Fiber optic LAN

Does anybody have experience with fibre LAN? I've been fiddling with
networks (not professionally, though I've always worked in IT and had
a network at home) for a decade or so, but never had then need to get
involved with fibre.

I'm looking at 100base-FX as a solution, but while I can understand
single-mode vs multi-mode fibres and the rest of the technical crap I
have no idea what is important in the real world. In essence, I am a
scientist and I need an engineer!

Decent links to suppliers, FAQs or personal experience would be most
welcome. I already know I'll have to by pre-made fibres and run them
through conduit and that it's not cheap, but compared to building and
equipping an observatory linked to the rest of my not-insubstantial
kit an extra £150 isn't the end of the world.

The background as to why I'm looking at fibre:

I'm building an observatory (read: shed for telescope) at the top of
the garden. It'll have power and needs LAN back to the house. The run
will end up being about 80m, including a bit for going round corners
at either end.

I've looked at good ol' CAT-5 (or 5e or 6), but that would involve
either putting it in the same trench as the (armoured) cable using
shielded cable and hoping it'll be OK, or digging another trench. I
figure it might be pushing it having such a long run of even shielded
cable right next to a mains cable. 70m long trenches aren't fun to
dig, and it's far closer to the maximum length spec than I've ever
needed to go. However, I have even greater concerns with worst-case
electrical issues: ground potential differences and lightning-related
induced potentials - both of which could fry the somewhat expensive
kit which will be hanging off either end. The shed will be near the
top of the highest hill for a mile or so and there was a big storm
tonight, which made me think seriously about lightning and its
effects.

I've considered wireless too, but 70m or so is a fair way for Wi-Fi
anyway and there is plenty of foliage in the way, so while it may work
with some decent antennas I doubt I'd get full speed or decent
reliability without similar cost and hassle as fibre. I'd much prefer
at least 100Mbit speeds too and from what I read the fibres I'd need
would work with gigabit if I decide to upgrade.


Tim
--
Copyright, patents and trademarks are government-granted,
time-limited monopolies. Intellectual property does not exist.

Tim Auton <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>. ..
> Does anybody have experience with fibre LAN? I've been fiddling with
> networks (not professionally, though I've always worked in IT and had
> a network at home) for a decade or so, but never had then need to get
> involved with fibre.
>
> I'm looking at 100base-FX as a solution, but while I can understand
> single-mode vs multi-mode fibres and the rest of the technical crap I
> have no idea what is important in the real world. In essence, I am a
> scientist and I need an engineer!
>
> Decent links to suppliers, FAQs or personal experience would be most
> welcome. I already know I'll have to by pre-made fibres and run them
> through conduit and that it's not cheap, but compared to building and
> equipping an observatory linked to the rest of my not-insubstantial
> kit an extra £150 isn't the end of the world.
>
> The background as to why I'm looking at fibre:
>
> I'm building an observatory (read: shed for telescope) at the top of
> the garden. It'll have power and needs LAN back to the house. The run
> will end up being about 80m, including a bit for going round corners
> at either end.
>
> I've looked at good ol' CAT-5 (or 5e or 6), but that would involve
> either putting it in the same trench as the (armoured) cable using
> shielded cable and hoping it'll be OK, or digging another trench. I
> figure it might be pushing it having such a long run of even shielded
> cable right next to a mains cable. 70m long trenches aren't fun to
> dig, and it's far closer to the maximum length spec than I've ever
> needed to go. However, I have even greater concerns with worst-case
> electrical issues: ground potential differences and lightning-related
> induced potentials - both of which could fry the somewhat expensive
> kit which will be hanging off either end. The shed will be near the
> top of the highest hill for a mile or so and there was a big storm
> tonight, which made me think seriously about lightning and its
> effects.
>
> I've considered wireless too, but 70m or so is a fair way for Wi-Fi
> anyway and there is plenty of foliage in the way, so while it may work
> with some decent antennas I doubt I'd get full speed or decent
> reliability without similar cost and hassle as fibre. I'd much prefer
> at least 100Mbit speeds too and from what I read the fibres I'd need
> would work with gigabit if I decide to upgrade.
>
>
> Tim

You could have a look at a pair of fibre converters. We use them
around our site to extend 100Mbps circuits over fairly long distances
and they work very well. We use the Allied Telesyn converters
(http://www.microwarehouse.co.uk/prod...x?SKU=E440806), but there
are lots of alternatives ( for example
http://www.omniotech.co.uk/network-c...ing-fibre.htm).

If you are looking at gigabit speeds, things get a lot more expensive.
Gigabit GBICs are quite pricey in comparison to the fibre converters.

Pete

"Tim Auton" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Does anybody have experience with fibre LAN? I've been fiddling with
> networks (not professionally, though I've always worked in IT and had
> a network at home) for a decade or so, but never had then need to get
> involved with fibre.
>
> I'm looking at 100base-FX as a solution, but while I can understand
> single-mode vs multi-mode fibres and the rest of the technical crap I
> have no idea what is important in the real world. In essence, I am a
> scientist and I need an engineer!
>
> Decent links to suppliers, FAQs or personal experience would be most
> welcome. I already know I'll have to by pre-made fibres and run them
> through conduit and that it's not cheap, but compared to building and
> equipping an observatory linked to the rest of my not-insubstantial
> kit an extra £150 isn't the end of the world.
>
> The background as to why I'm looking at fibre:
>
> I'm building an observatory (read: shed for telescope) at the top of
> the garden. It'll have power and needs LAN back to the house. The run
> will end up being about 80m, including a bit for going round corners
> at either end.
>
> I've looked at good ol' CAT-5 (or 5e or 6), but that would involve
> either putting it in the same trench as the (armoured) cable using
> shielded cable and hoping it'll be OK, or digging another trench. I
> figure it might be pushing it having such a long run of even shielded
> cable right next to a mains cable. 70m long trenches aren't fun to
> dig, and it's far closer to the maximum length spec than I've ever
> needed to go. However, I have even greater concerns with worst-case
> electrical issues: ground potential differences and lightning-related
> induced potentials - both of which could fry the somewhat expensive
> kit which will be hanging off either end. The shed will be near the
> top of the highest hill for a mile or so and there was a big storm
> tonight, which made me think seriously about lightning and its
> effects.
>
> I've considered wireless too, but 70m or so is a fair way for Wi-Fi
> anyway and there is plenty of foliage in the way, so while it may work
> with some decent antennas I doubt I'd get full speed or decent
> reliability without similar cost and hassle as fibre. I'd much prefer
> at least 100Mbit speeds too and from what I read the fibres I'd need
> would work with gigabit if I decide to upgrade.
>
>
> Tim
> --
> Copyright, patents and trademarks are government-granted,
> time-limited monopolies. Intellectual property does not exist.

Not an answer, but I'm looking at a fibre network as part of a new house
that I am building.

Is Fibre more secure than copper? What do the MOD/Security agencies use for
their 'secure' networks.

I once heard a story that a fibre network was 'hacked' using mirrors? Is
this possible?

Clive

"Clive" wrote
> > Not an answer, but I'm looking at a fibre network as part of a new house
> that I am building.
>
> Is Fibre more secure than copper? What do the MOD/Security agencies use
for
> their 'secure' networks.
>
> I once heard a story that a fibre network was 'hacked' using mirrors? Is
> this possible?
>
> Clive
>
>
Hi Clive,
The MOD normally use fibre within sites, as it's a *lot* more secure than
copper - even shielded cat-5 (STP) radiates a signal which can be received
with the right hardware. This generally applies to anything that isn't
Tempest RFI qualified. Outside sites, the military/etc tend to use strong
encryption (essentially stream-cyphers with very long keys generated by
synchronised hardware at both ends of a link) whatever the actual
transmission medium - which could be a dedicated dark fibre, an ATM 155 Mbit
circuit, an E1/E3 or a satellite link, quite often with error-correction
coding applied to the cypherstream.
Fibre *can* be tapped, e.g. by bending and causing light to leave the core
and exit the fibre surface, this results in an additional loss over the
length of the circuit: I dunno about what the MOD uses (been out of all that
for too long now), but the banks, civilian "security" organisations etc
using DWDM (Dense Wavelength Division Multiplex) links (a number of
independent lasers at different wavelengths in the same fibre, each
transmitting a separate data stream) normally have optical link monitoring
to trigger an alarn should the fibre loss suddenly increase (either due to
an attempted security breach or physical damage to the circuit)

Many of the ISP's and carriers use DWDM for their national rings, with
wavelengths carrying (for instance) 10 Gbit SDH (Synchronous Data Heirarchy)
signals between regional offices for telephone traffic etc, others carrying
10Gbit Ethernet, still others with digital video via ATM (Asynchronous
Transfer Mode).
DWDM for medium-haul is getting increasingly popular, e.g. BT's Wavestream
Connect service, as the independent channels are totally isolated from each
other and the management platform, hence pretty secure end-to-end, and allow
existing fibre plant to carry very large amounts of data (the Adva FSP
currently used by BT can at the moment run up to 80 Gigabits over 32 2.5G
channels, and will probably ramp up to 32 10G channels in the mid-term
future, over distances up to around 50Km without intermediate hardware).

For short-haul (within a building, for instance) fibre is a little more
costly that cat-5 and more hassle to install, but does eliminate the
possibility of RFI to the network or other equipment and, the best reason
for it, is electrically isolating so can obviate problems with differences
in ground potentials, electrolytic corrosion etc.. Although the majority of
Ethernet tranceivers connect to the twisted-pair cable via transformers,
these are not to be relied on during a thunderstorm )

Hope that helps,
Dave H.
(The engineer formerly known as Homeless)