the wireless
access point. Since they're on different channels, there's no speed
loss as you would get with a store an forward repeater.

Also, note that you don't have to buy an access point. A wireless
router will suffice if you disable the DHCP server, and don't connect
anything to the WAN (internet) port.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thanks for the reply, Jeff!

My understanding is that running ethernet lines outside (even well
insulated ones) can risk equipment damage from lightening / stray
voltage. Is that true?

Thanks! -Cloy

Cloy <(E-Mail Removed)> fired this volley in news:1187285779.787138.277590
@q4g2000prc.googlegroups.com:

> Thanks for the reply, Jeff!
>
> My understanding is that running ethernet lines outside (even well
> insulated ones) can risk equipment damage from lightening / stray
> voltage. Is that true?

Twisted-pair without insulation would be a trick. I think they call that
stuff "wire rope".

"Stray voltage" in the form of ground potential differences between
buildings on different supplies is a problem, yes.

But there's no particular potential for a buried connection between
buildings to invite lightning hits.

Fiber eliminates both problems.

LLoyd

"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message
news:Xns998E8D7B9252Blloydspmindspringcom@216.168. 3.70...
> Cloy <(E-Mail Removed)> fired this volley in news:1187285779.787138.277590
> @q4g2000prc.googlegroups.com:
>
> > Thanks for the reply, Jeff!
> >
> > My understanding is that running ethernet lines outside (even well
> > insulated ones) can risk equipment damage from lightening / stray
> > voltage. Is that true?
>
> Twisted-pair without insulation would be a trick. I think they call that
> stuff "wire rope".
>
> "Stray voltage" in the form of ground potential differences between
> buildings on different supplies is a problem, yes.
>
> But there's no particular potential for a buried connection between
> buildings to invite lightning hits.

i have had parts of a multiuser Unix box vaporised by a lightning strike
over a copper cable (this was high speed twisted pair for a distributed
terminal mux system - no fibre option then).

the hit was on a tarmac road (someone there during the storm described the
hit area, and we found the melt pool after the storm) - the duct was buried
about a meter under the surface........
>
> Fiber eliminates both problems.

only if the strike doesnt induce a big pulse via ground or power supply into
the electrics and get into equipment that way....
>
> LLoyd
>
--
Regards

(E-Mail Removed) - replace xyz with ntl

On Thu, 16 Aug 2007 10:36:19 -0700, Cloy <(E-Mail Removed)> wrote:

>My understanding is that running ethernet lines outside (even well
>insulated ones) can risk equipment damage from lightening / stray
>voltage. Is that true?

Generally true. Any conductor can attract lightning, act as an
inductive pickup, or become part of the lightning's path to ground.
Let's take them one at a time.

If you run the CAT5 in the air between buildings, you've increased the
effective area of the "ground" that is seen by the charge cloud.
However, lightning is more likely to hit the buildings than the wire
because of their larger surface areas. If the CAT5 is buried, it's
not an issue.

Inductive pickup is a problem with any conductor. If there's a nearby
lightning strike, the CAT5 can become part of a transformer. The "one
turn" primary is the lightning strike itself between the clouds and
the ground at 20,000 amps. The secondary is the CAT5 where the
current varies with just about everything, but can still be
substantial. The primary effect is to destroy electronics or fuse the
copper wires. If the CAT5 is buried, it's less of a problem because
the earth absorbs much of the charge. The induced voltage can also be
substantial. EIA-568A/B specifies 2500volt isolation, which is a huge
help. The twisted pairs also allow considerable induced current in
the wires, but since they're the same in each pair of wires, they
cancel at the transformers at each end.

You can obtain better isolation using an ethernet isolator:
<http://www.perfcomcat.com/b50255.html>
<http://www.pepperl-fuchs.com/pa/news/produkte/09765/index3_e.html>
(lots more). Note that this is NOT a "surge protector", which is
un-necessary. The idea is to isolate the ends of the cable so that if
one building gets a lightning strike which temporarily raises the
ground potential a few thousand volts, the current will not go through
the CAT5 and into the circuitry in the other building. It will also
protect users in the unlikely even that one building AC power ground
goes away (which happened here after the 1989 earthquake). You only
need one ethernet isolator.

Ground current is what fries most electronics. What happens is that
the CAT5 and its associated electronics is grounded at both ends. A
lightning hit to the ground will dissipate the charge over a wide
area. If one building is closer to the lightning ground hit than the
other, there will be a differential voltage produced between buildings
as the charge dissipates through the ground. The induced voltage (and
current) can be substantial. After having a few expensive ethernet
switches vaporized by this effect, I've take to installing cheap
sacrificial ethernet hubs or switches at each end. If they blow up,
they get replaced by another sacrificial switch or hub.

I suggest you do NOT use shielded CAT5 cable. If you do decide to use
shielded CAT5 (because buriable waterproof gel filled CAT5 is most
commonly offered as shielded cable), ground only one end of the
shield, not both. If you're seriously worried about lightning, you
might invest in two (one for each end) CAT5 lightning protectors:
<http://www.hyperlinktech.com/web/data_line_lightning_protectors.php>
<http://www.polyphaser.com/productdata.aspx?class=nx>

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

On Thu, 16 Aug 2007 23:27:40 GMT, Jeff Liebermann
<(E-Mail Removed)> wrote:

>On Thu, 16 Aug 2007 10:36:19 -0700, Cloy <(E-Mail Removed)> wrote:
>
>>My understanding is that running ethernet lines outside (even well
>>insulated ones) can risk equipment damage from lightening / stray
>>voltage. Is that true?
>
>Generally true. Any conductor can attract lightning, act as an
>inductive pickup, or become part of the lightning's path to ground.

I must be slipping in my old age. My previous rant is all about
copper wire (CAT5). Fiber optic cable has none of the problems
mentioned and is completely lightning proof. Depending on sheathing,
you can bury it, or run it between buildings (with a messenger wire
for support). No worries about lightning or ground faults with fiber.

You'll need two 100baseTX(copper) to 100baseFX (fiber) "media
converters", one at each end. Over the <50ft distance you're working
with, almost any fiber technology will work. Note that there are
different types of fiber and many different types of connectors. I
would go with cheap dual mode fiber, with either ST or SC connectors.
<http://www.alliedtelesyn.com/products/line.aspx?pid=3>
<http://www.milan.com/TransitionNetworks/Products2/Family.aspx?Name=SSETF101x-205>

If you feel ambitious, you might even go with 1000SX gigabit fiber
links (which costs more):
<http://www.alliedtelesyn.com/products/line.aspx?pid=2>
<http://www.milan.com/TransitionNetworks/Products2/Intersection.aspx?Definition=Stand-Alone+Converter&Topology=10%2F100%2F1000+Ethernet>

Plenty more vendors can be found by googling for:
"ethernet fiber media converter"

Also, look on eBay. This looks close. However you'll need a pair of
them plus buriable fiber cable:
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9727679747>

Pricewise, I suspect you want to do this cheaply. Brand new buriable
fiber is not cheap. However, if you can bury waterproof conduit
(sprinkler pipe?), you can use any flavor fiber cable inside. If you
settle for slow 10baseT transceivers, you can probably find a used
pair for about $25/ea. 100baseT will be about $100/ea. No clue on
gigabit.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

On Wed, 15 Aug 2007 15:10:33 -0700, Cloy <(E-Mail Removed)> wrote:

>I'm helping a downtown non-profit that operates a daycare center in
>the building next door to its main offices. They would like to bridge
>the Internet connection from the main building to the daycare so staff
>can check e-mail, web, etc. -- general purpose communication, nothing
>mission critical. [The daycare staff will have wifi cards on their
>desktops and laptops.]
>
>The two buildings are brick/stucco/steel and the distance between them
>is 10 or 15 feet of open space. There is also a furnace/plumbing room
>in the daycare building that seems to cause some attenuation.
>
>I've tried a couple Linksys WRE54g network extenders (one in each
>building) to bridge the distance, but the connection is weak and
>unstable at best. (Not sure if this is a problem with the extenders,
>or limits imposed by the architecture.)
>
>Any suggestions on an inexpensive way to connect between the buildings
>would be appreciated.
>
>Thanks, in advance!
>
>-Cloy


I agree with Jeff, First choice, run a piece of outdoor cat5 betwen
the buildings.. Short and sweet

Second, the wireless bridges are ok, but you now how the problem of
waterproofing them, or at least the antenna and coax that 'might' be
outside. You could also purchase two wireless bridges in waterproof
boxes with antennas built inside the box. But you have to waterproof
the entry into the building (the hole where the coax goes into the
building.)..

here's a place you can get a decently priced wireless bridge like I
described using above:

http://www.highgainantennas.com/category_s/90.htm

Yes I know they say CPE, but they are all able to be configured as a
CPE, a Bridge, or an AP/CPE, just with the firmware. I've used alot
of them for building to building bridges because of asphalt parking
lots between the building, ec.


take your choice, if lightning is a big factor in your area, the the
buildings are probably a bigger target with the AC overhead, the pipes
out the top of the building, etc. I really don't think lightning is
going to find the CAT5 before the building.. And since you have to
run cat5 to the wireless bridges on each side of the building, another
15' of cat5 ain't no big thing.

Bob Smith

Robert Smith Consulting
"Wireless Installations -- Government, Businesses & ISP's"
F.C.C. Licensed-Commercial & Amateur Services
A.R.S NA6T
ARRL Life Member
1-707-964-4931 w/answering machine
Fort Bragg, California 95437

"On The Air-Conditioned Mendocino Coast, In REAL Northern California"
No trees were destroyed in the sending of this message.
However, a large number of electrons were terribly inconvenienced.

"Jeff Liebermann" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On Thu, 16 Aug 2007 23:27:40 GMT, Jeff Liebermann
> <(E-Mail Removed)> wrote:
>
> >On Thu, 16 Aug 2007 10:36:19 -0700, Cloy <(E-Mail Removed)> wrote:
> >
> >>My understanding is that running ethernet lines outside (even well
> >>insulated ones) can risk equipment damage from lightening / stray
> >>voltage. Is that true?
> >
> >Generally true. Any conductor can attract lightning, act as an
> >inductive pickup, or become part of the lightning's path to ground.
>
> I must be slipping in my old age. My previous rant is all about
> copper wire (CAT5). Fiber optic cable has none of the problems
> mentioned and is completely lightning proof. Depending on sheathing,
> you can bury it, or run it between buildings (with a messenger wire
> for support). No worries about lightning or ground faults with fiber.
>
> You'll need two 100baseTX(copper) to 100baseFX (fiber) "media
> converters", one at each end. Over the <50ft distance you're working
> with, almost any fiber technology will work. Note that there are
> different types of fiber and many different types of connectors. I
> would go with cheap dual mode fiber, with either ST or SC connectors.
> <http://www.alliedtelesyn.com/products/line.aspx?pid=3>
>
<http://www.milan.com/TransitionNetwo...?Name=SSETF101
x-205>
>
> If you feel ambitious, you might even go with 1000SX gigabit fiber
> links (which costs more):
> <http://www.alliedtelesyn.com/products/line.aspx?pid=2>
>
<http://www.milan.com/TransitionNetwo...n.aspx?Definit
ion=Stand-Alone+Converter&Topology=10%2F100%2F1000+Ethernet>
>
> Plenty more vendors can be found by googling for:
> "ethernet fiber media converter"
>
> Also, look on eBay. This looks close. However you'll need a pair of
> them plus buriable fiber cable:
> <http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9727679747>
>
> Pricewise, I suspect you want to do this cheaply. Brand new buriable
> fiber is not cheap. However, if you can bury waterproof conduit
> (sprinkler pipe?), you can use any flavor fiber cable inside.

2 issues.

1. - you have to pull it thru the pipe. Some kinds of fibre will not take
lots of mechanical stress, so a good choice, plenty of grease, and bit of
care....
2. around here at least the pipe will spend a lof of time full of water.
Ideally, you actually need fibre cable with waterproofing built in, as over
time hydrogen ions can degrade the glass (may not be an issue in practice
with a short run, but replacing it will be a pain, and 1st you would need to
figure out what is happening).

Finally - you can get fibre cables with no metal inside, which removes the
issue of grounding and lightning pulse induction from that route into the
buildings......

If you
> settle for slow 10baseT transceivers, you can probably find a used
> pair for about $25/ea. 100baseT will be about $100/ea. No clue on
> gigabit.

i hate media convertors - had lots of hassle getting them to work, making
them work again when they stop, or the power gets cycled.....

A fair few switches now have SFP connectors which take modular optics -
mainly GigE these days, but some 100 Mbps ones around as well.
>
>
> --
> # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
> # 831-336-2558 (E-Mail Removed)
> # http://802.11junk.com (E-Mail Removed)
> # http://www.LearnByDestroying.com AE6KS
--
Regards

(E-Mail Removed) - replace xyz with ntl

"stephen" <(E-Mail Removed)> hath wroth:

>"Jeff Liebermann" <(E-Mail Removed)> wrote in message

>1. - you have to pull it thru the pipe. Some kinds of fibre will not take
>lots of mechanical stress, so a good choice, plenty of grease, and bit of
>care....

Nobody uses grease. They use some kind of soapy goo that washes off
with water. For example:
<http://www.polywater.com/polyf.html>
<http://www.idealindustries.com/products/wire_installation/lubricants/>
Lots of fun when someone spills a gallon of the stuff on the concrete
floor.

Pull strength on buriable fiber is about 600-1000 lbs per cable.
<http://www.timbercon.com/Pull-Strength.html>
<http://ecmweb.com/mag/electric_setting_fiberoptic_cable/>
That's a problem when pulling a bundle, where the totally pull stress
for the bundle may be transfered to a single cable. However, a spring
scale can usually be employed to avoid getting near the tension limit.
For an estimated 15ft pull, lube and tension are not even an issue.

>2. around here at least the pipe will spend a lof of time full of water.

Then, you're doing it wrong. For a 15ft run, almost any type of
conduit will work. Properly sealed and terminated with end points
forming an inverted siphon, the system is essentially waterproof. If
there is a danger of flooding, install a drain at an intentional low
point. It would be tempting to use flexible water pipe to avoid
cracking caused by asphalt movement, but I'm not familiar with the
code requirements.

>Ideally, you actually need fibre cable with waterproofing built in, as over
>time hydrogen ions can degrade the glass (may not be an issue in practice
>with a short run, but replacing it will be a pain, and 1st you would need to
>figure out what is happening).

What water damage I've seen has been either in the connector area,
where the water pressure has displaced the optical gel outer coating
on the fiber. The gel is necessary to fill in micro-cracks in the
fiber and to act as refractive boundary layer to enhance internal
reflections. When displaced by water, the cable losses increase
dramatically. It takes substantial heat and water pressure to do
this, but flooding will do. The best defense is to simply keep the
end points, splices, and terminations elevated and dry.

Again, for a 15ft run, the cable losses are so minimal, that even if
water incursion causes additional losses, they would not affect
performance much.

>Finally - you can get fibre cables with no metal inside, which removes the
>issue of grounding and lightning pulse induction from that route into the
>buildings......

>i hate media convertors - had lots of hassle getting them to work, making
>them work again when they stop, or the power gets cycled.....

Well, I only have about 10 pairs of Milan and Allied Telesyn media
converters in service. Mostly at radio sites, where RF pickup in the
networking cable is a problem. I've lost a few to lightning hits and
mechanical damage. Several are in outdoor NEMA boxes and have
suffered corrosion damage. I don't recall any of them hanging or
having power problems. For me, they're all plug-config-n-play. Any
particular type, brand, or model that you were having problems with?

If I had anything to complain about, it's the tendency for all the
media converter manufacturers to use power supplies with odd voltages.
I often have to connect these to -48VDC telecom power buses or
12/24/48VDC solar power systems using DC-DC converters.

Duh. I almost forgot. My ability to properly attach a connector to
fiber (using 3M hot melt method) is rather marginal. I did have some
reliability problems with what I thought was a media converter issue,
but turned out to be my sloppy termination job.

>A fair few switches now have SFP connectors which take modular optics -
>mainly GigE these days, but some 100 Mbps ones around as well.

Yep. You can buy modules to plug into the "backbone" port on most
managed ethernet switches. These make a very nice media converter.
However, for the single wireless device that needs to be bridged in
this case, methinks a modular fiber switch might be a bit overkill.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558