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Suggestions for connecting 2 buildings > 300 feet apart

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Anonymous
October 11, 2004 4:56:42 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Hi all,

I had a question posed to me and I'm looking for some ideas on a
reliable/inexpensive (as possible) solution.

We have 2 buildings about 450 feet apart separated by a field.
We need to get these buildings together on a network. I'm reading
varying opinions regarding the ability to connect at > 300 feet
assuming you run at 10 megabit with cat5 cabling.

There's no easy way to provide a repeater between these 2 buildings,
as the cable needs to be buried in the field separating the buildings.
I need a reliable link between the buildings, so if 10-baseT beyond
100 meters is not within spec and reliable, I need to go with
something else.

What alternatives do I have here?

thanks much!

-Joseph
Anonymous
October 12, 2004 12:00:15 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Joseph Minckler wrote:

> Hi all,
>
> I had a question posed to me and I'm looking for some ideas on a
> reliable/inexpensive (as possible) solution.
>
> We have 2 buildings about 450 feet apart separated by a field.
> We need to get these buildings together on a network. I'm reading
> varying opinions regarding the ability to connect at > 300 feet
> assuming you run at 10 megabit with cat5 cabling.
>
> There's no easy way to provide a repeater between these 2 buildings,
> as the cable needs to be buried in the field separating the buildings.
> I need a reliable link between the buildings, so if 10-baseT beyond
> 100 meters is not within spec and reliable, I need to go with
> something else.
>
> What alternatives do I have here?

10baseT is typically capable of running over 150 to 200 meters of CAT5 or
better cable. It's not specified to do that but it it does. 10baseT span
is limited by signal quality, not timing, and CAT5 has electrical
properties enough better than those of CAT3 to You could also run 100VG,
which _is_ specified to do that, if you can find the necessary hardware,
and that would give you 100 Mb/sec.

However, it's a bad idea from a safety viewpoint as the two buildings very
likely have different electrical grounds and so there may be a significant
potential difference between them which may damage equipment and/or injure
staff.

There are other alternatives. Doing it _right_ you'd run fiber between the
buildings. Doing it _cheap_ if there's clear line of sight, you could use
two wireless access points with high-gain directional antennas.


>
> thanks much!
>
> -Joseph

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Anonymous
October 12, 2004 1:17:32 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

In article <20277cf5.0410111156.74812105@posting.google.com>,
Joseph Minckler <joey@minckler.net> wrote:
:I had a question posed to me and I'm looking for some ideas on a
:reliable/inexpensive (as possible) solution.

:We have 2 buildings about 450 feet apart separated by a field.
:We need to get these buildings together on a network. I'm reading
:varying opinions regarding the ability to connect at > 300 feet
:assuming you run at 10 megabit with cat5 cabling.

450 feet apart suggests strongly to me that the two buildings have
different electrical feeds. If so, then if you were to connect them
by any kind of electricity carrying cable, you could run into
substantial problems with ground differentials, and could end up frying
the connecting equipment.

When you have areas that do not have a common ground and you need to
put a LAN between them, you should likely be putting in fibre or wireless.


:I need a reliable link between the buildings, so if 10-baseT beyond
:100 meters is not within spec and reliable, I need to go with
:something else.

The traditional answer has been to install fibre in a waterproof
shielding, and fibre is still a good choice if you need more than
about 20 megabits per second half duplex bandwidth. But if
about 4.5 megabits per second half duplex or about 22 megabits per
second half duplex are acceptable, then a single 802.11b (~4.5) or
802.11g (~23) outdoor wireless bridge could be a strong contender
when you have clear line of sight between the two facilities.
Either 802.11b or 802.11g can -easily- go 450 feet if you add
nearly any kind of external antenna on. The more directional the
antenna, the stronger the signal you will get when the links
are properly aligned, and thus the more link loss you would be
able to withstand due to -thin- obstacles (such as the fringe
of a tree's leaves) or fog or mist (rain drops are the wrong size
to affect 2.4 GHz wireless but fog or mist can), or due to misalignments
as the wind moves the antenna.

For more information on the possibilities with wireless, I suggest
that you post to alt.internet.wireless, giving details of any
potential obstructions such as trees or road traffic. 450' is
not far at all for wireless, provided that you have a clear line of
sight through a big enough volume of space [radio doesn't
go point to point like a laser beam, so it needs a clear space
around the centre of the path.]
--
Can a statement be self-referential without knowing it?
Related resources
October 12, 2004 7:47:05 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

On Mon, 11 Oct 2004 20:00:15 -0400, "J. Clarke"
<jclarke@nospam.invalid> wrote:

>Joseph Minckler wrote:
>
>> Hi all,
>>
>> I had a question posed to me and I'm looking for some ideas on a
>> reliable/inexpensive (as possible) solution.
>>
>> We have 2 buildings about 450 feet apart separated by a field.
>> We need to get these buildings together on a network. I'm reading
>> varying opinions regarding the ability to connect at > 300 feet
>> assuming you run at 10 megabit with cat5 cabling.
>>
>> There's no easy way to provide a repeater between these 2 buildings,
>> as the cable needs to be buried in the field separating the buildings.
>> I need a reliable link between the buildings, so if 10-baseT beyond
>> 100 meters is not within spec and reliable, I need to go with
>> something else.
>>
>> What alternatives do I have here?
>
>10baseT is typically capable of running over 150 to 200 meters of CAT5 or
>better cable. It's not specified to do that but it it does. 10baseT span
>is limited by signal quality, not timing, and CAT5 has electrical
>properties enough better than those of CAT3 to You could also run 100VG,
>which _is_ specified to do that, if you can find the necessary hardware,
>and that would give you 100 Mb/sec.
>
>However, it's a bad idea from a safety viewpoint as the two buildings very
>likely have different electrical grounds and so there may be a significant
>potential difference between them which may damage equipment and/or injure
>staff.
>
>There are other alternatives. Doing it _right_ you'd run fiber between the
>buildings. Doing it _cheap_ if there's clear line of sight, you could use
>two wireless access points with high-gain directional antennas.


And given the insecure nature of wireless, I strongly recommend an
encrypted vpn tunnel between the wireless access points. For example
a pair of Netscreen 5XPs at either end, between the access-points and
the network. Plus, this would allow laptops with the proper vpn
software to connect. Much better to be secure that have to deal with
getting hacked by anyone driving by with a laptop.
Anonymous
October 12, 2004 10:14:30 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

chris@nospam.com wrote:

> On Mon, 11 Oct 2004 20:00:15 -0400, "J. Clarke"
> <jclarke@nospam.invalid> wrote:
>
>>Joseph Minckler wrote:
>>
>>> Hi all,
>>>
>>> I had a question posed to me and I'm looking for some ideas on a
>>> reliable/inexpensive (as possible) solution.
>>>
>>> We have 2 buildings about 450 feet apart separated by a field.
>>> We need to get these buildings together on a network. I'm reading
>>> varying opinions regarding the ability to connect at > 300 feet
>>> assuming you run at 10 megabit with cat5 cabling.
>>>
>>> There's no easy way to provide a repeater between these 2 buildings,
>>> as the cable needs to be buried in the field separating the buildings.
>>> I need a reliable link between the buildings, so if 10-baseT beyond
>>> 100 meters is not within spec and reliable, I need to go with
>>> something else.
>>>
>>> What alternatives do I have here?
>>
>>10baseT is typically capable of running over 150 to 200 meters of CAT5 or
>>better cable. It's not specified to do that but it it does. 10baseT span
>>is limited by signal quality, not timing, and CAT5 has electrical
>>properties enough better than those of CAT3 to You could also run 100VG,
>>which _is_ specified to do that, if you can find the necessary hardware,
>>and that would give you 100 Mb/sec.
>>
>>However, it's a bad idea from a safety viewpoint as the two buildings very
>>likely have different electrical grounds and so there may be a significant
>>potential difference between them which may damage equipment and/or injure
>>staff.
>>
>>There are other alternatives. Doing it _right_ you'd run fiber between
>>the
>>buildings. Doing it _cheap_ if there's clear line of sight, you could use
>>two wireless access points with high-gain directional antennas.
>
>
> And given the insecure nature of wireless, I strongly recommend an
> encrypted vpn tunnel between the wireless access points. For example
> a pair of Netscreen 5XPs at either end, between the access-points and
> the network. Plus, this would allow laptops with the proper vpn
> software to connect. Much better to be secure that have to deal with
> getting hacked by anyone driving by with a laptop.

The "insecure nature of wireless" is greatly exaggerated. Do you know of
any cracks for WPA/802.11i? For that matter, do you know of any facilities
using 128 bit WEP-Plus that have in the real world and not some contrived
test "gotten hacked by anyone driving by with a laptop"? And that leaves
aside the kind of signal that your hypothetical wardriver can get out of
the side lobes of directional antennas.

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Anonymous
October 13, 2004 12:31:03 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Joseph Minckler <joey@minckler.net> wrote:
> Hi all,

> I had a question posed to me and I'm looking for some ideas on a
> reliable/inexpensive (as possible) solution.

> We have 2 buildings about 450 feet apart separated by a field.
> We need to get these buildings together on a network. I'm reading
> varying opinions regarding the ability to connect at > 300 feet
> assuming you run at 10 megabit with cat5 cabling.

> There's no easy way to provide a repeater between these 2 buildings,
> as the cable needs to be buried in the field separating the buildings.
> I need a reliable link between the buildings, so if 10-baseT beyond
> 100 meters is not within spec and reliable, I need to go with
> something else.

> What alternatives do I have here?

Fiber and radio. Dont even think about STP/UTP


--
Peter Håkanson
IPSec Sverige ( At Gothenburg Riverside )
Sorry about my e-mail address, but i'm trying to keep spam out,
remove "icke-reklam" if you feel for mailing me. Thanx.
Anonymous
October 13, 2004 4:26:42 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Thanks to all for your suggestions, they helped immensely!

> >
> >>Joseph Minckler wrote:
> >>
> >>> Hi all,
> >>>
> >>> I had a question posed to me and I'm looking for some ideas on a
> >>> reliable/inexpensive (as possible) solution.
Anonymous
October 20, 2004 1:29:07 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

"Walter Roberson" <roberson@ibd.nrc-cnrc.gc.ca> wrote in message
news:cket9c$b7q$1@canopus.cc.umanitoba.ca...
> In article <20277cf5.0410111156.74812105@posting.google.com>,
> Joseph Minckler <joey@minckler.net> wrote:
> :I had a question posed to me and I'm looking for some ideas on a
> :reliable/inexpensive (as possible) solution.
>
> :We have 2 buildings about 450 feet apart separated by a field.
> :We need to get these buildings together on a network. I'm reading
> :varying opinions regarding the ability to connect at > 300 feet
> :assuming you run at 10 megabit with cat5 cabling.
>
> 450 feet apart suggests strongly to me that the two buildings have
> different electrical feeds. If so, then if you were to connect them
> by any kind of electricity carrying cable, you could run into
> substantial problems with ground differentials, and could end up frying
> the connecting equipment.
>
> When you have areas that do not have a common ground and you need to
> put a LAN between them, you should likely be putting in fibre or wireless.

When you say don't have a common ground, you mean that the resistance of the
soil might be too "high" for them to be considered at the same potential,
right?
Even within buildings, it isn't unusual for the earth from one outlet to the
other to vary because of earth leakage and magnetic coupling, so logically,
for safety reasons, it isn't recommended to connect up different lans in
different rooms!.

> :I need a reliable link between the buildings, so if 10-baseT beyond
> :100 meters is not within spec and reliable, I need to go with
> :something else.
>
> The traditional answer has been to install fibre in a waterproof
> shielding, and fibre is still a good choice if you need more than
> about 20 megabits per second half duplex bandwidth. But if
> about 4.5 megabits per second half duplex or about 22 megabits per
> second half duplex are acceptable, then a single 802.11b (~4.5) or
> 802.11g (~23) outdoor wireless bridge could be a strong contender
> when you have clear line of sight between the two facilities.
> Either 802.11b or 802.11g can -easily- go 450 feet if you add
> nearly any kind of external antenna on. The more directional the
> antenna, the stronger the signal you will get when the links
> are properly aligned, and thus the more link loss you would be
> able to withstand due to -thin- obstacles (such as the fringe
> of a tree's leaves) or fog or mist (rain drops are the wrong size
> to affect 2.4 GHz wireless but fog or mist can), or due to misalignments
> as the wind moves the antenna.
>
> For more information on the possibilities with wireless, I suggest
> that you post to alt.internet.wireless, giving details of any
> potential obstructions such as trees or road traffic. 450' is
> not far at all for wireless, provided that you have a clear line of
> sight through a big enough volume of space [radio doesn't
> go point to point like a laser beam, so it needs a clear space
> around the centre of the path.]
> --
> Can a statement be self-referential without knowing it?
Anonymous
October 20, 2004 1:29:08 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

In article <cl3rt3$c2$1@newsg4.svr.pol.co.uk>, fellow <Jameson@god.com> wrote:
:When you say don't have a common ground, you mean that the resistance of the
:soil might be too "high" for them to be considered at the same potential,
:right?
:Even within buildings, it isn't unusual for the earth from one outlet to the
:o ther to vary because of earth leakage and magnetic coupling, so logically,
:for safety reasons, it isn't recommended to connect up different lans in
:D ifferent rooms!.

Within the same building, if you are starting from the same power feed
and splitting it up, then the ground potential should have only
-relatively- small variations. When you are working with different
buildings, you do not immediately know if the buildings are served
by the same power company, let alone the same power line, so you
must prepare for the possibility of substantial ground differences.
--
Any sufficiently advanced bug is indistinguishable from a feature.
-- Rich Kulawiec
Anonymous
October 20, 2004 1:29:08 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

fellow <Jameson@god.com> wrote:
> When you say don't have a common ground, you mean that
> the resistance of the soil might be too "high" for them to
> be considered at the same potential, right?

This isn't normally a problem. The Chunnel has only 3.6V of
ground differential across it. But during lightening storms,
a nearby (100m) lightening hit can elevate ground potentials
so that one stake is much higher (500+V) than another.

DO NOT RUN COPPER ETHERNET BETWEEN BUILDINGS.

> Even within buildings, it isn't unusual for the earth from
> one outlet to the other to vary because of earth leakage and
> magnetic coupling, so logically, for safety reasons, it isn't
> recommended to connect up different lans in different rooms!.

This is called a ground-fault and can be very dangerous.
The only reason for single-building grounds to differ is
current leakage from hot into ground rather than neutral,
plus a high-resistance ground path. Not acceptable even
in the strange land of ring-mains.

-- Robert
October 20, 2004 7:19:44 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

On Tue, 12 Oct 2004 06:14:30 -0400, "J. Clarke"
<jclarke@nospam.invalid> wrote:

>chris@nospam.com wrote:
>
>> On Mon, 11 Oct 2004 20:00:15 -0400, "J. Clarke"
>> <jclarke@nospam.invalid> wrote:
>>
>>>Joseph Minckler wrote:
>>>
>>>> Hi all,
>>>>
>>>> I had a question posed to me and I'm looking for some ideas on a
>>>> reliable/inexpensive (as possible) solution.
>>>>
>>>> We have 2 buildings about 450 feet apart separated by a field.
>>>> We need to get these buildings together on a network. I'm reading
>>>> varying opinions regarding the ability to connect at > 300 feet
>>>> assuming you run at 10 megabit with cat5 cabling.
>>>>
>>>> There's no easy way to provide a repeater between these 2 buildings,
>>>> as the cable needs to be buried in the field separating the buildings.
>>>> I need a reliable link between the buildings, so if 10-baseT beyond
>>>> 100 meters is not within spec and reliable, I need to go with
>>>> something else.
>>>>
>>>> What alternatives do I have here?
>>>
>>>10baseT is typically capable of running over 150 to 200 meters of CAT5 or
>>>better cable. It's not specified to do that but it it does. 10baseT span
>>>is limited by signal quality, not timing, and CAT5 has electrical
>>>properties enough better than those of CAT3 to You could also run 100VG,
>>>which _is_ specified to do that, if you can find the necessary hardware,
>>>and that would give you 100 Mb/sec.
>>>
>>>However, it's a bad idea from a safety viewpoint as the two buildings very
>>>likely have different electrical grounds and so there may be a significant
>>>potential difference between them which may damage equipment and/or injure
>>>staff.
>>>
>>>There are other alternatives. Doing it _right_ you'd run fiber between
>>>the
>>>buildings. Doing it _cheap_ if there's clear line of sight, you could use
>>>two wireless access points with high-gain directional antennas.
>>
>>
>> And given the insecure nature of wireless, I strongly recommend an
>> encrypted vpn tunnel between the wireless access points. For example
>> a pair of Netscreen 5XPs at either end, between the access-points and
>> the network. Plus, this would allow laptops with the proper vpn
>> software to connect. Much better to be secure that have to deal with
>> getting hacked by anyone driving by with a laptop.
>
>The "insecure nature of wireless" is greatly exaggerated. Do you know of
>any cracks for WPA/802.11i? For that matter, do you know of any facilities
>using 128 bit WEP-Plus that have in the real world and not some contrived
>test "gotten hacked by anyone driving by with a laptop"? And that leaves
>aside the kind of signal that your hypothetical wardriver can get out of
>the side lobes of directional antennas.


Wireless has yet to prove itself as secure, no matter how
theoretically secure WPA and WPA2 are claimed to be. Do you recall
how secure WEP was originally claimed to be? Know any big businesses
that use it without additional protection?

Until it has a proven track record, I consider wireless to be
insecure. My business network is too sensitive and valuable to risk
otherwise.


Since 802.11i was only ratified less than 6-months ago, finding
equipment at a reasonable price might be an issue. Properly setting
it up and being sure the vendors implemented it right is another
issue. You do realize it relies on RADIUS and AAA accounting which
can be a bitch to setup securely. I suspect the OP might not be very
IT saavy.

I also assumed the original poster was going for a cheap option and
suggested vpn as a way of securing a cheap wireless implementation.
Going with new WPA2 equipment might be more expensive than fiber.



-Chris
Anonymous
October 20, 2004 7:19:45 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

chris@nospam.com wrote:

> On Tue, 12 Oct 2004 06:14:30 -0400, "J. Clarke"
> <jclarke@nospam.invalid> wrote:
>
>>chris@nospam.com wrote:
>>
>>> On Mon, 11 Oct 2004 20:00:15 -0400, "J. Clarke"
>>> <jclarke@nospam.invalid> wrote:
>>>
>>>>Joseph Minckler wrote:
>>>>
>>>>> Hi all,
>>>>>
>>>>> I had a question posed to me and I'm looking for some ideas on a
>>>>> reliable/inexpensive (as possible) solution.
>>>>>
>>>>> We have 2 buildings about 450 feet apart separated by a field.
>>>>> We need to get these buildings together on a network. I'm reading
>>>>> varying opinions regarding the ability to connect at > 300 feet
>>>>> assuming you run at 10 megabit with cat5 cabling.
>>>>>
>>>>> There's no easy way to provide a repeater between these 2 buildings,
>>>>> as the cable needs to be buried in the field separating the buildings.
>>>>> I need a reliable link between the buildings, so if 10-baseT beyond
>>>>> 100 meters is not within spec and reliable, I need to go with
>>>>> something else.
>>>>>
>>>>> What alternatives do I have here?
>>>>
>>>>10baseT is typically capable of running over 150 to 200 meters of CAT5
>>>>or
>>>>better cable. It's not specified to do that but it it does. 10baseT
>>>>span is limited by signal quality, not timing, and CAT5 has electrical
>>>>properties enough better than those of CAT3 to You could also run
>>>>100VG, which _is_ specified to do that, if you can find the necessary
>>>>hardware, and that would give you 100 Mb/sec.
>>>>
>>>>However, it's a bad idea from a safety viewpoint as the two buildings
>>>>very likely have different electrical grounds and so there may be a
>>>>significant potential difference between them which may damage equipment
>>>>and/or injure staff.
>>>>
>>>>There are other alternatives. Doing it _right_ you'd run fiber between
>>>>the
>>>>buildings. Doing it _cheap_ if there's clear line of sight, you could
>>>>use two wireless access points with high-gain directional antennas.
>>>
>>>
>>> And given the insecure nature of wireless, I strongly recommend an
>>> encrypted vpn tunnel between the wireless access points. For example
>>> a pair of Netscreen 5XPs at either end, between the access-points and
>>> the network. Plus, this would allow laptops with the proper vpn
>>> software to connect. Much better to be secure that have to deal with
>>> getting hacked by anyone driving by with a laptop.
>>
>>The "insecure nature of wireless" is greatly exaggerated. Do you know of
>>any cracks for WPA/802.11i? For that matter, do you know of any
>>facilities using 128 bit WEP-Plus that have in the real world and not some
>>contrived
>>test "gotten hacked by anyone driving by with a laptop"? And that leaves
>>aside the kind of signal that your hypothetical wardriver can get out of
>>the side lobes of directional antennas.
>
>
> Wireless has yet to prove itself as secure, no matter how
> theoretically secure WPA and WPA2 are claimed to be. Do you recall
> how secure WEP was originally claimed to be? Know any big businesses
> that use it without additional protection?
>
> Until it has a proven track record, I consider wireless to be
> insecure. My business network is too sensitive and valuable to risk
> otherwise.

I presume then that you run everything encrypted on fiber. Not that that's
completely secure.

> Since 802.11i was only ratified less than 6-months ago, finding
> equipment at a reasonable price might be an issue.

It's available off the shelf from several vendors, including the Cisco
consumer line. And not particularly expensive.

> Properly setting
> it up and being sure the vendors implemented it right is another
> issue. You do realize it relies on RADIUS and AAA accounting which
> can be a bitch to setup securely. I suspect the OP might not be very
> IT saavy.

"Relies on" or "can use"?

> I also assumed the original poster was going for a cheap option and
> suggested vpn as a way of securing a cheap wireless implementation.
> Going with new WPA2 equipment might be more expensive than fiber.

Nope.

> -Chris

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
October 23, 2004 8:44:08 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

>> Until it has a proven track record, I consider wireless to be
>> insecure. My business network is too sensitive and valuable to risk
>> otherwise.
>
>I presume then that you run everything encrypted on fiber. Not that that's
>completely secure.

No just the wireless connections. Fiber at least needs to be touched
to be sniffed and the fences and guards are good for that.
Anonymous
October 23, 2004 4:56:00 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

chris@nospam.com wrote:

>
>
>>> Until it has a proven track record, I consider wireless to be
>>> insecure. My business network is too sensitive and valuable to risk
>>> otherwise.
>>
>>I presume then that you run everything encrypted on fiber. Not that
>>that's completely secure.
>
> No just the wireless connections. Fiber at least needs to be touched
> to be sniffed and the fences and guards are good for that.

If you have fences and guards your security needs are likely a good deal
higher than those of most businesses.

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
October 23, 2004 10:14:45 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

On Sat, 23 Oct 2004 12:56:00 -0400, "J. Clarke"
<jclarke@nospam.invalid> wrote:

>chris@nospam.com wrote:
>
>>
>>
>>>> Until it has a proven track record, I consider wireless to be
>>>> insecure. My business network is too sensitive and valuable to risk
>>>> otherwise.
>>>
>>>I presume then that you run everything encrypted on fiber. Not that
>>>that's completely secure.
>>
>> No just the wireless connections. Fiber at least needs to be touched
>> to be sniffed and the fences and guards are good for that.
>
>If you have fences and guards your security needs are likely a good deal
>higher than those of most businesses.

Perhaps. Then again, some big businesses deal with very sensitive
stuff as well. Industrial espionage is at an all time high. Not so
much for small mom & pop businesses, but some businesses could be
devasted if sensitive stuff like business plans and designs are leaked
out. Even worse, software companies need to be very sure people are
getting in and making changes. Anyone want a copy of half-life2?

-Chris
Anonymous
October 24, 2004 12:27:40 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

In article <cle2n901ppc@news1.newsguy.com>,
J. Clarke <jclarke@nospam.invalid> wrote:
:If you have fences and guards your security needs are likely a good deal
:higher than those of most businesses.

If he had said "fences and guards and guard-dogs", then I might agree
with you, but:

- We have some fences to keep people from falling in the holes where we
are building. We have other fences to keep people outside the intensity
range of the supermagnets that has been deemed 'safe' to the
unprepared public.

- Our premises (at the edge of the downtown office buildings) happen to
border upon the part of our city that is commonly believed to have the
greatest concentration of murders; I would evaluate the high-murder
area as being at least 6 blocks away... but the area next to us
-does- appear to have the highest concentration of drug deals,
so fences in the area are a common petty- theft- prevention measure>

- We have guards all night, every night -- but mostly they are there
to check up on the boilers, air blowers, cryo-freezers and other
similar equipment. Having a human on hand is less expensive than
investing heavily into intelligent monitoring systems that can
(for example) hear the "wuffing" noise that the air blowers make
when the bearings start to fail, and make decisions about whether to
call someone out of bed to look at them.
--
"No one has the right to destroy another person's belief by
demanding empirical evidence." -- Ann Landers
Anonymous
November 7, 2004 5:07:49 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Joseph Minckler wrote:

> Hi all,
>
> I had a question posed to me and I'm looking for some ideas on a
> reliable/inexpensive (as possible) solution.
>
> We have 2 buildings about 450 feet apart separated by a field.
> We need to get these buildings together on a network. I'm reading
> varying opinions regarding the ability to connect at > 300 feet
> assuming you run at 10 megabit with cat5 cabling.
>
> There's no easy way to provide a repeater between these 2 buildings,
> as the cable needs to be buried in the field separating the buildings.
> I need a reliable link between the buildings, so if 10-baseT beyond
> 100 meters is not within spec and reliable, I need to go with
> something else.
>
> What alternatives do I have here?

http://www.cisco.com/en/US/products/hw/switches/ps4916/
Anonymous
November 7, 2004 5:11:00 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Walter Roberson wrote:

> 450 feet apart suggests strongly to me that the two buildings have
> different electrical feeds. If so, then if you were to connect them
> by any kind of electricity carrying cable, you could run into
> substantial problems with ground differentials, and could end up frying
> the connecting equipment.

NICs have to be able to withstand a few hundred volts, without creating a
safety hazard. If you've got that much difference between grounds in 2
nearby buildings, you've got a very severe problem, that must be corrected,
before someone gets killed.

Network cards are isolated from the cable by transformers. There is no
other connection between the card and cable.
Anonymous
November 7, 2004 5:13:14 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Robert Redelmeier wrote:

> DO NOT RUN COPPER ETHERNET BETWEEN BUILDINGS.
>

The phone company runs copper cables miles long, between buildings. What
makes ethernet so different?
Anonymous
November 7, 2004 5:21:30 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

J. Clarke wrote:

>> No just the wireless connections.  Fiber at least needs to be touched
>> to be sniffed and the fences and guards are good for that.
>
> If you have fences and guards your security needs are likely a good deal
> higher than those of most businesses.

I recently read a book called "Spy Dust", which was written by a couple of
CIA agents. One operation they wrote about, was stealing an encryption
machine, that was bolted down, in a locked vault, in a Soviet embassy.
Even fences and guards don't do much, against a determined and capable
intruder.

Incidentally, according to that book, some of the stuff the CIA uses, is
right out of "Mission Impossible"!
Anonymous
November 7, 2004 10:23:36 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

James Knott <james.knott@rogers.com> wrote:
> Robert Redelmeier wrote:

>> DO NOT RUN COPPER ETHERNET BETWEEN BUILDINGS.
>>

> The phone company runs copper cables miles long, between buildings. What
> makes ethernet so different?

Resistance to surges. Remember phones was invented before fiber sp phone
equipment had to be quite tolerant.

But by all means, run your RJ-45 between buildings. It won't cost me a cent :-)


--
Peter Håkanson
IPSec Sverige ( At Gothenburg Riverside )
Sorry about my e-mail address, but i'm trying to keep spam out,
remove "icke-reklam" if you feel for mailing me. Thanx.
Anonymous
November 7, 2004 10:23:37 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

phn@icke-reklam.ipsec.nu wrote:

> James Knott <james.knott@rogers.com> wrote:
>> Robert Redelmeier wrote:
>
>>> DO NOT RUN COPPER ETHERNET BETWEEN BUILDINGS.
>>>
>
>> The phone company runs copper cables miles long, between buildings. What
>> makes ethernet so different?
>
> Resistance to surges. Remember phones was invented before fiber sp phone
> equipment had to be quite tolerant.
>
> But by all means, run your RJ-45 between buildings. It won't cost me a
> cent :-)
>
>

Any ethernet equipment has to be able to safely withstand a few hundred
volts, to be legally sold.

I'm not against using fibre and in fact think it's a good idea, however some
people get all upset at using copper, when it's perfectly safe, when used
in a properly engineered environment.
November 10, 2004 7:41:06 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

On Sun, 07 Nov 2004 14:13:14 -0500, James Knott
<james.knott@rogers.com> wrote:

>Robert Redelmeier wrote:
>
>> DO NOT RUN COPPER ETHERNET BETWEEN BUILDINGS.
>>
>
>The phone company runs copper cables miles long, between buildings. What
>makes ethernet so different?


Surge protectors are required. These surge protectors would interfer
with proper ethernet.

-Chris
Anonymous
November 10, 2004 1:46:16 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

chris@nospam.com wrote:

> On Sun, 07 Nov 2004 14:13:14 -0500, James Knott
> <james.knott@rogers.com> wrote:
>
>>Robert Redelmeier wrote:
>>
>>> DO NOT RUN COPPER ETHERNET BETWEEN BUILDINGS.
>>>
>>
>>The phone company runs copper cables miles long, between buildings. What
>>makes ethernet so different?
>
>
> Surge protectors are required. These surge protectors would interfer
> with proper ethernet.

I am aware of surge protectors as used on the phone networks. However, some
people have a phobia about running cables between two building, talking
about differences in ground potential etc. Given that ethernets are
capable of withstanding a few hundred volts and there's no connection to
the NICs, other than the coupling transformers, there's no way that's
likely to be a problem. If there is enough voltage difference to be a
problem, then a very unsafe situation exists, even without ethernet. What
may be a problem, is nearby lightning strikes, but if there's one close
enough to be a problem for ethernet cables, it's also likely to cause
problems via phone and power lines. Also, I seem to recall surge
protectors for ethernet were availble, but I don't recall where.
Anonymous
November 10, 2004 7:45:05 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

James Knott <james.knott@rogers.com> wrote:
> What may be a problem, is nearby lightning strikes, but if

Yes, this is the main concern. A strike elevates
ground potentials ringwise (kV/m), and the two buildings
groundstakes could be momentarily pushed beyond the 500V
transformer isolation.

> there's one close enough to be a problem for ethernet cables,
> it's also likely to cause problems via phone and power lines.

Yep, them too. That's why they have surge protectors.
Phones normally have surge protection on the NID (grey
box on the outside of the house). A friend would lose a
couple of modems every year because his wasn't grounded.

Power systems are similar, but the PSU systems give some
protection to the more vulnerable electronics.

-- Robert
Anonymous
November 10, 2004 9:47:52 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Both phones and ethernet cards are rated for about same
voltages. IOW both already have internal protection.
Protection that is overwhelmed if the incoming wire is not
earthed before entering a building. That is what the service
entrance protector does - earth. Any wire that enters a
building must first connect to the single point earth ground -
either by direct hardwire or via a surge protector. This is
why phone companies could interconnect buildings even three
miles apart with no damage and no human safety problems.

phn@icke-reklam.ipsec.nu wrote:
> James Knott <james.knott@rogers.com> wrote:
>> The phone company runs copper cables miles long, between buildings.
>> What makes ethernet so different?
>
> Resistance to surges. Remember phones was invented before fiber sp
> phone equipment had to be quite tolerant.
>
> But by all means, run your RJ-45 between buildings. It won't cost
> me a cent :-)
Anonymous
November 10, 2004 9:55:34 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Surge protectors that would not interfere with ethernet may
not be acceptable on phone lines. Phone lines with surge
protectors even must carry ISDN and xDSL on those wires
without problem. Phone line protectors are more than
sufficient for ethernet because they must not interfere with
xDSL.

In the meantime, any connection between two buildings
requires a connection to single point earth ground. Some
wires make that earthing connection via a protector. Others
earth by a hard wire connection. But it is not the protector
that provides protection. Wires must be earthed before
entering the building. Earthing is the protection. Any wire
between two buildings is earthed at both ends - where the wire
enters each building. That is how phone companies did it 70
years ago. That is how copper wire ethernet is safely run
between buildings.

Effective protector are sold both for ethernet and phones:


chris@nospam.com wrote:
> On Sun, 07 Nov 2004 14:13:14 -0500, James Knott
> <james.knott@rogers.com> wrote:
>>Robert Redelmeier wrote:
>>
>>> DO NOT RUN COPPER ETHERNET BETWEEN BUILDINGS.
>>>
>>
>> The phone company runs copper cables miles long, between buildings.
>> What makes ethernet so different?
>
> Surge protectors are required. These surge protectors would interfer
> with proper ethernet.
>
> -Chris
Anonymous
November 11, 2004 12:28:55 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

w_tom wrote:

> Both phones and ethernet cards are rated for about same
> voltages.  IOW both already have internal protection.
> Protection that is overwhelmed if the incoming wire is not
> earthed before entering a building.  That is what the service
> entrance protector does - earth.  Any wire that enters a
> building must first connect to the single point earth ground -
> either by direct hardwire or via a surge protector.  This is
> why phone companies could interconnect buildings even three
> miles apart with no damage and no human safety problems.

Telephone lines are not grounded, except at the CO, where the positive side
of the 48V batteries are grounded. At the subscribers end, there is a
protection block, which is grounded, but the wires are not. A brief high
voltage surge, will be shunted to ground, by the protection block. If you
were to ground the phone line, you'd unbalance the circuit and likely get a
lot of noise on the phone.
Anonymous
November 11, 2004 12:32:09 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

w_tom wrote:

> That is how phone companies did it 70
> years ago.  That is how copper wire ethernet is safely run
> between buildings.

Phone lines are NOT connected to ground at the subscribers premise. Only
the protection block is grounded, so that it can shunt voltage surges to
ground. Ethernet cable is electrically isolated from the equipment, by the
transformers that pass the desired signal between the NIC and cable, but
cannot pass DC or low frequency AC.
Anonymous
November 11, 2004 3:47:58 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

w_tom <w_tom1@hotmail.com> wrote:
> Phone line protectors are more than sufficient for ethernet
> because they must not interfere with xDSL.

Why is this a guarantee? xDSL was specifically designed
to pass through carbon blocks and other telco antisurge
protection. It also operates at much lower frequency
(3-5 MHz) than ethernet (5-50MHz sorta).

> Wires must be earthed before entering the building. Earthing
> is the protection. Any wire between two buildings is
> earthed at both ends - where the wire enters each building.
> That is how phone companies did it 70 years ago. That is
> how copper wire ethernet is safely run between buildings.

Agreed, with the refinement that interbuilding wiring
isn't directly earthed (that would kill signal) but
an earth path is available through an antisurge device.

-- Robert
Anonymous
November 11, 2004 4:36:42 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

chris@nospam.com wrote:

> Surge protectors are required. These surge protectors would interfer
> with proper ethernet.

I've got no personal experiance with this, but here is a product that
seems to contridict you. Am I misunderstanding what this thing does?

http://www.apcc.com/resource/include/techspec_index.cfm...

--
Frank Stutzman
Anonymous
November 11, 2004 1:17:47 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

First I said earthed - not grounded. The word earth defines
a specific type of ground. Second, even the NEC requires that
the earthing connection to incoming phone line be less than 20
feet to the same earth ground used by AC electric breaker
box. As posted previously - some incoming services are
earthed by a hardwire (CATV). Others must be earthed through
a surge protector (phone). But every incoming utility wire
must connect to single point earth ground before entering the
building.

In North America, properly installed phone line entering the
building has an earthing connection for the phone line 'whole
house' protector. It is even required by National Electrical
Code Article 800.30A:
> A listed primary protector shall be provided on each circuit
> run partly or entirely in aerial wire or aerial cable not
> confined within the block containing the building served so
> as to be exposed to accidental contact with electric light or
> power conductor operating at over 300 volts to ground. In
> addition, where there exists a lightning exposure, each
> interbuilding circuit on a premise shall be protected by a
> listed primary protector at each end of the interbuilding
> circuit.


James Knott wrote:
> w_tom wrote:
>> Both phones and ethernet cards are rated for about same
>> voltages. IOW both already have internal protection.
>> Protection that is overwhelmed if the incoming wire is not
>> earthed before entering a building. That is what the service
>> entrance protector does - earth. Any wire that enters a
>> building must first connect to the single point earth ground -
>> either by direct hardwire or via a surge protector. This is
>> why phone companies could interconnect buildings even three
>> miles apart with no damage and no human safety problems.
>
> Telephone lines are not grounded, except at the CO, where the
> positive side of the 48V batteries are grounded. At the
> subscribers end, there is a protection block, which is grounded,
> but the wires are not. A brief high voltage surge, will be
> shunted to ground, by the protection block. If you were to
> ground the phone line, you'd unbalance the circuit and likely
> get a lot of noise on the phone.
Anonymous
November 11, 2004 1:23:02 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Others may have assumed surge protectors sit between the
appliance and a surge. Effective protectors don't work that
way as you have noted. Shunt mode protectors connect to the
uility wires just as another light bulb connects to AC mains.
The surge protector makes no connection to earth - does not
conduct telephone signals - until voltage is exceeded.
Numbers for that threshold are provided in another post that
specifically quotes the National Electrical Code requirements
for that protector.

xDSL signals do not pass through carbon blocks (obsolete
technology) or the newer semiconductor based protectors. xDSL
is short wave frequencies - at and above the frequencies used
in 10Base-T ethernet. Conventional MOVs are not used on phone
lines (except in many cheap plug-in protectors) due to too
much capactiance. Telephone 'whole house' protectors
(provided free by the telco) must have so little capactiance
as to not even interfere with xDSL. These would also be more
than sufficient for ethernet.

Others also make protectors for ethernet. In each case, the
protector would only be as effective as its earth ground
(earthing - not the protector - is the protection):
http://www.keison.co.uk/furse/furse19.htm
http://www.tripplite.com/products/product.cfm?productID...
http://www.tripplite.com/products/product.cfm?productID...
http://www.keison.co.uk/furse/furse08.htm
http://www.keison.co.uk/furse/furse07.htm
http://www.itwlinx.com/products/pdf/MicroModule.pdf
http://www.digitaltele.com/edco.htm

Again for the benefit of others, an effective protector does
not sit between the CO and premise telephone. That connection
from CO to household phone is straight through wire. The
surge protector connects from each phone wire to earth
ground. xDSL signals don't pass through a surge protector.

In the meantime, every incoming service including phone is
earthed at the premise interface. Specific paragraph from
National Electrical Code that requires this earthing is
provided in another post.

Bottom line - ethernet between two buildings does exactly as
phone companies have demonstrated 60+ years ago. The ethernet
wire is earthed where it enters each building. This is
important because each building can be the lightning rod that
connects surges to appliances in the other building. With
proper earthing (and that means to every other utility wire
that enter the building; especially AC electric that typically
has no such protection), then damage does not happen.

Robert Redelmeier wrote:
> w_tom <w_tom1@hotmail.com> wrote:
>> Phone line protectors are more than sufficient for ethernet
>> because they must not interfere with xDSL.
>
> Why is this a guarantee? xDSL was specifically designed
> to pass through carbon blocks and other telco antisurge
> protection. It also operates at much lower frequency
> (3-5 MHz) than ethernet (5-50MHz sorta).
>
>> Wires must be earthed before entering the building. Earthing
>> is the protection. Any wire between two buildings is
>> earthed at both ends - where the wire enters each building.
>> That is how phone companies did it 70 years ago. That is
>> how copper wire ethernet is safely run between buildings.
>
> Agreed, with the refinement that interbuilding wiring
> isn't directly earthed (that would kill signal) but
> an earth path is available through an antisurge device.
>
> -- Robert
Anonymous
November 11, 2004 1:29:27 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Don't let that product deceive you. Protection is not in
the protector. See that green ground wire? Some pictures type
to hide that wire. Wire must make a less than ten foot
connection to single point earth ground. A very specific earth
ground. Many APC products don't have such necessary earthing
wires. Therefore APC forgets to mention that earthing - not
the protector - is protection. If they mentioned earthing,
then many would learn which grossly profitable APC products
are ineffective.

How to identify an ineffective protector - 1) no dedicated
connection to earth ground AND 2) manufacturer avoid all
discussion about earthing. The PNET1 does have necessary
earthing. I don't remember if it meets other necessary
parameters. But the PNET1 appears to be an effective
protection - even though most APC products are not.

It is not that surge protectors are required. Some
connection to single point earth ground must exist at the
service entrance. PNET1 is one product that could make a
necessary earthing connection.

Frank Stutzman wrote:
> chris@nospam.com wrote:
>> Surge protectors are required. These surge protectors would interfer
>> with proper ethernet.
>
> I've got no personal experiance with this, but here is a product that
> seems to contridict you. Am I misunderstanding what this thing does?
>
> http://www.apcc.com/resource/include/techspec_index.cfm...
>
> --
> Frank Stutzman
Anonymous
November 12, 2004 12:16:30 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

w_tom <w_tom1@hotmail.com> wrote:
> xDSL signals do not pass through carbon blocks (obsolete
> technology) or the newer semiconductor based protectors.

Do you have some reference? I find this hard to believe
because carbon blocks were used through the late 1970s, and
I haven't heard of many people needing their NID replaced to
get xDSL. Sometimes a whole-house splitter is installed.

I don't see carbon blocks or MOVs as having capacitance
that would cause problems.

> http://www.keison.co.uk/furse/furse19.htm
> http://www.tripplite.com/products/product.cfm?productID...
> http://www.tripplite.com/products/product.cfm?productID...
> http://www.keison.co.uk/furse/furse08.htm
> http://www.keison.co.uk/furse/furse07.htm
> http://www.itwlinx.com/products/pdf/MicroModule.pdf
> http://www.digitaltele.com/edco.htm

Useful references. I think I'd prefer an NID-type device
that I could tie to the building groundstake nearby. Some of
these are just dongles, longwired to ground. But I suppose
it depends on ground impedence versus rise rates.

-- Robert
Anonymous
November 12, 2004 12:16:31 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

Carbon blocks were obsoleted sometime after the seventies.
The carbons were a special design MOV structured to have lower
capacitance than conventional MOVs. Pictures of the carbons:
http://thekramers.net/tmp/phonething.jpg
http://www.inwap.com/inwap/chez/Phoneline.jpg

Carbons also were a junction block between incoming telco
wire and interior building wire. Notice the carbons do not
sit between incoming and interior wires. Center in the
assembly is the earth ground bolt. Each carbon remains open
circuit most of the time. When excessive voltage appears on a
wire, then the carbon connects that phone wire to the earth
ground bolt (which connects to earth ground using a 12 AWG
green or gray wire).

Newer construction replaces the carbons with an NID:
http://www.alarmsuperstore.com/bw/bw%20connectors.htm
http://www.bass-home.com/gotoproduct.cfm?item=91598
NIDs typically use a semiconductor protector (that also
doubles as the junction bolts for telco wire). Unlike
carbons, the semiconductor protector becomes a dead short
circuit when failed. Unlike the carbons, the semiconductor
protector therefore announces its failure by keeping phone
line connected to earth.

This semiconductor protector acts like conventional avalanch
diodes (Transzorb or Transil) but was specially constructed to
have low capacitance. It was sufficient for xDSL (in most
cases) before xDSL even was implemented. (I heard of but
cannot confirm a notification for some NID surge protectors
that had too much capacitance for xDSL and had to be
replaced.) The concepts are described in:
http://www.semtech.com/html/tvs_low_capacitance.html

I am posting these from memory and did not check the URLs.
Hope they still work and are informative.


Robert Redelmeier wrote:
>
> w_tom <w_tom1@hotmail.com> wrote:
> > xDSL signals do not pass through carbon blocks (obsolete
> > technology) or the newer semiconductor based protectors.
>
> Do you have some reference? I find this hard to believe
> because carbon blocks were used through the late 1970s, and
> I haven't heard of many people needing their NID replaced to
> get xDSL. Sometimes a whole-house splitter is installed.
>
> I don't see carbon blocks or MOVs as having capacitance
> that would cause problems.
>
> > http://www.keison.co.uk/furse/furse19.htm
> > http://www.tripplite.com/products/product.cfm?productID...
> > http://www.tripplite.com/products/product.cfm?productID...
> > http://www.keison.co.uk/furse/furse08.htm
> > http://www.keison.co.uk/furse/furse07.htm
> > http://www.itwlinx.com/products/pdf/MicroModule.pdf
> > http://www.digitaltele.com/edco.htm
>
> Useful references. I think I'd prefer an NID-type device
> that I could tie to the building groundstake nearby. Some of
> these are just dongles, longwired to ground. But I suppose
> it depends on ground impedence versus rise rates.
>
> -- Robert
!