Re: Long cat5 run question

> Will I be able to run a 200ft distance to another computer in another
> building?

100BaseT supports up to 330 feet. That's total distance, not line of sight.
So don't forget to take into account the lengths necessary to get from the
router, up/down the wall, over to the building exit, down/up the wall, under
the ground, etc, all the way to the other end. You'd be surprised how much
distance gets chewed up.

> Suggestions on what type of router to get for this endevour would be
> helpful.

If all you're doing is adding to the current subnet there's no router
needed. You can just hang another switch off the connection. Just don't
chain more than 3 switches. If you needed more than that you'd need to use
a router. How much traffic or how many computers are expected to be active
in the other building?

> It will be running outside. Can cat5 wire be buried?

Direct-burial jacket covered wire is available. Conduit is better as it
allows much better maintenance. But for inter-building connections it's
often common to use fiber optic cable. There are 100mb converters available
for the purpose, you'd use one on each end. Using fiber allows going longer
distances and avoids risks like lightning and surges. I'd much rather have
fiber in conduit that anything directly buried into the soil.

-Bill Kearney

"Bill Kearney" <wkearney99@hotmail.com> wrote in message
news:w7adnc1mocs4vgvanZ2dnUVZ_oGjnZ2d@speakeasy.ne t...
>> Will I be able to run a 200ft distance to another computer in another
>> building?
>
> 100BaseT supports up to 330 feet. That's total distance, not line of
> sight. So don't forget to take into account the lengths necessary to get
> from the router, up/down the wall, over to the building exit, down/up the
> wall, under the ground, etc, all the way to the other end. You'd be
> surprised how much distance gets chewed up.

The spec actually states 100 meters being the max length which is 328 feet,
this includes all patch cables.

>
>> Suggestions on what type of router to get for this endevour would be
>> helpful.
>
> If all you're doing is adding to the current subnet there's no router
> needed. You can just hang another switch off the connection. Just don't
> chain more than 3 switches. If you needed more than that you'd need to
> use a router. How much traffic or how many computers are expected to be
> active in the other building?

Plug it into a switch or computer on each end. It doesn't have to be
anything special. But you might want to let us know what your doing just in
case further equipment is needed.

>
>> It will be running outside. Can cat5 wire be buried?

Yes, there are bury grade/outdoor cable available. I bought the last stuff I
used to put on a tower and between some buildings from www.wisp-router.com

>
> Direct-burial jacket covered wire is available. Conduit is better as it
> allows much better maintenance. But for inter-building connections it's
> often common to use fiber optic cable. There are 100mb converters
> available for the purpose, you'd use one on each end. Using fiber allows
> going longer distances and avoids risks like lightning and surges. I'd
> much rather have fiber in conduit that anything directly buried into the
> soil.

True, however there is nothing wrong with using cat5e cable if 10/100 is all
that's required. Fiber cable, the terminations and and media converters can
be pretty expensive. If i wanted gigabit speed i'd consider fiber for a run
that short other wise the cat5 will be fine, just all depends on what you
want to do and what you have planned in the future.

Adair

> The spec actually states 100 meters being the max length which is 328
> feet, this includes all patch cables.

Indeed. I've had runs slightly longer that worked, and ones shorter that
didn't. There are enough variables to make it reasonable to think of it as
a 300' limit. My point wasn't to quibble over the total limit, but to
stress that the distance needs to include ALL portions of the connection.
To the wall, up and over the ceiling, etc. If the other build is really
only 200' away then he's got plenty of distance to play with inside the
buildings.

> True, however there is nothing wrong with using cat5e cable if 10/100 is
> all that's required.

Two reasons I refuse to use ethernet wire buried: lightning and voltage
transients. If only because I've had personal experience with both wrecking
equipment.

> Fiber cable, the terminations and and media converters can be pretty
> expensive.

Not as expensive as the hassle of replacing fried equipment. I'd much
rather spend a few bucks on media converters instead of hundreds of dollars
on blown routers, switches and PC motherboards. But hey, feel free to
gamble.

> If i wanted gigabit speed i'd consider fiber for a run that short other
> wise the cat5 will be fine, just all depends on what you want to do and
> what you have planned in the future.

Yes, gigabit media converters ARE a lot more expensive. And quite probably
not worth doing in most situations. Heck, I'd probably go for bonding
multiple 100mb fiber links first. More often than not the network is not
the bottleneck. The host CPU, local disk drives, and processing times are
usually bigger bottlenecks.

-Bill Kearney

On Tue, 22 Jan 2008 22:24:29 -0500, "Bill Kearney"
<wkearney99@hotmail.com> wrote:

>> The spec actually states 100 meters being the max length which is 328
>> feet, this includes all patch cables.
>
>Indeed. I've had runs slightly longer that worked, and ones shorter that
>didn't. There are enough variables to make it reasonable to think of it as
>a 300' limit.

Nope. One of my fun demos is to take a 1000ft roll of CAT5, crimp
connectors at both ends, and connect it between my laptop and a Cisco
1900 managed switch. It won't do 100mbits/sec (100baseTX) in either
HDX or FDX, but will certainly do 10mbits/sec (10baseT) in either HDX
or FDX. The trick is to force the connection to 10mbits/sec and don't
let NWAY try to set it to 100mbits/sec. SNMP from the switch and
netstat shows no transmission errors. Thruput is also at wire speed
with FDX.

>My point wasn't to quibble over the total limit, but to
>stress that the distance needs to include ALL portions of the connection.
>To the wall, up and over the ceiling, etc. If the other build is really
>only 200' away then he's got plenty of distance to play with inside the
>buildings.

Yep. You're also correct about the extra cable for bends and turns.
I've gone over 300ft several times by forgetting about such details.

Note that the 100meter limit is between switches. You can add as many
ethernet switches as needed along the line to deal with regenerating
the signal. I've done 1500ft that way with 3 switches between
endpoints. I think that's about the limit as it was a bit flakey when
the switches got hot. I think (not sure) that the limit is set by the
end to end latency (delay), which causes ACK timing problems.

>Two reasons I refuse to use ethernet wire buried: lightning and voltage
>transients. If only because I've had personal experience with both wrecking
>equipment.

Sigh. We don't get much lightning in California, but the few
lightning bolts that hit a local tower managed to blow up most of my
media converters. Fiber works much better.

>Not as expensive as the hassle of replacing fried equipment.

The equipment is fairly cheap. My time to drive up to some mountain
top, with the wind blowing, rain falling, and lightning zapping, is
considerably more expensive. In retrospect, I should charge hazzard
or combat pay. However, if you wanna do gigabit fiber, the media
converters are VERY expensive. It's often easier to settle for
100mbits/sec and save your dollars until the prices drop.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

"Bill Kearney" <wkearney99@hotmail.com> wrote in message
>> The spec actually states 100 meters being the max length which is 328
>> feet, this includes all patch cables.
>
> Indeed. I've had runs slightly longer that worked, and ones shorter that
> didn't. There are enough variables to make it reasonable to think of it
> as a 300' limit. My point wasn't to quibble over the total limit, but to
> stress that the distance needs to include ALL portions of the connection.
> To the wall, up and over the ceiling, etc. If the other build is really
> only 200' away then he's got plenty of distance to play with inside the
> buildings.

My point was not to piss over the actual distance, if you've had shorter
cables fail something was wrong with your termination or equipment. I
install and terminate cat5/cat6 cables daily and have never had a short
cable fail but we did have a customer that had us install 600ft of cat5e
against our will and it would not work.

>
>> True, however there is nothing wrong with using cat5e cable if 10/100 is
>> all that's required.
>
> Two reasons I refuse to use ethernet wire buried: lightning and voltage
> transients. If only because I've had personal experience with both
> wrecking equipment.

Not always possible for some applications say for traditional phone cabling
of course, as with anything standard grounding and bonding techniques needs
to be followed.
I agree that fiber is the way to go, it's just not cheap.
I just installed ST connectors on a 6 strand multimode fiber (12 total
connectors) for a customer who installed the cable themselves, still cost
them around $800 for my travel, connectors and test equipment. Lets add the
cost of media converters (around $100 each) and cable ($1 per foot?). Lets
not consider what connectors, and the termination and test equipment cost.
Our fluke DTX-1800 with fiber moduals was about $16,000 and our splice kits
were several hundred dollars. This is all assuming that someone has the know
how to install, terminate and test the fiber correctly.

>
>> Fiber cable, the terminations and and media converters can be pretty
>> expensive.
>
> Not as expensive as the hassle of replacing fried equipment. I'd much
> rather spend a few bucks on media converters instead of hundreds of
> dollars on blown routers, switches and PC motherboards. But hey, feel
> free to gamble.

Agreed

>
>> If i wanted gigabit speed i'd consider fiber for a run that short other
>> wise the cat5 will be fine, just all depends on what you want to do and
>> what you have planned in the future.
>
> Yes, gigabit media converters ARE a lot more expensive. And quite
> probably not worth doing in most situations. Heck, I'd probably go for
> bonding multiple 100mb fiber links first. More often than not the network
> is not the bottleneck. The host CPU, local disk drives, and processing
> times are usually bigger bottlenecks.

Right, that's my point, what does he need to do with this link? If it's one
computer or access point can he justify the cost of a fiber solution?
Reguardless
>
> -Bill Kearney
>

Jerff said:

> Note that the 100meter limit is between switches. *You can add as many
> ethernet switches as needed along the line to deal with regenerating
> the signal. *I've done 1500ft that way with 3 switches between
> endpoints. *I think that's about the limit as it was a bit flakey when
> the switches got hot. *I think (not sure) that the limit is set by the
> end to end latency (delay), which causes ACK timing problems.

The 802.1d standard says 7 (or it is 8?) intermediate
switches however that limit is for the Spanning Tree
Protocol and if you were not using redundant
paths managed by STP then there is no reason
to stick to it.

Of course you could use routers and add an arbitrary
number of hops. There are fewer now however at one
time it was not unusual for internet paths to have 25
router hops (and an unknown number of switchhops).

Each hop will add 2 x Transmission Delay to the
RTT. Say 2ms at 10M for full size packets.

On Jan 22, 9:11 am, "Bill Kearney" <wkearne...@hotmail.com> wrote:
> > Will I be able to run a 200ft distance to another computer in another
> > building?
>
> 100BaseT supports up to 330 feet. That's total distance, not line of sight.
> So don't forget to take into account the lengths necessary to get from the
> router, up/down the wall, over to the building exit, down/up the wall, under
> the ground, etc, all the way to the other end. You'd be surprised how much
> distance gets chewed up.
>
> > Suggestions on what type of router to get for this endevour would be
> > helpful.
>
> If all you're doing is adding to the current subnet there's no router
> needed. You can just hang another switch off the connection. Just don't
> chain more than 3 switches. If you needed more than that you'd need to use
> a router. How much traffic or how many computers are expected to be active
> in the other building?
>
> > It will be running outside. Can cat5 wire be buried?
>
> Direct-burial jacket covered wire is available. Conduit is better as it
> allows much better maintenance. But for inter-building connections it's
> often common to use fiber optic cable. There are 100mb converters available
> for the purpose, you'd use one on each end. Using fiber allows going longer
> distances and avoids risks like lightning and surges. I'd much rather have
> fiber in conduit that anything directly buried into the soil.
>
> -Bill Kearney

Isn't there an issue with the potential difference between the grounds
of the two buildings?

As Jeff points out you can 'abuse' the distances but need to make sure to
manually lock the port configuration. And have equipment that can actually
be configured to do this, many cheapie switches will not. To say nothing of
crappy drivers on various PC network cards. Know what your gear can and
can't do reliably.

> Note that the 100meter limit is between switches. You can add as many
> ethernet switches as needed along the line to deal with regenerating
> the signal. I've done 1500ft that way with 3 switches between
> endpoints.

I was a bit suprised to see the old 3-4-5 rule has less applicability
(none?) with switches. I'd still want to avoid stringing things along
through too many devices, if just to avoid debugging nightmares. But a
typical residential setting (or even a small office) isn't likely to run
into things like arp cache overflows and the like.

> Sigh. We don't get much lightning in California, but the few
> lightning bolts that hit a local tower managed to blow up most of my
> media converters. Fiber works much better.

At least the damage stopped there, not followed along the wire and to the
computers themselves.

-Bill Kearney

> Right, that's my point, what does he need to do with this link? If it's
> one computer or access point can he justify the cost of a fiber solution?

Yep, we're on the same page. It really does depend on what's really
necessary over the link.

"Bill Kearney" <wkearney99@hotmail.com> wrote in message
news:B6mdncUIA9sY-granZ2dnUVZ_vKunZ2d@speakeasy.net...
> As Jeff points out you can 'abuse' the distances but need to make sure to
> manually lock the port configuration. And have equipment that can
actually
> be configured to do this, many cheapie switches will not. To say nothing
of
> crappy drivers on various PC network cards. Know what your gear can and
> can't do reliably.
>
> > Note that the 100meter limit is between switches. You can add as many
> > ethernet switches as needed along the line to deal with regenerating
> > the signal. I've done 1500ft that way with 3 switches between
> > endpoints.
>
> I was a bit suprised to see the old 3-4-5 rule has less applicability
> (none?) with switches. I'd still want to avoid stringing things along
> through too many devices, if just to avoid debugging nightmares. But a
> typical residential setting (or even a small office) isn't likely to run
> into things like arp cache overflows and the like.
>
> > Sigh. We don't get much lightning in California, but the few
> > lightning bolts that hit a local tower managed to blow up most of my
> > media converters. Fiber works much better.
>
> At least the damage stopped there, not followed along the wire and to the
> computers themselves.

1) I seem to remember a 1500 ft. limit for 10Mb. - not certain if that's
10BaseT or 10base2.

2) For underground, one can always run it inside a buried metal pipe.
Theoretically, the pipe will isolate all static electricity (including
lightening) to its outside. Note that this is for METAL pipe, so don't use
ABS or PVC and think the same thing. 1/2" galvanized water pipe will do.

On Wed, 23 Jan 2008 11:12:57 -0500, "Bill Kearney"
<wkearney99@hotmail.com> wrote:

>I was a bit suprised to see the old 3-4-5 rule has less applicability
>(none?) with switches.

It's the 5-4-3 rule. It's totally non-applicable to ethernet switches
and only applies to hubs (i.e. ethernet repeaters).
<http://en.wikipedia.org/wiki/5-4-3_rule>
Hubs are useful sacrificial offerings. See below.

>I'd still want to avoid stringing things along
>through too many devices, if just to avoid debugging nightmares. But a
>typical residential setting (or even a small office) isn't likely to run
>into things like arp cache overflows and the like.

Not the ARP cache but the MAC address to port number table as found in
all ethernet switches. The cheap switches just discard as fast as
possible. The good switches have huge table space and keep the table
populated as long as possible. I had to deal with an Allied Telesyn
switch that had exactly 1 slot in the table as it was assumed that the
backbone was connected to a router, which (usually) requires only a
single MAC address. It's a rare problem, but I've seen it.

However idiots like me are certainly capeable of doing something
similar. It seems that one of my coffee shop customers was
complaining that *SOME* customers are connecting, but not getting DHCP
assigned IP's. An important clue was that regular customers were
working, while new customers and visitors were not getting IP's.

Dumping the DHCP lease database from DD-WRT v24 sp3 (old), I found
that the table had filled up all 100 addresses that I allowed in the
DHCP addressable space. It had saved 100 leases and said it's time to
give up. After upgrading to v24 RC6.2, I found a check box to
"Save DHCP table in NVRAM".
Unchecking the box allowed the DHCP lease database to flush normally.

>At least the damage stopped there, not followed along the wire and to the
>computers themselves.

I have a sacrificial ethernet hub at each end of the link. One of the
media converters was smoked, as were both hubs. Sacrifices must be
made to the thunder gods. A $10 junk hub apparently placated the
thunder god's anger and restored connectivity to us mere mortals.

As far as following the rules are concerned, I rarely do that. My
definition of experience is knowing what rules can be broken, under
what circumstances, and with what limitations.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

On Wed, 23 Jan 2008 08:07:45 -0800 (PST), miso@sushi.com wrote:

>Isn't there an issue with the potential difference between the grounds
>of the two buildings?

I think ethernet is guaranteed to have 1500 volt (common mode)
isolation between any of the signal wires and ground. I'm too lazy to
look it up.

The only way that a hot ground is gonna cause a problem is if you:
1. Ground one or both ends of the data lines. (won't happen)
2. If the CAT5 is shielded and you ground both ends.
3. If the tiny isolation xformers on the ethernet interfaces decide
to arc over or short in some weird way.

Even if you were running 10base2 (RG-58a/u coax) between buildings,
the coax is suppose to be grounded at one end only. Now, if you
grounded both ends of the coax, then you've got a real problem. At
best, you'll have a ground loop which couples 60Hz crud onto the data
stream. At worst, you'll have a smoking mess as the current heats up
the coax and eventually melts it. That's happened to me when I ran
RG-58a/u between building for a WWV and stabilized clock distribution
system for the test equipment clocks. It was not suppose to be
grounded at either end, but someone decided I was in error and
grounded everything. It took a few minutes to start a fire and fill
the building with smog as several hundred feet of coax literally
melted. I think the potential difference was only about 10-20VAC, but
it had full PG&E power behind it.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

D. Stussy wrote:


>
> 1) I seem to remember a 1500 ft. limit for 10Mb. - not certain if that's
> 10BaseT or 10base2.

10base5 "thick coax" has a 500 meter limitation.

>
> 2) For underground, one can always run it inside a buried metal pipe.
> Theoretically, the pipe will isolate all static electricity (including
> lightening) to its outside. Note that this is for METAL pipe, so don't use
> ABS or PVC and think the same thing. 1/2" galvanized water pipe will do.
>
>

The metal conduit won't help for lightning. The large difference in
potential between "building A" and "building B" is what toasts stuff.

On Jan 23, 11:07 am, m...@sushi.com wrote:
> Isn't there an issue with the potential difference between the grounds
> of the two buildings?

Yes. And the technology used even 100 years ago (and often unknown
to computer techs) makes that potential difference completely
irrelevant.

The discussion is about an ethernet cable between two buildings.
Why is this a problem? Lightning striking one building can find earth
ground, destructively, via equipment in the other. IOW one building
becomes a lightning rod connected directly to electronics in the other
building. Damage is created only when current has both in incoming
and outgoing path through that electronics.

Every building in town connects to the telco's Central Office (CO)
$multi-million computer. Why is that computer not damaged? According
to 1950s research, that computer (connected to overhead wires all over
town) is typically threatened by 100 surges during every
thunderstorm. Why no damage? Again the same technology used even 100
years ago. Every wire entering (or leaving) the building must first
connect to earth. Every wire inside every cable.

If every wire connects directly to earth, then no service. If
every wire inside that ethernet cable connects directly to earth, then
no ethernet. So we make that earthing connection via a protector.
The protector is not protection. Earthing is the protection.
Protector is simply a connecting device. Better earthing and a
shorter connection to earth make protection better. Yes, distance to
earth affects how well a protector performs. Therefore that CO puts
each protector (for each wire) at earth ground and up to 50 meters
distant from electronics.

If your ethernet cable makes that earthing connection where it
enters every building, then electronics in the other building are no
longer connected to a 'lightning rod' - that first building. That
earth ground must be same earthing electrode used by AC electric,
telephone, etc. That connection but be short (ie 'less than 10
feet'). Protection for everything in the building made even better
when the earthing system is enhanced. Protection is defined by the
quality of earthing and how every incoming wire connects to earthing.

Two front page articles discuss this in Electrical Engineering Times
on 1 Oct and 8 Oct 2007 entitled "Protecting Electrical Devices from
Lightning Transients" at:
http://www.planetanalog.com/showArti...leID=201807127
http://www.planetanalog.com/showArti...leID=201807830
Notice everything is about earthing and how that earthing connection
is established. It is routine to have direct lightning strikes
without damage. But when one assumed the protector is some kind of
'magic box' protection, then damage becomes acceptable.

Important to inter-building ethernet (both overhead and underground)
is how each end connects to earth where it enters the building. No
earth ground means no effective protection - which scam protector
promoters forget to mention. Why is damage unacceptable in any telco
CO? It connects to every building in town and suffers no damage.

Proper earthing means no destructive potential difference. As Jeff
notes, ethernet already has (the required) internal protection. All
electronics do. But that internal protection can be compromised IF a
human does not properly earth every incoming wire. Effective
protectors mean a surge (potential difference) is earthed before
entering the building - so that protection inside electronics is not
overwhelmed.

w_tom wrote:
> On Jan 23, 11:07 am, m...@sushi.com wrote:
>> Isn't there an issue with the potential difference between the grounds
>> of the two buildings?
>

Excellent information on surges and surge protection (including
lightning produced) is in an IEEE guide at:
http://omegaps.com/Lightning%20Guide...ion_May051.pdf
And one from the NIST at:
http://www.nist.gov/public_affairs/p.../surgesfnl.pdf

>
> The discussion is about an ethernet cable between two buildings.
> Why is this a problem? Lightning striking one building can find earth
> ground, destructively, via equipment in the other. IOW one building
> becomes a lightning rod connected directly to electronics in the other
> building. Damage is created only when current has both in incoming
> and outgoing path through that electronics.
>
But lightning doesn’t have to strike one of the buildings to be a problem.

>
> If every wire connects directly to earth, then no service. If
> every wire inside that ethernet cable connects directly to earth, then
> no ethernet. So we make that earthing connection via a protector.
> The protector is not protection. Earthing is the protection.
> Protector is simply a connecting device. Better earthing and a
> shorter connection to earth make protection better.

If you have a 1000A surge current to earth and a very good resistance to
earth of 10 Ohms the ground reference system will rise to 10,000V above
absolute earth potential. Within a building the protection is largely by
having the ground reference of all systems rise together. That means
having a short connection from the phone and other entrance protectors
to the earthing electrode conductor at the power service. The author of
NIST guide has written “the impedance of the grounding system to ‘true
earth’ is far less important than the integrity of the bonding of the
various parts of the grounding system.”

I agree with w_ that ethernet between buildings should connect to an
entrance protector at each building with a short ground connection to
the earthing wire at the power service. That may not be possible. An
example of a long connection is in the IEEE guide starting pdf page 40.

As Bill and Jeff wrote, fiber is a safer option. Depends on risk, value
of what you are protecting, cost of outage.

> But when one assumed the protector is some kind of
> 'magic box' protection, then damage becomes acceptable.
>
w_ refers to plug-in surge suppressors as a ‘magic box’ because he can’t
figure out how they work. It is explained in the IEEE guide starting pdf
page 40. Both guides say plug-in suppressors are effective.

When using plug-in suppressors all interconnected equipment needs to be
connected to the same plug-in suppressor, or interconnecting wires need
to go through the suppressor. External connections, like phone, also
need to go through the suppressor. Connecting all wiring through the
suppressor prevents damaging voltages between power and signal wires.
These multiport suppressors are described in both guides.

--
bud--

"Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
news:3fddp3dj87ee797n9dethg08oebbdn1ini@4ax.com...
> On Tue, 22 Jan 2008 22:24:29 -0500, "Bill Kearney"
> <wkearney99@hotmail.com> wrote:
>
> >> The spec actually states 100 meters being the max length which is 328
> >> feet, this includes all patch cables.
> >
> >Indeed. I've had runs slightly longer that worked, and ones shorter that
> >didn't. There are enough variables to make it reasonable to think of it
as
> >a 300' limit.
>
> Nope. One of my fun demos is to take a 1000ft roll of CAT5, crimp
> connectors at both ends, and connect it between my laptop and a Cisco
> 1900 managed switch. It won't do 100mbits/sec (100baseTX) in either
> HDX or FDX, but will certainly do 10mbits/sec (10baseT) in either HDX
> or FDX. The trick is to force the connection to 10mbits/sec and don't
> let NWAY try to set it to 100mbits/sec. SNMP from the switch and
> netstat shows no transmission errors. Thruput is also at wire speed
> with FDX.
>
> >My point wasn't to quibble over the total limit, but to
> >stress that the distance needs to include ALL portions of the connection.
> >To the wall, up and over the ceiling, etc. If the other build is really
> >only 200' away then he's got plenty of distance to play with inside the
> >buildings.
>
> Yep. You're also correct about the extra cable for bends and turns.
> I've gone over 300ft several times by forgetting about such details.
>
> Note that the 100meter limit is between switches.

one of the wiring standards for putting Cat5 into buildings puts this as 90m
for the fixed wiring, and 10m for 2 patch leads (1 each end). AFAIR this was
for that wiring system rather than the 100 Base-Tx standard.

You can add as many
> ethernet switches as needed along the line to deal with regenerating
> the signal. I've done 1500ft that way with 3 switches between
> endpoints. I think that's about the limit as it was a bit flakey when
> the switches got hot. I think (not sure) that the limit is set by the
> end to end latency (delay), which causes ACK timing problems.

not really. dealy thru a modern switch hardware is a few 10s of uSec.

Then you have added a store and forward delay (in each direction)
- but a 1500 byte packet is 12k bits, so even at 10 Mbps that is 1.2 mSec -
say 2 mSec at 10M, and 200 - 300 uSec at 100M

ACK timers at the IP and above layers are Sec or more so are not going to
care, and there arent any L2 ones in Ethernet (unlike wireless).

FWIW Ethernet bridging over SDH is now fairly common in telco networks -
these have a bridge each end and then adapt the bits from the Ethernet
frames to run across 1 or more VC-x "pipes" inside the SDH cloud.

They work fine over 100s of Km, so a few hops over Cat5 or local fibre are
not going to be a problem.

Maybe you need better switches?
>
> >Two reasons I refuse to use ethernet wire buried: lightning and voltage
> >transients. If only because I've had personal experience with both
wrecking
> >equipment.
>
> Sigh. We don't get much lightning in California, but the few
> lightning bolts that hit a local tower managed to blow up most of my
> media converters. Fiber works much better.

Agreed. And the "fault caused by a hit can be spectactular.

We had a wall mounted Cisco router took a hit on an overhead cable carrying
its ISDN line (which was "surge protected).

The smoke marks were 2 or 3 feet long, and most of the innards had very
briefly been molten.....

So - a significant fire risk as well if your area is exposed to this risk -
and as lightning is classed as "act of god" might be a problem with
insurance...

>
> >Not as expensive as the hassle of replacing fried equipment.

Yes - if you have external maintenance, the cost of an engineer visit is
probably more than that of a router or switch.

And - act of god again, so it may all be chargeable......
>
> The equipment is fairly cheap. My time to drive up to some mountain
> top, with the wind blowing, rain falling, and lightning zapping, is
> considerably more expensive. In retrospect, I should charge hazzard
> or combat pay. However, if you wanna do gigabit fiber, the media
> converters are VERY expensive. It's often easier to settle for
> 100mbits/sec and save your dollars until the prices drop.
>
> --
> # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
> # 831-336-2558 jeffl@comix.santa-cruz.ca.us
> # http://802.11junk.com jeffl@cruzio.com
> # http://www.LearnByDestroying.com AE6KS
--
Regards

stephen_hope@xyzworld.com - replace xyz with ntl

Review numeric specs for any protector recommended by Bud (who
forgets to mention who he is promoting for and will not provide those
spec numbers). None claim to provide protection from this type of
surge. Moreso, specs for protectors without that 'less than 10 foot'
earth connection routinely forget to list any type of surge and
numbers for that protection. They hope you believe half truths
promoted by Bud. Myths routinely ignore what is required for surge
protection. Myths hope you never read that Electrical Engineering
Times article on 1 Oct and 8 Oct 2007 entitled "Protecting Electrical
Devices from Lightning Transients". Myths would have us ignore the
1500+ volt protection already in every ethernet interface (see Jeff
Liebermann's post).

Described is a solution standard even 100 years ago and that is
routine where damage is not an option (ie. in virtually every telco
CO). What don't telcos use? Solutions promoted by Bud. Why? Bud
hopes you ignore Page 42 Figure 8. and those Electrical Engineering
Times articles. Lightning seeks earth ground either harmlessly, or
destructively via electronics. Protection from lightning is about
earthing before surges from a first building can enter electronics
inside the second building.

On Page 42 Figure 8, a plug-in protector is too close to a TV and
too far from earth ground. Surge is earthed, 8000 volts destructively,
through an adjacent TV.

Protection is always about earthing before surges can enter a
building. A properly installed ethernet cable between buildings makes
a 'less than 10 foot' earth connection when entering each building. A
protector (that has no earthing) in Bud's Page 42 Figure 8 earths that
surge 8000 volts destructively through electronics.

Why does every telco switching center, with wires connected to all
other buildings, not suffer damage from maybe 100 surges during every
thunderstorm? Telcos don't use what Bud promotes. Every telco
properly earths every incoming wire in every cable either direct to
earth or via a surge protector. Protection is not a surge
protector. Proper earthing means 1500 volts protection inside
ethernet devices is not overwhelmed.

What must Bud forget to mention? A quote from his NIST citation
Page 8 defines an effective protector:
> You cannot really suppress a surge altogether, nor
> "arrest" it. What these protective devices do is
> neither suppress nor arrest a surge, but simply
> divert it to ground, where it can do no harm.

Only one protector, properly earthed at the service entrance,
accomplishes far more than 100 separate plug-in protectors advocated
by Bud. But profits would be at risk. No wonder that solution is
installed routinely in every 911 emergency response center. Superior
protection for so little money and labor. Protection not even claimed
by a plug-in solution.

In a latest post, Stephen notes a damaged ISDN Cisco. He says it
was surge protected. Was it? Did he assume a surge protector means
protection? Or did they learn from that damage by locating a
defective earthing connection? Cisco router damaged because a surge
was permitted inside the building. Protection is not provided by a
protector. A protector is only as effective as its earth ground which
is why effective inter-building protection locates a protector where
that cable enters the building AND connected short to an earthing
eletrode used by AC electric and all other incoming utilities.

On Jan 26, 4:28 am, bud-- <remove.budn...@isp.com> wrote:
> Excellent information on surges and surge protection (including
> lightning produced) is in an IEEE guide at:http://omegaps.com/Lightning%20Guide...ion_May051.pdf
> And one from the NIST at:http://www.nist.gov/public_affairs/p.../surgesfnl.pdf
> ...
>
> If you have a 1000A surge current to earth and a very good resistance to
> earth of 10 Ohms the ground reference system will rise to 10,000V above
> absolute earth potential. Within a building the protection is largely by
> having the ground reference of all systems rise together. That means
> having a short connection from the phone and other entrance protectors
> to the earthing electrode conductor at the power service. The author of
> NIST guide has written "the impedance of the grounding system to 'true
> earth' is far less important than the integrity of the bonding of the
> various parts of the grounding system."
>
> I agree with w_ that ethernet between buildings should connect to an
> entrance protector at each building with a short ground connection to
> the earthing wire at the power service. That may not be possible. An
> example of a long connection is in the IEEE guide starting pdf page 40.
>
> As Bill and Jeff wrote, fiber is a safer option. Depends on risk, value
> of what you are protecting, cost of outage.
>
> > But when one assumed the protector is some kind of
> > 'magic box' protection, then damage becomes acceptable.
>
> w_ refers to plug-in surge suppressors as a 'magic box' because he can't
> figure out how they work. It is explained in the IEEE guide starting pdf
> page 40. Both guides say plug-in suppressors are effective.
>
> When using plug-in suppressors all interconnected equipment needs to be
> connected to the same plug-insuppressor, or interconnecting wires need
> to go through thesuppressor. External connections, like phone, also
> need to go through thesuppressor. Connecting all wiring through thesuppressorprevents damaging voltages between power and signal wires.
> These multiport suppressors are described in both guides.
> bud--

w_tom wrote:
> Review numeric specs for any protector recommended by Bud

I recommended no ‘protector’.

> who
> forgets to mention who he is promoting for

To quote w_ "It is an old political trick. When facts cannot be
challenged technically, then attack the messenger." My only association
with surge protectors is I have some.

>
> On Page 42 Figure 8, a plug-in protector is too close to a TV and
> too far from earth ground. Surge is earthed, 8000 volts destructively,
> through an adjacent TV.

The illustration in the IEEE guide has a surge coming in on a cable
service. There are 2 TVs, one is on a plug-in suppressor. The plug-in
suppressor protects TV1, connected to it.

Without the plug-in suppressor the surge voltage at TV2 is 10,000V. With
the suppressor at TV1 the voltage at TV2 is 8,000V. The plug-in
suppressor at TV1 does not contribute to damage at TV2.

The point of the illustration for the IEEE, and anyone who can think, is
"to protect TV2, a second multiport protector located at TV2 is required."

The problem is the wire connecting the cable entry block to the power
service ‘ground’ is too long allowing a high voltage between power and
cable wires. Ethernet connections between buildings can have the same
problem if they do not enter the building near the power service. The
IEEE guide says in that case "the only effective way of protecting the
equipment is to use a multiport protector." Fortunately ethernet has
higher surge immunity than most equipment.

>
> What must Bud forget to mention? A quote from his NIST citation
> Page 8 defines an effective protector:

What does the NIST guide really say about plug-in suppressors?
They are "the easiest solution".

I made a rather brief comment about plug-in suppressors in response to
w_’s ‘magic box’ nonsense, resulting in a rant from w_.

Contrary to w_’s misrepresentation, both the IEEE and NIST guides say
plug-in suppressors are effective. The IEEE guide has 2 examples of
surge suppression - both use plug-in suppressors. (They may, or may not,
be useful for ethernet between buildings.)

w_ can not find a link agreeing that plug-in suppressors are NOT effective.

–-
bud--

Bud must post anything to avoid what is standard and fundamental to
surge protection. A protector is only as effective as its earth
ground. Earth ground - not a protector - provides protection.
Protection even for an ethernet cable between buildings. Surge energy
must be harmlessly dissipated in earth - not in some 'magic box'.
Bud is promoting 'magic box' protectors that have no dedicated
earthing connection AND do not even claim to provide that protection
in numeric specs.

OP is installing an ethernet cable between two buildings. The
effective solution has been standard for over 100 years. Telcos
connect to every building in town and suffer no damage. Telco earths
every wire before it enters a building. A connection from each wire
to earth provides effective protection. There is no 'magic box'
solution.

No earthing where surge entered a building and no earthing for
Bud's plug-in protector means surge energy was earthed 8000 volts
destructively through adjacent electronics: Page 42 Figure 8. The
solution to an ethernet cable between buildings is earthing where each
cable enters each building. Why does Bud recommend an ineffective
solution that is irrelevant to the OP's question?

.. As predicted, Bud provides no manufacture specifications for
protection. Even the manufacturer will not claim what Bud recommends.
So why is that a solution to the OP's question? Profits are at risk
should everyone learn that earthing - not a protector - provides the
protection. What do two front page articles in Electrical Engineering
Times define for surge protection? Earthing. A protector is only as
effective as its earth ground. A fact that puts profits at risk. The
fact that provides the answer to Idone1's original post: how to
connect communication cables between buildings.

On Jan 27, 2:17 am, bud-- <remove.budn...@isp.com> wrote:
> ...
> I recommended no 'protector'.
> ...
> To quote w_ "It is an old political trick. When facts cannot be
> challenged technically, then attack the messenger." My only association
> with surge protectors is I have some.
> ...
> The illustration in the IEEE guide has a surge coming in on a cable
> service. There are 2 TVs, one is on a plug-in suppressor. The plug-in
> suppressor protects TV1, connected to it.
>
> Without the plug-in suppressor the surge voltage at TV2 is 10,000V. With
> the suppressor at TV1 the voltage at TV2 is 8,000V. The plug-in
> suppressor at TV1 does not contribute to damage at TV2.
>
> The point of the illustration for the IEEE, and anyone who can think, is
> "to protect TV2, a second multiport protector located at TV2 is required."
>
> The problem is the wire connecting the cable entry block to the power
> service 'ground' is too long allowing a high voltage between power and
> cable wires. Ethernet connections between buildings can have the same
> problem if they do not enter the building near the power service. The
> IEEE guide says in that case "the only effective way of protecting the
> equipment is to use a multiport protector." Fortunately ethernet has
> higher surge immunity than most equipment.
> ...
> What does the NIST guide really say about plug-in suppressors?
> They are "the easiest solution".
>
> I made a rather brief comment about plug-in suppressors in response to
> w_'s 'magic box' nonsense, resulting in a rant from w_.
>
> Contrary to w_'s misrepresentation, both the IEEE and NIST guides say
> plug-in suppressors are effective. The IEEE guide has 2 examples of
> surge suppression - both use plug-in suppressors. (They may, or may not,
> be useful for ethernet between buildings.)
>
> w_ can not find a link agreeing that plug-in suppressors are NOT effective.

w_tom wrote:
> Bud must post anything to avoid what is standard and fundamental to
> surge protection. A protector is only as effective as its earth
> ground. Earth ground - not a protector - provides protection.
..
w_ has a religious belief (immune from challenge) that surge protection
must use earthing. Thus in his view plug-in suppressors (which are not
well earthed) can not possibly work. The IEEE guide explains plug-in
suppressors work by CLAMPING the voltage on all wires (signal and power)
to the common ground at the suppressor. Plug-in suppressors do not work
primarily by earthing (or stopping or absorbing). The guide explains
earthing occurs elsewhere. (Read the guide starting pdf page 40).
..
> Why does Bud recommend an ineffective
> solution that is irrelevant to the OP's question?
..
My only recommendation was: “I agree with w_ that ethernet between
buildings should connect to an entrance protector at each building“ and
short connection of that protector to the earthing wire at the power
service. Or fiber.

I made a comment in passing about plug-in surge suppressors in response
to w_’s ‘magic box’ nonsense. But w_ has to defend his religious
belief in earthing.
..
> A protector is only as
> effective as its earth ground.
..
The religious mantra #2.
Everyone is for earthing. The question is whether plug-in suppressors
are effective. Both the IEEE and NIST guides say they are effective.

w_ still has not provided a link to a source that says plug-in
suppressors are NOT effective. There is only w_’s opinion based on his
religious belief in earthing.

Never answered:
- Why do the only 2 examples of protection in the IEEE guide use plug-in
suppressors?
- Why does the NIST guide says plug-in suppressors are "the easiest
solution"?

Bizarre claim - plug-in surge suppressors don't work
Never any sources that say plug-in suppressors are NOT effective.
Twists opposing sources to say the opposite of what they really say.
Attempts to discredit opponents.
w_ is a purveyor of junk science.

--
bud--

I think ya'll aren't on the same page here, compounded by taking
quotes and references out of context.

There are two kinds of protection. The exact description may vary,
but its still a function of clamping the over voltage and shunting
the over voltage to ground, may it be done in a single device or with
two separate devices.

A MOS "surge protector" found in an outlet strip merely clamps
(or blocks) excessive voltage up to the point where the MOS device
fails. It offers virtually no lightning protection, per se.

A gas tube (or old style carbon block) arrestor shunts the over
voltage to ground. Its very robust, but if the voltage is not high
enough to arc over the arrestor (as in the leading edge of the spike),
then the "surge protector" will block it.

Either device if used by itself is not entirely effective.

bud-- wrote:
> w_ refers to plug-in surge suppressors as a ‘magic box’ because he
> can’t figure out how they work.

That was taken completely out of context.

w_tom wrote:
> Bud must post anything to avoid what is standard and fundamental to
> surge protection. A protector is only as effective as its earth
> ground. Earth ground - not a protector - provides protection.

Also taken out of context as Bud did indeed say proper earth grounding
was important.

bud-- wrote:
> w_ has a religious belief (immune from challenge) that surge
> protection must use earthing. Thus in his view plug-in suppressors
> (which are not well earthed) can not possibly work.

LITERALLY taken, an in-line "surge protector" won't need a direct
ground to block a transient spike, so earthing doesn't come into
the picture. Look at a MOS device, there are two wires attached to it,
neither one goes to ground, its KIND OF like the reverse of a Zener
diode that doesn't conduct until a threshold voltage is reached. Look
at a gas tube protector, it has three wires - where the "third" wire
is the grounded shell of the device.

Read both Electrical Engineering Times articles entitled
"Protecting Electrical Devices from Lightning Transients" to
appreciate which type of transient does damage. Destructive surges
seek earth ground. Never forget a damning question: where is surge
energy dissipated? An MOS does not absorb that energy. Review its
spec numbers. It cannot. Where is that energy dissipated? That EE
Times article describes what an effective MOS device does.

MOVs, gas discharge tubes, 3 mm 'carbons', and avalanche diodes (ie
MOS devices) are all shunt mode devices. All protect by doing same
concept. Same concept also makes lightning rods effective. All
connect a typically destructive surge to earth. Again, the damning
question. Where is that surge energy dissipated? No earth ground
means no effective protection. Applies even to MOS devices.

We routinely fixed things by learning how damage happened. For
example, a network of powered off computers were connected to plug-in
protectors. Protectors damaged adjacent computers. A surge entered on
black (hot) wire. Adjacent plug-in protector performed as an MOS
device does. Surge was shunted from black wire to white (neutral) and
green (safety ground) wire - just like an MOS device. Surge
distributed (shunted) to other wires and still seeking earth ground.
We learned by doing and by asking damning questions such as "where is
surge energy dissipated?" An adjacent protector (MOS, MOV, GDT,
etc) simply distributed that surge to more paths; to find earth ground
destructively. Surge also used network cable to find a third
computer and earth ground via that computer's modem (this sentence
specifically relevant to the OP's question). All three 'powered off'
computers were damaged. We replaced every semiconductor to make all
three computers working - by following the surge path. A subtle hint
as to how much knowledge and experience is behind this post. Surge
found earth ground destructively to earth when a plug-in protector was
adjacent to a computer AND too far from earth ground.

Where was surge energy dissipated? Protector (MOS, GDT, MOV, etc)
does not stop, absorb, or "block" the typically destructive surge.
Does not even claim to. Do you really believe anything will stop
what three miles of sky could not? That is what your GDT example
claims; what the MOS device must do according to DTC's post.

Show me those MOS energy numbers if it absorbs a surge. Absorbing or
blocking surges is not what an MOS device does. If MOS protectors
'block' surges, then neither phone nor ethernet communication would be
possible - just another reason why that MOS device does not 'block' as
assumed.

Telco also uses MOS devices. MOS devices are located where?
Adjacent to earth ground and up to 50 meters distant from
electronics. What makes a telco's MOS devices so effective? Superior
earthing AND that 50 meters separation means even better protection.
Telcos have over 100 years experience making surge damage irrelevant.
Same solutions apply to the OP's question.

The OP asked about an ethernet cable between two buildings. OP
needs a solution routinely installed in all telco COs where maybe 100
surges during every thunderstorm create no damage. Their effective
MOS device (and yes, that is what many COs use to eliminate lightning
damage) is located where each wire enters the building, adjacent to
the earthing electrode used by all protectors, and up to 50 meters
distant from electronics.

Surges are not voltage events, as was implied. Destructive surges
are current events. Notice that protectors are rated in current -
amps. Voltage rises as necessary so that same current will flow.
There is no 'stopping' a typically destructive surge. Voltage will
rise as necessary to 'blow through' that protector. Any attempt to
block a surge current means voltage increases. More energy is
dissipated in the wrong place. Same principle even makes Ben
Franklin's lightning rods effective. Effective protector shunts a
surge current to earth meaning less voltage and meaning less energy
dissipates in a building. No effective protector stops or blocks the
typically destructive surge. That Electrical Engineering Times
article describes what is necessary for surge protection. Where is
surge energy dissipated? Bud routinely ignores that question to
promote ineffective and profitable 'magic box' protectors. Where is
that energy dissipated - the damning question? Two front page EE
Times articles define surge protection. The NIST also states bluntly
where surge energy must be dissipated:
> You cannot really suppress a surge altogether, nor
> "arrest" it. What these protective devices do is
> neither suppress nor arrest a surge, but simply
> divert it to ground, where it can do no harm.

"What these protective devices do ..." - and that includes the MOS
device.

How does every ethernet wire make a connection to earth? Some use
MOS devices. But again, why does the MOS device provide protection?
Because massive energy is shunted to and absorbed by earth. MOS
protector to absorb that energy would, instead, just fail. No
protection. A protector that 'protects' by failing means no effective
protection. A protector must earth a surge AND remain functional.
What makes the MOS device effective? A short connection to earth
ground - a solution to the OP's question.

Ethernet cable must be earthed where it enters a building. That
means a low capacitance device. MOVs typically have excessive
capacitance which is why MOS type devices are sometimes used.
Protector (ie MOS device) is only as effective as its earth ground.
Again, the EE Times articles.

Provided are more answers to the OP's original question including
what makes that earthing connection - ie MOS devices. Stated is what
provides the protection and where energy must be dissipated. A long
list of reasons and examples why a single solution means protection
inside electronics (ie 1500 volt ethernet interface) is not
overwhelmed. This solution that has been standard and understood for
over 100 years.

On Jan 28, 12:26 pm, DTC <m...@nothingtoseehere.zzx> wrote:
> I think ya'll aren't on the same page here, compounded by taking
> quotes and references out of context.
>
> There are two kinds of protection. The exact description may vary,
> but its still a function of clamping the over voltage and shunting
> the over voltage to ground, may it be done in a single device or with
> two separate devices.
>
> A MOS "surge protector" found in an outlet strip merely clamps
> (or blocks) excessive voltage up to the point where the MOS device
> fails. It offers virtually no lightning protection, per se.
>
> A gas tube (or old style carbon block) arrestor shunts the over
> voltage to ground. Its very robust, but if the voltage is not high
> enough to arc over the arrestor (as in the leading edge of the spike),
> then the "surge protector" will block it.
> ...

On Jan 28, 12:26*pm, DTC <m...@nothingtoseehere.zzx> wrote:
> A gas tube (or old style carbon block) arrestor shunts the over
> voltage to ground. Its very robust, but if the voltage is not high
> enough to arc over the arrestor (as in the leading edge of the spike),
> then the "surge protector" will block it.

Now put numbers to your assumption. The numbers are commonly
available including TIA, Telcordia, FCC part 68, component application
notes, and basic engineering texts. Get numbers to appreciate why
your assumptions are invalid. To promote those half truths, other
forget to provide numbers. No numbers is how junk science gets so
easily promoted. Get numbers to appreciate the errors in that
paragraph.

w_tom wrote:
> On Jan 28, 12:26 pm, DTC <m...@nothingtoseehere.zzx> wrote:
>> A gas tube (or old style carbon block) arrestor shunts the over
>> voltage to ground. Its very robust, but if the voltage is not high
>> enough to arc over the arrestor (as in the leading edge of the spike),
>> then the "surge protector" will block it.
>
> Now put numbers to your assumption. The numbers are commonly
> available including TIA, Telcordia, FCC part 68, component application
> notes, and basic engineering texts. Get numbers to appreciate why
> your assumptions are invalid. To promote those half truths, other
> forget to provide numbers. No numbers is how junk science gets so
> easily promoted. Get numbers to appreciate the errors in that
> paragraph.

You don't seem to have much real world experience as an everyday
professional.

DTC wrote:
> I think ya'll aren't on the same page here, compounded by taking
> quotes and references out of context.
..
Where have I taken any reference out of context?
..
>
> There are two kinds of protection. The exact description may vary,
> but its still a function of clamping the over voltage and shunting
> the over voltage to