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ethernet over long distance

 
 
Graham
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      Apr 1st, 06, 2:38 PM
Has anybody any experience with using cat5 cable over distances greater than
the 100 metres specified for ethernet? For example up to 1 km?

If each end of the cable connects to a switch, the switches should use full
duplex, so the transport delay would not be a problem. (Managed switches
would allow you to fix full duplex and 10Mbits/sec.)

What about loss and crosstalk?

This is for a domestic application where fibre or wireless would be too
expensive - but a km of outdoor grade Cat 5 cable plus some home-made
waterproof junctions would be under 200.

--- Graham



 
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pete devlin
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      Apr 1st, 06, 4:15 PM
In message <e0lvm7$fao$1$>, Graham
<> writes
>Has anybody any experience with using cat5 cable over distances greater
>than the 100 metres specified for ethernet? For example up to 1 km?


You'll get up to 150m in exceptional circumstances but I wouldn't rely
on it. 1km is out of the question for cat5 unless you use repeaters.
--
Pete Devlin
[{//////news03//////at\\\\\secondrow/////co\\\\\uk}]
"And don’t forget my dog, fixed and consequent"
 
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Richard Clayton
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      Apr 1st, 06, 5:09 PM
In article <e0lvm7$fao$1$>, Graham
<> writes

>Has anybody any experience with using cat5 cable over distances greater than
>the 100 metres specified for ethernet? For example up to 1 km?


I used to read a mailing list for the operators of campus networks
(where they regularly ran cables from building to building...)

My main memory was that one used fibre for this, not copper ... because
otherwise electrical storms would take out all of your kit! There were
a number of war stories to emphasise the point

--
richard Richard Clayton

Those who would give up essential Liberty, to purchase a little temporary
Safety, deserve neither Liberty nor Safety. Benjamin Franklin 11 Nov 1755
 
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Robin Faichney
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      Apr 1st, 06, 6:25 PM
On Sat, 1 Apr 2006 14:38:03 +0100, "Graham"
<> wrote:

>Has anybody any experience with using cat5 cable over distances greater than
>the 100 metres specified for ethernet? For example up to 1 km?
>
>If each end of the cable connects to a switch, the switches should use full
>duplex, so the transport delay would not be a problem. (Managed switches
>would allow you to fix full duplex and 10Mbits/sec.)
>
>What about loss and crosstalk?
>
>This is for a domestic application where fibre or wireless would be too
>expensive - but a km of outdoor grade Cat 5 cable plus some home-made
>waterproof junctions would be under 200.


I'd have thought standard wireless gear but with high gain aerials
would do it at a price well below that, at least if you have
line-of-sight. And I have an aerial you might be interested in!
--
mind, matter, meaning and information at http://www.mmmi.org
 
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Graham
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      Apr 1st, 06, 7:52 PM

"Robin Faichney" <> wrote in message
news:...
> On Sat, 1 Apr 2006 14:38:03 +0100, "Graham"
> <> wrote:
>
> >Has anybody any experience with using cat5 cable over distances greater

than
> >the 100 metres specified for ethernet? For example up to 1 km?
> >
> >If each end of the cable connects to a switch, the switches should use

full
> >duplex, so the transport delay would not be a problem. (Managed switches
> >would allow you to fix full duplex and 10Mbits/sec.)
> >
> >What about loss and crosstalk?
> >
> >This is for a domestic application where fibre or wireless would be too
> >expensive - but a km of outdoor grade Cat 5 cable plus some home-made
> >waterproof junctions would be under 200.

>
> I'd have thought standard wireless gear but with high gain aerials
> would do it at a price well below that, at least if you have
> line-of-sight. And I have an aerial you might be interested in!


My sums suggest:

Buffalo-WLA2-G54L54 Mbps* Wireless Bridge Access Point 40.00
Buffalo-WLE-LNC AirStation Pigtail Adapter for Outdoor Antenna 12.00
Lightning arrestor - price guess 5.00
6 metre antenna cable 20.41
Buffalo-WLE-HG-DYG yagi antenna 118.00
Buffalo-LE-KG-VPA small antenna mount kit 30.00
Total 225.41
At each end, so 450.82 in all - then the work of mounting the antennae ...

I can get similar figures using D-Link - although they have a cheaper
antenna which comes complete with the lightning arrester.


-- Graham







 
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Mike Tomlinson
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      Apr 1st, 06, 9:29 PM
In article <e0lvm7$fao$1$>, Graham
<> writes

>Has anybody any experience with using cat5 cable over distances greater than
>the 100 metres specified for ethernet?


Yes, but not to 1km. I've had Ethernet working at 200m with the data
rate fixed to 10Mbps half duplex and using very good quality cable
(Belkin Cat6), but for a point to point link only, and have not analysed
the low-level traffic to see if excessive retransmissions are occurring.

> For example up to 1 km?


No chance, I would have said, but others may differ. Cable is cheap
enough in 300m boxes that you could mock up a test bed and try it.
Connect up two machines using one box of 300m, see if it works, add
another box of 300m into the link, see if it works, etc. If you do
this, please post back with your findings!

>If each end of the cable connects to a switch, the switches should use full
>duplex, so the transport delay would not be a problem.


agreed in principle.

> (Managed switches
>would allow you to fix full duplex and 10Mbits/sec.)


agreed.

>What about loss and crosstalk?


Loss is going to be your main worry. Crosstalk is going to be the least
of your problems (particularly if you force half duplex.)

>This is for a domestic application where fibre or wireless would be too
>expensive


Fibre is nowhere as expensive as it once was.

> - but a km of outdoor grade Cat 5 cable plus some home-made
>waterproof junctions would be under 200.


Your main concerns should be twofold:

i) you should not connect buildings together using copper, ever. Even
though ethernet cards have 2kV isolation built in, this is a Bad Idea,
because: a) different buildings may be on different phases of the mains
supply, b) a copper cable will be at serious risk of surges from
lightning strikes, even those that occur miles away, and c) buildings
1km apart will have non-trivial differences in their earth potential,
and some non-trivial currents may flow (this particularly applies if
you're using STP, but shouldn't be disregarded if using UTP.)

_If_ your test bed works, and you decide to press ahead with a copper
connection regardless, I'd strongly recommend you invest in some serious
surge protection and galvanic isolators. Note though that by the time
you've done this, you've probably exceeded the cost of having a fibre
installed and terminated.

ii) Wireless may be do-able using a couple of high-gain antennas. You
may even get the Pringles can trick to work if you have line-of-sight
between the two buildings.

You should also post to comp.dcom.lans.ethernet for good advice from the
regulars. I've taken the liberty of crossposting there.

--
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(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.

 
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Tony Wright
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      Apr 1st, 06, 9:34 PM
In message <e0lvm7$fao$1$>, Graham
<> writes

[CAT5E to 1Km)

>This is for a domestic application where fibre or wireless would be too
>expensive - but a km of outdoor grade Cat 5 cable plus some home-made
>waterproof junctions would be under 200.


1. Running CAT5e over that kind of distance is dangerous -- particularly
if the two ends are on different mains power/different earths.
2. You won't have a signal without repeaters/signal boosters (which need
power) and you can usually only daisy-chain a max of five repeaters.
3. 100BaseFX (fiber) is the way to go unless you've line-of-sight in
which case you could Wifi via 2 directional antennae.
--
Tony
 
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Jim Crowther
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      Apr 1st, 06, 10:08 PM
On Sat, 1 Apr 2006 14:38:03, Graham wrote:

>Has anybody any experience with using cat5 cable over distances greater than
>the 100 metres specified for ethernet? For example up to 1 km?
>
>If each end of the cable connects to a switch, the switches should use full
>duplex, so the transport delay would not be a problem. (Managed switches
>would allow you to fix full duplex and 10Mbits/sec.)
>
>What about loss and crosstalk?
>
>This is for a domestic application where fibre or wireless would be too
>expensive - but a km of outdoor grade Cat 5 cable plus some home-made
>waterproof junctions would be under 200.


Perhaps if you explained what the domestic application was, there might
be a completely different answer, that did not involve direct
connection.

--
Jim Crowther. "Life is not a journey to the grave with the intention of
arriving safely in a well preserved body, but rather to skid in broadside,
thoroughly used up , totally worn out and loudly proclaiming;
WOW!!! What a ride." "It's MY computer!" (tm SMG)
 
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Graham
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      Apr 1st, 06, 10:42 PM
All your points well taken, but...

> Yes, but not to 1km. I've had Ethernet working at 200m with the data
> rate fixed to 10Mbps half duplex and using very good quality cable
> (Belkin Cat6), but for a point to point link only, and have not analysed
> the low-level traffic to see if excessive retransmissions are occurring.


I think Half Duplex uses the traditional 10Base-2 collision detection
mechanism to manage the traffic on just one pair, and so is sensitive to the
length of the cable, whereas full duplex does not need to worry about
collisions because it uses two separate pairs for send and receive.

> Loss is going to be your main worry. Crosstalk is going to be the least
> of your problems (particularly if you force half duplex.)



As you say, a good reason for half duplex.

-- Graham


 
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Graham
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      Apr 1st, 06, 11:01 PM
> Perhaps if you explained what the domestic application was, there might
> be a completely different answer, that did not involve direct
> connection.


Good idea!

This is for a friend who lives in a *****very****** rural location. His
phone line measures 8km to the local exchange, and Zen and BT between them
were unable to get ADSL to work even at a specially slow 256 kbits/sec rate.

However there is a farm about 1km away and he is on very good terms with
the owner. They are getting ADSL - I think their phone line goes to a
different exchange which is only about 5km distant, so 512Mbit/sec ADSL
should be possible.

So could friend share their ADSL service by extending their network?

I have posted my costings for wireless (at about 450) since he will need
external antennae and some clever mounting to get the signal past the
trees - even though the land is basically flat.

I haven't yet done costings for fibre but two AT-MC101XL copper to fibre
convertors were about 150 the pair last time I bought any. I expect
ready-terminated fibre with proper termination boxes will be few hundred
quid. We then only have to dig a couple of trenches across some farm
tracks - the fibre can then be hidden in the bottom of a hedge.

Alternatively, can BT be persuaded to re-route his phone line to the nearer
exchange? Do you think we should contact the local MP and make a political
issue out of it?

-- Graham








 
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